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<h1 class="top" id="GNU-troff">GNU <code class="code">troff</code></h1>


<p>This manual documents GNU <code class="code">troff</code> version 1.23.0.
</p>
<p>Copyright &copy; 1994&ndash;2023 Free Software Foundation, Inc.
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<blockquote class="quotation">
<p>Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
copy of the license is included in the section entitled &ldquo;GNU Free
Documentation License&rdquo;.
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<div class="element-contents" id="SEC_Contents">
<h2 class="contents-heading">Table of Contents</h2>

<div class="contents">

<ul class="toc-numbered-mark">
  <li><a id="toc-Introduction-1" href="#Introduction">1 Introduction</a>
  <ul class="toc-numbered-mark">
    <li><a id="toc-Background-1" href="#Background">1.1 Background</a></li>
    <li><a id="toc-What-Is-groff_003f-1" href="#What-Is-groff_003f">1.2 What Is <code class="code">groff</code>?</a></li>
    <li><a id="toc-groff-Capabilities-1" href="#groff-Capabilities">1.3 <code class="code">groff</code> Capabilities</a></li>
    <li><a id="toc-Macro-Packages-1" href="#Macro-Package-Intro">1.4 Macro Packages</a></li>
    <li><a id="toc-Preprocessors" href="#Preprocessor-Intro">1.5 Preprocessors</a></li>
    <li><a id="toc-Output-Devices" href="#Output-Device-Intro">1.6 Output Devices</a></li>
    <li><a id="toc-Installation-1" href="#Installation">1.7 Installation</a></li>
    <li><a id="toc-Conventions-Used-in-This-Manual-1" href="#Conventions-Used-in-This-Manual">1.8 Conventions Used in This Manual</a></li>
    <li><a id="toc-Credits-1" href="#Credits">1.9 Credits</a></li>
  </ul></li>
  <li><a id="toc-Invoking-groff-1" href="#Invoking-groff">2 Invoking <code class="code">groff</code></a>
  <ul class="toc-numbered-mark">
    <li><a id="toc-Options" href="#Groff-Options">2.1 Options</a></li>
    <li><a id="toc-Environment-1" href="#Environment">2.2 Environment</a></li>
    <li><a id="toc-Macro-Directories-1" href="#Macro-Directories">2.3 Macro Directories</a></li>
    <li><a id="toc-Font-Directories-1" href="#Font-Directories">2.4 Font Directories</a></li>
    <li><a id="toc-Paper-Format-1" href="#Paper-Format">2.5 Paper Format</a></li>
    <li><a id="toc-Invocation-Examples-1" href="#Invocation-Examples">2.6 Invocation Examples</a></li>
  </ul></li>
  <li><a id="toc-Tutorial-for-Macro-Users-1" href="#Tutorial-for-Macro-Users">3 Tutorial for Macro Users</a>
  <ul class="toc-numbered-mark">
    <li><a id="toc-Basics-1" href="#Basics">3.1 Basics</a></li>
    <li><a id="toc-Common-Features-1" href="#Common-Features">3.2 Common Features</a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-Paragraphs-1" href="#Paragraphs">3.2.1 Paragraphs</a></li>
      <li><a id="toc-Sections-and-Chapters-1" href="#Sections-and-Chapters">3.2.2 Sections and Chapters</a></li>
      <li><a id="toc-Headers-and-Footers-1" href="#Headers-and-Footers">3.2.3 Headers and Footers</a></li>
      <li><a id="toc-Page-Layout-1" href="#Page-Layout-Adjustment">3.2.4 Page Layout</a></li>
      <li><a id="toc-Displays-and-Keeps-1" href="#Displays-and-Keeps">3.2.5 Displays and Keeps</a></li>
      <li><a id="toc-Footnotes-and-Endnotes-1" href="#Footnotes-and-Endnotes">3.2.6 Footnotes and Endnotes</a></li>
      <li><a id="toc-Table-of-Contents-1" href="#Table-of-Contents">3.2.7 Table of Contents</a></li>
      <li><a id="toc-Indexing-1" href="#Indexing">3.2.8 Indexing</a></li>
      <li><a id="toc-Document-Formats-1" href="#Document-Formats">3.2.9 Document Formats</a></li>
      <li><a id="toc-Columnation-1" href="#Columnation">3.2.10 Columnation</a></li>
      <li><a id="toc-Font-and-Size-Changes-1" href="#Font-and-Size-Changes">3.2.11 Font and Size Changes</a></li>
      <li><a id="toc-Predefined-Text-1" href="#Predefined-Text">3.2.12 Predefined Text</a></li>
      <li><a id="toc-Preprocessor-Support-1" href="#Preprocessor-Support">3.2.13 Preprocessor Support</a></li>
      <li><a id="toc-Configuration-and-Customization-1" href="#Configuration-and-Customization">3.2.14 Configuration and Customization</a></li>
    </ul></li>
  </ul></li>
  <li><a id="toc-Macro-Packages-2" href="#Major-Macro-Packages">4 Macro Packages</a>
  <ul class="toc-numbered-mark">
    <li><a id="toc-man-1" href="#man">4.1 <samp class="file">man</samp></a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-Optional-man-extensions-1" href="#Optional-man-extensions">4.1.1 Optional <samp class="file">man</samp> extensions</a>
      <ul class="toc-numbered-mark">
        <li><a id="toc-Custom-headers-and-footers" href="#Custom-headers-and-footers">Custom headers and footers</a></li>
        <li><a id="toc-Ultrix_002dspecific-man-macros" href="#Ultrix_002dspecific-man-macros">Ultrix-specific man macros</a></li>
        <li><a id="toc-Simple-example" href="#Simple-example">Simple example</a></li>
      </ul></li>
    </ul></li>
    <li><a id="toc-mdoc-1" href="#mdoc">4.2 <samp class="file">mdoc</samp></a></li>
    <li><a id="toc-me-1" href="#me">4.3 <samp class="file">me</samp></a></li>
    <li><a id="toc-mm-1" href="#mm">4.4 <samp class="file">mm</samp></a></li>
    <li><a id="toc-mom-1" href="#mom">4.5 <samp class="file">mom</samp></a></li>
    <li><a id="toc-ms-1" href="#ms">4.6 <samp class="file">ms</samp></a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-Introduction-2" href="#ms-Introduction">4.6.1 Introduction</a>
      <ul class="toc-numbered-mark">
        <li><a id="toc-Basic-information" href="#ms-basic-information">4.6.1.1 Basic information</a></li>
      </ul></li>
      <li><a id="toc-Document-Structure" href="#ms-Document-Structure">4.6.2 Document Structure</a></li>
      <li><a id="toc-Document-Control-Settings" href="#ms-Document-Control-Settings">4.6.3 Document Control Settings</a>
      <ul class="toc-numbered-mark">
        <li><a id="toc-Margin-settings" href="#Margin-settings">Margin settings</a></li>
        <li><a id="toc-Titles-_0028headers_002c-footers_0029" href="#Titles-_0028headers_002c-footers_0029">Titles (headers, footers)</a></li>
        <li><a id="toc-Text-settings" href="#Text-settings">Text settings</a></li>
        <li><a id="toc-Paragraph-settings" href="#Paragraph-settings">Paragraph settings</a></li>
        <li><a id="toc-Heading-settings" href="#Heading-settings">Heading settings</a></li>
        <li><a id="toc-Footnote-settings" href="#Footnote-settings">Footnote settings</a></li>
        <li><a id="toc-Display-settings" href="#Display-settings">Display settings</a></li>
        <li><a id="toc-Other-settings" href="#Other-settings">Other settings</a></li>
      </ul></li>
      <li><a id="toc-Document-Description-Macros" href="#ms-Document-Description-Macros">4.6.4 Document Description Macros</a></li>
      <li><a id="toc-Body-Text" href="#ms-Body-Text">4.6.5 Body Text</a>
      <ul class="toc-numbered-mark">
        <li><a id="toc-Text-settings-1" href="#Text-settings-in-ms">4.6.5.1 Text settings</a></li>
        <li><a id="toc-Typographical-symbols" href="#Typographical-symbols-in-ms">4.6.5.2 Typographical symbols</a></li>
        <li><a id="toc-Paragraphs-2" href="#Paragraphs-in-ms">4.6.5.3 Paragraphs</a></li>
        <li><a id="toc-Headings" href="#Headings-in-ms">4.6.5.4 Headings</a></li>
        <li><a id="toc-Typeface-and-decoration-1" href="#Typeface-and-decoration">4.6.5.5 Typeface and decoration</a></li>
        <li><a id="toc-Lists" href="#Lists-in-ms">4.6.5.6 Lists</a></li>
        <li><a id="toc-Indented-regions" href="#Indented-regions-in-ms">4.6.5.7 Indented regions</a></li>
        <li><a id="toc-Keeps_002c-boxed-keeps_002c-and-displays" href="#ms-keeps-and-displays">4.6.5.8 Keeps, boxed keeps, and displays</a></li>
        <li><a id="toc-Tables_002c-figures_002c-equations_002c-and-references" href="#ms-Insertions">4.6.5.9 Tables, figures, equations, and references</a></li>
        <li><a id="toc-Footnotes" href="#ms-Footnotes">4.6.5.10 Footnotes</a></li>
        <li><a id="toc-Language-and-localization" href="#ms-language-and-localization">4.6.5.11 Language and localization</a></li>
      </ul></li>
      <li><a id="toc-Page-layout" href="#ms-Page-Layout">4.6.6 Page layout</a>
      <ul class="toc-numbered-mark">
        <li><a id="toc-Headers-and-footers" href="#ms-Headers-and-Footers">4.6.6.1 Headers and footers</a></li>
        <li><a id="toc-Tab-stops" href="#Tab-Stops-in-ms">4.6.6.2 Tab stops</a></li>
        <li><a id="toc-Margins" href="#ms-Margins">4.6.6.3 Margins</a></li>
        <li><a id="toc-Multiple-columns" href="#ms-Multiple-Columns">4.6.6.4 Multiple columns</a></li>
        <li><a id="toc-Creating-a-table-of-contents" href="#ms-TOC">4.6.6.5 Creating a table of contents</a></li>
      </ul></li>
      <li><a id="toc-Differences-from-AT_0026T-ms-1" href="#Differences-from-AT_0026T-ms">4.6.7 Differences from <abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp></a>
      <ul class="toc-numbered-mark">
        <li><a id="toc-Unix-Version-7-ms-macros-not-implemented-by-groff-ms" href="#Missing-Unix-Version-7-ms-Macros">4.6.7.1 Unix Version 7 <samp class="file">ms</samp> macros not implemented by <code class="code">groff</code> <samp class="file">ms</samp></a></li>
      </ul></li>
      <li><a id="toc-Legacy-Features" href="#ms-Legacy-Features">4.6.8 Legacy Features</a>
      <ul class="toc-numbered-mark">
        <li><a id="toc-AT_0026T-accent-mark-strings" href="#AT_0026T-accent-mark-strings">AT&amp;T accent mark strings</a></li>
        <li><a id="toc-Berkeley-accent-mark-and-glyph-strings" href="#Berkeley-accent-mark-and-glyph-strings">Berkeley accent mark and glyph strings</a></li>
      </ul></li>
      <li><a id="toc-Naming-Conventions" href="#ms-Naming-Conventions">4.6.9 Naming Conventions</a></li>
    </ul></li>
  </ul></li>
  <li><a id="toc-GNU-troff-Reference-1" href="#GNU-troff-Reference">5 GNU <code class="code">troff</code> Reference</a>
  <ul class="toc-numbered-mark">
    <li><a id="toc-Text-1" href="#Text">5.1 Text</a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-Filling-1" href="#Filling">5.1.1 Filling</a></li>
      <li><a id="toc-Sentences-1" href="#Sentences">5.1.2 Sentences</a></li>
      <li><a id="toc-Hyphenation-1" href="#Hyphenation">5.1.3 Hyphenation</a></li>
      <li><a id="toc-Breaking-1" href="#Breaking">5.1.4 Breaking</a></li>
      <li><a id="toc-Adjustment-1" href="#Adjustment">5.1.5 Adjustment</a></li>
      <li><a id="toc-Tabs-and-Leaders-1" href="#Tabs-and-Leaders">5.1.6 Tabs and Leaders</a></li>
      <li><a id="toc-Requests-and-Macros-1" href="#Requests-and-Macros">5.1.7 Requests and Macros</a></li>
      <li><a id="toc-Macro-Packages-3" href="#Macro-Packages">5.1.8 Macro Packages</a></li>
      <li><a id="toc-Input-Encodings-1" href="#Input-Encodings">5.1.9 Input Encodings</a></li>
      <li><a id="toc-Input-Conventions-1" href="#Input-Conventions">5.1.10 Input Conventions</a></li>
    </ul></li>
    <li><a id="toc-Page-Geometry-1" href="#Page-Geometry">5.2 Page Geometry</a></li>
    <li><a id="toc-Measurements-1" href="#Measurements">5.3 Measurements</a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-Motion-Quanta-1" href="#Motion-Quanta">5.3.1 Motion Quanta</a></li>
      <li><a id="toc-Default-Units-1" href="#Default-Units">5.3.2 Default Units</a></li>
    </ul></li>
    <li><a id="toc-Numeric-Expressions-1" href="#Numeric-Expressions">5.4 Numeric Expressions</a></li>
    <li><a id="toc-Identifiers-1" href="#Identifiers">5.5 Identifiers</a></li>
    <li><a id="toc-Formatter-Instructions-1" href="#Formatter-Instructions">5.6 Formatter Instructions</a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-Control-Characters-1" href="#Control-Characters">5.6.1 Control Characters</a></li>
      <li><a id="toc-Invoking-Requests-1" href="#Invoking-Requests">5.6.2 Invoking Requests</a></li>
      <li><a id="toc-Calling-Macros-1" href="#Calling-Macros">5.6.3 Calling Macros</a></li>
      <li><a id="toc-Using-Escape-Sequences-1" href="#Using-Escape-Sequences">5.6.4 Using Escape Sequences</a></li>
      <li><a id="toc-Delimiters-1" href="#Delimiters">5.6.5 Delimiters</a></li>
    </ul></li>
    <li><a id="toc-Comments-1" href="#Comments">5.7 Comments</a></li>
    <li><a id="toc-Registers-1" href="#Registers">5.8 Registers</a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-Setting-Registers-1" href="#Setting-Registers">5.8.1 Setting Registers</a></li>
      <li><a id="toc-Interpolating-Registers-1" href="#Interpolating-Registers">5.8.2 Interpolating Registers</a></li>
      <li><a id="toc-Auto_002dincrement-1" href="#Auto_002dincrement">5.8.3 Auto-increment</a></li>
      <li><a id="toc-Assigning-Register-Formats-1" href="#Assigning-Register-Formats">5.8.4 Assigning Register Formats</a></li>
      <li><a id="toc-Built_002din-Registers-1" href="#Built_002din-Registers">5.8.5 Built-in Registers</a></li>
    </ul></li>
    <li><a id="toc-Manipulating-Filling-and-Adjustment-1" href="#Manipulating-Filling-and-Adjustment">5.9 Manipulating Filling and Adjustment</a></li>
    <li><a id="toc-Manipulating-Hyphenation-1" href="#Manipulating-Hyphenation">5.10 Manipulating Hyphenation</a></li>
    <li><a id="toc-Manipulating-Spacing-1" href="#Manipulating-Spacing">5.11 Manipulating Spacing</a></li>
    <li><a id="toc-Tabs-and-Fields-1" href="#Tabs-and-Fields">5.12 Tabs and Fields</a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-Leaders-1" href="#Leaders">5.12.1 Leaders</a></li>
      <li><a id="toc-Fields-1" href="#Fields">5.12.2 Fields</a></li>
    </ul></li>
    <li><a id="toc-Character-Translations-1" href="#Character-Translations">5.13 Character Translations</a></li>
    <li><a id="toc-troff-and-nroff-Modes-1" href="#troff-and-nroff-Modes">5.14 <code class="code">troff</code> and <code class="code">nroff</code> Modes</a></li>
    <li><a id="toc-Line-Layout-1" href="#Line-Layout">5.15 Line Layout</a></li>
    <li><a id="toc-Line-Continuation-1" href="#Line-Continuation">5.16 Line Continuation</a></li>
    <li><a id="toc-Page-Layout-2" href="#Page-Layout">5.17 Page Layout</a></li>
    <li><a id="toc-Page-Control-1" href="#Page-Control">5.18 Page Control</a></li>
    <li><a id="toc-Using-Fonts-1" href="#Using-Fonts">5.19 Using Fonts</a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-Selecting-Fonts-1" href="#Selecting-Fonts">5.19.1 Selecting Fonts</a></li>
      <li><a id="toc-Font-Families-1" href="#Font-Families">5.19.2 Font Families</a></li>
      <li><a id="toc-Font-Positions-1" href="#Font-Positions">5.19.3 Font Positions</a></li>
      <li><a id="toc-Using-Symbols-1" href="#Using-Symbols">5.19.4 Using Symbols</a></li>
      <li><a id="toc-Character-Classes-1" href="#Character-Classes">5.19.5 Character Classes</a></li>
      <li><a id="toc-Special-Fonts-1" href="#Special-Fonts">5.19.6 Special Fonts</a></li>
      <li><a id="toc-Artificial-Fonts-1" href="#Artificial-Fonts">5.19.7 Artificial Fonts</a></li>
      <li><a id="toc-Ligatures-and-Kerning-1" href="#Ligatures-and-Kerning">5.19.8 Ligatures and Kerning</a></li>
      <li><a id="toc-Italic-Corrections-1" href="#Italic-Corrections">5.19.9 Italic Corrections</a></li>
      <li><a id="toc-Dummy-Characters-1" href="#Dummy-Characters">5.19.10 Dummy Characters</a></li>
    </ul></li>
    <li><a id="toc-Manipulating-Type-Size-and-Vertical-Spacing-1" href="#Manipulating-Type-Size-and-Vertical-Spacing">5.20 Manipulating Type Size and Vertical Spacing</a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-Changing-the-Type-Size-1" href="#Changing-the-Type-Size">5.20.1 Changing the Type Size</a></li>
      <li><a id="toc-Changing-the-Vertical-Spacing-1" href="#Changing-the-Vertical-Spacing">5.20.2 Changing the Vertical Spacing</a></li>
      <li><a id="toc-Using-Fractional-Type-Sizes-1" href="#Using-Fractional-Type-Sizes">5.20.3 Using Fractional Type Sizes</a></li>
    </ul></li>
    <li><a id="toc-Colors-1" href="#Colors">5.21 Colors</a></li>
    <li><a id="toc-Strings-1" href="#Strings">5.22 Strings</a></li>
    <li><a id="toc-Conditionals-and-Loops-1" href="#Conditionals-and-Loops">5.23 Conditionals and Loops</a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-Operators-in-Conditionals-1" href="#Operators-in-Conditionals">5.23.1 Operators in Conditionals</a></li>
      <li><a id="toc-if_002dthen-1" href="#if_002dthen">5.23.2 if-then</a></li>
      <li><a id="toc-if_002delse-1" href="#if_002delse">5.23.3 if-else</a></li>
      <li><a id="toc-Conditional-Blocks-1" href="#Conditional-Blocks">5.23.4 Conditional Blocks</a></li>
      <li><a id="toc-while-1" href="#while">5.23.5 while</a></li>
    </ul></li>
    <li><a id="toc-Writing-Macros-1" href="#Writing-Macros">5.24 Writing Macros</a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-Parameters-1" href="#Parameters">5.24.1 Parameters</a></li>
      <li><a id="toc-Copy-Mode-1" href="#Copy-Mode">5.24.2 Copy Mode</a></li>
    </ul></li>
    <li><a id="toc-Page-Motions-1" href="#Page-Motions">5.25 Page Motions</a></li>
    <li><a id="toc-Drawing-Geometric-Objects-1" href="#Drawing-Geometric-Objects">5.26 Drawing Geometric Objects</a></li>
    <li><a id="toc-Deferring-Output-1" href="#Deferring-Output">5.27 Deferring Output</a></li>
    <li><a id="toc-Traps-1" href="#Traps">5.28 Traps</a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-Vertical-Position-Traps-1" href="#Vertical-Position-Traps">5.28.1 Vertical Position Traps</a>
      <ul class="toc-numbered-mark">
        <li><a id="toc-Page-Location-Traps-1" href="#Page-Location-Traps">5.28.1.1 Page Location Traps</a></li>
        <li><a id="toc-The-Implicit-Page-Trap-1" href="#The-Implicit-Page-Trap">5.28.1.2 The Implicit Page Trap</a></li>
        <li><a id="toc-Diversion-Traps-1" href="#Diversion-Traps">5.28.1.3 Diversion Traps</a></li>
      </ul></li>
      <li><a id="toc-Input-Line-Traps-1" href="#Input-Line-Traps">5.28.2 Input Line Traps</a></li>
      <li><a id="toc-Blank-Line-Traps-1" href="#Blank-Line-Traps">5.28.3 Blank Line Traps</a></li>
      <li><a id="toc-Leading-Space-Traps-1" href="#Leading-Space-Traps">5.28.4 Leading Space Traps</a></li>
      <li><a id="toc-End_002dof_002dinput-Traps-1" href="#End_002dof_002dinput-Traps">5.28.5 End-of-input Traps</a></li>
    </ul></li>
    <li><a id="toc-Diversions-1" href="#Diversions">5.29 Diversions</a></li>
    <li><a id="toc-Punning-Names-1" href="#Punning-Names">5.30 Punning Names</a></li>
    <li><a id="toc-Environments-1" href="#Environments">5.31 Environments</a></li>
    <li><a id="toc-Suppressing-Output-1" href="#Suppressing-Output">5.32 Suppressing Output</a></li>
    <li><a id="toc-I_002fO-1" href="#I_002fO">5.33 I/O</a></li>
    <li><a id="toc-Postprocessor-Access-1" href="#Postprocessor-Access">5.34 Postprocessor Access</a></li>
    <li><a id="toc-Miscellaneous-1" href="#Miscellaneous">5.35 Miscellaneous</a></li>
    <li><a id="toc-gtroff-Internals" href="#Gtroff-Internals">5.36 <code class="code">gtroff</code> Internals</a></li>
    <li><a id="toc-Debugging-1" href="#Debugging">5.37 Debugging</a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-Warnings-1" href="#Warnings">5.37.1 Warnings</a></li>
    </ul></li>
    <li><a id="toc-Implementation-Differences-1" href="#Implementation-Differences">5.38 Implementation Differences</a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-Safer-Mode-1" href="#Safer-Mode">5.38.1 Safer Mode</a></li>
      <li><a id="toc-Compatibility-Mode-1" href="#Compatibility-Mode">5.38.2 Compatibility Mode</a></li>
      <li><a id="toc-Other-Differences-1" href="#Other-Differences">5.38.3 Other Differences</a></li>
    </ul></li>
  </ul></li>
  <li><a id="toc-File-Formats-1" href="#File-Formats">6 File Formats</a>
  <ul class="toc-numbered-mark">
    <li><a id="toc-gtroff-Output-1" href="#gtroff-Output">6.1 <code class="code">gtroff</code> Output</a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-Language-Concepts-1" href="#Language-Concepts">6.1.1 Language Concepts</a>
      <ul class="toc-numbered-mark">
        <li><a id="toc-Separation-1" href="#Separation">6.1.1.1 Separation</a></li>
        <li><a id="toc-Argument-Units-1" href="#Argument-Units">6.1.1.2 Argument Units</a></li>
        <li><a id="toc-Document-Parts-1" href="#Document-Parts">6.1.1.3 Document Parts</a></li>
      </ul></li>
      <li><a id="toc-Command-Reference-1" href="#Command-Reference">6.1.2 Command Reference</a>
      <ul class="toc-numbered-mark">
        <li><a id="toc-Comment-Command-1" href="#Comment-Command">6.1.2.1 Comment Command</a></li>
        <li><a id="toc-Simple-Commands-1" href="#Simple-Commands">6.1.2.2 Simple Commands</a></li>
        <li><a id="toc-Graphics-Commands-1" href="#Graphics-Commands">6.1.2.3 Graphics Commands</a></li>
        <li><a id="toc-Device-Control-Commands-1" href="#Device-Control-Commands">6.1.2.4 Device Control Commands</a></li>
        <li><a id="toc-Obsolete-Command-1" href="#Obsolete-Command">6.1.2.5 Obsolete Command</a></li>
      </ul></li>
      <li><a id="toc-Intermediate-Output-Examples-1" href="#Intermediate-Output-Examples">6.1.3 Intermediate Output Examples</a></li>
      <li><a id="toc-Output-Language-Compatibility-1" href="#Output-Language-Compatibility">6.1.4 Output Language Compatibility</a></li>
    </ul></li>
    <li><a id="toc-Device-and-Font-Description-Files-1" href="#Device-and-Font-Description-Files">6.2 Device and Font Description Files</a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-DESC-File-Format-1" href="#DESC-File-Format">6.2.1 <samp class="file">DESC</samp> File Format</a></li>
      <li><a id="toc-Font-Description-File-Format-1" href="#Font-Description-File-Format">6.2.2 Font Description File Format</a></li>
    </ul></li>
  </ul></li>
  <li><a id="toc-Copying-This-Manual-1" href="#Copying-This-Manual">Appendix A Copying This Manual</a></li>
  <li><a id="toc-Request-Index-1" href="#Request-Index" rel="index">Appendix B Request Index</a></li>
  <li><a id="toc-Escape-Sequence-Index-1" href="#Escape-Sequence-Index" rel="index">Appendix C Escape Sequence Index</a></li>
  <li><a id="toc-Operator-Index-1" href="#Operator-Index" rel="index">Appendix D Operator Index</a></li>
  <li><a id="toc-Register-Index-1" href="#Register-Index" rel="index">Appendix E Register Index</a></li>
  <li><a id="toc-Macro-Index-1" href="#Macro-Index" rel="index">Appendix F Macro Index</a></li>
  <li><a id="toc-String-Index-1" href="#String-Index" rel="index">Appendix G String Index</a></li>
  <li><a id="toc-File-Keyword-Index-1" href="#File-Keyword-Index" rel="index">Appendix H File Keyword Index</a></li>
  <li><a id="toc-Program-and-File-Index-1" href="#Program-and-File-Index" rel="index">Appendix I Program and File Index</a></li>
  <li><a id="toc-Concept-Index-1" href="#Concept-Index" rel="index">Appendix J Concept Index</a></li>
</ul>
</div>
</div>
<hr>
<div class="chapter-level-extent" id="Introduction">
<div class="nav-panel">
<p>
Next: <a href="#Invoking-groff" accesskey="n" rel="next">Invoking <code class="code">groff</code></a>, Previous: <a href="#Top" accesskey="p" rel="prev">GNU <code class="code">troff</code></a>, Up: <a href="#Top" accesskey="u" rel="up">GNU <code class="code">troff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="chapter" id="Introduction-1">1 Introduction</h2>
<a class="index-entry-id" id="index-introduction"></a>

<p>GNU <code class="code">roff</code> (or <code class="code">groff</code>) is a programming system for
typesetting documents.  It is highly flexible and has been used
extensively for over thirty years.
</p>



<ul class="mini-toc">
<li><a href="#Background" accesskey="1">Background</a></li>
<li><a href="#What-Is-groff_003f" accesskey="2">What Is <code class="code">groff</code>?</a></li>
<li><a href="#groff-Capabilities" accesskey="3"><code class="code">groff</code> Capabilities</a></li>
<li><a href="#Macro-Package-Intro" accesskey="4">Macro Packages</a></li>
<li><a href="#Preprocessor-Intro" accesskey="5">Preprocessors</a></li>
<li><a href="#Output-Device-Intro" accesskey="6">Output Devices</a></li>
<li><a href="#Installation" accesskey="7">Installation</a></li>
<li><a href="#Conventions-Used-in-This-Manual" accesskey="8">Conventions Used in This Manual</a></li>
<li><a href="#Credits" accesskey="9">Credits</a></li>
</ul>
<hr>
<div class="section-level-extent" id="Background">
<div class="nav-panel">
<p>
Next: <a href="#What-Is-groff_003f" accesskey="n" rel="next">What Is <code class="code">groff</code>?</a>, Previous: <a href="#Introduction" accesskey="p" rel="prev">Introduction</a>, Up: <a href="#Introduction" accesskey="u" rel="up">Introduction</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Background-1">1.1 Background</h3>
<a class="index-entry-id" id="index-background"></a>

<p>M. Douglas McIlroy, formerly of AT&amp;T Bell Laboratories and present at
the creation of the Unix operating system, offers an authoritative
historical summary.
</p>
<blockquote class="quotation">
<p>The prime reason for Unix was the desire of Ken [Thompson], Dennis
[Ritchie], and Joe Ossanna to have a pleasant environment for software
development.  The fig leaf that got the nod from &hellip;
management was that an early use would be to develop a &ldquo;stand-alone&rdquo;
word-processing system for use in typing pools and secretarial offices.
Perhaps they had in mind &ldquo;dedicated&rdquo;, as distinct from
&ldquo;stand-alone&rdquo;; that&rsquo;s what eventuated in various cases, most notably
in the legal/patent department and in the AT&amp;T CEO&rsquo;s office.
</p>
<p>Both those systems were targets of opportunity, not foreseen from the
start.  When Unix was up and running on the PDP-11, Joe got wind of
the legal department having installed a commercial word processor.
He went to pitch Unix as an alternative and clinched a trial by
promising to make <code class="code">roff</code> able to number lines by tomorrow in order
to fulfill a patent-office requirement that the commercial system did
not support.
</p>
<p>Modems were installed so legal-department secretaries could try the
Research machine.  They liked it and Joe&rsquo;s superb customer service.
Soon the legal department got a system of their own.  Joe went on to
create <code class="code">nroff</code> and <code class="code">troff</code>.  Document preparation became a
widespread use of Unix, but no stand-alone word-processing system was
ever undertaken.
</p></blockquote>

<p>A history relating <code class="code">groff</code> to its predecessors <code class="code">roff</code>,
<code class="code">nroff</code>, and <code class="code">troff</code> is available in the <cite class="cite">roff<span class="r">(7)</span></cite>
man page.
</p>


<hr>
</div>
<div class="section-level-extent" id="What-Is-groff_003f">
<div class="nav-panel">
<p>
Next: <a href="#groff-Capabilities" accesskey="n" rel="next"><code class="code">groff</code> Capabilities</a>, Previous: <a href="#Introduction" accesskey="p" rel="prev">Introduction</a>, Up: <a href="#Introduction" accesskey="u" rel="up">Introduction</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="What-Is-groff_003f-1">1.2 What Is <code class="code">groff</code>?</h3>
<a class="index-entry-id" id="index-what-is-groff_003f"></a>
<a class="index-entry-id" id="index-groff_002d_002d_002dwhat-is-it_003f"></a>

<p><code class="code">groff</code> (GNU <code class="code">roff</code>) is a typesetting system that reads plain
text input files that include formatting commands to produce output in
PostScript, PDF, HTML, DVI, or other formats, or for display to a
terminal.  Formatting commands can be low-level typesetting primitives,
macros from a supplied package, or user-defined macros.  All three
approaches can be combined.
</p>
<p>A reimplementation and extension of the typesetter from <abbr class="acronym">AT&amp;T</abbr>
Unix, <code class="code">groff</code> is present on most <abbr class="acronym">POSIX</abbr> systems owing to
its long association with Unix manuals (including man pages).  It and
its predecessor are notable for their production of several best-selling
software engineering texts.  <code class="code">groff</code> is capable of producing
typographically sophisticated documents while consuming minimal system
resources.
</p>


<hr>
</div>
<div class="section-level-extent" id="groff-Capabilities">
<div class="nav-panel">
<p>
Next: <a href="#Macro-Package-Intro" accesskey="n" rel="next">Macro Packages</a>, Previous: <a href="#What-Is-groff_003f" accesskey="p" rel="prev">What Is <code class="code">groff</code>?</a>, Up: <a href="#Introduction" accesskey="u" rel="up">Introduction</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="groff-Capabilities-1">1.3 <code class="code">groff</code> Capabilities</h3>
<a class="index-entry-id" id="index-groff-capabilities"></a>
<a class="index-entry-id" id="index-capabilities-of-groff"></a>

<p>GNU <code class="code">troff</code> is a typesetting document formatter; it provides a wide
range of low-level text and page operations within the framework of a
programming language.  These operations compose to generate footnotes,
tables of contents, mathematical equations, diagrams, multi-column text,
and other elements of typeset works.  Here is a survey of formatter
features; all are under precise user control.
</p>
<ul class="itemize mark-bullet">
<li>text filling, breaking, alignment to the left or right margin; centering

</li><li>adjustment of inter-word space size to justify text, and of
inter-sentence space size to suit local style conventions

</li><li>automatic and manual determination of hyphenation break points

</li><li>pagination

</li><li>selection of any font available to the output device

</li><li>adjustment of type size and vertical spacing (or &ldquo;leading&rdquo;)

</li><li>configuration of line length and indentation amounts; columnation

</li><li>drawing of geometric primitives (lines, arcs, polygons, circles,
&hellip;)

</li><li>setup of stroke and fill colors (where supported by the output
device)

</li><li>embedding of hyperlinks, images, document metadata, and other inclusions
(where supported by the output device)
</li></ul>



<hr>
</div>
<div class="section-level-extent" id="Macro-Package-Intro">
<div class="nav-panel">
<p>
Next: <a href="#Preprocessor-Intro" accesskey="n" rel="next">Preprocessors</a>, Previous: <a href="#groff-Capabilities" accesskey="p" rel="prev"><code class="code">groff</code> Capabilities</a>, Up: <a href="#Introduction" accesskey="u" rel="up">Introduction</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Macro-Packages-1">1.4 Macro Packages</h3>
<a class="index-entry-id" id="index-macro-package_002c-introduction"></a>
<a class="index-entry-id" id="index-package_002c-macro_002c-introduction"></a>

<p>Elemental typesetting functions can be be challenging to use directly
with complex documents.  A <em class="dfn">macro</em> facility specifies how certain
routine operations, such as starting paragraphs, or printing headers and
footers, should be performed in terms of those low-level instructions.
Macros can be specific to one document or collected together into a
<em class="dfn">macro package</em> for use by many.  Several macro packages available;
the most widely used are provided with <code class="code">groff</code>.  They are
<samp class="file">man</samp>, <samp class="file">mdoc</samp>, <samp class="file">me</samp>, <samp class="file">mm</samp>, <samp class="file">mom</samp>, and
<samp class="file">ms</samp>.
</p>


<hr>
</div>
<div class="section-level-extent" id="Preprocessor-Intro">
<div class="nav-panel">
<p>
Next: <a href="#Output-Device-Intro" accesskey="n" rel="next">Output Devices</a>, Previous: <a href="#Macro-Package-Intro" accesskey="p" rel="prev">Macro Packages</a>, Up: <a href="#Introduction" accesskey="u" rel="up">Introduction</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Preprocessors">1.5 Preprocessors</h3>
<a class="index-entry-id" id="index-preprocessors"></a>

<p>An alternative approach to complexity management, particularly when
constructing tables, setting mathematics, or drawing diagrams, lies in
preprocessing.  A <em class="dfn">preprocessor</em> employs a domian-specific language
to ease the generation of tables, equations, and so forth in terms that
are convenient for human entry.  Each preprocessor reads a document and
translates the parts of it that apply to it into GNU <code class="code">troff</code> input.
Command-line options to <code class="command">groff</code> tell it which preprocessors to
use.
</p>
<p><code class="code">groff</code> provides preprocessors for laying out tables
(<code class="command">gtbl</code>), typesetting equations (<code class="command">geqn</code>), drawing
diagrams (<code class="command">gpic</code> and <code class="command">ggrn</code>), inserting bibliographic
references (<code class="command">grefer</code>), and drawing chemical structures
(<code class="command">gchem</code>).  An associated program that is useful when dealing
with preprocessors is <code class="command">gsoelim</code>.<a class="footnote" id="DOCF1" href="#FOOT1"><sup>1</sup></a>
</p>
<p><code class="code">groff</code> also supports <code class="code">grap</code>, a preprocessor for drawing
graphs.  A free implementation of it can be obtained separately.
</p>
<p>Unique to <code class="code">groff</code> is the <code class="code">preconv</code> preprocessor that enables
<code class="code">groff</code> to handle documents in a variety of input encodings.
</p>
<p>Other preprocessors exist, but no free implementations
are known.  An example is <code class="command">ideal</code>, which draws diagrams using a
mathematical constraint language.
</p>


<hr>
</div>
<div class="section-level-extent" id="Output-Device-Intro">
<div class="nav-panel">
<p>
Next: <a href="#Installation" accesskey="n" rel="next">Installation</a>, Previous: <a href="#Preprocessor-Intro" accesskey="p" rel="prev">Preprocessors</a>, Up: <a href="#Introduction" accesskey="u" rel="up">Introduction</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Output-Devices">1.6 Output Devices</h3>
<a class="index-entry-id" id="index-postprocessors"></a>
<a class="index-entry-id" id="index-output-devices"></a>
<a class="index-entry-id" id="index-devices-for-output"></a>

<p>GNU <code class="code">troff</code>&rsquo;s output is in a device-independent page description
language, which is then read by an <em class="dfn">output driver</em> that translates
this language into a file format or byte stream that a piece of
(possibly emulated) hardware understands.  <code class="code">groff</code> features output
drivers for PostScript devices, terminal emulators (and other simple
typewriter-like machines), X11 (for previewing), TeX DVI, HP
LaserJet&nbsp;4/PCL5 and Canon LBP printers (which use <abbr class="acronym">CaPSL</abbr>),
<abbr class="acronym">HTML</abbr>, <abbr class="acronym">XHTML</abbr>, and <abbr class="acronym">PDF</abbr>.
</p>


<hr>
</div>
<div class="section-level-extent" id="Installation">
<div class="nav-panel">
<p>
Next: <a href="#Conventions-Used-in-This-Manual" accesskey="n" rel="next">Conventions Used in This Manual</a>, Previous: <a href="#Output-Device-Intro" accesskey="p" rel="prev">Output Devices</a>, Up: <a href="#Introduction" accesskey="u" rel="up">Introduction</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Installation-1">1.7 Installation</h3>
<a class="index-entry-id" id="index-installation"></a>

<p>Locate installation instructions in the files <samp class="file">INSTALL</samp>,
<samp class="file">INSTALL.extra</samp>, and <samp class="file">INSTALL.REPO</samp> in the <code class="code">groff</code> source
distribution.  Being a GNU project, <code class="code">groff</code> supports the familiar
&lsquo;<samp class="samp">./configure &amp;&amp; make</samp>&rsquo; command sequence.
</p>


<hr>
</div>
<div class="section-level-extent" id="Conventions-Used-in-This-Manual">
<div class="nav-panel">
<p>
Next: <a href="#Credits" accesskey="n" rel="next">Credits</a>, Previous: <a href="#Installation" accesskey="p" rel="prev">Installation</a>, Up: <a href="#Introduction" accesskey="u" rel="up">Introduction</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Conventions-Used-in-This-Manual-1">1.8 Conventions Used in This Manual</h3>

<p>We apply the term &ldquo;groff&rdquo; to the language documented here, the GNU
implementation of the overall system, the project that develops that
system, and the command of that name.  In the first sense, <code class="code">groff</code>
is an extended dialect of the <code class="code">roff</code> language, for which many
similar implementations exist.
</p>
<p>The <code class="code">roff</code> language features several major categories for which
many items are predefined.  Presentations of these items feature the
form in which the item is most commonly used on the left, and, aligned
to the right margin, the name of the category in brackets.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bexample_005d"><span class="category-def">Register: </span><span><strong class="def-name">\n[example]</strong><a class="copiable-link" href='#index-_005cn_005bexample_005d'> &para;</a></span></dt>
<dd><p>The register &lsquo;<samp class="samp">example</samp>&rsquo; is one that that <code class="code">groff</code> <em class="emph">doesn&rsquo;t</em>
predefine.  You can create it yourself, though; see <a class="ref" href="#Setting-Registers">Setting Registers</a>.
</p></dd></dl>

<p>To make this document useful as a reference and not merely amiable
bedtime reading, we tend to present these syntax items in exhaustive
detail when they arise.  References to topics discussed later in the
text are frequent; skip material you don&rsquo;t understand yet.
</p>
<p>We use Texinfo&rsquo;s &ldquo;result&rdquo; (&rArr;) and error&rarr; notations to
present output written to the standard output and standard error
streams, respectively.  Diagnostic messages from the GNU <code class="code">troff</code>
formatter and other programs are examples of the latter, but the
formatter can also be directed to write user-specified messages to the
standard error stream.  The notation then serves to identify the
output stream and does not necessarily mean that an error has
occurred.<a class="footnote" id="DOCF2" href="#FOOT2"><sup>2</sup></a>
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">$ echo &quot;Twelve o'clock and&quot; | groff -Tascii | sed '/^$/d'
    &rArr; Twelve o'clock and
$ echo '.tm all is well.' | groff &gt; /dev/null
    error&rarr; all is well.
</pre></div></div>

<p>Sometimes we use &rArr; somewhat abstractly to represent formatted
text that you will need to use a PostScript or PDF viewer program (or a
printer) to observe.  While arguably an abuse of notation, we think this
preferable to requiring the reader to understand the syntax of these
page description languages.
</p>
<p>We also present diagnostic messages in an abbreviated form, often
omitting the name of the program issuing them, the input file name, and
line number or other positional information when such data do not serve
to illuminate the topic under discussion.
</p>
<p>Most examples are of <code class="code">roff</code> language input that would be placed in
a text file.  Occasionally, we start an example with a &lsquo;<samp class="samp">$</samp>&rsquo;
character to indicate a shell prompt, as seen above.
</p>
<p>You are encouraged to try the examples yourself, and to alter them to
better learn <code class="code">groff</code>&rsquo;s behavior.  Our examples frequently need to
direct the formatter to set a line length (with &lsquo;<samp class="samp">.ll</samp>&rsquo;) that will
fit within the page margins of this manual.  We mention this so that you
know why it is there before we discuss the <code class="code">ll</code> request
formally.<a class="footnote" id="DOCF3" href="#FOOT3"><sup>3</sup></a>
</p>


<hr>
</div>
<div class="section-level-extent" id="Credits">
<div class="nav-panel">
<p>
Previous: <a href="#Conventions-Used-in-This-Manual" accesskey="p" rel="prev">Conventions Used in This Manual</a>, Up: <a href="#Introduction" accesskey="u" rel="up">Introduction</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Credits-1">1.9 Credits</h3>
<a class="index-entry-id" id="index-credits"></a>

<p>We adapted portions of this manual from existing documents.  James
Clark&rsquo;s man pages were an essential resource; we have updated them in
parallel with the development of this manual.  We based the tutorial for
macro users on Eric Allman&rsquo;s introduction to his <samp class="file">me</samp> macro package
(which we also provide, little altered from 4.4BSD).  Larry Kollar
contributed much of the material on the <samp class="file">ms</samp> macro package.
</p>


<hr>
</div>
</div>
<div class="chapter-level-extent" id="Invoking-groff">
<div class="nav-panel">
<p>
Next: <a href="#Tutorial-for-Macro-Users" accesskey="n" rel="next">Tutorial for Macro Users</a>, Previous: <a href="#Introduction" accesskey="p" rel="prev">Introduction</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU <code class="code">troff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="chapter" id="Invoking-groff-1">2 Invoking <code class="code">groff</code></h2>
<a class="index-entry-id" id="index-invoking-groff"></a>
<a class="index-entry-id" id="index-groff-invocation"></a>

<p>This chapter focuses on how to invoke the <code class="code">groff</code> front end.  This
front end takes care of the details of constructing the pipeline among
the preprocessors, <code class="code">gtroff</code> and the postprocessor.
</p>
<p>It has become a tradition that GNU programs get the prefix &lsquo;<samp class="samp">g</samp>&rsquo; to
distinguish them from their original counterparts provided by the host
(see <a class="pxref" href="#Environment">Environment</a>).  Thus, for example, <code class="code">geqn</code> is GNU
<code class="code">eqn</code>.  On operating systems like GNU/Linux or the Hurd, which
don&rsquo;t contain proprietary versions of <code class="code">troff</code>, and on
MS-DOS/MS-Windows, where <code class="code">troff</code> and associated programs are not
available at all, this prefix is omitted since GNU <code class="code">troff</code> is the
only incarnation of <code class="code">troff</code> used.  Exception: &lsquo;<samp class="samp">groff</samp>&rsquo; is never
replaced by &lsquo;<samp class="samp">roff</samp>&rsquo;.
</p>
<p>In this document, we consequently say &lsquo;<samp class="samp">gtroff</samp>&rsquo; when talking about
the GNU <code class="code">troff</code> program.  All other implementations of <code class="code">troff</code> are called <abbr class="acronym">AT&amp;T</abbr>
<code class="code">troff</code>, which is the common origin of almost all <code class="code">troff</code>
implementations<a class="footnote" id="DOCF4" href="#FOOT4"><sup>4</sup></a> (with more or less compatible changes).  Similarly, we say
&lsquo;<samp class="samp">gpic</samp>&rsquo;, &lsquo;<samp class="samp">geqn</samp>&rsquo;, and so on.
</p>



<ul class="mini-toc">
<li><a href="#Groff-Options" accesskey="1">Options</a></li>
<li><a href="#Environment" accesskey="2">Environment</a></li>
<li><a href="#Macro-Directories" accesskey="3">Macro Directories</a></li>
<li><a href="#Font-Directories" accesskey="4">Font Directories</a></li>
<li><a href="#Paper-Format" accesskey="5">Paper Format</a></li>
<li><a href="#Invocation-Examples" accesskey="6">Invocation Examples</a></li>
</ul>
<hr>
<div class="section-level-extent" id="Groff-Options">
<div class="nav-panel">
<p>
Next: <a href="#Environment" accesskey="n" rel="next">Environment</a>, Previous: <a href="#Invoking-groff" accesskey="p" rel="prev">Invoking <code class="code">groff</code></a>, Up: <a href="#Invoking-groff" accesskey="u" rel="up">Invoking <code class="code">groff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Options">2.1 Options</h3>
<a class="index-entry-id" id="index-options"></a>

<a class="index-entry-id" id="index-groff"></a>
<a class="index-entry-id" id="index-gtroff"></a>
<a class="index-entry-id" id="index-gpic"></a>
<a class="index-entry-id" id="index-geqn"></a>
<a class="index-entry-id" id="index-ggrn"></a>
<a class="index-entry-id" id="index-grap"></a>
<a class="index-entry-id" id="index-gtbl"></a>
<a class="index-entry-id" id="index-gchem"></a>
<a class="index-entry-id" id="index-grefer"></a>
<a class="index-entry-id" id="index-gsoelim"></a>
<a class="index-entry-id" id="index-preconv"></a>
<p><code class="code">groff</code> normally runs the <code class="code">gtroff</code> program and a
postprocessor appropriate for the selected device.  The default device
is &lsquo;<samp class="samp">ps</samp>&rsquo; (but it can be changed when <code class="code">groff</code> is configured and
built).  It can optionally preprocess with any of <code class="code">gpic</code>,
<code class="code">geqn</code>, <code class="code">gtbl</code>, <code class="code">ggrn</code>, <code class="code">grap</code>, <code class="code">gchem</code>,
<code class="code">grefer</code>, <code class="code">gsoelim</code>, or <code class="code">preconv</code>.
</p>
<p>This section documents only options to the <code class="code">groff</code> front end.  Many
of the arguments to <code class="code">groff</code> are passed on to <code class="code">gtroff</code>;
therefore, those are also included.  Arguments to preprocessors and
output drivers can be found in the man pages <cite class="cite">gpic<span class="r">(1)</span></cite>,
<cite class="cite">geqn<span class="r">(1)</span></cite>, <cite class="cite">gtbl<span class="r">(1)</span></cite>, <cite class="cite">ggrn<span class="r">(1)</span></cite>,
<cite class="cite">grefer<span class="r">(1)</span></cite>, <cite class="cite">gchem<span class="r">(1)</span></cite>, <cite class="cite">gsoelim<span class="r">(1)</span></cite>,
<cite class="cite">preconv<span class="r">(1)</span></cite>, <cite class="cite">grotty<span class="r">(1)</span></cite>, <cite class="cite">grops<span class="r">(1)</span></cite>,
<cite class="cite">gropdf<span class="r">(1)</span></cite>, <cite class="cite">grohtml<span class="r">(1)</span></cite>, <cite class="cite">grodvi<span class="r">(1)</span></cite>,
<cite class="cite">grolj4<span class="r">(1)</span></cite>, <cite class="cite">grolbp<span class="r">(1)</span></cite>, and <cite class="cite">gxditview<span class="r">(1)</span></cite>.
</p>
<p>The command-line format for <code class="code">groff</code> is:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">groff [ -abceghijklpstvzCEGNRSUVXZ ] [ -d<var class="var">cs</var> ] [ -D<var class="var">arg</var> ]
      [ -f<var class="var">fam</var> ] [ -F<var class="var">dir</var> ] [ -I<var class="var">dir</var> ] [ -K<var class="var">arg</var> ]
      [ -L<var class="var">arg</var> ] [ -m<var class="var">name</var> ] [ -M<var class="var">dir</var> ] [ -n<var class="var">num</var> ]
      [ -o<var class="var">list</var> ] [ -P<var class="var">arg</var> ] [ -r<var class="var">cn</var> ] [ -T<var class="var">dev</var> ]
      [ -w<var class="var">name</var> ] [ -W<var class="var">name</var> ] [ <var class="var">files</var>&hellip; ]
</pre></div></div>

<p>The command-line format for <code class="code">gtroff</code> is as follows.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">gtroff [ -abcivzCERU ] [ -d<var class="var">cs</var> ] [ -f<var class="var">fam</var> ] [ -F<var class="var">dir</var> ]
       [ -m<var class="var">name</var> ] [ -M<var class="var">dir</var> ] [ -n<var class="var">num</var> ] [ -o<var class="var">list</var> ]
       [ -r<var class="var">cn</var> ] [ -T<var class="var">name</var> ] [ -w<var class="var">name</var> ] [ -W<var class="var">name</var> ]
       [ <var class="var">files</var>&hellip; ]
</pre></div></div>

<p>Obviously, many of the options to <code class="code">groff</code> are actually passed on to
<code class="code">gtroff</code>.
</p>
<p>Options without an argument can be grouped behind a
single&nbsp;<samp class="option">-</samp>.  A filename of&nbsp;<samp class="file">-</samp> denotes the
standard input.  Whitespace is permitted between an option and its
argument.
</p>
<p>The <code class="code">grog</code> command can be used to guess the correct <code class="code">groff</code>
command to format a file.  See its man page <cite class="cite">grog<span class="r">(1)</span></cite>; type
&lsquo;<samp class="samp">man grog</samp>&rsquo; at the command line to view it.
</p>
<p><code class="command">groff</code>&rsquo;s command-line options are as follows.
</p>
<a class="index-entry-id" id="index-command_002dline-options"></a>
<dl class="table">
<dt id='index-plain-text-approximation-output-register-_0028_002eA_0029'><span>&lsquo;<samp class="samp">-a</samp>&rsquo;<a class="copiable-link" href='#index-plain-text-approximation-output-register-_0028_002eA_0029'> &para;</a></span></dt>
<dd><p>Generate a plain text approximation of the typeset output.  The
read-only register <code class="code">.A</code> is set to&nbsp;1.  See <a class="xref" href="#Built_002din-Registers">Built-in Registers</a>.  This option produces a sort of abstract preview of the
formatted output.
</p>
<ul class="itemize mark-bullet">
<li>Page breaks are marked by a phrase in angle brackets; for example,
&lsquo;<samp class="samp">&lt;beginning of page&gt;</samp>&rsquo;.

</li><li>Lines are broken where they would be in the formatted output.

</li><li>A horizontal motion of any size is represented as one space.  Adjacent
horizontal motions are not combined.  Inter-sentence space nodes (those
arising from the second argument to the <code class="code">ss</code> request) are not
represented.

</li><li>Vertical motions are not represented.

</li><li>Special characters are rendered in angle brackets; for example, the
default soft hyphen character appears as &lsquo;<samp class="samp">&lt;hy&gt;</samp>&rsquo;.
</li></ul>

<p>The above description should not be considered a specification; the
details of <samp class="option">-a</samp> output are subject to change.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-b</samp>&rsquo;</dt>
<dd><p>Write a backtrace reporting the state of <code class="command">gtroff</code>&rsquo;s input parser
to the standard error stream with each diagnostic message.  The line
numbers given in the backtrace might not always be correct, because
<code class="command">gtroff</code>&rsquo;s idea of line numbers can be confused by requests that
append to
macros.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-c</samp>&rsquo;</dt>
<dd><p>Start with color output disabled.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-C</samp>&rsquo;</dt>
<dd><p>Enable AT&amp;T <code class="command">troff</code> compatibility mode; implies <samp class="option">-c</samp>.
See <a class="xref" href="#Implementation-Differences">Implementation Differences</a>, for the list of incompatibilities
between <code class="command">groff</code> and <abbr class="acronym">AT&amp;T</abbr> <code class="command">troff</code>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-d<var class="var">c</var><var class="var">text</var></samp>&rsquo;</dt>
<dt>&lsquo;<samp class="samp">-d<var class="var">string</var>=<var class="var">text</var></samp>&rsquo;</dt>
<dd><p>Define <code class="code">roff</code> string <var class="var">c</var> or <var class="var">string</var> as&nbsp;<var class="var">t</var> or
<var class="var">text</var>.  <var class="var">c</var>&nbsp;must be one character; <var class="var">string</var> can be
of arbitrary length.  Such string assignments happen before any macro
file is loaded, including the startup file.  Due to <code class="code">getopt_long</code>
limitations, <var class="var">c</var>&nbsp;cannot be, and <var class="var">string</var> cannot contain, an
equals sign, even though that is a valid character in a <code class="code">roff</code>
identifier.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-D<var class="var">enc</var></samp>&rsquo;</dt>
<dd><p>Set fallback input encoding used by <code class="command">preconv</code> to <var class="var">enc</var>;
implies <samp class="option">-k</samp>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-e</samp>&rsquo;</dt>
<dd><p>Run <code class="command">geqn</code> preprocessor.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-E</samp>&rsquo;</dt>
<dd><p>Inhibit <code class="command">gtroff</code> error messages.  This option does <em class="emph">not</em>
suppress messages sent to the standard error stream by documents or
macro packages using <code class="code">tm</code> or related requests.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-f<var class="var">fam</var></samp>&rsquo;</dt>
<dd><p>Use <var class="var">fam</var> as the default font family.  See <a class="xref" href="#Font-Families">Font Families</a>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-F<var class="var">dir</var></samp>&rsquo;</dt>
<dd><p>Search in directory <samp class="file"><var class="var">dir</var></samp> for the selected output device&rsquo;s
directory of device and font description files.  See the description of
<code class="env">GROFF_FONT_PATH</code> in <a class="ref" href="#Environment">Environment</a> below for the default search
locations and ordering.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-g</samp>&rsquo;</dt>
<dd><p>Run <code class="command">ggrn</code> preprocessor.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-G</samp>&rsquo;</dt>
<dd><p>Run <code class="command">grap</code> preprocessor; implies <samp class="option">-p</samp>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-h</samp>&rsquo;</dt>
<dd><p>Display a usage message and exit.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-i</samp>&rsquo;</dt>
<dd><p>Read the standard input after all the named input files have been
processed.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-I<var class="var">dir</var></samp>&rsquo;</dt>
<dd><p>Search the directory <var class="var">dir</var> for files named in several contexts;
implies <samp class="option">-g</samp> and <samp class="option">-s</samp>.
</p>
<ul class="itemize mark-bullet">
<li><code class="command">gsoelim</code> replaces <code class="code">so</code> requests with the contents of their
file name arguments.

</li><li><code class="command">gtroff</code> searches for files named as operands in its command
line and as arguments to <code class="code">psbb</code>, <code class="code">so</code>, and <code class="code">soquiet</code>
requests.

</li><li>Output drivers may search for files; for instance, <code class="command">grops</code> looks
for files named in &lsquo;<samp class="samp">\X'ps: import <span class="r">&hellip;</span>'</samp>&rsquo;, &lsquo;<samp class="samp">\X'ps: file
<span class="r">&hellip;</span>'</samp>&rsquo;, and &lsquo;<samp class="samp">\X'pdf: pdfpic <span class="r">&hellip;</span>'</samp>&rsquo; device control
escape sequences.
</li></ul>

<p>This option may be specified more than once; the directories are
searched in the order specified.  If you want to search the current
directory before others, add &lsquo;<samp class="samp">-I .</samp>&rsquo; at the desired place.  The
current working directory is otherwise searched last.  <samp class="option">-I</samp> works
similarly to, and is named for, the &ldquo;include&rdquo; option of Unix C
compilers.
</p>
<p><samp class="option">-I</samp> options are passed to <code class="command">gsoelim</code>, <code class="command">gtroff</code>,
and output drivers; with the flag letter changed to <samp class="option">-M</samp>, they
are also passed to <code class="command">ggrn</code>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-j</samp>&rsquo;</dt>
<dd><p>Run <code class="command">gchem</code> preprocessor.  Implies <samp class="option">-p</samp>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-k</samp>&rsquo;</dt>
<dd><p>Run <code class="command">preconv</code> preprocessor.  Refer to its man page for its
behavior if neither of <code class="command">groff</code>&rsquo;s <samp class="option">-K</samp> or <samp class="option">-D</samp>
options is also specified.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-K<var class="var">enc</var></samp>&rsquo;</dt>
<dd><p>Set input encoding used by <code class="command">preconv</code> to <var class="var">enc</var>; implies
<samp class="option">-k</samp>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-l</samp>&rsquo;</dt>
<dd><p>Send the output to a spooler for printing.  The <code class="code">print</code> directive
in the device description file specifies the default command to be used;
see <a class="ref" href="#Device-and-Font-Description-Files">Device and Font Description Files</a>.
See options <samp class="option">-L</samp> and <samp class="option">-X</samp>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-L<var class="var">arg</var></samp>&rsquo;</dt>
<dd><p>Pass <var class="var">arg</var> to the print spooler program.  If multiple <var class="var">arg</var>s are
required, pass each with a separate <samp class="option">-L</samp> option.  <code class="command">groff</code>
does not prefix an option dash to <var class="var">arg</var> before passing it to the
spooler program.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-m<var class="var">name</var></samp>&rsquo;</dt>
<dd><p>Process the file <samp class="file"><var class="var">name</var>.tmac</samp> prior to any input files.
If not found, <samp class="file">tmac.<var class="var">name</var></samp> is attempted.  <var class="var">name</var>
(in both arrangements) is presumed to be a macro file; see the
description of <code class="env">GROFF_TMAC_PATH</code> in <a class="ref" href="#Environment">Environment</a> below for the
default search locations and ordering.  This option and its argument are
also passed to <code class="command">geqn</code>, <code class="command">grap</code>, and <code class="command">ggrn</code>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-M<var class="var">dir</var></samp>&rsquo;</dt>
<dd><p>Search directory <samp class="file"><var class="var">dir</var></samp> for macro files;  see the description
of <code class="env">GROFF_TMAC_PATH</code> in <a class="ref" href="#Environment">Environment</a> below for the default
search locations and ordering.  This option and its argument are also
passed to <code class="command">geqn</code>, <code class="command">grap</code>, and <code class="command">ggrn</code>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-n<var class="var">num</var></samp>&rsquo;</dt>
<dd><p>Number the first page <var class="var">num</var>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-N</samp>&rsquo;</dt>
<dd><p>Prohibit newlines between <code class="code">eqn</code> delimiters: pass <samp class="option">-N</samp> to
<code class="command">geqn</code>.
</p>
</dd>
<dt id='index-print-current-page-register-_0028_002eP_0029'><span>&lsquo;<samp class="samp">-o<var class="var">list</var></samp>&rsquo;<a class="copiable-link" href='#index-print-current-page-register-_0028_002eP_0029'> &para;</a></span></dt>
<dd><p>Output only pages in <var class="var">list</var>, which is a comma-separated list of page
ranges; &lsquo;<samp class="samp"><var class="var">n</var></samp>&rsquo; means page&nbsp;<var class="var">n</var>, &lsquo;<samp class="samp"><var class="var">m</var>-<var class="var">n</var></samp>&rsquo;
means every page between <var class="var">m</var> and&nbsp;<var class="var">n</var>, &lsquo;<samp class="samp">-<var class="var">n</var></samp>&rsquo; means
every page up to&nbsp;<var class="var">n</var>, &lsquo;<samp class="samp"><var class="var">n</var>-</samp>&rsquo; means every page from
<var class="var">n</var>&nbsp;on.  <code class="command">gtroff</code> stops processing and exits after
formatting the last page enumerated in <var class="var">list</var>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-p</samp>&rsquo;</dt>
<dd><p>Run <code class="command">gpic</code> preprocessor.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-P<var class="var">arg</var></samp>&rsquo;</dt>
<dd><p>Pass <var class="var">arg</var> to the postprocessor.  If multiple <var class="var">arg</var>s are
required, pass each with a separate <samp class="option">-P</samp> option.  <code class="command">groff</code>
does not prefix an option dash to <var class="var">arg</var> before passing it to the
postprocessor.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-r<var class="var">c</var><var class="var">numeric-expression</var></samp>&rsquo;</dt>
<dt>&lsquo;<samp class="samp">-r<var class="var">register</var>=<var class="var">expr</var></samp>&rsquo;</dt>
<dd><p>Set <code class="code">roff</code> register&nbsp;<var class="var">c</var> or <var class="var">register</var> to the value
<var class="var">numeric-expression</var> (see <a class="pxref" href="#Numeric-Expressions">Numeric Expressions</a>).
<var class="var">c</var>&nbsp;must be one character; <var class="var">register</var> can be of arbitrary
length.  Such register assignments happen before any macro file is
loaded, including the startup file.  Due to <code class="code">getopt_long</code>
limitations, <var class="var">c</var>&nbsp;cannot be, and <var class="var">register</var> cannot contain,
an equals sign, even though that is a valid character in a <code class="code">roff</code>
identifier.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-R</samp>&rsquo;</dt>
<dd><p>Run <code class="command">grefer</code> preprocessor.  No mechanism is provided for passing
arguments to <code class="command">grefer</code> because most <code class="command">grefer</code> options have
equivalent language elements that can be specified within the document.
</p>
<a class="index-entry-id" id="index-troffrc"></a>
<a class="index-entry-id" id="index-troffrc_002dend"></a>
<p><code class="command">gtroff</code> also accepts a <samp class="option">-R</samp> option, which is not
accessible via <code class="command">groff</code>.  This option prevents the loading of the
<samp class="file">troffrc</samp> and <samp class="file">troffrc-end</samp> files.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-s</samp>&rsquo;</dt>
<dd><p>Run <code class="command">gsoelim</code> preprocessor.
</p>
</dd>
<dt id='index-open-request_002c-and-safer-mode'><span>&lsquo;<samp class="samp">-S</samp>&rsquo;<a class="copiable-link" href='#index-open-request_002c-and-safer-mode'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-opena-request_002c-and-safer-mode"></a>
<a class="index-entry-id" id="index-pso-request_002c-and-safer-mode"></a>
<a class="index-entry-id" id="index-sy-request_002c-and-safer-mode"></a>
<a class="index-entry-id" id="index-pi-request_002c-and-safer-mode"></a>
<a class="index-entry-id" id="index-safer-mode"></a>
<a class="index-entry-id" id="index-mode_002c-safer"></a>
<p>Operate in &ldquo;safer&rdquo; mode; see <samp class="option">-U</samp> below for its opposite.  For
security reasons, safer mode is enabled by default.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-t</samp>&rsquo;</dt>
<dd><p>Run <code class="command">gtbl</code> preprocessor.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-T<var class="var">dev</var></samp>&rsquo;</dt>
<dd><p>Direct <code class="command">gtroff</code> to format the input for the output device
<var class="var">dev</var>.  <code class="command">groff</code> then calls an output driver to convert
<code class="command">gtroff</code>&rsquo;s output to a form appropriate for <var class="var">dev</var>.  The
following output devices are available.
</p>
<dl class="table">
<dt><code class="code">ps</code></dt>
<dd><p>For PostScript printers and previewers.
</p>
</dd>
<dt><code class="code">pdf</code></dt>
<dd><p>For <abbr class="acronym">PDF</abbr> viewers or printers.
</p>
</dd>
<dt><code class="code">dvi</code></dt>
<dd><p>For TeX DVI format.
</p>
</dd>
<dt><code class="code">X75</code></dt>
<dd><p>For a 75<span class="dmn">dpi</span> X11 previewer.
</p>
</dd>
<dt><code class="code">X75-12</code></dt>
<dd><p>For a 75<span class="dmn">dpi</span> X11 previewer with a 12-point base font in the
document.
</p>
</dd>
<dt><code class="code">X100</code></dt>
<dd><p>For a 100<span class="dmn">dpi</span> X11 previewer.
</p>
</dd>
<dt><code class="code">X100-12</code></dt>
<dd><p>For a 100<span class="dmn">dpi</span> X11 previewer with a 12-point base font in the
document.
</p>
</dd>
<dt id='index-encoding_002c-output_002c-ASCII'><span><code class="code">ascii</code><a class="copiable-link" href='#index-encoding_002c-output_002c-ASCII'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-encoding_002c-output_002c-ISO-646"></a>
<a class="index-entry-id" id="index-ASCII-output-encoding"></a>
<a class="index-entry-id" id="index-ISO-646-output-encoding"></a>
<a class="index-entry-id" id="index-output-encoding_002c-ASCII"></a>
<a class="index-entry-id" id="index-output-encoding_002c-ISO-646"></a>
<p>For typewriter-like devices using the (7-bit) <abbr class="acronym">ASCII</abbr>
(ISO&nbsp;646) character set.
</p>
</dd>
<dt id='index-encoding_002c-output_002c-Latin_002d1-_0028ISO-8859_002d1_0029'><span><code class="code">latin1</code><a class="copiable-link" href='#index-encoding_002c-output_002c-Latin_002d1-_0028ISO-8859_002d1_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-Latin_002d1-_0028ISO-8859_002d1_0029-output-encoding"></a>
<a class="index-entry-id" id="index-ISO-8859_002d1-_0028Latin_002d1_0029-output-encoding"></a>
<a class="index-entry-id" id="index-output-encoding_002c-Latin_002d1-_0028ISO-8859_002d1_0029"></a>
<p>For typewriter-like devices that support the <span class="w-nolinebreak-text">Latin-1</span><!-- /@w -->
(ISO&nbsp;<span class="w-nolinebreak-text">8859-1</span><!-- /@w -->) character set.
</p>
</dd>
<dt id='index-encoding_002c-output_002c-UTF_002d8'><span><code class="code">utf8</code><a class="copiable-link" href='#index-encoding_002c-output_002c-UTF_002d8'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-UTF_002d8-output-encoding"></a>
<a class="index-entry-id" id="index-output-encoding_002c-UTF_002d8"></a>
<p>For typewriter-like devices that use the Unicode (ISO&nbsp;10646)
character set with <span class="w-nolinebreak-text">UTF-8</span><!-- /@w --> encoding.
</p>
</dd>
<dt id='index-encoding_002c-output_002c-EBCDIC'><span><code class="code">cp1047</code><a class="copiable-link" href='#index-encoding_002c-output_002c-EBCDIC'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-EBCDIC-output-encoding"></a>
<a class="index-entry-id" id="index-output-encoding_002c-EBCDIC"></a>
<a class="index-entry-id" id="index-encoding_002c-output_002c-code-page-1047"></a>
<a class="index-entry-id" id="index-code-page-1047-output-encoding"></a>
<a class="index-entry-id" id="index-output-encoding_002c-code-page-1047"></a>
<a class="index-entry-id" id="index-IBM-code-page-1047-output-encoding"></a>
<a class="index-entry-id" id="index-CCSID-1047-output-encoding-_0028EBCDIC_0029"></a>
<p>For typewriter-like devices that use the <abbr class="acronym">EBCDIC</abbr> encoding IBM
code page 1047.
</p>
</dd>
<dt><code class="code">lj4</code></dt>
<dd><p>For HP LaserJet4-compatible (or other PCL5-compatible) printers.
</p>
</dd>
<dt><code class="code">lbp</code></dt>
<dd><p>For Canon <abbr class="acronym">CaPSL</abbr> printers (<span class="w-nolinebreak-text">LBP-4</span><!-- /@w --> and <span class="w-nolinebreak-text">LBP-8</span><!-- /@w --> series laser
printers).
</p>
<a class="index-entry-id" id="index-pre_002dgrohtml"></a>
<a class="index-entry-id" id="index-post_002dgrohtml"></a>
<a class="index-entry-id" id="index-grohtml_002c-the-program"></a>
</dd>
<dt><code class="code">html</code></dt>
<dt><code class="code">xhtml</code></dt>
<dd><p>To produce <abbr class="acronym">HTML</abbr> and <abbr class="acronym">XHTML</abbr> output, respectively.
This driver consists of two parts, a preprocessor
(<code class="command">pre-grohtml</code>) and a postprocessor (<code class="command">post-grohtml</code>).
</p></dd>
</dl>

<a class="index-entry-id" id="index-output-device-name-string-_0028_002eT_0029"></a>
<a class="index-entry-id" id="index-output-device-usage-register-_0028_002eT_0029"></a>
<p>The predefined GNU <code class="code">troff</code> string <code class="code">.T</code> contains the name of
the output device; the read-only register <code class="code">.T</code> is set to&nbsp;1 if
this option is used (which is always true if <code class="command">groff</code> is used to
call GNU <code class="command">troff</code>).  See <a class="xref" href="#Built_002din-Registers">Built-in Registers</a>.
</p>
<p>The postprocessor to be used for a device is specified by the
<code class="code">postpro</code> command in the device description file.  (See <a class="xref" href="#Device-and-Font-Description-Files">Device and Font Description Files</a>.)  This can be overridden with the
<samp class="option">-X</samp> option.
</p>
</dd>
<dt id='index-mode_002c-unsafe'><span>&lsquo;<samp class="samp">-U</samp>&rsquo;<a class="copiable-link" href='#index-mode_002c-unsafe'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-unsafe-mode"></a>
<p>Operate in <em class="dfn">unsafe mode</em>, which enables the <code class="code">open</code>,
<code class="code">opena</code>, <code class="code">pi</code>, <code class="code">pso</code>, and <code class="code">sy</code> requests.  These
requests are disabled by default because they allow an untrusted input
document to write to arbitrary file names and run arbitrary commands.
This option also adds the current directory to the macro package search
path; see the <samp class="option">-m</samp> option above.  <samp class="option">-U</samp> is passed to
<code class="command">gpic</code> and <code class="command">gtroff</code>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-v</samp>&rsquo;</dt>
<dd><p>Write version information for <code class="command">groff</code> and all programs run by it
to the standard output stream; that is, the given command line is
processed in the usual way, passing <samp class="option">-v</samp> to the formatter and any
pre- or postprocessors invoked.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-V</samp>&rsquo;</dt>
<dd><p>Output the pipeline that would be run by <code class="command">groff</code>
(as a wrapper program) to the standard output stream, but do not execute
it.  If given more than once, the pipeline is both written to the
standard error stream and run.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-w<var class="var">category</var></samp>&rsquo;</dt>
<dd><p>Enable warnings in <var class="var">category</var>.  Categories are listed in
<a class="ref" href="#Warnings">Warnings</a>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-W<var class="var">category</var></samp>&rsquo;</dt>
<dd><p>Inhibit warnings in <var class="var">category</var>.  Categories are listed in
<a class="ref" href="#Warnings">Warnings</a>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-X</samp>&rsquo;</dt>
<dd><p>Use <code class="command">gxditview</code> instead of the usual postprocessor to (pre)view
a document on an X11 display.  Combining this option with
<samp class="option">-Tps</samp> uses the font metrics of the PostScript device, whereas
the <samp class="option">-TX75</samp> and <samp class="option">-TX100</samp> options use the metrics of X11
fonts.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-z</samp>&rsquo;</dt>
<dd><p>Suppress formatted output from <code class="command">gtroff</code>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">-Z</samp>&rsquo;</dt>
<dd><p>Disable postprocessing.  <code class="command">gtroff</code> output will appear on the
standard output stream (unless suppressed with <samp class="option">-z</samp>; see
<a class="ref" href="#gtroff-Output"><code class="code">gtroff</code> Output</a> for a description of this format.
</p></dd>
</dl>



<hr>
</div>
<div class="section-level-extent" id="Environment">
<div class="nav-panel">
<p>
Next: <a href="#Macro-Directories" accesskey="n" rel="next">Macro Directories</a>, Previous: <a href="#Groff-Options" accesskey="p" rel="prev">Options</a>, Up: <a href="#Invoking-groff" accesskey="u" rel="up">Invoking <code class="code">groff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Environment-1">2.2 Environment</h3>
<a class="index-entry-id" id="index-environment-variables"></a>
<a class="index-entry-id" id="index-variables-in-environment"></a>

<p>There are also several environment variables (of the operating system,
not within <code class="code">gtroff</code>) that can modify the behavior of <code class="code">groff</code>.
</p>
<dl class="table">
<dt id='index-GROFF_005fBIN_005fPATH_002c-environment-variable'><span><code class="code">GROFF_BIN_PATH</code><a class="copiable-link" href='#index-GROFF_005fBIN_005fPATH_002c-environment-variable'> &para;</a></span></dt>
<dd><p>This search path, followed by <code class="code">PATH</code>, is used for commands executed
by <code class="code">groff</code>.
</p>
</dd>
<dt id='index-GROFF_005fCOMMAND_005fPREFIX_002c-environment-variable'><span><code class="code">GROFF_COMMAND_PREFIX</code><a class="copiable-link" href='#index-GROFF_005fCOMMAND_005fPREFIX_002c-environment-variable'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-command-prefix"></a>
<a class="index-entry-id" id="index-prefix_002c-for-commands"></a>
<p>If this is set to&nbsp;<var class="var">X</var>, then <code class="command">groff</code> runs
<code class="command"><var class="var">X</var>troff</code> instead of <code class="command">gtroff</code>.  This also applies
to <code class="command">tbl</code>, <code class="command">pic</code>, <code class="command">eqn</code>, <code class="command">grn</code>,
<code class="command">chem</code>, <code class="command">refer</code>, and <code class="command">soelim</code>.  It does not
apply to <code class="command">grops</code>, <code class="command">grodvi</code>, <code class="command">grotty</code>,
<code class="command">pre-grohtml</code>, <code class="command">post-grohtml</code>, <code class="command">preconv</code>,
<code class="command">grolj4</code>, <code class="command">gropdf</code>, and <code class="command">gxditview</code>.
</p>
<p>The default command prefix is determined during the installation
process.  If a non-GNU <code class="code">troff</code> system is found, prefix &lsquo;<samp class="samp">g</samp>&rsquo; is
used, none otherwise.
</p>
</dd>
<dt id='index-GROFF_005fENCODING_002c-environment-variable'><span><code class="code">GROFF_ENCODING</code><a class="copiable-link" href='#index-GROFF_005fENCODING_002c-environment-variable'> &para;</a></span></dt>
<dd><p>The value of this variable is passed to the <code class="code">preconv</code>
preprocessor&rsquo;s <samp class="option">-e</samp> option to select the character encoding of
input files.  This variable&rsquo;s existence implies the <code class="code">groff</code> option
<samp class="option">-k</samp>.  If set but empty, <code class="code">groff</code> calls <code class="code">preconv</code>
without an <samp class="option">-e</samp> option.  <code class="code">groff</code>&rsquo;s <samp class="option">-K</samp> option
overrides <code class="env">GROFF_ENCODING</code>.  See the <cite class="cite">preconv<span class="r">(7)</span></cite> man page;
type &lsquo;<samp class="samp">man preconv</samp>&rsquo; at the command line to view it.
</p>
</dd>
<dt id='index-GROFF_005fFONT_005fPATH_002c-environment-variable'><span><code class="code">GROFF_FONT_PATH</code><a class="copiable-link" href='#index-GROFF_005fFONT_005fPATH_002c-environment-variable'> &para;</a></span></dt>
<dd><p>A list of directories in which to seek the selected output device&rsquo;s
directory of device and font description files.  GNU <code class="code">troff</code>
will search directories given as arguments to any specified <samp class="option">-F</samp>
options before these, and a built-in list of directories after them.
See <a class="xref" href="#Font-Directories">Font Directories</a> and the <cite class="cite">troff<span class="r">(1)</span></cite> or
<cite class="cite">gtroff<span class="r">(1)</span></cite> man pages.
</p>
</dd>
<dt id='index-GROFF_005fTMAC_005fPATH_002c-environment-variable'><span><code class="code">GROFF_TMAC_PATH</code><a class="copiable-link" href='#index-GROFF_005fTMAC_005fPATH_002c-environment-variable'> &para;</a></span></dt>
<dd><p>A list of directories in which to seek macro files.  GNU <code class="code">troff</code>
will search directories given as arguments to any specified <samp class="option">-M</samp>
options before these, and a built-in list of directories after them.
See <a class="xref" href="#Macro-Directories">Macro Directories</a> and the <cite class="cite">troff<span class="r">(1)</span></cite> or
<cite class="cite">gtroff<span class="r">(1)</span></cite> man pages.
</p>
</dd>
<dt id='index-GROFF_005fTMPDIR_002c-environment-variable'><span><code class="code">GROFF_TMPDIR</code><a class="copiable-link" href='#index-GROFF_005fTMPDIR_002c-environment-variable'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-TMPDIR_002c-environment-variable"></a>
<p>The directory in which <code class="code">groff</code> creates temporary files.  If this is
not set and <code class="env">TMPDIR</code> is set, temporary files are created in that
directory.  Otherwise temporary files are created in a system-dependent
default directory (on Unix and GNU/Linux systems, this is usually
<samp class="file">/tmp</samp>).  <code class="code">grops</code>, <code class="code">grefer</code>, <code class="code">pre-grohtml</code>, and
<code class="code">post-grohtml</code> can create temporary files in this directory.
</p>
</dd>
<dt id='index-GROFF_005fTYPESETTER_002c-environment-variable'><span><code class="code">GROFF_TYPESETTER</code><a class="copiable-link" href='#index-GROFF_005fTYPESETTER_002c-environment-variable'> &para;</a></span></dt>
<dd><p>Sets the default output device.  If empty or not set, a build-time
default (often <code class="code">ps</code>) is used.  The <samp class="option">-T<var class="var">dev</var></samp> option
overrides <code class="env">GROFF_TYPESETTER</code>.
</p>
</dd>
<dt id='index-SOURCE_005fDATE_005fEPOCH_002c-environment-variable'><span><code class="code">SOURCE_DATE_EPOCH</code><a class="copiable-link" href='#index-SOURCE_005fDATE_005fEPOCH_002c-environment-variable'> &para;</a></span></dt>
<dd><p>A timestamp (expressed as seconds since the Unix epoch) to use as the
output creation timestamp in place of the current time.  The time is
converted to human-readable form using <cite class="cite">localtime<span class="r">(3)</span></cite> when the
formatter starts up and stored in registers usable by documents and
macro packages (see <a class="pxref" href="#Built_002din-Registers">Built-in Registers</a>).
</p>
</dd>
<dt id='index-TZ_002c-environment-variable'><span><code class="code">TZ</code><a class="copiable-link" href='#index-TZ_002c-environment-variable'> &para;</a></span></dt>
<dd><p>The time zone to use when converting the current time (or value of
<code class="env">SOURCE_DATE_EPOCH</code>) to human-readable form; see
<cite class="cite">tzset<span class="r">(3)</span></cite>.
</p></dd>
</dl>

<p>MS-DOS and MS-Windows ports of <code class="code">groff</code> use semicolons, rather than
colons, to separate the directories in the lists described above.
</p>


<hr>
</div>
<div class="section-level-extent" id="Macro-Directories">
<div class="nav-panel">
<p>
Next: <a href="#Font-Directories" accesskey="n" rel="next">Font Directories</a>, Previous: <a href="#Environment" accesskey="p" rel="prev">Environment</a>, Up: <a href="#Invoking-groff" accesskey="u" rel="up">Invoking <code class="code">groff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Macro-Directories-1">2.3 Macro Directories</h3>
<a class="index-entry-id" id="index-macro-directories"></a>
<a class="index-entry-id" id="index-directories-for-macros"></a>
<a class="index-entry-id" id="index-searching-macros"></a>
<a class="index-entry-id" id="index-macros_002c-searching"></a>

<p>A macro file must have a name in the form <code class="code"><var class="var">name</var>.tmac</code> or
<code class="code">tmac.<var class="var">name</var></code> and be placed in a <em class="dfn">tmac directory</em> to be
found by the <samp class="option">-m<var class="var">name</var></samp> command-line option.<a class="footnote" id="DOCF5" href="#FOOT5"><sup>5</sup></a>
<a class="index-entry-id" id="index-tmac_002c-directory"></a>
<a class="index-entry-id" id="index-directory_002c-for-tmac-files"></a>
<a class="index-entry-id" id="index-tmac_002c-path"></a>
<a class="index-entry-id" id="index-path_002c-for-tmac-files"></a>
<a class="index-entry-id" id="index-locating-macro-files"></a>
<a class="index-entry-id" id="index-macro-file-search-path"></a>
<a class="index-entry-id" id="index-file_002c-macro_002c-search-path"></a>
<a class="index-entry-id" id="index-locating-macro-packages"></a>
<a class="index-entry-id" id="index-macro-package-search-path"></a>
<a class="index-entry-id" id="index-package_002c-macro_002c-search-path"></a>
Together, these directories constitute the <em class="dfn">tmac path</em>.  Each
directory is searched in the following order until the desired macro
file is found or the list is exhausted.
</p>
<ul class="itemize mark-bullet">
<li>Directories specified with GNU <code class="code">troff</code>&rsquo;s or <code class="code">groff</code>&rsquo;s
<samp class="option">-M</samp> command-line option.

</li><li><a class="index-entry-id" id="index-GROFF_005fTMAC_005fPATH_002c-environment-variable-1"></a>
Directories listed in the <code class="env">GROFF_TMAC_PATH</code> environment variable.

</li><li><a class="index-entry-id" id="index-safer-mode-1"></a>
<a class="index-entry-id" id="index-mode_002c-safer-1"></a>
<a class="index-entry-id" id="index-unsafe-mode-1"></a>
<a class="index-entry-id" id="index-mode_002c-unsafe-1"></a>
<a class="index-entry-id" id="index-current-directory"></a>
<a class="index-entry-id" id="index-directory_002c-current"></a>
The current working directory (only if in unsafe mode using the
<samp class="option">-U</samp> command-line option).

</li><li><a class="index-entry-id" id="index-home-directory"></a>
<a class="index-entry-id" id="index-directory_002c-home"></a>
The user&rsquo;s home directory, <code class="env">HOME</code>.

</li><li><a class="index-entry-id" id="index-site_002dlocal-directory"></a>
<a class="index-entry-id" id="index-directory_002c-site_002dlocal"></a>
<a class="index-entry-id" id="index-platform_002dspecific-directory"></a>
<a class="index-entry-id" id="index-directory_002c-platform_002dspecific"></a>
A platform-dependent directory, a site-local (platform-independent)
directory, and the main <i class="slanted">tmac</i> directory.  The locations
corresponding to your installation are listed in section &ldquo;Environment&rdquo;
of <cite class="cite">gtroff<span class="r">(1)</span></cite>.  If not otherwise configured, they are as
follows.

<div class="example">
<div class="group"><pre class="example-preformatted">/usr/local/lib/groff/site-tmac
/usr/local/share/groff/site-tmac
/usr/local/share/groff/1.23.0/tmac
</pre></div></div>

<p>The foregoing assumes that the version of <code class="code">groff</code> is 1.23.0, and
that the installation prefix was <samp class="file">/usr/local</samp>.  It is possible to
fine-tune these locations during the source configuration process.
</p></li></ul>



<hr>
</div>
<div class="section-level-extent" id="Font-Directories">
<div class="nav-panel">
<p>
Next: <a href="#Paper-Format" accesskey="n" rel="next">Paper Format</a>, Previous: <a href="#Macro-Directories" accesskey="p" rel="prev">Macro Directories</a>, Up: <a href="#Invoking-groff" accesskey="u" rel="up">Invoking <code class="code">groff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Font-Directories-1">2.4 Font Directories</h3>
<a class="index-entry-id" id="index-font-directories"></a>
<a class="index-entry-id" id="index-directories-for-fonts"></a>
<a class="index-entry-id" id="index-searching-fonts"></a>
<a class="index-entry-id" id="index-fonts_002c-searching"></a>

<p><code class="code">groff</code> enforces few restrictions on how font description files are
named.  For its family/style mechanism to work (see <a class="pxref" href="#Font-Families">Font Families</a>),
the names of fonts within a family should start with the family name,
followed by the style.  For example, the Times family uses &lsquo;<samp class="samp">T</samp>&rsquo; for
the family name and &lsquo;<samp class="samp">R</samp>&rsquo;, &lsquo;<samp class="samp">B</samp>&rsquo;, &lsquo;<samp class="samp">I</samp>&rsquo;, and &lsquo;<samp class="samp">BI</samp>&rsquo; to
indicate the styles &lsquo;roman&rsquo;, &lsquo;bold&rsquo;, &lsquo;italic&rsquo;, and &lsquo;bold italic&rsquo;,
respectively.  Thus the final font names are &lsquo;<samp class="samp">TR</samp>&rsquo;, &lsquo;<samp class="samp">TB</samp>&rsquo;,
&lsquo;<samp class="samp">TI</samp>&rsquo;, and &lsquo;<samp class="samp">TBI</samp>&rsquo;.
</p>
<a class="index-entry-id" id="index-font-path"></a>
<a class="index-entry-id" id="index-path_002c-for-font-files"></a>
<p>Font description files are kept in <em class="dfn">font directories</em>, which
together constitute the <em class="dfn">font path</em>.  The search procedure
always appends the directory <code class="code">dev</code><var class="var">name</var>, where <var class="var">name</var> is
the name of the output device.  Assuming TeX DVI output, and
<samp class="file">/foo/bar</samp> as a font directory, the font description files for
<code class="command">grodvi</code> must be in <samp class="file">/foo/bar/devdvi</samp>.
Each directory in the font path is searched in the following order until
the desired font description file is found or the list is exhausted.
</p>
<ul class="itemize mark-bullet">
<li>Directories specified with GNU <code class="code">troff</code>&rsquo;s or <code class="code">groff</code>&rsquo;s
<samp class="option">-f</samp> command-line option.  All output drivers (and some
preprocessors) support this option as well, because they require
information about the glyphs to be rendered in the document.

</li><li><a class="index-entry-id" id="index-GROFF_005fFONT_005fPATH_002c-environment-variable-1"></a>
Directories listed in the <code class="env">GROFF_FONT_PATH</code> environment variable.

</li><li><a class="index-entry-id" id="index-site_002dlocal-directory-1"></a>
<a class="index-entry-id" id="index-directory_002c-site_002dlocal-1"></a>
A site-local directory and the main font description directory.
The locations corresponding to your installation are listed in section
&ldquo;Environment&rdquo; of <cite class="cite">gtroff<span class="r">(1)</span></cite>.  If not otherwise configured,
they are as follows.

<div class="example">
<div class="group"><pre class="example-preformatted">/usr/local/share/groff/site-font
/usr/local/share/groff/1.23.0/font
</pre></div></div>

<p>The foregoing assumes that the version of <code class="code">groff</code> is 1.23.0, and
that the installation prefix was <samp class="file">/usr/local</samp>.  It is possible to
fine-tune these locations during the source configuration process.
</p></li></ul>



<hr>
</div>
<div class="section-level-extent" id="Paper-Format">
<div class="nav-panel">
<p>
Next: <a href="#Invocation-Examples" accesskey="n" rel="next">Invocation Examples</a>, Previous: <a href="#Font-Directories" accesskey="p" rel="prev">Font Directories</a>, Up: <a href="#Invoking-groff" accesskey="u" rel="up">Invoking <code class="code">groff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Paper-Format-1">2.5 Paper Format</h3>
<a class="index-entry-id" id="index-paper-format"></a>
<a class="index-entry-id" id="index-format_002c-paper"></a>
<a class="index-entry-id" id="index-paper-size"></a>
<a class="index-entry-id" id="index-size_002c-paper"></a>
<a class="index-entry-id" id="index-landscape-page-orientation"></a>
<a class="index-entry-id" id="index-orientation_002c-landscape"></a>
<a class="index-entry-id" id="index-page-orientation_002c-landscape"></a>

<p>In <code class="code">groff</code>, the page dimensions for the formatter GNU <code class="code">troff</code>
and for output devices are handled separately.  See <a class="xref" href="#Page-Layout">Page Layout</a>, for
vertical manipulation of the page size, and See <a class="xref" href="#Line-Layout">Line Layout</a>, for
horizontal changes.
<a class="index-entry-id" id="index-papersize_002etmac"></a>
<a class="index-entry-id" id="index-troffrc-1"></a>
The <samp class="file">papersize</samp> macro package, normally loaded by <samp class="file">troffrc</samp> at
startup, provides an interface for configuring page dimensions by
convenient names, like &lsquo;<samp class="samp">letter</samp>&rsquo; or &lsquo;<samp class="samp">a4</samp>&rsquo;; see
<cite class="cite">groff_tmac<span class="r">(5)</span></cite>.  The default used by the formatter depends on
its build configuration, but is usually one of the foregoing, as
geographically appropriate.
</p>
<p>It is up to each macro package to respect the page dimensions configured
in this way.
</p>
<p>For each output device, the size of the output medium can be set in its
<samp class="file">DESC</samp> file.  Most output drivers also recognize a command-line
option <samp class="option">-p</samp> to override the default dimensions and an option
<samp class="option">-l</samp> to use landscape orientation.  See <a class="xref" href="#DESC-File-Format"><samp class="file">DESC</samp> File Format</a>, for
a description of the <code class="code">papersize</code> keyword, which takes an argument
of the same form as <samp class="option">-p</samp>.  The output driver&rsquo;s man page, such as
<cite class="cite">grops<span class="r">(1)</span></cite>, may also be helpful.
</p>
<p><code class="code">groff</code> uses the command-line option <samp class="option">-P</samp> to pass options to
postprocessors; for example, use the following for PostScript output on
A4 paper in landscape orientation.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">groff -Tps -dpaper=a4l -P-pa4 -P-l -ms foo.ms &gt; foo.ps
</pre></div></div>



<hr>
</div>
<div class="section-level-extent" id="Invocation-Examples">
<div class="nav-panel">
<p>
Previous: <a href="#Paper-Format" accesskey="p" rel="prev">Paper Format</a>, Up: <a href="#Invoking-groff" accesskey="u" rel="up">Invoking <code class="code">groff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Invocation-Examples-1">2.6 Invocation Examples</h3>
<a class="index-entry-id" id="index-invocation-examples"></a>
<a class="index-entry-id" id="index-examples-of-invocation"></a>

<p><code class="code">roff</code> systems are best known for formatting man pages.  Once a
<code class="command">man</code> librarian program has located a man page, it may execute
a <code class="code">groff</code> command much like the following.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">groff -t -man -Tutf8 /usr/share/man/man1/groff.1
</pre></div></div>

<p>The librarian will also pipe the output through a pager, which might not
interpret the SGR terminal escape sequences <code class="command">groff</code> emits for
boldface, underlining, or italics; see the <cite class="cite">grotty<span class="r">(1)</span></cite> man page
for a discussion.
</p>
<p>To process a <code class="code">roff</code> input file using the preprocessors
<code class="command">gtbl</code> and <code class="command">gpic</code> and the <samp class="file">me</samp> macro package in the
way to which AT&amp;T <code class="code">troff</code> users were accustomed, one would type (or
script) a pipeline.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">gpic foo.me | gtbl | gtroff -me -Tutf8 | grotty
</pre></div></div>

<p>Using <code class="command">groff</code>, this pipe can be shortened to an equivalent
command.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">groff -p -t -me -T utf8 foo.me
</pre></div></div>

<p>An even easier way to do this is to use <code class="command">grog</code> to guess the
preprocessor and macro options and execute the result by using the
command substitution feature of the shell.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">$(grog -Tutf8 foo.me)
</pre></div></div>

<p>Each command-line option to a postprocessor must be specified with any
required leading dashes &lsquo;<samp class="samp">-</samp>&rsquo;
because <code class="command">groff</code> passes the arguments as-is to the postprocessor;
this permits arbitrary arguments to be transmitted.  For example, to
pass a title to the <code class="command">gxditview</code> postprocessor,
the shell commands
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">groff -X -P -title -P 'trial run' mydoc.t
</pre></div></div>

<p>and
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">groff -X -Z mydoc.t | gxditview -title 'trial run' -
</pre></div></div>

<p>are equivalent.
</p>



<hr>
</div>
</div>
<div class="chapter-level-extent" id="Tutorial-for-Macro-Users">
<div class="nav-panel">
<p>
Next: <a href="#Major-Macro-Packages" accesskey="n" rel="next">Macro Packages</a>, Previous: <a href="#Invoking-groff" accesskey="p" rel="prev">Invoking <code class="code">groff</code></a>, Up: <a href="#Top" accesskey="u" rel="up">GNU <code class="code">troff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="chapter" id="Tutorial-for-Macro-Users-1">3 Tutorial for Macro Users</h2>
<a class="index-entry-id" id="index-tutorial-for-macro-users"></a>
<a class="index-entry-id" id="index-macros_002c-tutorial-for-users"></a>
<a class="index-entry-id" id="index-user_0027s-tutorial-for-macros"></a>
<a class="index-entry-id" id="index-user_0027s-macro-tutorial"></a>

<p>Most users of the <code class="code">roff</code> language employ a macro package to format
their documents.  Successful macro packages ease the composition
process; their users need not have mastered the full formatting
language, nor understand features like diversions, traps, and
environments.  This chapter aims to familiarize you with basic concepts
and mechanisms common to many macro packages (like &ldquo;displays&rdquo;).  If
you prefer a meticulous and comprehensive presentation, try <a class="ref" href="#GNU-troff-Reference">GNU <code class="code">troff</code> Reference</a> instead.
</p>



<ul class="mini-toc">
<li><a href="#Basics" accesskey="1">Basics</a></li>
<li><a href="#Common-Features" accesskey="2">Common Features</a></li>
</ul>
<hr>
<div class="section-level-extent" id="Basics">
<div class="nav-panel">
<p>
Next: <a href="#Common-Features" accesskey="n" rel="next">Common Features</a>, Previous: <a href="#Tutorial-for-Macro-Users" accesskey="p" rel="prev">Tutorial for Macro Users</a>, Up: <a href="#Tutorial-for-Macro-Users" accesskey="u" rel="up">Tutorial for Macro Users</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Basics-1">3.1 Basics</h3>
<a class="index-entry-id" id="index-basics-of-macro-package-usage"></a>
<a class="index-entry-id" id="index-macro-package-usage_002c-basics-of"></a>

<p>Let us first survey some basic concepts necessary to use a macro package
fruitfully.<a class="footnote" id="DOCF6" href="#FOOT6"><sup>6</sup></a>
References are made throughout to more detailed information.
</p>
<p>GNU <code class="code">troff</code> reads an input file prepared by the user and outputs a
formatted document suitable for publication or framing.  The input
consists of text, or words to be printed, and embedded commands
(<i class="slanted">requests</i> and <i class="slanted">escape sequences</i>), which tell GNU
<code class="code">troff</code> how to format the output.  See <a class="xref" href="#Formatter-Instructions">Formatter Instructions</a>.
</p>
<p>The word <i class="slanted">argument</i> is used in this chapter to mean a word or
number that appears on the same line as a request, and which modifies
the meaning of that request.  For example, the request
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.sp
</pre></div></div>

<p>spaces one line, but
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.sp 4
</pre></div></div>

<p>spaces four lines.  The number&nbsp;4 is an argument to the <code class="code">sp</code>
request, which says to space four lines instead of one.  Arguments are
separated from the request and from each other by spaces (<em class="emph">not</em>
tabs).  See <a class="xref" href="#Invoking-Requests">Invoking Requests</a>.
</p>
<p>The primary function of GNU <code class="code">troff</code> is to collect words from input
lines, fill output lines with those words, adjust the line to the
right-hand margin by widening spaces, and output the result.  For
example, the input:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">Now is the time
for all good men
to come to the aid
of their party.
Four score and seven
years ago, etc.
</pre></div></div>

<p>is read, packed onto output lines, and justified to produce:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">  &rArr; Now is the time for all good men to come to the aid of
  &rArr; their party.  Four score and seven years ago, etc.
</pre></div></div>

<p>Sometimes a new output line should be started even though the current
line is not yet full&mdash;for example, at the end of a paragraph.  To do
this it is possible to force a <i class="slanted">break</i>, starting a new output
line.  Some requests cause a break automatically, as do (normally) blank
input lines and input lines beginning with a space or tab.
</p>
<p>Not all input lines are <i class="slanted">text lines</i>&mdash;words to be formatted.
Some are <i class="slanted">control lines</i> that tell a macro package (or GNU
<code class="code">troff</code> directly) how to format the text.  Control lines start with
a dot (&lsquo;<samp class="samp">.</samp>&rsquo;) or an apostrophe (&lsquo;<samp class="samp">'</samp>&rsquo;) as the first character, and
can be followed by a <i class="slanted">macro call</i>.
</p>
<p>The formatter also does more complex things, such as automatically
numbering pages, skipping over page boundaries, putting footnotes in the
correct place, and so forth.
</p>
<p>Here are a few hints for preparing text for input to GNU <code class="code">troff</code>.
</p>
<ul class="itemize mark-bullet">
<li>First, keep the input lines short.  Short input lines are easier to
edit, and GNU <code class="code">troff</code> packs words onto longer lines anyhow.

</li><li>In keeping with this, it is helpful to begin a new line after every
comma or phrase, since common corrections are to add or delete sentences
or phrases.

</li><li>End each sentence with two spaces&mdash;or better, start each sentence on a
new line.  GNU <code class="code">troff</code> recognizes characters that usually end a
sentence, and inserts inter-sentence space accordingly.

</li><li>Do not hyphenate words at the end of lines&mdash;GNU <code class="code">troff</code> is smart
enough to hyphenate words as needed, but is not smart enough to take
hyphens out and join a word back together.  Also, words such as
&ldquo;mother-in-law&rdquo; should not be broken over a line, since then a space
can occur where not wanted, such as &ldquo;<span class="w-nolinebreak-text">mother-</span>&nbsp;in<!-- /@w -->-law&rdquo;.
</li></ul>

<p>We offer further advice in <a class="ref" href="#Input-Conventions">Input Conventions</a>.
</p>
<a class="index-entry-id" id="index-vertical-spacing-_0028introduction_0029"></a>
<a class="index-entry-id" id="index-spacing_002c-vertical-_0028introduction_0029"></a>
<p>GNU <code class="code">troff</code> permits alteration of the distance between lines of
text.  This is termed <i class="slanted">vertical spacing</i> and is expressed in the
same units as the type size&mdash;the point.  The default is 10-point type
on 12-point spacing.  To get <i class="slanted">double-spaced</i> text you would set
the vertical spacing to 24 points.  Some, but not all, macro packages
expose a macro or register to configure the vertical spacing.
</p>
<p>A number of requests allow you to change the way the output is arranged
on the page, sometimes called the <i class="slanted">layout</i> of the output page.
Most macro packages don&rsquo;t supply macros for performing these (at least
not without performing other actions besides), as they are such basic
operations.  The macro packages for writing man pages, <samp class="file">man</samp> and
<samp class="file">mdoc</samp>, don&rsquo;t encourage explicit use of these requests at all.
</p>
<a class="index-entry-id" id="index-spacing-_0028introduction_0029"></a>
<p>The request &lsquo;<samp class="samp">.sp&nbsp;<var class="var">N</var></samp>&rsquo;<!-- /@w --> leaves <var class="var">N</var>&nbsp;lines of blank
space.  <var class="var">N</var>&nbsp;can be omitted (skipping a single line) or can
be of the form <var class="var">N</var>i (for <var class="var">N</var>&nbsp;inches) or <var class="var">N</var>c (for
<var class="var">N</var>&nbsp;centimeters).  For example, the input:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.sp 1.5i
My thoughts on the subject
.sp
</pre></div></div>

<p>leaves one and a half inches of space, followed by the line &ldquo;My
thoughts on the subject&rdquo;, followed by a single blank line (more
measurement units are available; see <a class="ref" href="#Measurements">Measurements</a>).
</p>
<p>If you seek precision in spacing, be advised when using a macro package
that it might not honor <code class="code">sp</code> requests as you expect; it can use a
formatter feature called <i class="slanted">no-space mode</i> to prevent excess space
from accumulating.  Macro packages typically offer registers to control
spacing between paragraphs, before section headings, and around displays
(discussed below); use these facilities preferentially.
See <a class="xref" href="#Manipulating-Spacing">Manipulating Spacing</a>.
</p>
<a class="index-entry-id" id="index-centering-lines-_0028introduction_0029"></a>
<a class="index-entry-id" id="index-lines_002c-centering-_0028introduction_0029"></a>
<p>Text lines can be centered by using the <code class="code">ce</code> request.  The line
after <code class="code">ce</code> is centered (horizontally) on the page.  To center more
than one line, use &lsquo;<samp class="samp">.ce&nbsp;<var class="var">N</var></samp>&rsquo;<!-- /@w --> (where <var class="var">N</var> is the number
of lines to center), followed by the <var class="var">N</var>&nbsp;lines.  To center many
lines without counting them, type:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ce 1000
lines to center
.ce 0
</pre></div></div>

<p>The &lsquo;<samp class="samp">.ce&nbsp;0</samp>&rsquo;<!-- /@w --> request tells GNU <code class="code">troff</code> to center zero more
lines, in other words, stop centering.
</p>
<a class="index-entry-id" id="index-right_002daligning-lines-_0028introduction_0029"></a>
<a class="index-entry-id" id="index-lines_002c-right_002daligning-_0028introduction_0029"></a>
<a class="index-entry-id" id="index-right_002djustifying-lines-_0028introduction_0029"></a>
<a class="index-entry-id" id="index-lines_002c-right_002djustifying-_0028introduction_0029"></a>
<p>GNU <code class="code">troff</code> also offers the <code class="code">rj</code> request for right-aligning
text.  It works analogously to <code class="code">ce</code> and is convenient for setting
epigraphs.
</p>
<a class="index-entry-id" id="index-page-break-_0028introduction_0029"></a>
<a class="index-entry-id" id="index-break_002c-page-_0028introduction_0029"></a>
<p>The <code class="code">bp</code> request starts a new page; this necessarily implies an
ordinary (line) break.
</p>
<a class="index-entry-id" id="index-break-_0028introduction_0029"></a>
<a class="index-entry-id" id="index-line-break-_0028introduction_0029"></a>
<p>All of these requests cause a break; that is, they always start a new
line.  To start a new line without performing any other action, use
<code class="code">br</code>.  If you invoke them with the apostrophe &lsquo;<samp class="samp">'</samp>&rsquo;, the
<i class="slanted">no-break control character</i>, the (initial) break they normally
perform is suppressed.  &lsquo;<samp class="samp">'br</samp>&rsquo; does nothing.
</p>


<hr>
</div>
<div class="section-level-extent" id="Common-Features">
<div class="nav-panel">
<p>
Previous: <a href="#Basics" accesskey="p" rel="prev">Basics</a>, Up: <a href="#Tutorial-for-Macro-Users" accesskey="u" rel="up">Tutorial for Macro Users</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Common-Features-1">3.2 Common Features</h3>
<a class="index-entry-id" id="index-common-features"></a>
<a class="index-entry-id" id="index-features_002c-common"></a>

<p>GNU <code class="code">troff</code> provides low-level operations for formatting a
document.  Many routine operations are undertaken in nearly all
documents that require a series of such primitive operations to be
performed.  These common tasks are grouped into <i class="slanted">macros</i>, which
are then collected into a <i class="slanted">macro package</i>.
</p>
<p>Macro packages come in two varieties: &ldquo;major&rdquo; or &ldquo;full-service&rdquo;
ones that manage page layout, and &ldquo;minor&rdquo; or &ldquo;auxiliary&rdquo; ones that
do not, instead fulfilling narrow, specific tasks.  Find a list in the
<cite class="cite">groff_tmac<span class="r">(5)</span></cite> man page.  Type &lsquo;<samp class="samp">man groff_tmac</samp>&rsquo; at the
command line to view it.
</p>
<p>We survey several capabilities of full-service macro package below.
Each package employs its own macros to exercise them.  For details,
consult its man page or, for <samp class="file">ms</samp>, see <a class="ref" href="#ms"><samp class="file">ms</samp></a>.
</p>


<ul class="mini-toc">
<li><a href="#Paragraphs" accesskey="1">Paragraphs</a></li>
<li><a href="#Sections-and-Chapters" accesskey="2">Sections and Chapters</a></li>
<li><a href="#Headers-and-Footers" accesskey="3">Headers and Footers</a></li>
<li><a href="#Page-Layout-Adjustment" accesskey="4">Page Layout</a></li>
<li><a href="#Displays-and-Keeps" accesskey="5">Displays and Keeps</a></li>
<li><a href="#Footnotes-and-Endnotes" accesskey="6">Footnotes and Endnotes</a></li>
<li><a href="#Table-of-Contents" accesskey="7">Table of Contents</a></li>
<li><a href="#Indexing" accesskey="8">Indexing</a></li>
<li><a href="#Document-Formats" accesskey="9">Document Formats</a></li>
<li><a href="#Columnation">Columnation</a></li>
<li><a href="#Font-and-Size-Changes">Font and Size Changes</a></li>
<li><a href="#Predefined-Text">Predefined Text</a></li>
<li><a href="#Preprocessor-Support">Preprocessor Support</a></li>
<li><a href="#Configuration-and-Customization">Configuration and Customization</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="Paragraphs">
<div class="nav-panel">
<p>
Next: <a href="#Sections-and-Chapters" accesskey="n" rel="next">Sections and Chapters</a>, Previous: <a href="#Common-Features" accesskey="p" rel="prev">Common Features</a>, Up: <a href="#Common-Features" accesskey="u" rel="up">Common Features</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Paragraphs-1">3.2.1 Paragraphs</h4>
<a class="index-entry-id" id="index-paragraphs"></a>

<p>Paragraphs can be separated and indented in various ways.  Some start
with a blank line and have a first-line indentation, like most of the
ones in this manual.  Block paragraphs omit the indentation.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">  &rArr; Some  men  look  at constitutions with sanctimonious
  &rArr; reverence,  and  deem  them  like  the  ark  of  the
  &rArr; covenant, too sacred to be touched.
</pre></div></div>

<a class="index-entry-id" id="index-tags_002c-paragraph"></a>
<a class="index-entry-id" id="index-tagged-paragraphs"></a>
<a class="index-entry-id" id="index-lists"></a>
<p>We also frequently encounter <i class="slanted">tagged</i> paragraphs, which begin
with a tag or label at the left margin and indent the remaining text.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">  &rArr; one  This  is the first paragraph.  Notice how the
  &rArr;      first line of the resulting  paragraph  lines
  &rArr;      up with the other lines in the paragraph.
</pre></div></div>

<p>If the tag is too wide for the indentation, the line is broken.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">  &rArr; longlabel
  &rArr;      The  label does not align with the subsequent
  &rArr;      lines, but they align with each other.
</pre></div></div>

<p>A variation of the tagged paragraph is the itemized or enumerated
paragraph, which might use punctuation or a digit for a tag,
respectively.  These are frequently used to construct lists.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">  &rArr; o    This  list  item  starts with a bullet.  When
  &rArr;      producing output for a device using the ASCII
  &rArr;      character set, an 'o' is formatted instead.
</pre></div></div>

<p>Often, use of the same macro without a tag continues such a discussion.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">  &rArr; -xyz  This option is recognized but ignored.
  &rArr;
  &rArr;       It had a security hole that we don't discuss.
</pre></div></div>


<hr>
</div>
<div class="subsection-level-extent" id="Sections-and-Chapters">
<div class="nav-panel">
<p>
Next: <a href="#Headers-and-Footers" accesskey="n" rel="next">Headers and Footers</a>, Previous: <a href="#Paragraphs" accesskey="p" rel="prev">Paragraphs</a>, Up: <a href="#Common-Features" accesskey="u" rel="up">Common Features</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Sections-and-Chapters-1">3.2.2 Sections and Chapters</h4>

<p>The simplest kind of section heading is unnumbered, set in a bold or
italic style, and occupies a line by itself.  Others possess
automatically numbered multi-level headings and/or different typeface
styles or sizes at different levels.  More sophisticated macro packages
supply macros for designating chapters and appendices.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Headers-and-Footers">
<div class="nav-panel">
<p>
Next: <a href="#Page-Layout-Adjustment" accesskey="n" rel="next">Page Layout</a>, Previous: <a href="#Sections-and-Chapters" accesskey="p" rel="prev">Sections and Chapters</a>, Up: <a href="#Common-Features" accesskey="u" rel="up">Common Features</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Headers-and-Footers-1">3.2.3 Headers and Footers</h4>

<p><i class="slanted">Headers</i> and <i class="slanted">footers</i> occupy the top and bottom of
each page, respectively, and contain data like the page number and the
article or chapter title.  Their appearance is not affected by the
running text.  Some packages allow for different titles on even- and
odd-numbered pages (for printed, bound material).
</p>
<p>Headers and footers are together called <i class="slanted">titles</i>, and comprise
three parts: left-aligned, centered, and right-aligned.  A &lsquo;<samp class="samp">%</samp>&rsquo;
character appearing anywhere in a title is automatically replaced by the
page number.  See <a class="xref" href="#Page-Layout">Page Layout</a>.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Page-Layout-Adjustment">
<div class="nav-panel">
<p>
Next: <a href="#Displays-and-Keeps" accesskey="n" rel="next">Displays and Keeps</a>, Previous: <a href="#Headers-and-Footers" accesskey="p" rel="prev">Headers and Footers</a>, Up: <a href="#Common-Features" accesskey="u" rel="up">Common Features</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Page-Layout-1">3.2.4 Page Layout</h4>

<p>Most macro packages let the user specify the size of the page margins.
The top and bottom margins are typically handled differently than the
left and right margins; the latter two are derived from the
<i class="slanted">page offset</i>, <i class="slanted">indentation</i>, and <i class="slanted">line length</i>.
See <a class="xref" href="#Line-Layout">Line Layout</a>.  Commonly, packages support registers to tune these
values.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Displays-and-Keeps">
<div class="nav-panel">
<p>
Next: <a href="#Footnotes-and-Endnotes" accesskey="n" rel="next">Footnotes and Endnotes</a>, Previous: <a href="#Page-Layout-Adjustment" accesskey="p" rel="prev">Page Layout</a>, Up: <a href="#Common-Features" accesskey="u" rel="up">Common Features</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Displays-and-Keeps-1">3.2.5 Displays and Keeps</h4>
<a class="index-entry-id" id="index-displays"></a>

<p><i class="slanted">Displays</i> are sections of text set off from the surrounding
material (typically paragraphs), often differing in indentation, and/or
spacing.  Tables, block quotations, and figures are displayed.
Equations and code examples, when not much shorter than an output line,
often are.  Lists may or may not be.  Packages for setting man pages
support example displays but not keeps.
</p>
<a class="index-entry-id" id="index-keeps-_0028introduction_0029"></a>
<p>A <i class="slanted">keep</i> is a group of output lines, often a display, that is
formatted on a single page if possible; it causes a page break to happen
early so as to not interrupt the kept material.
</p>
<a class="index-entry-id" id="index-keep_002c-floating"></a>
<a class="index-entry-id" id="index-floating-keep"></a>
<p><i class="slanted">Floating keeps</i> can move, or &ldquo;float&rdquo;, relative to the text
around them in the input.  They are useful for displays that are
captioned and referred to by name, as with &ldquo;See figure&nbsp;3&rdquo;.
Depending on the package, a floating keep appears at the bottom of the
current page if it fits, and at the top of the next otherwise.
Alternatively, floating keeps might be deferred to the end of a section.
Using a floating keep can avoid the large vertical spaces that may
precede a tall keep of the ordinary sort when it won&rsquo;t fit on the page.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Footnotes-and-Endnotes">
<div class="nav-panel">
<p>
Next: <a href="#Table-of-Contents" accesskey="n" rel="next">Table of Contents</a>, Previous: <a href="#Displays-and-Keeps" accesskey="p" rel="prev">Displays and Keeps</a>, Up: <a href="#Common-Features" accesskey="u" rel="up">Common Features</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Footnotes-and-Endnotes-1">3.2.6 Footnotes and Endnotes</h4>
<a class="index-entry-id" id="index-footnotes"></a>
<a class="index-entry-id" id="index-endnotes"></a>

<p><i class="slanted">Footnotes</i> and <i class="slanted">endnotes</i> are forms of delayed
formatting.  They are recorded at their points of relevance in
the input, but not formatted there.  Instead, a <i class="slanted">mark</i> cues the
reader to check the &ldquo;foot&rdquo;, or bottom, of the current page, or in the
case of endnotes, an annotation list later in the document.  Macro
packages that support these features also supply a means of
automatically numbering either type of annotation.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Table-of-Contents">
<div class="nav-panel">
<p>
Next: <a href="#Indexing" accesskey="n" rel="next">Indexing</a>, Previous: <a href="#Footnotes-and-Endnotes" accesskey="p" rel="prev">Footnotes and Endnotes</a>, Up: <a href="#Common-Features" accesskey="u" rel="up">Common Features</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Table-of-Contents-1">3.2.7 Table of Contents</h4>
<a class="index-entry-id" id="index-table-of-contents"></a>
<a class="index-entry-id" id="index-contents_002c-table-of"></a>

<p>A package may handle a <i class="slanted">table of contents</i> by directing section
heading macros to save section heading text and the page number where it
occurs for use in a later <i class="slanted">entry</i> for a table of contents.  It
writes the collected entries at the end of the document, once all are
known, upon request.  A row of dots (a <i class="slanted">leader</i>) bridges the
text on the left with its location on the right.  Other collections
might work in this manner, providing lists of figures or tables.
</p>
<p>A table of contents is often found at the end of a GNU <code class="code">troff</code>
document because the formatter processes the document in a single pass.
The <code class="command">gropdf</code> output driver supports a PDF feature that relocates
pages at the time the document is rendered; see the <cite class="cite">gropdf<span class="r">(1)</span></cite>
man page.  Type &lsquo;<samp class="samp">man gropdf</samp>&rsquo; at the command line to view it.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Indexing">
<div class="nav-panel">
<p>
Next: <a href="#Document-Formats" accesskey="n" rel="next">Document Formats</a>, Previous: <a href="#Table-of-Contents" accesskey="p" rel="prev">Table of Contents</a>, Up: <a href="#Common-Features" accesskey="u" rel="up">Common Features</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Indexing-1">3.2.8 Indexing</h4>
<a class="index-entry-id" id="index-index_002c-in-macro-package"></a>

<a class="index-entry-id" id="index-makeindex"></a>
<p>An index is similar to a table of contents, in that entry labels and
locations must be collected, but poses a greater challenge because it
needs to be sorted before it is output.  Here, processing the document
in multiple passes is inescapable, and tools like the <code class="code">makeindex</code>
program are necessary.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Document-Formats">
<div class="nav-panel">
<p>
Next: <a href="#Columnation" accesskey="n" rel="next">Columnation</a>, Previous: <a href="#Indexing" accesskey="p" rel="prev">Indexing</a>, Up: <a href="#Common-Features" accesskey="u" rel="up">Common Features</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Document-Formats-1">3.2.9 Document Formats</h4>
<a class="index-entry-id" id="index-document-formats"></a>

<p>Some macro packages supply stock configurations of certain documents,
like business letters and memoranda.  These often also have provision
for a <i class="slanted">cover sheet</i>, which may be rigid in its format.  With
these features, it is even more important to use the package&rsquo;s macros in
preference to the formatter requests presented earlier, where possible.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Columnation">
<div class="nav-panel">
<p>
Next: <a href="#Font-and-Size-Changes" accesskey="n" rel="next">Font and Size Changes</a>, Previous: <a href="#Document-Formats" accesskey="p" rel="prev">Document Formats</a>, Up: <a href="#Common-Features" accesskey="u" rel="up">Common Features</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Columnation-1">3.2.10 Columnation</h4>

<p>Macro packages apart from <samp class="file">man</samp> and <samp class="file">mdoc</samp> for man page
formatting offer a facility for setting multiple columns on the page.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Font-and-Size-Changes">
<div class="nav-panel">
<p>
Next: <a href="#Predefined-Text" accesskey="n" rel="next">Predefined Text</a>, Previous: <a href="#Columnation" accesskey="p" rel="prev">Columnation</a>, Up: <a href="#Common-Features" accesskey="u" rel="up">Common Features</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Font-and-Size-Changes-1">3.2.11 Font and Size Changes</h4>

<p>The formatter&rsquo;s requests and escape sequences for setting the typeface
and size are not always intuitive, so all macro packages provide macros
to make these operations simpler.  They also make it more convenient to
change typefaces in the middle of a word and can handle italic
corrections automatically.  See <a class="xref" href="#Italic-Corrections">Italic Corrections</a>.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Predefined-Text">
<div class="nav-panel">
<p>
Next: <a href="#Preprocessor-Support" accesskey="n" rel="next">Preprocessor Support</a>, Previous: <a href="#Font-and-Size-Changes" accesskey="p" rel="prev">Font and Size Changes</a>, Up: <a href="#Common-Features" accesskey="u" rel="up">Common Features</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Predefined-Text-1">3.2.12 Predefined Text</h4>

<p>Most macro packages supply predefined strings to set prepared text like
the date, or to perform operations like super- and subscripting.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Preprocessor-Support">
<div class="nav-panel">
<p>
Next: <a href="#Configuration-and-Customization" accesskey="n" rel="next">Configuration and Customization</a>, Previous: <a href="#Predefined-Text" accesskey="p" rel="prev">Predefined Text</a>, Up: <a href="#Common-Features" accesskey="u" rel="up">Common Features</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Preprocessor-Support-1">3.2.13 Preprocessor Support</h4>

<p>All macro packages provide support for various preprocessors and may
extend their functionality by defining macros to set their contents in
displays.  Examples include <code class="code">TS</code> and <code class="code">TE</code> for <code class="command">gtbl</code>,
<code class="code">EQ</code> and <code class="code">EN</code> for <code class="command">geqn</code>, and <code class="code">PS</code> and <code class="code">PE</code>
for <code class="command">gpic</code>.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Configuration-and-Customization">
<div class="nav-panel">
<p>
Previous: <a href="#Preprocessor-Support" accesskey="p" rel="prev">Preprocessor Support</a>, Up: <a href="#Common-Features" accesskey="u" rel="up">Common Features</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Configuration-and-Customization-1">3.2.14 Configuration and Customization</h4>

<p>Packages provide means of customizing many of the details of how the
package behaves.  These range from setting the default type size to
changing the appearance of section headers.
</p>




<hr>
</div>
</div>
</div>
<div class="chapter-level-extent" id="Major-Macro-Packages">
<div class="nav-panel">
<p>
Next: <a href="#GNU-troff-Reference" accesskey="n" rel="next">GNU <code class="code">troff</code> Reference</a>, Previous: <a href="#Tutorial-for-Macro-Users" accesskey="p" rel="prev">Tutorial for Macro Users</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU <code class="code">troff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="chapter" id="Macro-Packages-2">4 Macro Packages</h2>
<a class="index-entry-id" id="index-major-macro-package"></a>
<a class="index-entry-id" id="index-package_002c-macro_002c-major"></a>
<a class="index-entry-id" id="index-macro-package_002c-major"></a>

<p>This chapter surveys the &ldquo;major&rdquo; macro packages that come with
<code class="code">groff</code>.  One, <samp class="file">ms</samp>, is presented in detail.
</p>
<a class="index-entry-id" id="index-full_002dservice-macro-package"></a>
<a class="index-entry-id" id="index-package_002c-macro_002c-full_002dservice"></a>
<a class="index-entry-id" id="index-macro-package_002c-full_002dservice"></a>
<p>Major macro packages are also sometimes described as <em class="dfn">full-service</em>
due to the breadth of features they provide and because more than one
cannot be used by the same document; for example
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">groff -m man foo.man -m ms bar.doc
</pre></div></div>

<p>doesn&rsquo;t work.  Option arguments are processed before non-option
arguments; the above (failing) sample is thus reordered to
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">groff -m man -m ms foo.man bar.doc
</pre></div></div>

<a class="index-entry-id" id="index-minor-macro-package"></a>
<a class="index-entry-id" id="index-package_002c-macro_002c-minor"></a>
<a class="index-entry-id" id="index-macro-package_002c-minor"></a>
<a class="index-entry-id" id="index-auxiliary-macro-package"></a>
<a class="index-entry-id" id="index-package_002c-macro_002c-auxiliary"></a>
<a class="index-entry-id" id="index-macro-package_002c-auxiliary"></a>
<p>Many auxiliary, or &ldquo;minor&rdquo;, macro packages are also available.  They
may in general be used with any full-service macro package and handle a
variety of tasks from character encoding selection, to language
localization, to inlining of raster images.  See the
<cite class="cite">groff_tmac<span class="r">(5)</span></cite> man page for a list.  Type &lsquo;<samp class="samp">man
groff_tmac</samp>&rsquo; at the command line to view it.
</p>



<ul class="mini-toc">
<li><a href="#man" accesskey="1"><samp class="file">man</samp></a></li>
<li><a href="#mdoc" accesskey="2"><samp class="file">mdoc</samp></a></li>
<li><a href="#me" accesskey="3"><samp class="file">me</samp></a></li>
<li><a href="#mm" accesskey="4"><samp class="file">mm</samp></a></li>
<li><a href="#mom" accesskey="5"><samp class="file">mom</samp></a></li>
<li><a href="#ms" accesskey="6"><samp class="file">ms</samp></a></li>
</ul>
<hr>
<div class="section-level-extent" id="man">
<div class="nav-panel">
<p>
Next: <a href="#mdoc" accesskey="n" rel="next"><samp class="file">mdoc</samp></a>, Previous: <a href="#Major-Macro-Packages" accesskey="p" rel="prev">Macro Packages</a>, Up: <a href="#Major-Macro-Packages" accesskey="u" rel="up">Macro Packages</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="man-1">4.1 <samp class="file">man</samp></h3>
<a class="index-entry-id" id="index-manual-pages"></a>
<a class="index-entry-id" id="index-man-pages"></a>
<a class="index-entry-id" id="index-an_002etmac"></a>
<a class="index-entry-id" id="index-man_002etmac"></a>

<p>The <code class="code">man</code> macro package is the most widely used and probably the
most important ever developed for <code class="code">troff</code>.  It is easy to use, and
a vast majority of manual pages (&ldquo;man pages&rdquo;) are written in it.
</p>
<p><code class="code">groff</code>&rsquo;s implementation is documented in the
<cite class="cite">groff_man<span class="r">(7)</span></cite> man page.  Type &lsquo;<samp class="samp">man groff_man</samp>&rsquo; at the
command line to view it.
</p>


<ul class="mini-toc">
<li><a href="#Optional-man-extensions" accesskey="1">Optional <samp class="file">man</samp> extensions</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="Optional-man-extensions">
<div class="nav-panel">
<p>
Up: <a href="#man" accesskey="u" rel="up"><samp class="file">man</samp></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Optional-man-extensions-1">4.1.1 Optional <samp class="file">man</samp> extensions</h4>

<a class="index-entry-id" id="index-man_002elocal"></a>
<p>Use the file <samp class="file">man.local</samp> for local extensions to the <code class="code">man</code>
macros or for style changes.
</p>
<ul class="mini-toc">
<li><a href="#Custom-headers-and-footers" accesskey="1">Custom headers and footers</a></li>
<li><a href="#Ultrix_002dspecific-man-macros" accesskey="2">Ultrix-specific man macros</a></li>
<li><a href="#Simple-example" accesskey="3">Simple example</a></li>
</ul>
<div class="unnumberedsubsubsec-level-extent" id="Custom-headers-and-footers">
<h4 class="unnumberedsubsubsec">Custom headers and footers</h4>
<a class="index-entry-id" id="index-man-macros_002c-custom-headers-and-footers"></a>

<p>In <code class="code">groff</code> versions 1.18.2 and later, you can specify custom
headers and footers by redefining the following macros in
<samp class="file">man.local</samp>.
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002ePT"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.PT</code></strong><a class="copiable-link" href='#index-_002ePT'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-PT-_005bman_005d"></a>
<p>Control the content of the headers.  Normally, the header prints the
command name and section number on either side, and the optional fifth
argument to <code class="code">TH</code> in the center.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eBT"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.BT</code></strong><a class="copiable-link" href='#index-_002eBT'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-BT-_005bman_005d"></a>
<p>Control the content of the footers.  Normally, the footer prints the
page number and the third and fourth arguments to <code class="code">TH</code>.
</p>
<p>Use the <code class="code">FT</code> register to specify the footer position.  The default
is &minus;0.5<span class="dmn">i</span>.
</p></dd></dl>

</div>
<div class="unnumberedsubsubsec-level-extent" id="Ultrix_002dspecific-man-macros">
<h4 class="unnumberedsubsubsec">Ultrix-specific man macros</h4>
<a class="index-entry-id" id="index-Ultrix_002dspecific-man-macros"></a>
<a class="index-entry-id" id="index-man-macros_002c-Ultrix_002dspecific"></a>

<a class="index-entry-id" id="index-man_002eultrix"></a>
<p>The <code class="code">groff</code> source distribution includes a file named
<samp class="file">man.ultrix</samp>, containing macros compatible with the Ultrix variant
of <code class="code">man</code>.  Copy this file into <samp class="file">man.local</samp> (or use the
<code class="code">mso</code> request to load it) to enable the following macros.
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eCT"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.CT</code></strong> <var class="def-var-arguments"><span class="r"><i class="slanted">key</i></span></var><a class="copiable-link" href='#index-_002eCT'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-CT-_005bman_005d"></a>
<p>Print &lsquo;<samp class="samp">&lt;CTRL/<var class="var">key</var>&gt;</samp>&rsquo;.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eCW"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.CW</code></strong><a class="copiable-link" href='#index-_002eCW'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-CW-_005bman_005d"></a>
<p>Print subsequent text using a &ldquo;constant-width&rdquo; (monospaced) typeface
(Courier roman).
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eDs"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.Ds</code></strong><a class="copiable-link" href='#index-_002eDs'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-Ds-_005bman_005d"></a>
<p>Begin a non-filled display.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eDe"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.De</code></strong><a class="copiable-link" href='#index-_002eDe'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-De-_005bman_005d"></a>
<p>End a non-filled display started with <code class="code">Ds</code>.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eEX"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.EX</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">indent</i></span>]</var><a class="copiable-link" href='#index-_002eEX'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-EX-_005bman_005d"></a>
<p>Begin a non-filled display using a monospaced typeface (Courier roman).
Use the optional <var class="var">indent</var> argument to indent the display.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eEE"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.EE</code></strong><a class="copiable-link" href='#index-_002eEE'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-EE-_005bman_005d"></a>
<p>End a non-filled display started with <code class="code">EX</code>.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eG"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.G</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">text</i></span>]</var><a class="copiable-link" href='#index-_002eG'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-G-_005bman_005d"></a>
<p>Set <var class="var">text</var> in Helvetica.  If no text is present on the line where
the macro is called, then the text of the next line appears in
Helvetica.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eGL"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.GL</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">text</i></span>]</var><a class="copiable-link" href='#index-_002eGL'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-GL-_005bman_005d"></a>
<p>Set <var class="var">text</var> in Helvetica oblique.  If no text is present on the line
where the macro is called, then the text of the next line appears in
Helvetica Oblique.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eHB"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.HB</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">text</i></span>]</var><a class="copiable-link" href='#index-_002eHB'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-HB-_005bman_005d"></a>
<p>Set <var class="var">text</var> in Helvetica bold.  If no text is present on the line
where the macro is called, then all text up to the next <code class="code">HB</code>
appears in Helvetica bold.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eTB"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.TB</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">text</i></span>]</var><a class="copiable-link" href='#index-_002eTB'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-TB-_005bman_005d"></a>
<p>Identical to <code class="code">HB</code>.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eMS"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.MS</code></strong> <var class="def-var-arguments"><span class="r"><i class="slanted">title</i></span> <span class="r"><i class="slanted">sect</i></span> [<span class="r"><i class="slanted">punct</i></span>]</var><a class="copiable-link" href='#index-_002eMS'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-MS-_005bman_005d"></a>
<p>Set a man page reference in Ultrix format.  The <var class="var">title</var> is in
Courier instead of italic.  Optional punctuation follows the section
number without an intervening space.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eNT"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.NT</code></strong> <var class="def-var-arguments">[<code class="code">C</code>] [<span class="r"><i class="slanted">title</i></span>]</var><a class="copiable-link" href='#index-_002eNT'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-NT-_005bman_005d"></a>
<p>Begin a note.  Print the optional <span class="r"><i class="slanted">title</i></span>, or the word &ldquo;Note&rdquo;,
centered on the page.  Text following the macro makes up the body of the
note, and is indented on both sides.  If the first argument is <code class="code">C</code>,
the body of the note is printed centered (the second argument replaces
the word &ldquo;Note&rdquo; if specified).
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eNE"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.NE</code></strong><a class="copiable-link" href='#index-_002eNE'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-NE-_005bman_005d"></a>
<p>End a note begun with <code class="code">NT</code>.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002ePN"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.PN</code></strong> <var class="def-var-arguments"><span class="r"><i class="slanted">path</i></span> [<span class="r"><i class="slanted">punct</i></span>]</var><a class="copiable-link" href='#index-_002ePN'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-PN-_005bman_005d"></a>
<p>Set the path name in a monospaced typeface (Courier roman), followed by
optional punctuation.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002ePn"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.Pn</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">punct</i></span>] <span class="r"><i class="slanted">path</i></span> [<span class="r"><i class="slanted">punct</i></span>]</var><a class="copiable-link" href='#index-_002ePn'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-Pn-_005bman_005d"></a>
<p>If called with two arguments, identical to <code class="code">PN</code>.  If called with
three arguments, set the second argument in a monospaced typeface
(Courier roman), bracketed by the first and third arguments in the
current font.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eR"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.R</code></strong><a class="copiable-link" href='#index-_002eR'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-R-_005bman_005d"></a>
<p>Switch to roman font and turn off any underlining in effect.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eRN"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.RN</code></strong><a class="copiable-link" href='#index-_002eRN'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-RN-_005bman_005d"></a>
<p>Print the string &lsquo;<samp class="samp">&lt;RETURN&gt;</samp>&rsquo;.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eVS"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.VS</code></strong> <var class="def-var-arguments">[<code class="code">4</code>]</var><a class="copiable-link" href='#index-_002eVS'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-VS-_005bman_005d"></a>
<p>Start printing a change bar in the margin if the number&nbsp;<code class="code">4</code> is
specified.  Otherwise, this macro does nothing.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eVE"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.VE</code></strong><a class="copiable-link" href='#index-_002eVE'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-VE-_005bman_005d"></a>
<p>End printing the change bar begun by <code class="code">VS</code>.
</p></dd></dl>

</div>
<div class="unnumberedsubsubsec-level-extent" id="Simple-example">
<h4 class="unnumberedsubsubsec">Simple example</h4>

<p>The following example <samp class="file">man.local</samp> file alters the <code class="code">SH</code> macro
to add some extra vertical space before printing the heading.  Headings
are printed in Helvetica bold.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.\&quot; Make the heading fonts Helvetica
.ds HF HB
.
.\&quot; Put more space in front of headings.
.rn SH SH-orig
.de SH
.  if t .sp (u;\\n[PD]*2)
.  SH-orig \\$*
..
</pre></div></div>



<hr>
</div>
</div>
</div>
<div class="section-level-extent" id="mdoc">
<div class="nav-panel">
<p>
Next: <a href="#me" accesskey="n" rel="next"><samp class="file">me</samp></a>, Previous: <a href="#man" accesskey="p" rel="prev"><samp class="file">man</samp></a>, Up: <a href="#Major-Macro-Packages" accesskey="u" rel="up">Macro Packages</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="mdoc-1">4.2 <samp class="file">mdoc</samp></h3>
<a class="index-entry-id" id="index-mdoc-macros"></a>

<p><code class="code">groff</code>&rsquo;s implementation of the BSD <samp class="file">doc</samp> package for man
pages is documented in the <cite class="cite">groff_mdoc<span class="r">(7)</span></cite> man page.  Type
&lsquo;<samp class="samp">man groff_mdoc</samp>&rsquo; at the command line to view it.
</p>


<hr>
</div>
<div class="section-level-extent" id="me">
<div class="nav-panel">
<p>
Next: <a href="#mm" accesskey="n" rel="next"><samp class="file">mm</samp></a>, Previous: <a href="#mdoc" accesskey="p" rel="prev"><samp class="file">mdoc</samp></a>, Up: <a href="#Major-Macro-Packages" accesskey="u" rel="up">Macro Packages</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="me-1">4.3 <samp class="file">me</samp></h3>
<a class="index-entry-id" id="index-me-macro-package"></a>

<p><code class="code">groff</code>&rsquo;s implementation of the BSD <samp class="file">me</samp> macro package is
documented using itself.  A tutorial, <samp class="file">meintro.me</samp>, and reference,
<samp class="file">meref.me</samp>, are available in <code class="code">groff</code>&rsquo;s documentation
directory.  A <cite class="cite">groff_me<span class="r">(7)</span></cite> man page is also available and
identifies the installation path for these documents.  Type &lsquo;<samp class="samp">man
groff_me</samp>&rsquo; at the command line to view it.
</p>
<p>A French translation of the tutorial is available as
<samp class="file">meintro_fr.me</samp> and installed parallel to the English version.
</p>


<hr>
</div>
<div class="section-level-extent" id="mm">
<div class="nav-panel">
<p>
Next: <a href="#mom" accesskey="n" rel="next"><samp class="file">mom</samp></a>, Previous: <a href="#me" accesskey="p" rel="prev"><samp class="file">me</samp></a>, Up: <a href="#Major-Macro-Packages" accesskey="u" rel="up">Macro Packages</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="mm-1">4.4 <samp class="file">mm</samp></h3>
<a class="index-entry-id" id="index-mm-macro-package"></a>

<p><code class="code">groff</code>&rsquo;s implementation of the <abbr class="acronym">AT&amp;T</abbr> memorandum macro
package is documented in the <cite class="cite">groff_mm<span class="r">(7)</span></cite> man page.  Type
&lsquo;<samp class="samp">man groff_mm</samp>&rsquo; at the command line) to view it.
</p>
<p>A Swedish localization of <samp class="file">mm</samp> is also available; see
<cite class="cite">groff_mmse<span class="r">(7)</span></cite>.
</p>


<hr>
</div>
<div class="section-level-extent" id="mom">
<div class="nav-panel">
<p>
Next: <a href="#ms" accesskey="n" rel="next"><samp class="file">ms</samp></a>, Previous: <a href="#mm" accesskey="p" rel="prev"><samp class="file">mm</samp></a>, Up: <a href="#Major-Macro-Packages" accesskey="u" rel="up">Macro Packages</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="mom-1">4.5 <samp class="file">mom</samp></h3>
<a class="index-entry-id" id="index-mom-macro-package"></a>

<p>The main documentation files for the <samp class="file">mom</samp> macros are in
<abbr class="acronym">HTML</abbr> format.  Additional, useful documentation is in
<abbr class="acronym">PDF</abbr> format.  See the <cite class="cite">groff<span class="r">(1)</span></cite> man page, section
&ldquo;Installation Directories&rdquo;, for their location.
</p>
<ul class="itemize mark-bullet">
<li><samp class="file">toc.html</samp>
Entry point to the full mom manual.

</li><li><samp class="file">macrolist.html</samp>
Hyperlinked index of macros with brief descriptions, arranged by
category.

</li><li><samp class="file">mom-pdf.pdf</samp>
<abbr class="acronym">PDF</abbr> features and usage.
</li></ul>

<p>The mom macros are in active development between <code class="code">groff</code> releases.
The most recent version, along with up-to-date documentation, is
available at <a class="uref" href="http://www.schaffter.ca/mom/mom-05.html">http://www.schaffter.ca/mom/mom-05.html</a>.
</p>
<p>The <cite class="cite">groff_mom<span class="r">(7)</span></cite> man page (type &lsquo;<samp class="samp">man groff_mom</samp>&rsquo; at
the command line) contains a partial list of available macros, however
their usage is best understood by consulting the <abbr class="acronym">HTML</abbr>
documentation.
</p>



<hr>
</div>
<div class="section-level-extent" id="ms">
<div class="nav-panel">
<p>
Previous: <a href="#mom" accesskey="p" rel="prev"><samp class="file">mom</samp></a>, Up: <a href="#Major-Macro-Packages" accesskey="u" rel="up">Macro Packages</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="ms-1">4.6 <samp class="file">ms</samp></h3>
<a class="index-entry-id" id="index-ms-macros"></a>

<p>The <samp class="file">ms</samp> (&ldquo;manuscript&rdquo;) package is suitable for the preparation
of letters, memoranda, reports, and books.  These <code class="code">groff</code>
macros feature cover page and table of contents generation,
automatically numbered headings, several paragraph styles, a variety of
text styling options, footnotes, and multi-column page layouts.
<samp class="file">ms</samp> supports the <code class="command">tbl</code>, <code class="command">eqn</code>, <code class="command">pic</code>, and
<code class="command">refer</code> preprocessors for inclusion of tables, mathematical
equations, diagrams, and standardized bibliographic citations.  This
implementation is mostly compatible with the documented interface and
behavior of AT&amp;T Unix Version&nbsp;7 <samp class="file">ms</samp>.  Many extensions from
4.2BSD (Berkeley)
and Tenth Edition Research Unix have been recreated.
</p>


<ul class="mini-toc">
<li><a href="#ms-Introduction" accesskey="1">Introduction</a></li>
<li><a href="#ms-Document-Structure" accesskey="2">Document Structure</a></li>
<li><a href="#ms-Document-Control-Settings" accesskey="3">Document Control Settings</a></li>
<li><a href="#ms-Document-Description-Macros" accesskey="4">Document Description Macros</a></li>
<li><a href="#ms-Body-Text" accesskey="5">Body Text</a></li>
<li><a href="#ms-Page-Layout" accesskey="6">Page layout</a></li>
<li><a href="#Differences-from-AT_0026T-ms" accesskey="7">Differences from <abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp></a></li>
<li><a href="#ms-Legacy-Features" accesskey="8">Legacy Features</a></li>
<li><a href="#ms-Naming-Conventions" accesskey="9">Naming Conventions</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="ms-Introduction">
<div class="nav-panel">
<p>
Next: <a href="#ms-Document-Structure" accesskey="n" rel="next">Document Structure</a>, Previous: <a href="#ms" accesskey="p" rel="prev"><samp class="file">ms</samp></a>, Up: <a href="#ms" accesskey="u" rel="up"><samp class="file">ms</samp></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Introduction-2">4.6.1 Introduction</h4>

<p>The <samp class="file">ms</samp> macros are the oldest surviving package for <code class="code">roff</code>
systems.<a class="footnote" id="DOCF7" href="#FOOT7"><sup>7</sup></a>  While the <samp class="file">man</samp>
package was designed for brief reference documents, the <samp class="file">ms</samp> macros
are also suitable for longer works intended for printing and possible
publication.
</p>


<ul class="mini-toc">
<li><a href="#ms-basic-information" accesskey="1">Basic information</a></li>
</ul>
<hr>
<div class="subsubsection-level-extent" id="ms-basic-information">
<div class="nav-panel">
<p>
Next: <a href="#ms-Document-Structure" accesskey="n" rel="next">Document Structure</a>, Previous: <a href="#ms-Introduction" accesskey="p" rel="prev">Introduction</a>, Up: <a href="#ms-Introduction" accesskey="u" rel="up">Introduction</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Basic-information">4.6.1.1 Basic information</h4>

<p><samp class="file">ms</samp> documents are plain text files; prepare them with your
preferred text editor.  If you&rsquo;re in a hurry to start, know that
<samp class="file">ms</samp> needs one of its macros called at the beginning of a document
so that it can initialize.  A <em class="dfn">macro</em> is a formatting instruction to
<samp class="file">ms</samp>.  Put a macro call on a line by itself.  Use &lsquo;<samp class="samp">.PP</samp>&rsquo; if you
want your paragraph&rsquo;s first line to be indented, or &lsquo;<samp class="samp">.LP</samp>&rsquo; if you
don&rsquo;t.
</p>
<p>After that, start typing normally.  It is a good practice to start each
sentence on a new line, or to put two spaces after sentence-ending
punctuation, so that the formatter knows where the sentence boundaries
are.  You can separate paragraphs with further paragraphing macros, or
with blank lines, and you can indent with tabs.  When you need one of
the features mentioned earlier (see <a class="pxref" href="#ms"><samp class="file">ms</samp></a>), return to this part of the
manual.
</p>
<p>Format the document with the <code class="command">groff</code> command.  <code class="command">nroff</code>
can be useful for previewing.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">$ editor radical.ms
$ nroff -ww -z -ms radical.ms # check for errors
$ nroff -ms radical.ms | less -R
$ groff -T ps -ms radical.ms &gt; radical.ps
$ see radical.ps
</pre></div>
</td></tr></table>

<p>Our <samp class="file">radical.ms</samp> document might look like this.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.LP
Radical novelties are so disturbing that they tend to be
suppressed or ignored, to the extent that even the
possibility of their existence in general is more often
denied than admitted.

&rarr;That's what Dijkstra said, anyway.
</pre></div>
</td></tr></table>

<p><samp class="file">ms</samp> exposes many aspects of document layout to user control via
<code class="code">groff</code>&rsquo;s <em class="dfn">registers</em> and <em class="dfn">strings</em>, which store numbers
and text, respectively.  Measurements in <code class="code">groff</code> are expressed with
a suffix called a <em class="dfn">scaling unit</em>.
</p>
<dl class="table">
<dt><code class="code">i</code></dt>
<dd><p>inches
</p>
</dd>
<dt><code class="code">c</code></dt>
<dd><p>centimeters
</p>
</dd>
<dt><code class="code">p</code></dt>
<dd><p>points (1/72 inch)
</p>
</dd>
<dt><code class="code">P</code></dt>
<dd><p>picas (1/6 inch)
</p>
</dd>
<dt><code class="code">v</code></dt>
<dd><p>vees; current vertical spacing
</p>
</dd>
<dt><code class="code">m</code></dt>
<dd><p>ems; width of an &ldquo;M&rdquo; in the current font
</p>
</dd>
<dt><code class="code">n</code></dt>
<dd><p>ens; one-half em
</p></dd>
</dl>

<p>Set registers with the <code class="code">nr</code> request and strings with the <code class="code">ds</code>
request.  <em class="dfn">Requests</em> are like macro calls; they go on lines by
themselves and start with the <em class="dfn">control character</em>, a dot (<code class="code">.</code>).
The difference is that they directly instruct the formatter program,
rather than the macro package.  We&rsquo;ll discuss a few as applicable.  It
is wise to specify a scaling unit when setting any register that
represents a length, size, or distance.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.nr PS 10.5p \&quot; Use 10.5-point type.
.ds FAM P    \&quot; Use Palatino font family.
</pre></div>
</td></tr></table>

<p>In the foregoing, we see that <code class="code">\&quot;</code> begins a comment.  This is an
example of an <em class="dfn">escape sequence</em>, the other kind of formatting
instruction.  Escape sequences can appear anywhere.  They begin with the
escape character (<code class="code">\</code>) and are followed by at least one more
character.  <samp class="file">ms</samp> documents
tend to use only a few of <code class="code">groff</code>&rsquo;s many requests and escape
sequences; see <a class="ref" href="#Request-Index">Request Index</a> and <a class="ref" href="#Escape-Sequence-Index">Escape Sequence Index</a> or
the <cite class="cite">groff<span class="r">(7)</span></cite> man page for complete lists.
</p>
<dl class="table">
<dt><code class="code">\&quot;</code></dt>
<dd><p>Begin comment; ignore remainder of line.
</p>
</dd>
<dt><code class="code">\n[<var class="var">reg</var>]</code></dt>
<dd><p>Interpolate value of register <var class="var">reg</var>.
</p>
</dd>
<dt><code class="code">\*[<var class="var">str</var>]</code></dt>
<dd><p>Interpolate contents of string <var class="var">str</var>.
</p>
</dd>
<dt><code class="code">\*<var class="var">s</var></code></dt>
<dd><p>abbreviation of <code class="code">\*[<var class="var">s</var>]</code>; the name <var class="var">s</var> must be only one
character
</p>
</dd>
<dt><code class="code">\[<var class="var">char</var>]</code></dt>
<dd><p>Interpolate glyph of special character named <var class="var">char</var>.
</p>
</dd>
<dt><code class="code">\&amp;</code></dt>
<dd><p>dummy character
</p>
</dd>
<dt><code class="code">\~</code></dt>
<dd><p>Insert an unbreakable space that is adjustable like a normal space.
</p>
</dd>
<dt><code class="code">\|</code></dt>
<dd><p>Move horizontally by one-sixth em (&ldquo;thin space&rdquo;).
</p></dd>
</dl>

<p>Prefix any words that start with a dot &lsquo;<samp class="samp">.</samp>&rsquo; or neutral apostrophe
&lsquo;<samp class="samp">'</samp>&rsquo; with <code class="code">\&amp;</code> if they are at the beginning of an input line
(or might become that way in editing) to prevent them from being
interpreted as macro calls or requests.  Suffix &lsquo;<samp class="samp">.</samp>&rsquo;, &lsquo;<samp class="samp">?</samp>&rsquo;, and
&lsquo;<samp class="samp">!</samp>&rsquo; with <code class="code">\&amp;</code> when needed to cancel end-of-sentence detection.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">My exposure was \&amp;.5 to \&amp;.6 Sv of neutrons, said Dr.\&amp;
Wallace after the criticality incident.
</pre></div>
</td></tr></table>


<hr>
</div>
</div>
<div class="subsection-level-extent" id="ms-Document-Structure">
<div class="nav-panel">
<p>
Next: <a href="#ms-Document-Control-Settings" accesskey="n" rel="next">Document Control Settings</a>, Previous: <a href="#ms-Introduction" accesskey="p" rel="prev">Introduction</a>, Up: <a href="#ms" accesskey="u" rel="up"><samp class="file">ms</samp></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Document-Structure">4.6.2 Document Structure</h4>
<a class="index-entry-id" id="index-ms-macros_002c-general-structure"></a>

<p>The <samp class="file">ms</samp> macro package expects a certain amount of structure:
a well-formed document contains at least one paragraphing or heading
macro call.  Longer documents have a structure as follows.
</p>
<dl class="table">
<dt><strong class="strong">Document type</strong></dt>
<dd><p>Calling the <code class="code">RP</code> macro at the beginning of your document puts the
document description (see below) on a cover page.  Otherwise, <samp class="file">ms</samp>
places the information (if any) on the first page, followed immediately
by the body text.  Some document types found in other <samp class="file">ms</samp>
implementations are specific to <abbr class="acronym">AT&amp;T</abbr> or Berkeley, and are not
supported by <code class="code">groff</code> <samp class="file">ms</samp>.
</p>
</dd>
<dt><strong class="strong">Format and layout</strong></dt>
<dd><p>By setting registers and strings, you can configure your document&rsquo;s
typeface, margins, spacing, headers and footers, and footnote
arrangement.  See <a class="xref" href="#ms-Document-Control-Settings">Document Control Settings</a>.
</p>
</dd>
<dt><strong class="strong">Document description</strong></dt>
<dd><p>A document description consists of any of: a title, one or more authors&rsquo;
names and affiliated institutions, an abstract, and a date or other
identifier.  See <a class="xref" href="#ms-Document-Description-Macros">Document Description Macros</a>.
</p>
</dd>
<dt><strong class="strong">Body text</strong></dt>
<dd><p>The main matter of your document follows its description (if any).
<samp class="file">ms</samp> supports highly structured text consisting of paragraphs
interspersed with multi-level headings (chapters, sections, subsections,
and so forth) and augmented by lists, footnotes, tables, diagrams, and
similar material.  See <a class="xref" href="#ms-Body-Text">Body Text</a>.
</p>
</dd>
<dt><strong class="strong">Tables of contents</strong></dt>
<dd><p>Macros enable the collection of entries for a table of contents (or
index) as the material they discuss appears in the document.  You then
call a macro to emit the table of contents at the end of your document.
The table of contents must necessarily follow the rest of the text since
GNU <code class="code">troff</code> is a single-pass formatter; it thus cannot determine
the page number of a division of the text until it has been set and
output.  Since <samp class="file">ms</samp> was designed for the production of hard copy,
the traditional procedure was to manually relocate the pages containing
the table of contents between the cover page and the body text.  Today,
page resequencing is more often done in the digital domain.  An index
works similarly, but because it typically needs to be sorted after
collection, its preparation requires separate processing.
</p></dd>
</dl>


<hr>
</div>
<div class="subsection-level-extent" id="ms-Document-Control-Settings">
<div class="nav-panel">
<p>
Next: <a href="#ms-Document-Description-Macros" accesskey="n" rel="next">Document Description Macros</a>, Previous: <a href="#ms-Document-Structure" accesskey="p" rel="prev">Document Structure</a>, Up: <a href="#ms" accesskey="u" rel="up"><samp class="file">ms</samp></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Document-Control-Settings">4.6.3 Document Control Settings</h4>
<a class="index-entry-id" id="index-ms-macros_002c-document-control-settings"></a>

<p><samp class="file">ms</samp> exposes many aspects of document layout to user control via
<code class="code">groff</code> requests.  To use them, you must understand how to define
registers and strings.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002enr"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.nr</code></strong> <var class="def-var-arguments">reg value</var><a class="copiable-link" href='#index-_002enr'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-nr"></a>
<p>Set register <var class="var">reg</var> to <var class="var">value</var>.  If <var class="var">reg</var> doesn&rsquo;t exist, GNU
<code class="code">troff</code> creates it.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eds"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ds</code></strong> <var class="def-var-arguments">name contents</var><a class="copiable-link" href='#index-_002eds'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ds"></a>
<p>Set string <var class="var">name</var> to <var class="var">contents</var>.
</p></dd></dl>

<p>A list of document control registers and strings follows.  For any
parameter whose default is unsatisfactory, define its register or string
before calling any <samp class="file">ms</samp> macro other than <code class="code">RP</code>.
</p>
<ul class="mini-toc">
<li><a href="#Margin-settings" accesskey="1">Margin settings</a></li>
<li><a href="#Titles-_0028headers_002c-footers_0029" accesskey="2">Titles (headers, footers)</a></li>
<li><a href="#Text-settings" accesskey="3">Text settings</a></li>
<li><a href="#Paragraph-settings" accesskey="4">Paragraph settings</a></li>
<li><a href="#Heading-settings" accesskey="5">Heading settings</a></li>
<li><a href="#Footnote-settings" accesskey="6">Footnote settings</a></li>
<li><a href="#Display-settings" accesskey="7">Display settings</a></li>
<li><a href="#Other-settings" accesskey="8">Other settings</a></li>
</ul>
<div class="unnumberedsubsubsec-level-extent" id="Margin-settings">
<h4 class="unnumberedsubsubsec">Margin settings</h4>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bPO_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[PO]</code></strong><a class="copiable-link" href='#index-_005cn_005bPO_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-PO-_005bms_005d"></a>
<p>Defines the page offset (i.e., the left margin).
</p>
<p>Effective: next page.
</p>
<p>Default: Varies by output device and paper format; 1<span class="dmn">i</span> is used for
typesetters using U.S. letter paper, and zero for terminals.
See <a class="xref" href="#Paper-Format">Paper Format</a>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bLL_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[LL]</code></strong><a class="copiable-link" href='#index-_005cn_005bLL_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-LL-_005bms_005d"></a>
<p>Defines the line length (i.e., the width of the body text).
</p>
<p>Effective: next paragraph.
</p>
<p>Default: Varies by output device and paper format; 6.5<span class="dmn">i</span> is used
for typesetters using U.S. letter paper (see <a class="pxref" href="#Paper-Format">Paper Format</a>) and
65<span class="dmn">n</span> on terminals.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bLT_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[LT]</code></strong><a class="copiable-link" href='#index-_005cn_005bLT_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-LT-_005bms_005d"></a>
<p>Defines the title line length (i.e., the header and footer width).  This
is usually the same as <code class="code">LL</code>, but need not be.
</p>
<p>Effective: next paragraph.
</p>
<p>Default: Varies by output device and paper format; 6.5<span class="dmn">i</span> is used
for typesetters using U.S. letter paper (see <a class="pxref" href="#Paper-Format">Paper Format</a>) and
65<span class="dmn">n</span> on terminals.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bHM_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[HM]</code></strong><a class="copiable-link" href='#index-_005cn_005bHM_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-HM-_005bms_005d"></a>
<p>Defines the header margin height at the top of the page.
</p>
<p>Effective: next page.
</p>
<p>Default: 1<span class="dmn">i</span>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bFM_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[FM]</code></strong><a class="copiable-link" href='#index-_005cn_005bFM_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-FM-_005bms_005d"></a>
<p>Defines the footer margin height at the bottom of the page.
</p>
<p>Effective: next page.
</p>
<p>Default: 1<span class="dmn">i</span>.
</p></dd></dl>

</div>
<div class="unnumberedsubsubsec-level-extent" id="Titles-_0028headers_002c-footers_0029">
<h4 class="unnumberedsubsubsec">Titles (headers, footers)</h4>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bLH_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[LH]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bLH_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-LH-_005bms_005d"></a>
<p>Defines the text displayed in the left header position.
</p>
<p>Effective: next header.
</p>
<p>Default: empty.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bCH_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[CH]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bCH_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-CH-_005bms_005d"></a>
<p>Defines the text displayed in the center header position.
</p>
<p>Effective: next header.
</p>
<p>Default: &lsquo;<samp class="samp">-\n[%]-</samp>&rsquo;.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bRH_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[RH]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bRH_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-RH-_005bms_005d"></a>
<p>Defines the text displayed in the right header position.
</p>
<p>Effective: next header.
</p>
<p>Default: empty.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bLF_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[LF]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bLF_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-LF-_005bms_005d"></a>
<p>Defines the text displayed in the left footer position.
</p>
<p>Effective: next footer.
</p>
<p>Default: empty.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bCF_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[CF]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bCF_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-CF-_005bms_005d"></a>
<p>Defines the text displayed in the center footer position.
</p>
<p>Effective: next footer.
</p>
<p>Default: empty.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bRF_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[RF]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bRF_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-RF-_005bms_005d"></a>
<p>Defines the text displayed in the right footer position.
</p>
<p>Effective: next footer.
</p>
<p>Default: empty.
</p></dd></dl>

</div>
<div class="unnumberedsubsubsec-level-extent" id="Text-settings">
<h4 class="unnumberedsubsubsec">Text settings</h4>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bPS_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[PS]</code></strong><a class="copiable-link" href='#index-_005cn_005bPS_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-PS-_005bms_005d-1"></a>
<p>Defines the type size of the body text.
</p>
<p>Effective: next paragraph.
</p>
<p>Default: 10<span class="dmn">p</span>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bVS_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[VS]</code></strong><a class="copiable-link" href='#index-_005cn_005bVS_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-VS-_005bms_005d"></a>
<p>Defines the vertical spacing (type size plus leading).
</p>
<p>Effective: next paragraph.
</p>
<p>Default: 12<span class="dmn">p</span>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bHY_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[HY]</code></strong><a class="copiable-link" href='#index-_005cn_005bHY_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-HY-_005bms_005d"></a>
<p>Defines the automatic hyphenation mode used with the <code class="code">hy</code> request.
Setting <code class="code">HY</code> to&nbsp;0 is equivalent to using the <code class="code">nh</code>
request.  This is a Tenth Edition Research Unix extension.
</p>
<p>Effective: next paragraph.
</p>
<p>Default: 6.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bFAM_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[FAM]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bFAM_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-FAM-_005bms_005d"></a>
<p>Defines the font family used to typeset the document.  This is a GNU
extension.
</p>
<p>Effective: next paragraph.
</p>
<p>Default: defined by the output device; often &lsquo;<samp class="samp">T</samp>&rsquo; (see <a class="pxref" href="#ms-Body-Text">Body Text</a>)
</p></dd></dl>

</div>
<div class="unnumberedsubsubsec-level-extent" id="Paragraph-settings">
<h4 class="unnumberedsubsubsec">Paragraph settings</h4>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bPI_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[PI]</code></strong><a class="copiable-link" href='#index-_005cn_005bPI_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-PI-_005bms_005d"></a>
<p>Defines the indentation amount used by the <code class="code">PP</code>, <code class="code">IP</code> (unless
overridden by an optional argument), <code class="code">XP</code>, and <code class="code">RS</code> macros.
</p>
<p>Effective: next paragraph.
</p>
<p>Default: 5<span class="dmn">n</span>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bPD_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[PD]</code></strong><a class="copiable-link" href='#index-_005cn_005bPD_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-PD-_005bms_005d"></a>
<p>Defines the space between paragraphs.
</p>
<p>Effective: next paragraph.
</p>
<p>Default: 0.3<span class="dmn">v</span> (1<span class="dmn">v</span> on low-resolution devices).
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bQI_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[QI]</code></strong><a class="copiable-link" href='#index-_005cn_005bQI_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-QI-_005bms_005d"></a>
<p>Defines the indentation amount used on both sides of a paragraph set
with the <code class="code">QP</code> or between the <code class="code">QS</code> and <code class="code">QE</code> macros.
</p>
<p>Effective: next paragraph.
</p>
<p>Default: 5<span class="dmn">n</span>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bPORPHANS_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[PORPHANS]</code></strong><a class="copiable-link" href='#index-_005cn_005bPORPHANS_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-PORPHANS-_005bms_005d"></a>
<p>Defines the minimum number of initial lines of any paragraph that must
be kept together to avoid isolated lines at the bottom of a page.  If a
new paragraph is started close to the bottom of a page, and there is
insufficient space to accommodate <code class="code">PORPHANS</code> lines before an
automatic page break, then a page break is forced before the start of
the paragraph.  This is a GNU extension.
</p>
<p>Effective: next paragraph.
</p>
<p>Default: 1.
</p></dd></dl>

</div>
<div class="unnumberedsubsubsec-level-extent" id="Heading-settings">
<h4 class="unnumberedsubsubsec">Heading settings</h4>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bPSINCR_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[PSINCR]</code></strong><a class="copiable-link" href='#index-_005cn_005bPSINCR_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-PSINCR-_005bms_005d"></a>
<p>Defines an increment in type size to be applied to a heading at a
lesser depth than that specified in <code class="code">GROWPS</code>.  The value of
<code class="code">PSINCR</code> should be specified in points with the <span class="dmn">p</span> scaling
unit and may include a fractional component; for example, &lsquo;<samp class="samp">.nr&nbsp;PSINCR&nbsp;1.5p</samp>&rsquo;<!-- /@w --> sets a type size increment of 1.5<span class="dmn">p</span>.  This is a GNU
extension.
</p>
<p>Effective: next heading.
</p>
<p>Default: 1<span class="dmn">p</span>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bGROWPS_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[GROWPS]</code></strong><a class="copiable-link" href='#index-_005cn_005bGROWPS_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-GROWPS-_005bms_005d"></a>
<p>Defines the heading depth above which the type size increment set by
<code class="code">PSINCR</code> becomes effective.  For each heading depth less than the
value of <code class="code">GROWPS</code>, the type size is increased by <code class="code">PSINCR</code>.
Setting <code class="code">GROWPS</code> to any value less than&nbsp;2 disables the
incremental heading size feature.  This is a GNU extension.
</p>
<p>Effective: next heading.
</p>
<p>Default: 0.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bHORPHANS_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[HORPHANS]</code></strong><a class="copiable-link" href='#index-_005cn_005bHORPHANS_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-HORPHANS-_005bms_005d"></a>
<p>Defines the minimum number of lines of an immediately succeeding
paragraph that should be kept together with any heading introduced by
the <code class="code">NH</code> or <code class="code">SH</code> macros.  If a heading is placed close to the
bottom of a page, and there is insufficient space to accommodate both
the heading and at least <code class="code">HORPHANS</code> lines of the following
paragraph, before an automatic page break, then the page break is forced
before the heading.  This is a GNU extension.
</p>
<p>Effective: next paragraph.
</p>
<p>Default: 1.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bSN_002dSTYLE_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[SN-STYLE]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bSN_002dSTYLE_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-SN_002dSTYLE-_005bms_005d"></a>
<p>Defines the style used to print numbered headings.  See <a class="xref" href="#Headings-in-ms">Headings</a>.  This is a GNU extension.
</p>
<p>Effective: next heading.
</p>
<p>Default: alias of <code class="code">SN-DOT</code>
</p></dd></dl>

</div>
<div class="unnumberedsubsubsec-level-extent" id="Footnote-settings">
<h4 class="unnumberedsubsubsec">Footnote settings</h4>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bFI_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[FI]</code></strong><a class="copiable-link" href='#index-_005cn_005bFI_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-FI-_005bms_005d"></a>
<p>Defines the footnote indentation.  This is a Berkeley extension.
</p>
<p>Effective: next footnote.
</p>
<p>Default: 2<span class="dmn">n</span>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bFF_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[FF]</code></strong><a class="copiable-link" href='#index-_005cn_005bFF_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-FF-_005bms_005d"></a>
<p>Defines the format of automatically numbered footnotes,
and those for which the <code class="code">FS</code> request is given a marker argument, at
the bottom of a column or page.  This is a Berkeley extension.
</p><dl class="table">
<dt><code class="code">0</code></dt>
<dd><p>Set an automatic number<a class="footnote" id="DOCF8" href="#FOOT8"><sup>8</sup></a> as a
superscript (on typesetter devices) or surrounded by square brackets (on
terminals).  The footnote paragraph is indented as with <code class="code">PP</code> if
there is an <code class="code">FS</code> argument or an automatic number, and as with
<code class="code">LP</code> otherwise.  This is the default.
</p>
</dd>
<dt><code class="code">1</code></dt>
<dd><p>As <code class="code">0</code>, but set the marker as regular text and follow an
automatic number with a period.
</p>
</dd>
<dt><code class="code">2</code></dt>
<dd><p>As <code class="code">1</code>, but without indentation (like <code class="code">LP</code>).
</p>
</dd>
<dt><code class="code">3</code></dt>
<dd><p>As <code class="code">1</code>, but set the footnote paragraph with the marker hanging
(like <code class="code">IP</code>).
</p></dd>
</dl>

<p>Effective: next footnote.
</p>
<p>Default: 0.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bFPS_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[FPS]</code></strong><a class="copiable-link" href='#index-_005cn_005bFPS_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-FPS-_005bms_005d"></a>
<p>Defines the footnote type size.
</p>
<p>Effective: next footnote.
</p>
<p>Default: <code class="code">\n[PS] - 2p</code>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bFVS_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[FVS]</code></strong><a class="copiable-link" href='#index-_005cn_005bFVS_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-FVS-_005bms_005d"></a>
<p>Defines the footnote vertical spacing.
</p>
<p>Effective: next footnote.
</p>
<p>Default: <code class="code">\n[FPS] + 2p</code>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bFPD_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[FPD]</code></strong><a class="copiable-link" href='#index-_005cn_005bFPD_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-FPD-_005bms_005d"></a>
<p>Defines the footnote paragraph spacing.  This is a GNU extension.
</p>
<p>Effective: next footnote.
</p>
<p>Default: <code class="code">\n[PD] / 2</code>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bFR_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[FR]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bFR_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-FR-_005bms_005d"></a>
<p>Defines the ratio of the footnote line length to the current line
length.  This is a GNU extension.
</p>
<p>Effective: next footnote in single-column arrangements, next page
otherwise.
</p>
<p>Default: <code class="code">11/12</code>.
</p></dd></dl>

</div>
<div class="unnumberedsubsubsec-level-extent" id="Display-settings">
<h4 class="unnumberedsubsubsec">Display settings</h4>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bDD_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[DD]</code></strong><a class="copiable-link" href='#index-_005cn_005bDD_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-DD-_005bms_005d"></a>
<p>Sets the display distance&mdash;the vertical spacing before and after a
display, a <code class="code">tbl</code> table, an <code class="code">eqn</code> equation, or a <code class="code">pic</code>
image.  This is a Berkeley extension.
</p>
<p>Effective: next display boundary.
</p>
<p>Default: 0.5<span class="dmn">v</span> (1<span class="dmn">v</span> on low-resolution devices).
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bDI_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[DI]</code></strong><a class="copiable-link" href='#index-_005cn_005bDI_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-DI-_005bms_005d"></a>
<p>Sets the default amount by which to indent a display started with
<code class="code">DS</code> and <code class="code">ID</code> without arguments, to &lsquo;<samp class="samp">.DS&nbsp;I</samp>&rsquo; without
an indentation argument, and to equations set with &lsquo;<samp class="samp">.EQ&nbsp;I</samp>&rsquo;.
This is a GNU extension.
</p>
<p>Effective: next indented display.
</p>
<p>Default: 0.5<span class="dmn">i</span>.
</p></dd></dl>

</div>
<div class="unnumberedsubsubsec-level-extent" id="Other-settings">
<h4 class="unnumberedsubsubsec">Other settings</h4>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bMINGW_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[MINGW]</code></strong><a class="copiable-link" href='#index-_005cn_005bMINGW_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-MINGW-_005bms_005d"></a>
<p>Defines the default minimum width between columns in a multi-column
document.  This is a GNU extension.
</p>
<p>Effective: next page.
</p>
<p>Default: 2<span class="dmn">n</span>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bTC_002dMARGIN_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[TC-MARGIN]</code></strong><a class="copiable-link" href='#index-_005cn_005bTC_002dMARGIN_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-TC_002dMARGIN-_005bms_005d"></a>
<p>Defines the width of the field in which page numbers are set in a table
of contents entry; the right margin thus moves inboard by this amount.
This is a GNU extension.
</p>
<p>Effective: next <code class="code">PX</code> call.
</p>
<p>Default: <code class="code">\w'000'</code>
</p></dd></dl>



<hr>
</div>
</div>
<div class="subsection-level-extent" id="ms-Document-Description-Macros">
<div class="nav-panel">
<p>
Next: <a href="#ms-Body-Text" accesskey="n" rel="next">Body Text</a>, Previous: <a href="#ms-Document-Control-Settings" accesskey="p" rel="prev">Document Control Settings</a>, Up: <a href="#ms" accesskey="u" rel="up"><samp class="file">ms</samp></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Document-Description-Macros">4.6.4 Document Description Macros</h4>
<a class="index-entry-id" id="index-ms-macros_002c-document-description"></a>
<a class="index-entry-id" id="index-document-description-macros_002c-_005bms_005d"></a>

<p>Only the simplest document lacks a title.<a class="footnote" id="DOCF9" href="#FOOT9"><sup>9</sup></a>  As its level of sophistication (or
complexity) increases, it tends to acquire a date of revision,
explicitly identified authors, sponsoring institutions for authors, and,
at the rarefied heights, an abstract of its content.  Define these
data by calling the macros below in the order shown; <code class="code">DA</code> or
<code class="code">ND</code> can be called to set the document date (or other identifier)
at any time before (a) the abstract, if present, or (b) its information
is required in a header or footer.  Use of these macros is optional,
except that <code class="code">TL</code> is mandatory if any of <code class="code">RP</code>, <code class="code">AU</code>,
<code class="code">AI</code>, or <code class="code">AB</code> is called, and <code class="code">AE</code> is mandatory if
<code class="code">AB</code> is called.
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eRP"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.RP</code></strong> <var class="def-var-arguments">[<code class="code">no-repeat-info</code>] [<code class="code">no-renumber</code>]</var><a class="copiable-link" href='#index-_002eRP'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-RP-_005bms_005d"></a>
<p>Use the &ldquo;report&rdquo; (<abbr class="acronym">AT&amp;T</abbr>: &ldquo;released paper&rdquo;) format for your
document, creating a separate cover page.  The default arrangement is to
place most of the document description (title, author names and
institutions, and abstract, but not the date) at the top of the first
page.  If the optional <code class="code">no-repeat-info</code> argument is given,
<samp class="file">ms</samp> produces a cover page but does not repeat any of its
information subsequently (but see the <code class="code">DA</code> macro below regarding
the date).  Normally, <code class="code">RP</code> sets the page number following the cover
page to&nbsp;1.  Specifying the optional <code class="code">no-renumber</code> argument
suppresses this alteration.  Optional arguments can occur in any order.
<code class="code">no</code> is recognized as a synonym of <code class="code">no-repeat-info</code> for
<code class="code">AT&amp;T</code> compatibility.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eTL"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.TL</code></strong><a class="copiable-link" href='#index-_002eTL'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-TL-_005bms_005d"></a>
<p>Specify the document title.  <samp class="file">ms</samp> collects text on input lines
following this call into the title until reaching <code class="code">AU</code>, <code class="code">AB</code>,
or a heading or paragraphing macro call.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eAU"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.AU</code></strong><a class="copiable-link" href='#index-_002eAU'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-AU-_005bms_005d"></a>
<p>Specify an author&rsquo;s name.  <samp class="file">ms</samp> collects text on input lines
following this call into the author&rsquo;s name until reaching <code class="code">AI</code>,
<code class="code">AB</code>, another <code class="code">AU</code>, or a heading or paragraphing macro call.
Call it repeatedly to specify multiple authors.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eAI"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.AI</code></strong><a class="copiable-link" href='#index-_002eAI'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-AI-_005bms_005d"></a>
<p>Specify the preceding author&rsquo;s institution.  An <code class="code">AU</code> call is
usefully followed by at most one <code class="code">AI</code> call; if there are more, the
last <code class="code">AI</code> call controls.  <samp class="file">ms</samp> collects text on input lines
following this call into the author&rsquo;s institution until reaching
<code class="code">AU</code>, <code class="code">AB</code>, or a heading or paragraphing macro call.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eDA"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.DA</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">x</i></span> &hellip;]</var><a class="copiable-link" href='#index-_002eDA'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-DA-_005bms_005d"></a>
<p>Typeset the current date, or any arguments <var class="var">x</var>, in the center
footer, and, if <code class="code">RP</code> is also called, left-aligned at the end of the
description information on the cover page.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eND"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.ND</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">x</i></span> &hellip;]</var><a class="copiable-link" href='#index-_002eND'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ND-_005bms_005d"></a>
<p>Typeset the current date, or any arguments <var class="var">x</var>, if <code class="code">RP</code> is also
called, left-aligned at the end of the document description on the cover
page.  This is <code class="code">groff</code> <samp class="file">ms</samp>&rsquo;s default.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eAB"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.AB</code></strong> <var class="def-var-arguments">[<code class="code">no</code>]</var><a class="copiable-link" href='#index-_002eAB'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-AB-_005bms_005d"></a>
<p>Begin the abstract.  <samp class="file">ms</samp> collects text on input lines following
this call into the abstract until reaching an <code class="code">AE</code> call.  By
default, <samp class="file">ms</samp> places the word &ldquo;ABSTRACT&rdquo; centered and in italics
above the text of the abstract.  The optional argument <code class="code">no</code>
suppresses this heading.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eAE"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.AE</code></strong><a class="copiable-link" href='#index-_002eAE'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-AE-_005bms_005d"></a>
<p>End the abstract.
</p></dd></dl>

<p>An example document description, using a cover page, follows.
<a class="index-entry-id" id="index-cover-page-in-_005bms_005d_002c-example-markup"></a>
<a class="index-entry-id" id="index-example-markup_002c-cover-page-in-_005bms_005d"></a>
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.RP
.TL
The Inevitability of Code Bloat
in Commercial and Free Software
.AU
J.\&amp; Random Luser
.AI
University of West Bumblefuzz
.AB
This report examines the long-term growth of the code
bases in two large,
popular software packages;
the free Emacs and the commercial Microsoft Word.
While differences appear in the type or order of
features added,
due to the different methodologies used,
the results are the same in the end.
.PP
The free software approach is shown to be superior in
that while free software can become as bloated as
commercial offerings,
free software tends to have fewer serious bugs and the
added features are more in line with user demand.
.AE

<span class="r">&hellip;the rest of the paper&hellip;</span>
</pre></div>
</td></tr></table>


<hr>
</div>
<div class="subsection-level-extent" id="ms-Body-Text">
<div class="nav-panel">
<p>
Next: <a href="#ms-Page-Layout" accesskey="n" rel="next">Page layout</a>, Previous: <a href="#ms-Document-Description-Macros" accesskey="p" rel="prev">Document Description Macros</a>, Up: <a href="#ms" accesskey="u" rel="up"><samp class="file">ms</samp></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Body-Text">4.6.5 Body Text</h4>
<a class="index-entry-id" id="index-ms-macros_002c-body-text"></a>

<p>A variety of macros, registers, and strings can be used to structure and
style the body of your document.  They organize your text into
paragraphs, headings, footnotes, and inclusions of material such as
tables and figures.
</p>


<ul class="mini-toc">
<li><a href="#Text-settings-in-ms" accesskey="1">Text settings</a></li>
<li><a href="#Typographical-symbols-in-ms" accesskey="2">Typographical symbols</a></li>
<li><a href="#Paragraphs-in-ms" accesskey="3">Paragraphs</a></li>
<li><a href="#Headings-in-ms" accesskey="4">Headings</a></li>
<li><a href="#Typeface-and-decoration" accesskey="5">Typeface and decoration</a></li>
<li><a href="#Lists-in-ms" accesskey="6">Lists</a></li>
<li><a href="#Indented-regions-in-ms" accesskey="7">Indented regions</a></li>
<li><a href="#ms-keeps-and-displays" accesskey="8">Keeps, boxed keeps, and displays</a></li>
<li><a href="#ms-Insertions" accesskey="9">Tables, figures, equations, and references</a></li>
<li><a href="#ms-Footnotes">Footnotes</a></li>
<li><a href="#ms-language-and-localization">Language and localization</a></li>
</ul>
<hr>
<div class="subsubsection-level-extent" id="Text-settings-in-ms">
<div class="nav-panel">
<p>
Next: <a href="#Typographical-symbols-in-ms" accesskey="n" rel="next">Typographical symbols</a>, Previous: <a href="#ms-Body-Text" accesskey="p" rel="prev">Body Text</a>, Up: <a href="#ms-Body-Text" accesskey="u" rel="up">Body Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Text-settings-1">4.6.5.1 Text settings</h4>
<a class="index-entry-id" id="index-ms-macros_002c-text-settings"></a>

<p>The <code class="code">FAM</code> string, a GNU extension, sets the font family for body
text; the default is &lsquo;<samp class="samp">T</samp>&rsquo;.  The <code class="code">PS</code> and <code class="code">VS</code> registers
set the type size and vertical spacing (distance between text
baselines), respectively.  The font family and type size are ignored on
terminal devices.  Setting these parameters before the first call of a
heading, paragraphing, or (non-date) document description macro also
applies them to headers, footers, and (for <code class="code">FAM</code>) footnotes.
</p>
<p>Which font families are available depends on the output device; as a
convention, <code class="code">T</code> selects a serif family (&ldquo;Times&rdquo;), <code class="code">H</code> a
sans-serif family (&ldquo;Helvetica&rdquo;), and <code class="code">C</code> a monospaced family
(&ldquo;Courier&rdquo;).  The man page for the output driver documents its font
repertoire.  Consult the <cite class="cite">groff<span class="r">(1)</span></cite> man page for lists of
available output devices and their drivers.
</p>
<p>The hyphenation mode (as used by the <code class="code">hy</code> request) is set from the
<code class="code">HY</code> register.  Setting <code class="code">HY</code> to &lsquo;<samp class="samp">0</samp>&rsquo; is equivalent to
using the <code class="code">nh</code> request.  This is a Tenth Edition Research Unix
extension.
</p>

<hr>
</div>
<div class="subsubsection-level-extent" id="Typographical-symbols-in-ms">
<div class="nav-panel">
<p>
Next: <a href="#Paragraphs-in-ms" accesskey="n" rel="next">Paragraphs</a>, Previous: <a href="#Text-settings-in-ms" accesskey="p" rel="prev">Text settings</a>, Up: <a href="#ms-Body-Text" accesskey="u" rel="up">Body Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Typographical-symbols">4.6.5.2 Typographical symbols</h4>
<a class="index-entry-id" id="index-ms-macros_002c-obtaining-typographical-symbols"></a>

<p><samp class="file">ms</samp> provides a few strings to obtain typographical symbols not
easily entered with the keyboard.  These and many others are available
as special character escape sequences&mdash;see the <cite class="cite">groff_char<span class="r">(7)</span></cite>
man page.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_002d_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[-]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_002d_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002d-_005bms_005d"></a>
<p>Interpolate an em dash.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bQ_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[Q]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bQ_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-Q-_005bms_005d"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002a_005bU_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[U]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bU_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-U-_005bms_005d"></a>
<p>Interpolate typographer&rsquo;s quotation marks where available, and neutral
double quotes otherwise.  <code class="code">\*Q</code> is the left quote and <code class="code">\*U</code>
the right.
</p></dd></dl>


<hr>
</div>
<div class="subsubsection-level-extent" id="Paragraphs-in-ms">
<div class="nav-panel">
<p>
Next: <a href="#Headings-in-ms" accesskey="n" rel="next">Headings</a>, Previous: <a href="#Typographical-symbols-in-ms" accesskey="p" rel="prev">Typographical symbols</a>, Up: <a href="#ms-Body-Text" accesskey="u" rel="up">Body Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Paragraphs-2">4.6.5.3 Paragraphs</h4>
<a class="index-entry-id" id="index-ms-macros_002c-paragraph-handling"></a>

<p>Paragraphing macros <em class="dfn">break</em>, or terminate, any pending output line
so that a new paragraph can begin.  Several paragraph types are
available, differing in how indentation applies to them: to left, right,
or both margins; to the first output line of the paragraph, all output
lines, or all but the first.  All paragraphing macro calls cause the
insertion of vertical space in the amount stored in the <code class="code">PD</code>
register, except at page or column breaks.  Alternatively, a blank input
line breaks the output line and vertically spaces by one vee.
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eLP"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.LP</code></strong><a class="copiable-link" href='#index-_002eLP'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-LP-_005bms_005d"></a>
<p>Set a paragraph without any (additional) indentation.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002ePP"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.PP</code></strong><a class="copiable-link" href='#index-_002ePP'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-PP-_005bms_005d"></a>
<p>Set a paragraph with a first-line left indentation in the amount stored
in the <code class="code">PI</code> register.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eIP"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.IP</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">marker</i></span> [<span class="r"><i class="slanted">width</i></span>]]</var><a class="copiable-link" href='#index-_002eIP'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-IP-_005bms_005d"></a>
<p>Set a paragraph with a left indentation.  The optional <var class="var">marker</var> is
not indented and is empty by default.  It has several applications;
see <a class="ref" href="#Lists-in-ms">Lists</a>.  <var class="var">width</var> overrides the indentation amount
stored in the <code class="code">PI</code> register; its default unit is &lsquo;<samp class="samp">n</samp>&rsquo;.  Once
specified, <var class="var">width</var> applies to further <code class="code">IP</code> calls until
specified again or a heading or different paragraphing macro is called.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eQP"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.QP</code></strong><a class="copiable-link" href='#index-_002eQP'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-QP-_005bms_005d"></a>
<p>Set a paragraph indented from both left and right margins by the amount
stored in the <code class="code">QI</code> register.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eQS"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.QS</code></strong><a class="copiable-link" href='#index-_002eQS'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-QS-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eQE"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.QE</code></strong><a class="copiable-link" href='#index-_002eQE'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-QE-_005bms_005d"></a>
<p>Begin (<code class="code">QS</code>) and end (<code class="code">QE</code>) a region where each paragraph is
indented from both margins by the amount stored in the <code class="code">QI</code>
register.  The text between <code class="code">QS</code> and <code class="code">QE</code> can be structured
further by use of other paragraphing macros.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eXP"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.XP</code></strong><a class="copiable-link" href='#index-_002eXP'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-XP-_005bms_005d"></a>
<p>Set an &ldquo;exdented&rdquo; paragraph&mdash;one with a left indentation in the
amount stored in the <code class="code">PI</code> register on every line <em class="emph">except</em> the
first (also known as a hanging indent).  This is a Berkeley extension.
</p></dd></dl>

<p>The following example illustrates the use of paragraphing macros.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.NH 2
Cases used in the 2001 study
.LP
Two software releases were considered for this report.
.PP
The first is commercial software;
the second is free.
.IP \[bu]
Microsoft Word for Windows,
starting with version 1.0 through the current version
(Word 2000).
.IP \[bu]
GNU Emacs,
from its first appearance as a standalone editor through
the current version (v20).
See [Bloggs 2002] for details.
.QP
Franklin's Law applied to software:
software expands to outgrow both RAM and disk space over
time.
.SH
Bibliography
.XP
Bloggs, Joseph R.,
.I &quot;Everyone's a Critic&quot; ,
Underground Press, March 2002.
A definitive work that answers all questions and
criticisms about the quality and usability of free
software.
</pre></div>
</td></tr></table>


<hr>
</div>
<div class="subsubsection-level-extent" id="Headings-in-ms">
<div class="nav-panel">
<p>
Next: <a href="#Typeface-and-decoration" accesskey="n" rel="next">Typeface and decoration</a>, Previous: <a href="#Paragraphs-in-ms" accesskey="p" rel="prev">Paragraphs</a>, Up: <a href="#ms-Body-Text" accesskey="u" rel="up">Body Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Headings">4.6.5.4 Headings</h4>
<a class="index-entry-id" id="index-ms-macros_002c-headings"></a>

<p>Use headings to create a sequential or hierarchical structure for your
document.  The <samp class="file">ms</samp> macros print headings in <strong class="strong">bold</strong> using
the same font family and, by default, type size as the body text.
Headings are available with and without automatic numbering.  Text on
input lines following the macro call becomes the heading&rsquo;s title.  Call
a paragraphing macro to end the heading text and start the section&rsquo;s
content.
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eNH"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.NH</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">depth</i></span>]</var><a class="copiable-link" href='#index-_002eNH'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-NH-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eNH-1"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.NH</code></strong> <var class="def-var-arguments"><code class="t">S</code> <span class="r"><i class="slanted">heading-depth-index</i></span> &hellip;</var><a class="copiable-link" href='#index-_002eNH-1'> &para;</a></span></dt>
<dd><p>Set an automatically numbered heading.
</p>
<p><samp class="file">ms</samp> produces a numbered heading the form <var class="var">a.b.c&hellip;</var>, to
any depth desired, with the numbering of each depth increasing
automatically and being reset to zero when a more significant level is
increased.  &ldquo;1&rdquo;&nbsp;is the most significant or coarsest division of
the document.  Only non-zero values are output.  If <var class="var">depth</var> is
omitted, it is taken to be &lsquo;<samp class="samp">1</samp>&rsquo;.
</p>
<p>If you specify <var class="var">depth</var> such that an ascending gap occurs relative to
the previous <code class="code">NH</code> call&mdash;that is, you &ldquo;skip a depth&rdquo;, as by
&lsquo;<samp class="samp">.NH 1</samp>&rsquo; and then &lsquo;<samp class="samp">.NH 3</samp>&rsquo;&mdash;<code class="code">groff</code> <samp class="file">ms</samp> emits a
warning on the standard error stream.
</p>
<p>Alternatively, you can give <code class="code">NH</code> a first argument of&nbsp;<code class="code">S</code>,
followed by integers to number the heading depths explicitly.  Further
automatic numbering, if used, resumes using the specified indices as
their predecessors.
This feature is a Berkeley extension.
</p></dd></dl>

<p>An example may be illustrative.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.NH 1
Animalia
.NH 2
Arthropoda
.NH 3
Crustacea
.NH 2
Chordata
.NH S 6 6 6
Daimonia
.NH 1
Plantae
</pre></div>
</td></tr></table>

<p>The above results in numbering as follows; the vertical space that
normally precedes each heading is omitted.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">1.  Animalia
1.1.  Arthropoda
1.1.1.  Crustacea
1.2.  Chordata
6.6.6.  Daimonia
7.  Plantae
</pre></div></div>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bSN_002dSTYLE_005d-1"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[SN-STYLE]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bSN_002dSTYLE_005d-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-SN_002dSTYLE-_005bms_005d-1"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002a_005bSN_002dDOT_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[SN-DOT]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bSN_002dDOT_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-SN_002dDOT-_005bms_005d"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002a_005bSN_002dNO_002dDOT_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[SN-NO-DOT]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bSN_002dNO_002dDOT_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-SN_002dNO_002dDOT-_005bms_005d"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002a_005bSN_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[SN]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bSN_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-SN-_005bms_005d"></a>
<p>After <code class="code">NH</code> is called, the assigned number is made available in the
strings <code class="code">SN-DOT</code> (as it appears in a printed heading with default
formatting, followed by a terminating period) and <code class="code">SN-NO-DOT</code> (with
the terminating period omitted).  These are GNU extensions.
</p>
<p>You can control the style used to print numbered headings by defining an
appropriate alias for the string <code class="code">SN-STYLE</code>.  By default,
<code class="code">SN-STYLE</code> is aliased to <code class="code">SN-DOT</code>.  If you prefer to omit the
terminating period from numbers appearing in numbered headings, you may
define the alias as follows.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.als SN-STYLE SN-NO-DOT
</pre></div></div>

<p>Any such change in numbering style becomes effective from the next use
of <code class="code">NH</code> following redefinition of the alias for <code class="code">SN-STYLE</code>.
The formatted number of the current heading is available in the
<code class="code">SN</code> string (a feature first documented by Berkeley), which
facilitates its inclusion in, for example, table captions, equation
labels, and <code class="code">XS</code>/<code class="code">XA</code>/<code class="code">XE</code> table of contents entries.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eSH"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.SH</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">depth</i></span>]</var><a class="copiable-link" href='#index-_002eSH'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-SH-_005bms_005d"></a>
<p>Set an unnumbered heading.
</p>
<p>The optional <var class="var">depth</var> argument is a GNU extension indicating the
heading depth corresponding to the <var class="var">depth</var> argument of <code class="code">NH</code>.
It matches the type size at which the heading is set to that of a
numbered heading at the same depth when the <code class="code">GROWPS</code> and
<code class="code">PSINCR</code> heading size adjustment mechanism is in effect.
</p></dd></dl>

<p>If the <code class="code">GROWPS</code> register is set to a value greater than the
<var class="var">level</var> argument to <code class="code">NH</code> or <code class="code">SH</code>, the type size of a
heading produced by these macros increases by <code class="code">PSINCR</code> units over
the size specified by <code class="code">PS</code> multiplied by the difference of
<code class="code">GROWPS</code> and <var class="var">level</var>.  The value stored in <code class="code">PSINCR</code> is
interpreted in <code class="code">groff</code> basic units; the <code class="code">p</code> scaling unit
should be employed when assigning a value specified in points.  For
example, the sequence
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.nr PS 10
.nr GROWPS 3
.nr PSINCR 1.5p
.NH 1
Carnivora
.NH 2
Felinae
.NH 3
Felis catus
.SH 2
Machairodontinae
</pre></div>
</td></tr></table>

<p>will cause &ldquo;1. Carnivora&rdquo; to be printed in 13-point text, followed by
&ldquo;1.1. Felinae&rdquo; in 11.5-point text, while &ldquo;1.1.1. Felis catus&rdquo; and
all more deeply nested heading levels will remain in the 10-point text
specified by the <code class="code">PS</code> register.  &ldquo;Machairodontinae&rdquo; is printed at
11.5 points, since it corresponds to heading level&nbsp;2.
</p>
<p>The <code class="code">HORPHANS</code> register operates in conjunction with the <code class="code">NH</code>
and <code class="code">SH</code> macros to inhibit the printing of isolated headings at the
bottom of a page; it specifies the minimum number of lines of an
immediately subsequent paragraph that must be kept on the same page as
the heading.  If insufficient space remains on the current page to
accommodate the heading and this number of lines of paragraph text, a
page break is forced before the heading is printed.  Any display macro
call or <code class="code">tbl</code>, <code class="code">pic</code>, or <code class="code">eqn</code> region between the heading
and the subsequent paragraph suppresses this grouping.  See <a class="xref" href="#ms-keeps-and-displays">Keeps, boxed keeps, and displays</a> and <a class="ref" href="#ms-Insertions">Tables, figures, equations, and references</a>.
</p>

<hr>
</div>
<div class="subsubsection-level-extent" id="Typeface-and-decoration">
<div class="nav-panel">
<p>
Next: <a href="#Lists-in-ms" accesskey="n" rel="next">Lists</a>, Previous: <a href="#Headings-in-ms" accesskey="p" rel="prev">Headings</a>, Up: <a href="#ms-Body-Text" accesskey="u" rel="up">Body Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Typeface-and-decoration-1">4.6.5.5 Typeface and decoration</h4>

<p>The <samp class="file">ms</samp> macros provide a variety of ways to style text.
Attend closely to the ordering of arguments labeled <var class="var">pre</var> and
<var class="var">post</var>, which is not intuitive.  Support for <var class="var">pre</var>
arguments is a GNU extension.<a class="footnote" id="DOCF10" href="#FOOT10"><sup>10</sup></a>
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eB"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.B</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">text</i></span> [<span class="r"><i class="slanted">post</i></span> [<span class="r"><i class="slanted">pre</i></span>]]]</var><a class="copiable-link" href='#index-_002eB'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-B-_005bms_005d"></a>
<p>Style <var class="var">text</var> in <b class="b">bold</b>, followed by <var class="var">post</var> in the previous
font style without intervening space, and preceded by <var class="var">pre</var>
similarly.  Without arguments, <samp class="file">ms</samp> styles subsequent text in bold
until the next paragraphing, heading, or no-argument typeface macro
call.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eR-1"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.R</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">text</i></span> [<span class="r"><i class="slanted">post</i></span> [<span class="r"><i class="slanted">pre</i></span>]]]</var><a class="copiable-link" href='#index-_002eR-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-R-_005bms_005d"></a>
<p>As <code class="code">B</code>, but use the roman style (upright text of normal weight)
instead of bold.  Argument recognition is a GNU extension.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eI"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.I</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">text</i></span> [<span class="r"><i class="slanted">post</i></span> [<span class="r"><i class="slanted">pre</i></span>]]]</var><a class="copiable-link" href='#index-_002eI'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-I-_005bms_005d"></a>
<p>As <code class="code">B</code>, but use an <i class="i">italic</i> or oblique style instead of bold.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eBI"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.BI</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">text</i></span> [<span class="r"><i class="slanted">post</i></span> [<span class="r"><i class="slanted">pre</i></span>]]]</var><a class="copiable-link" href='#index-_002eBI'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-BI-_005bms_005d"></a>
<p>As <code class="code">B</code>, but use a bold italic or bold oblique style instead of
upright bold.  This is a Tenth Edition Research Unix extension.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eCW-1"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.CW</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">text</i></span> [<span class="r"><i class="slanted">post</i></span> [<span class="r"><i class="slanted">pre</i></span>]]]</var><a class="copiable-link" href='#index-_002eCW-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-CW-_005bms_005d"></a>
<p>As <code class="code">B</code>, but use a <code class="t">constant-width</code> (monospaced) roman typeface
instead of bold.  This is a Tenth Edition Research Unix extension.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eBX"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.BX</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">text</i></span>]</var><a class="copiable-link" href='#index-_002eBX'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-BX-_005bms_005d"></a>
<p>Typeset <var class="var">text</var> and draw a box around it.  On terminal devices,
reverse video is used instead.  If you want <var class="var">text</var> to contain space,
use unbreakable space or horizontal motion escape sequences (<code class="code">\~</code>,
<code class="code">\<kbd class="key">SP</kbd></code>, <code class="code">\^</code>, <code class="code">\|</code>, <code class="code">\0</code> or <code class="code">\h</code>).
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eUL"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.UL</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">text</i></span> [<span class="r"><i class="slanted">post</i></span>]]</var><a class="copiable-link" href='#index-_002eUL'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-UL-_005bms_005d"></a>
<p>Typeset <var class="var">text</var> with an underline.  <var class="var">post</var>, if present, is set
after <var class="var">text</var> with no intervening space.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eLG"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.LG</code></strong><a class="copiable-link" href='#index-_002eLG'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-LG-_005bms_005d"></a>
<p>Set subsequent text in larger type (two points larger than the
current size) until the next type size, paragraphing, or heading macro
call.  You can specify this macro multiple times to enlarge the type
size as needed.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eSM"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.SM</code></strong><a class="copiable-link" href='#index-_002eSM'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-SM-_005bms_005d"></a>
<p>Set subsequent text in smaller type (two points smaller than the current
size) until the next type size, paragraphing, or heading macro call.
You can specify this macro multiple times to reduce the type size as
needed.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eNL"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.NL</code></strong><a class="copiable-link" href='#index-_002eNL'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-NL-_005bms_005d"></a>
<p>Set subsequent text at the normal type size (the amount in the <code class="code">PS</code>
register).
</p></dd></dl>

<p><var class="var">pre</var> and <var class="var">post</var> arguments are typically used to simplify the
attachment of punctuation to styled words.  When <var class="var">pre</var> is used,
a hyphenation control escape sequence <code class="code">\%</code> that would ordinarily
start <var class="var">text</var> must start <var class="var">pre</var> instead to have the desired
effect.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">The CS course's students found one C language keyword
.CW static ) \%(
most troublesome.
</pre></div>
</td></tr></table>

<p>The foregoing example produces output as follows.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted"><span class="r">The CS course&rsquo;s students found one C language keyword (<code class="t">static</code>)
most troublesome.</span>
</pre></div>
</td></tr></table>

<p>You can use the output line continuation escape sequence <code class="code">\c</code> to
achieve the same result (see <a class="pxref" href="#Line-Continuation">Line Continuation</a>).  It is also
portable to older <samp class="file">ms</samp> implementations.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">The CS course's students found one C language keyword
\%(\c
.CW \%static )
most troublesome.
</pre></div>
</td></tr></table>

<p><code class="code">groff</code> <samp class="file">ms</samp> also offers strings to begin and end super- and
subscripting.  These are GNU extensions.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_007b_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[{]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_007b_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_007b-_005bms_005d"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002a_005b_007d_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[}]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_007d_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_007d-_005bms_005d"></a>
<p>Begin and end superscripting, respectively.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_003c_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[&lt;]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_003c_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_003c-_005bms_005d"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002a_005b_003e_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[&gt;]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_003e_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_003e-_005bms_005d"></a>
<p>Begin and end subscripting, respectively.
</p></dd></dl>

<p>Rather than calling the <code class="code">CW</code> macro, in <code class="code">groff</code> <samp class="file">ms</samp> you
might prefer to change the font family to Courier by setting the
<code class="code">FAM</code> string to &lsquo;<samp class="samp">C</samp>&rsquo;.  You can then use all four style macros
above, returning to the default family (Times) with &lsquo;<samp class="samp">.ds FAM T</samp>&rsquo;.
Because changes to <code class="code">FAM</code> take effect only at the next paragraph,
<code class="code">CW</code> remains useful to &ldquo;inline&rdquo; a change to the font family,
similarly to the practice of this document in noting syntactical
elements of <samp class="file">ms</samp> and <code class="code">groff</code>.
</p>

<hr>
</div>
<div class="subsubsection-level-extent" id="Lists-in-ms">
<div class="nav-panel">
<p>
Next: <a href="#Indented-regions-in-ms" accesskey="n" rel="next">Indented regions</a>, Previous: <a href="#Typeface-and-decoration" accesskey="p" rel="prev">Typeface and decoration</a>, Up: <a href="#ms-Body-Text" accesskey="u" rel="up">Body Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Lists">4.6.5.6 Lists</h4>
<a class="index-entry-id" id="index-ms-macros_002c-lists"></a>

<p>The <var class="var">marker</var> argument to the <code class="code">IP</code> macro can be employed to
present a variety of lists; for instance, you can use a bullet glyph
(<code class="code">\[bu]</code>) for unordered lists, a number (or auto-incrementing
register) for numbered lists, or a word or phrase for glossary-style or
definition lists.  If you set the paragraph indentation register
<code class="code">PI</code> before calling <code class="code">IP</code>, you can later reorder the items in
the list without having to ensure that a <var class="var">width</var> argument remains
affixed to the first call.
</p>
<p>The following is an example of a bulleted list.
<a class="index-entry-id" id="index-example-markup_002c-bulleted-list-_005bms_005d"></a>
<a class="index-entry-id" id="index-bulleted-list_002c-example-markup-_005bms_005d"></a>
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.nr PI 2n
A bulleted list:
.IP \[bu]
lawyers
.IP \[bu]
guns
.IP \[bu]
money
</pre></div>
</td></tr></table>

<div class="example">
<div class="group"><pre class="example-preformatted">A bulleted list:

&bull; lawyers

&bull; guns

&bull; money
</pre></div></div>

<p>The following is an example of a numbered list.
<a class="index-entry-id" id="index-example-markup_002c-numbered-list-_005bms_005d"></a>
<a class="index-entry-id" id="index-numbered-list_002c-example-markup-_005bms_005d"></a>
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.nr step 0 1
.nr PI 3n
A numbered list:
.IP \n+[step]
lawyers
.IP \n+[step]
guns
.IP \n+[step]
money
</pre></div>
</td></tr></table>

<div class="example">
<div class="group"><pre class="example-preformatted">A numbered list:

1. lawyers

2. guns

3. money
</pre></div></div>

<p>Here we have employed the <code class="code">nr</code> request to create a register of our
own, &lsquo;<samp class="samp">step</samp>&rsquo;.  We initialized it to zero and assigned it an
auto-increment of 1.  Each time we use the escape sequence
&lsquo;<samp class="samp">\n+[PI]</samp>&rsquo; (note the plus sign), the formatter applies the increment
just before interpolating the register&rsquo;s value.  Preparing the <code class="code">PI</code>
register as well enables us to rearrange the list without the tedium of
updating macro calls.
</p>
<p>The next example illustrates a glossary-style list.
<a class="index-entry-id" id="index-example-markup_002c-glossary_002dstyle-list-_005bms_005d"></a>
<a class="index-entry-id" id="index-glossary_002dstyle-list_002c-example-markup-_005bms_005d"></a>
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">A glossary-style list:
.IP lawyers 0.4i
Two or more attorneys.
.IP guns
Firearms,
preferably large-caliber.
.IP money
Gotta pay for those
lawyers and guns!
</pre></div>
</td></tr></table>

<div class="example">
<div class="group"><pre class="example-preformatted">A glossary-style list:

lawyers
      Two or more attorneys.

guns  Firearms, preferably large-caliber.

money
      Gotta pay for those lawyers and guns!
</pre></div></div>

<p>In the previous example, observe how the <code class="code">IP</code> macro places the
definition on the same line as the term if it has enough space.  If this
is not what you want, there are a few workarounds we will illustrate by
modifying the example.  First, you can use a <code class="code">br</code> request to force
a break after printing the term or label.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.IP guns
.br
Firearms,
</pre></div>
</td></tr></table>

<p>Second, you could apply the <code class="code">\p</code> escape sequence to force a break.
The space following the escape sequence is important; if you omit it,
<code class="code">groff</code> prints the first word of the paragraph text on the same
line as the term or label (if it fits) <em class="emph">then</em> breaks the line.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.IP guns
\p Firearms,
</pre></div>
</td></tr></table>

<p>Finally, you may append a horizontal motion to the marker with the
<code class="code">\h</code> escape sequence; using the same amount as the indentation will
ensure that the marker is too wide for <code class="code">groff</code> to treat it as
&ldquo;fitting&rdquo; on the same line as the paragraph text.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.IP guns\h'0.4i'
Firearms,
</pre></div>
</td></tr></table>

<p>In each case, the result is the same.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">A glossary-style list:

lawyers
      Two or more attorneys.

guns
      Firearms, preferably large-caliber.

money
      Gotta pay for those lawyers and guns!
</pre></div></div>


<hr>
</div>
<div class="subsubsection-level-extent" id="Indented-regions-in-ms">
<div class="nav-panel">
<p>
Next: <a href="#ms-keeps-and-displays" accesskey="n" rel="next">Keeps, boxed keeps, and displays</a>, Previous: <a href="#Lists-in-ms" accesskey="p" rel="prev">Lists</a>, Up: <a href="#ms-Body-Text" accesskey="u" rel="up">Body Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Indented-regions">4.6.5.7 Indented regions</h4>

<p>You may need to indent a region of text while otherwise formatting it
normally.  Indented regions can be nested; you can change <code class="code">\n[PI]</code>
before each call to vary the amount of inset.
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eRS"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.RS</code></strong><a class="copiable-link" href='#index-_002eRS'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-RS-_005bms_005d"></a>
<p>Begin a region where headings, paragraphs, and displays are indented
(further) by the amount stored in the <code class="code">PI</code> register.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eRE"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.RE</code></strong><a class="copiable-link" href='#index-_002eRE'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-RE-_005bms_005d"></a>
<p>End the (next) most recent indented region.
</p></dd></dl>

<p>This feature enables you to easily line up text under hanging and
indented paragraphs.
<a class="index-entry-id" id="index-ms-macros_002c-nested-lists"></a>
<a class="index-entry-id" id="index-nested-lists-_005bms_005d"></a>
For example, you may wish to structure lists hierarchically.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.IP \[bu] 2
Lawyers:
.RS
.IP \[bu]
Dewey,
.IP \[bu]
Cheatham,
and
.IP \[bu]
and Howe.
.RE
.IP \[bu]
Guns
</pre></div>
</td></tr></table>

<div class="example">
<div class="group"><pre class="example-preformatted">&bull; Lawyers:

  &bull;  Dewey,

  &bull;  Cheatham, and

  &bull;  Howe.

&bull; Guns
</pre></div></div>


<hr>
</div>
<div class="subsubsection-level-extent" id="ms-keeps-and-displays">
<div class="nav-panel">
<p>
Next: <a href="#ms-Insertions" accesskey="n" rel="next">Tables, figures, equations, and references</a>, Previous: <a href="#Indented-regions-in-ms" accesskey="p" rel="prev">Indented regions</a>, Up: <a href="#ms-Body-Text" accesskey="u" rel="up">Body Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Keeps_002c-boxed-keeps_002c-and-displays">4.6.5.8 Keeps, boxed keeps, and displays</h4>
<a class="index-entry-id" id="index-ms-macros_002c-displays"></a>
<a class="index-entry-id" id="index-ms-macros_002c-keeps"></a>
<a class="index-entry-id" id="index-keeps-_005bms_005d"></a>

<p>On occasion, you may want to <em class="dfn">keep</em> several lines of text, or a
region of a document, together on a single page, preventing an automatic
page break within certain boundaries.  This can cause a page break to
occur earlier than it normally would.  For example, you may want to keep
two paragraphs together, or a paragraph that refers to a table, list, or
figure adjacent to the item it discusses.  <samp class="file">ms</samp> provides the
<code class="code">KS</code> and <code class="code">KE</code> macros for this purpose.
</p>
<p>You can alternatively specify a <em class="dfn">floating keep</em>: if a keep cannot
fit on the current page, <samp class="file">ms</samp> holds its contents and
allows material following the keep (in the source document) to fill the
remainder of the current page.  When the page breaks, whether by
reaching the end or <code class="code">bp</code> request, <samp class="file">ms</samp> puts the floating keep
at the beginning of the next page.  This is useful for placing large
graphics or tables that do not need to appear exactly where they occur
in the source document.
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eKS"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.KS</code></strong><a class="copiable-link" href='#index-_002eKS'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-KS-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eKF"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.KF</code></strong><a class="copiable-link" href='#index-_002eKF'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-KF-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eKE"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.KE</code></strong><a class="copiable-link" href='#index-_002eKE'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-KE-_005bms_005d"></a>
<p><code class="code">KS</code> begins a keep, <code class="code">KF</code> a floating keep, and <code class="code">KE</code> ends a
keep of either kind.
</p></dd></dl>

<p>As an alternative to the keep mechanism, the <code class="code">ne</code> request forces a
page break if there is not at least the amount of vertical space
specified in its argument remaining on the page (see <a class="pxref" href="#Page-Control">Page Control</a>).
One application of <code class="code">ne</code> is to reserve space on the page for a
figure or illustration to be included later.
</p>
<a class="index-entry-id" id="index-boxes-_005bms_005d"></a>
<p>A <em class="dfn">boxed keep</em> has a frame drawn around it.
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eB1"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.B1</code></strong><a class="copiable-link" href='#index-_002eB1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-B1-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eB2"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.B2</code></strong><a class="copiable-link" href='#index-_002eB2'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-B2-_005bms_005d"></a>
<p><code class="code">B1</code> begins a keep with a box drawn around it.  <code class="code">B2</code> ends a
boxed keep.
</p></dd></dl>

<p>Boxed keep macros cause breaks; if you need to box a word or phrase
within a line, see the <code class="code">BX</code> macro in <a class="ref" href="#Typeface-and-decoration">Typeface and decoration</a>.
Box lines are drawn as close as possible to the text they enclose so
that they are usable within paragraphs.  If you wish to box one or more
paragraphs, you may improve the appearance by calling <code class="code">B1</code> after
the first paragraphing macro, and by adding a small amount of vertical
space before calling <code class="code">B2</code>.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.LP
.B1
.I Warning:
Happy Fun Ball may suddenly accelerate to dangerous
speeds.
.sp \n[PD]/2 \&quot; space by half the inter-paragraph distance
.B2
</pre></div>
</td></tr></table>

<p>If you want a boxed keep to float, you will need to enclose the
<code class="code">B1</code> and <code class="code">B2</code> calls within a pair of <code class="code">KF</code> and <code class="code">KE</code>
calls.
</p>
<a class="index-entry-id" id="index-displays-_005bms_005d"></a>
<p><em class="dfn">Displays</em> turn off filling; lines of verse or program code are
shown with their lines broken as in the source document without
requiring <code class="code">br</code> requests between lines.  Displays can be kept on a
single page or allowed to break across pages.  The <code class="code">DS</code> macro
begins a kept display of the layout specified in its first argument;
non-kept displays are begun with dedicated macros corresponding to their
layout.
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eDS"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.DS</code></strong> <var class="def-var-arguments"><code class="t">L</code></var><a class="copiable-link" href='#index-_002eDS'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-DS-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eLD"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.LD</code></strong><a class="copiable-link" href='#index-_002eLD'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-LD-_005bms_005d"></a>
<p>Begin (<code class="code">DS</code>: kept) left-aligned display.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eDS-1"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.DS</code></strong> <var class="def-var-arguments">[<code class="t">I</code> [<span class="r"><i class="slanted">indent</i></span>]]</var><a class="copiable-link" href='#index-_002eDS-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-DS-_005bms_005d-1"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eID"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.ID</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">indent</i></span>]</var><a class="copiable-link" href='#index-_002eID'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ID-_005bms_005d"></a>
<p>Begin (<code class="code">DS</code>: kept) display indented by <var class="var">indent</var> if specified,
and by the amount of the <code class="code">DI</code> register otherwise.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eDS-2"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.DS</code></strong> <var class="def-var-arguments"><code class="t">B</code></var><a class="copiable-link" href='#index-_002eDS-2'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-DS-_005bms_005d-2"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eBD"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.BD</code></strong><a class="copiable-link" href='#index-_002eBD'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-BD-_005bms_005d"></a>
<p>Begin a (<code class="code">DS</code>: kept) a block display: the entire display is
left-aligned, but indented such that the longest line in the display
is centered on the page.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eDS-3"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.DS</code></strong> <var class="def-var-arguments"><code class="t">C</code></var><a class="copiable-link" href='#index-_002eDS-3'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-DS-_005bms_005d-3"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eCD"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.CD</code></strong><a class="copiable-link" href='#index-_002eCD'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-CD-_005bms_005d"></a>
<p>Begin a (<code class="code">DS</code>: kept) centered display: each line in the display
is centered.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eDS-4"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.DS</code></strong> <var class="def-var-arguments"><code class="t">R</code></var><a class="copiable-link" href='#index-_002eDS-4'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-DS-_005bms_005d-4"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eRD"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.RD</code></strong><a class="copiable-link" href='#index-_002eRD'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-RD-_005bms_005d"></a>
<p>Begin a (<code class="code">DS</code>: kept) right-aligned display.  This is a GNU
extension.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eDE"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.DE</code></strong><a class="copiable-link" href='#index-_002eDE'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-DE-_005bms_005d"></a>
<p>End any display.
</p></dd></dl>

<p>The distance stored in the <code class="code">DD</code> register is inserted before and
after each pair of display macros; this is a Berkeley extension.  In
<code class="code">groff</code> <samp class="file">ms</samp>, this distance replaces any adjacent
inter-paragraph distance or subsequent spacing prior to a section
heading.  The <code class="code">DI</code> register is a GNU extension; its value is an
indentation applied to displays created with &lsquo;<samp class="samp">.DS</samp>&rsquo; and &lsquo;<samp class="samp">.ID</samp>&rsquo;
without arguments, to &lsquo;<samp class="samp">.DS I</samp>&rsquo; without an indentation argument, and
to indented equations set with &lsquo;<samp class="samp">.EQ</samp>&rsquo;.  Changes to either register
take effect at the next display boundary.
</p>

<hr>
</div>
<div class="subsubsection-level-extent" id="ms-Insertions">
<div class="nav-panel">
<p>
Next: <a href="#ms-Footnotes" accesskey="n" rel="next">Footnotes</a>, Previous: <a href="#ms-keeps-and-displays" accesskey="p" rel="prev">Keeps, boxed keeps, and displays</a>, Up: <a href="#ms-Body-Text" accesskey="u" rel="up">Body Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Tables_002c-figures_002c-equations_002c-and-references">4.6.5.9 Tables, figures, equations, and references</h4>
<a class="index-entry-id" id="index-ms-macros_002c-tables"></a>
<a class="index-entry-id" id="index-ms-macros_002c-figures"></a>
<a class="index-entry-id" id="index-ms-macros_002c-equations"></a>
<a class="index-entry-id" id="index-ms-macros_002c-references"></a>
<a class="index-entry-id" id="index-tables-_005bms_005d"></a>
<a class="index-entry-id" id="index-figures-_005bms_005d"></a>
<a class="index-entry-id" id="index-equations-_005bms_005d"></a>
<a class="index-entry-id" id="index-references-_005bms_005d"></a>

<p>The <samp class="file">ms</samp> package is often used with the <code class="code">tbl</code>, <code class="code">pic</code>,
<code class="code">eqn</code>, and <code class="code">refer</code> preprocessors.
<a class="index-entry-id" id="index-tbl"></a>
<a class="index-entry-id" id="index-pic"></a>
<a class="index-entry-id" id="index-eqn"></a>
<a class="index-entry-id" id="index-refer"></a>
Mark text meant for preprocessors by enclosing it in pairs of tokens
as follows, with nothing between the dot and the macro name.  The
preprocessors match these tokens only at the start of an input line.
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eTS"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.TS</code></strong> <var class="def-var-arguments">[<code class="code">H</code>]</var><a class="copiable-link" href='#index-_002eTS'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-TS-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eTE"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.TE</code></strong><a class="copiable-link" href='#index-_002eTE'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-TE-_005bms_005d"></a>
<p>Demarcate a table to be processed by the <code class="code">tbl</code> preprocessor.  The
optional argument&nbsp;<code class="code">H</code> to <code class="code">TS</code> instructs <samp class="file">ms</samp> to
repeat table rows (often column headings) at the top of each new page
the table spans, if applicable; calling the <code class="code">TH</code> macro marks the
end of such rows.  The GNU <cite class="cite">tbl<span class="r">(1)</span></cite> man page provides a
comprehensive reference to the preprocessor and offers examples of its
use.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002ePS"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.PS</code></strong><a class="copiable-link" href='#index-_002ePS'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-PS-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002ePE"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.PE</code></strong><a class="copiable-link" href='#index-_002ePE'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-PE-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002ePF"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.PF</code></strong><a class="copiable-link" href='#index-_002ePF'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-PF-_005bms_005d"></a>
<p><code class="code">PS</code> begins a picture to be processed by the <code class="command">gpic</code>
preprocessor; either of <code class="code">PE</code> or <code class="code">PF</code> ends it, the latter with
&ldquo;flyback&rdquo; to the vertical position at its top.  You can create
<code class="code">pic</code> input manually or with a program such as <code class="code">xfig</code>.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eEQ"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.EQ</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">align</i></span> [<span class="r"><i class="slanted">label</i></span>]]</var><a class="copiable-link" href='#index-_002eEQ'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-EQ-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eEN"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.EN</code></strong><a class="copiable-link" href='#index-_002eEN'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-EN-_005bms_005d"></a>
<p>Demarcate an equation to be processed by the <code class="code">eqn</code> preprocessor.
The equation is centered by default; <var class="var">align</var> can be &lsquo;<samp class="samp">C</samp>&rsquo;,
&lsquo;<samp class="samp">L</samp>&rsquo;, or &lsquo;<samp class="samp">I</samp>&rsquo; to (explicitly) center, left-align, or indent it
by the amount stored in the <code class="code">DI</code> register, respectively.  If
specified, <var class="var">label</var> is set right-aligned.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002e_005b"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.[</code></strong><a class="copiable-link" href='#index-_002e_005b'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005b-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002e_005d"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.]</code></strong><a class="copiable-link" href='#index-_002e_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005d-_005bms_005d"></a>
<p>Demarcate a bibliographic citation to be processed by the <code class="code">refer</code>
preprocessor.  The GNU <cite class="cite">refer<span class="r">(1)</span></cite> man page provides a
comprehensive reference to the preprocessor and the format of its
bibliographic database.  Type &lsquo;<samp class="samp">man refer</samp>&rsquo; at the command line to
view it.
</p></dd></dl>

<p>When <code class="code">refer</code> emits collected references (as might be done on a
&ldquo;Works Cited&rdquo; page), it interpolates the <code class="code">REFERENCES</code> string as
an unnumbered heading (<code class="code">SH</code>).
</p>
<a class="index-entry-id" id="index-table_002c-multi_002dpage_002c-example-_005bms_005d"></a>
<a class="index-entry-id" id="index-multi_002dpage-table-example-_005bms_005d"></a>
<p>The following is an example of how to set up a table that may print
across two or more pages.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.TS H
allbox;
Cb | Cb .
Part&rarr;Description
_
.TH
.T&amp;
GH-1978&rarr;Fribulating gonkulator
<span class="r">&hellip;the rest of the table follows&hellip;</span>
.TE
</pre></div>
</td></tr></table>

<p>Attempting to place a multi-page table inside a keep can lead to
unpleasant results, particularly if the <code class="code">tbl</code> <code class="code">allbox</code> option
is used.
</p>
<a class="index-entry-id" id="index-equation-example-_005bms_005d"></a>
<p>Mathematics can be typeset using the language of the <code class="code">eqn</code>
preprocessor.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.EQ C (\*[SN-NO-DOT]a)
p ~ = ~ q sqrt { ( 1 + ~ ( x / q sup 2 ) }
.EN
</pre></div>
</td></tr></table>

<p>This input formats a labelled equation.  We used the <code class="code">SN-NO-DOT</code>
string to base the equation label on the current heading number, giving
us more flexibility to reorganize the document.
</p>
<p>Use <code class="command">groff</code> options to run preprocessors on the input:
<samp class="option">-e</samp> for <code class="command">geqn</code>, <samp class="option">-p</samp> for <code class="command">gpic</code>,
<samp class="option">-R</samp> for <code class="command">grefer</code>, and <samp class="option">-t</samp> for <code class="command">gtbl</code>.
</p>

<hr>
</div>
<div class="subsubsection-level-extent" id="ms-Footnotes">
<div class="nav-panel">
<p>
Previous: <a href="#ms-Insertions" accesskey="p" rel="prev">Tables, figures, equations, and references</a>, Up: <a href="#ms-Body-Text" accesskey="u" rel="up">Body Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Footnotes">4.6.5.10 Footnotes</h4>
<a class="index-entry-id" id="index-ms-macros_002c-footnotes"></a>
<a class="index-entry-id" id="index-footnotes-_005bms_005d"></a>

<a class="index-entry-id" id="index-footnote-marker-_005bms_005d"></a>
<a class="index-entry-id" id="index-marker_002c-footnote-_005bms_005d"></a>
<p>A footnote is typically anchored to a place in the text with a
<em class="dfn">marker</em>, which is a small integer, a symbol such as a dagger, or
arbitrary user-specified text.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_002a_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[*]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_002a_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002a-_005bms_005d"></a>
<p>Place an <em class="dfn">automatic number</em>, an automatically generated numeric
footnote marker, in the text.  Each time this string is interpolated,
the number it produces increments by one.  Automatic numbers start at 1.
This is a Berkeley extension.
</p></dd></dl>

<p>Enclose the footnote text in <code class="code">FS</code> and <code class="code">FE</code> macro calls to set
it at the nearest available &ldquo;foot&rdquo;, or bottom, of a text column or
page.
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eFS"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.FS</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">marker</i></span>]</var><a class="copiable-link" href='#index-_002eFS'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-FS-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eFE"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.FE</code></strong><a class="copiable-link" href='#index-_002eFE'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-FE-_005bms_005d"></a>
<p>Begin (<code class="code">FS</code>) and end (<code class="code">FE</code>) a footnote.  <code class="code">FS</code> calls
<code class="code">FS-MARK</code> with any supplied <var class="var">marker</var> argument, which is then
also placed at the beginning of the footnote text.  If <var class="var">marker</var> is
omitted, the next pending automatic footnote number enqueued by
interpolation of the <code class="code">*</code> string is used, and if none exists,
nothing is prefixed.
</p></dd></dl>

<p>You may not desire automatically numbered footnotes in spite of their
convenience.  You can indicate a footnote with a symbol or other text by
specifying its marker at the appropriate place (for example, by using
<code class="code">\[dg]</code> for the dagger glyph) <em class="emph">and</em> as an argument to the
<code class="code">FS</code> macro.  Such manual marks should be repeated as arguments to
<code class="code">FS</code> or as part of the footnote text to disambiguate their
correspondence.  You may wish to use <code class="code">\*{</code> and <code class="code">\*}</code> to
superscript the marker at the anchor point, in the footnote text, or
both.
</p>
<p><code class="code">groff</code> <samp class="file">ms</samp> provides a hook macro, <code class="code">FS-MARK</code>, for
user-determined operations to be performed when the <code class="code">FS</code> macro is
called.  It is passed the same arguments as <code class="code">FS</code> itself.  An
application of <code class="code">FS-MARK</code> is anchor placement for a hyperlink
reference, so that a footnote can link back to its referential
context.<a class="footnote" id="DOCF11" href="#FOOT11"><sup>11</sup></a>  By default, this macro has an empty definition.
<code class="code">FS-MARK</code> is a GNU extension.
</p>
<a class="index-entry-id" id="index-footnotes_002c-and-keeps-_005bms_005d"></a>
<a class="index-entry-id" id="index-keeps_002c-and-footnotes-_005bms_005d"></a>
<a class="index-entry-id" id="index-footnotes_002c-and-displays-_005bms_005d"></a>
<a class="index-entry-id" id="index-displays_002c-and-footnotes-_005bms_005d"></a>
<p>Footnotes can be safely used within keeps and displays, but you should
avoid using automatically numbered footnotes within floating keeps.  You
can place a second <code class="code">\**</code> interpolation between a <code class="code">\**</code> and its
corresponding <code class="code">FS</code> call as long as each <code class="code">FS</code> call occurs
<em class="emph">after</em> the corresponding <code class="code">\**</code> and occurrences of <code class="code">FS</code>
are in the same order as corresponding occurrences of <code class="code">\**</code>.
</p>
<p>Footnote text is formatted as paragraphs are, using analogous
parameters.  The registers <code class="code">FI</code>, <code class="code">FPD</code>, <code class="code">FPS</code>, and
<code class="code">FVS</code> correspond to <code class="code">PI</code>, <code class="code">PD</code>, <code class="code">PS</code>, and <code class="code">CS</code>,
respectively; <code class="code">FPD</code>, <code class="code">FPS</code>, and <code class="code">FVS</code> are GNU extensions.
</p>
<p>The <code class="code">FF</code> register controls the formatting of automatically numbered
footnote paragraphs and those for which <code class="code">FS</code> is given a marker
argument.  See <a class="xref" href="#ms-Document-Control-Settings">Document Control Settings</a>.
</p>
<p>The default footnote line length is 11/12ths of the normal line length
for compatibility with the expectations of historical <samp class="file">ms</samp>
documents; you may wish to set the <code class="code">FR</code> string to &lsquo;<samp class="samp">1</samp>&rsquo; to align
with contemporary typesetting practices.  In the
past,<a class="footnote" id="DOCF12" href="#FOOT12"><sup>12</sup></a> an <code class="code">FL</code> register
was used for the line length in footnotes; however, setting this
register at document initialization time had no effect on the footnote
line length in multi-column arrangements.<a class="footnote" id="DOCF13" href="#FOOT13"><sup>13</sup></a>
</p>
<p><code class="code">FR</code> should be used in preference to the old <code class="code">FL</code> register in
contemporary documents.  The footnote line length is effectively
computed as &lsquo;<samp class="samp"><i class="slanted">column-width</i> * \*[FR]</samp>&rsquo;.  If an absolute
footnote line length is required, recall that arithmetic expressions in
<code class="code">roff</code> input are evaluated strictly from left to right, with no
operator precedence (parentheses are honored).
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds FR 0+3i \&quot; Set footnote line length to 3 inches.
</pre></div></div>


<hr>
</div>
<div class="subsubsection-level-extent" id="ms-language-and-localization">
<div class="nav-panel">
<p>
Next: <a href="#ms-Page-Layout" accesskey="n" rel="next">Page layout</a>, Previous: <a href="#ms-Footnotes" accesskey="p" rel="prev">Footnotes</a>, Up: <a href="#ms-Body-Text" accesskey="u" rel="up">Body Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Language-and-localization">4.6.5.11 Language and localization</h4>
<a class="index-entry-id" id="index-ms-macros_002c-language"></a>
<a class="index-entry-id" id="index-ms-macros_002c-localization"></a>
<a class="index-entry-id" id="index-language-_005bms_005d"></a>
<a class="index-entry-id" id="index-localization-_005bms_005d"></a>

<p><code class="code">groff</code> <samp class="file">ms</samp> provides several strings that you can customize
for your own purposes, or redefine to adapt the macro package to
languages other than English.  It is already localized for
Czech, German, French, Italian, and Swedish.  Load the desired
localization macro package after <samp class="file">ms</samp>; see the
<cite class="cite">groff_tmac<span class="r">(5)</span></cite> man page.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">$ groff -ms -mfr bienvenue.ms
</pre></div>
</td></tr></table>

<p>The following strings are available.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bREFERENCES_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[REFERENCES]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bREFERENCES_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-REFERENCES-_005bms_005d"></a>
<p>Contains the string printed at the beginning of a references
(bibliography) page produced with GNU <cite class="cite">refer<span class="r">(1)</span></cite>.  The default
is &lsquo;<samp class="samp">References</samp>&rsquo;.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bABSTRACT_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[ABSTRACT]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bABSTRACT_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ABSTRACT-_005bms_005d"></a>
<p>Contains the string printed at the beginning of the abstract.  The
default is &lsquo;<samp class="samp">\f[I]ABSTRACT\f[]</samp>&rsquo;; it includes font selection escape
sequences to set the word in italics.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bTOC_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[TOC]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bTOC_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-TOC-_005bms_005d"></a>
<p>Contains the string printed at the beginning of the table of contents.
The default is &lsquo;<samp class="samp">Table of Contents</samp>&rsquo;.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bMONTH1_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[MONTH1]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bMONTH1_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-MONTH1-_005bms_005d"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002a_005bMONTH2_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[MONTH2]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bMONTH2_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-MONTH2-_005bms_005d"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002a_005bMONTH3_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[MONTH3]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bMONTH3_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-MONTH3-_005bms_005d"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002a_005bMONTH4_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[MONTH4]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bMONTH4_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-MONTH4-_005bms_005d"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002a_005bMONTH5_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[MONTH5]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bMONTH5_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-MONTH5-_005bms_005d"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002a_005bMONTH6_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[MONTH6]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bMONTH6_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-MONTH6-_005bms_005d"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002a_005bMONTH7_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[MONTH7]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bMONTH7_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-MONTH7-_005bms_005d"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002a_005bMONTH8_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[MONTH8]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bMONTH8_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-MONTH8-_005bms_005d"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002a_005bMONTH9_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[MONTH9]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bMONTH9_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-MONTH9-_005bms_005d"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002a_005bMONTH10_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[MONTH10]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bMONTH10_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-MONTH10-_005bms_005d"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002a_005bMONTH11_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[MONTH11]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bMONTH11_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-MONTH11-_005bms_005d"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002a_005bMONTH12_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[MONTH12]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bMONTH12_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-MONTH12-_005bms_005d"></a>
<p>Contain the full names of the calendar months.  The defaults are in
English: &lsquo;<samp class="samp">January</samp>&rsquo;, &lsquo;<samp class="samp">February</samp>&rsquo;, and so on.
</p></dd></dl>


<hr>
</div>
</div>
<div class="subsection-level-extent" id="ms-Page-Layout">
<div class="nav-panel">
<p>
Next: <a href="#Differences-from-AT_0026T-ms" accesskey="n" rel="next">Differences from <abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp></a>, Previous: <a href="#ms-Body-Text" accesskey="p" rel="prev">Body Text</a>, Up: <a href="#ms" accesskey="u" rel="up"><samp class="file">ms</samp></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Page-layout">4.6.6 Page layout</h4>
<a class="index-entry-id" id="index-ms-macros_002c-page-layout"></a>
<a class="index-entry-id" id="index-page-layout-_005bms_005d"></a>

<p><samp class="file">ms</samp>&rsquo;s default page layout arranges text in a single column with
the page number between hyphens centered in a header on each page except
the first, and produces no footers.  You can customize this arrangement.
</p>


<ul class="mini-toc">
<li><a href="#ms-Headers-and-Footers" accesskey="1">Headers and footers</a></li>
<li><a href="#Tab-Stops-in-ms" accesskey="2">Tab stops</a></li>
<li><a href="#ms-Margins" accesskey="3">Margins</a></li>
<li><a href="#ms-Multiple-Columns" accesskey="4">Multiple columns</a></li>
<li><a href="#ms-TOC" accesskey="5">Creating a table of contents</a></li>
</ul>
<hr>
<div class="subsubsection-level-extent" id="ms-Headers-and-Footers">
<div class="nav-panel">
<p>
Next: <a href="#Tab-Stops-in-ms" accesskey="n" rel="next">Tab stops</a>, Previous: <a href="#ms-Page-Layout" accesskey="p" rel="prev">Page layout</a>, Up: <a href="#ms-Page-Layout" accesskey="u" rel="up">Page layout</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Headers-and-footers">4.6.6.1 Headers and footers</h4>
<a class="index-entry-id" id="index-ms-macros_002c-headers"></a>
<a class="index-entry-id" id="index-ms-macros_002c-footers"></a>
<a class="index-entry-id" id="index-headers-_005bms_005d"></a>
<a class="index-entry-id" id="index-footers-_005bms_005d"></a>

<p>There are multiple ways to produce headers and footers.  One is to
define the strings <code class="code">LH</code>, <code class="code">CH</code>, and <code class="code">RH</code> to set the left,
center, and right headers, respectively; and <code class="code">LF</code>, <code class="code">CF</code>, and
<code class="code">RF</code> to set the left, center, and right footers.  This approach
suffices for documents that do not distinguish odd- and even-numbered
pages.
</p>
<p>Another method is to call macros that set headers or footers for odd- or
even-numbered pages.  Each such macro takes a delimited argument
separating the left, center, and right header or footer texts from each
other.  You can replace the neutral apostrophes (<code class="code">'</code>) shown below
with any character not appearing in the header or footer text.  These
macros are Berkeley extensions.
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eOH"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.OH</code></strong> <var class="def-var-arguments"><code class="code">'</code><span class="r"><i class="slanted">left</i></span><code class="code">'</code><span class="r"><i class="slanted">center</i></span><code class="code">'</code><span class="r"><i class="slanted">right</i></span><code class="code">'</code></var><a class="copiable-link" href='#index-_002eOH'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-OH-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eEH"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.EH</code></strong> <var class="def-var-arguments"><code class="code">'</code><span class="r"><i class="slanted">left</i></span><code class="code">'</code><span class="r"><i class="slanted">center</i></span><code class="code">'</code><span class="r"><i class="slanted">right</i></span><code class="code">'</code></var><a class="copiable-link" href='#index-_002eEH'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-EH-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eOF"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.OF</code></strong> <var class="def-var-arguments"><code class="code">'</code><span class="r"><i class="slanted">left</i></span><code class="code">'</code><span class="r"><i class="slanted">center</i></span><code class="code">'</code><span class="r"><i class="slanted">right</i></span><code class="code">'</code></var><a class="copiable-link" href='#index-_002eOF'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-OF-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eEF"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.EF</code></strong> <var class="def-var-arguments"><code class="code">'</code><span class="r"><i class="slanted">left</i></span><code class="code">'</code><span class="r"><i class="slanted">center</i></span><code class="code">'</code><span class="r"><i class="slanted">right</i></span><code class="code">'</code></var><a class="copiable-link" href='#index-_002eEF'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-EF-_005bms_005d"></a>
<p>The <code class="code">OH</code> and <code class="code">EH</code> macros define headers for odd- (recto)
and even-numbered (verso) pages, respectively; the <code class="code">OF</code> and
<code class="code">EF</code> macros define footers for them.
</p></dd></dl>

<p>With either method, a percent sign <code class="code">%</code> in header or footer text is
replaced by the current page number.  By default, <samp class="file">ms</samp> places no
header on a page numbered &ldquo;1&rdquo; (regardless of its number format).
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eP1"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.P1</code></strong><a class="copiable-link" href='#index-_002eP1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-P1-_005bms_005d"></a>
<p>Typeset the header even on page&nbsp;1.  To be effective, this macro
must be called before the header trap is sprung on any page numbered
&ldquo;1&rdquo;; in practice, unless your page numbering is unusual, this means
that you should call it early, before <code class="code">TL</code> or any heading or
paragraphing macro.  This is a Berkeley extension.
</p></dd></dl>

<p>For even greater flexibility, <samp class="file">ms</samp> is designed to permit the
redefinition of the macros that are called when the <code class="code">groff</code> traps
that ordinarily cause the headers and footers to be output are sprung.
<code class="code">PT</code> (&ldquo;page trap&rdquo;) is called by <samp class="file">ms</samp> when the header is to
be written, and <code class="code">BT</code> (&ldquo;bottom trap&rdquo;) when the footer is to be.
The <code class="code">groff</code> page location trap that <samp class="file">ms</samp> sets up to format the
header also calls the (normally undefined) <code class="code">HD</code> macro after
<code class="code">PT</code>; you can define <code class="code">HD</code> if you need additional processing
after setting the header (for example, to draw a line below it).
The <code class="code">HD</code> hook is a Berkeley extension.  Any such macros you
(re)define must implement any desired specialization for odd-, even-, or
first numbered pages.
</p>

<hr>
</div>
<div class="subsubsection-level-extent" id="Tab-Stops-in-ms">
<div class="nav-panel">
<p>
Next: <a href="#ms-Margins" accesskey="n" rel="next">Margins</a>, Previous: <a href="#ms-Headers-and-Footers" accesskey="p" rel="prev">Headers and footers</a>, Up: <a href="#ms-Page-Layout" accesskey="u" rel="up">Page layout</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Tab-stops">4.6.6.2 Tab stops</h4>

<p>Use the <code class="code">ta</code> request to define tab stops as needed.  See <a class="xref" href="#Tabs-and-Fields">Tabs and Fields</a>.
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eTA"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.TA</code></strong><a class="copiable-link" href='#index-_002eTA'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-TA-_005bms_005d"></a>
<p>Reset the tab stops to the <samp class="file">ms</samp> default (every 5 ens).
Redefine this macro to create a different set of default tab stops.
</p></dd></dl>


<hr>
</div>
<div class="subsubsection-level-extent" id="ms-Margins">
<div class="nav-panel">
<p>
Next: <a href="#ms-Multiple-Columns" accesskey="n" rel="next">Multiple columns</a>, Previous: <a href="#Tab-Stops-in-ms" accesskey="p" rel="prev">Tab stops</a>, Up: <a href="#ms-Page-Layout" accesskey="u" rel="up">Page layout</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Margins">4.6.6.3 Margins</h4>
<a class="index-entry-id" id="index-ms-macros_002c-margins"></a>

<p>Control margins using the registers summarized in &ldquo;Margin settings&rdquo; in
<a class="ref" href="#ms-Document-Control-Settings">Document Control Settings</a> above.  There is no setting for the
right margin; the combination of page offset <code class="code">\n[PO]</code> and line
length <code class="code">\n[LL]</code> determines it.
</p>

<hr>
</div>
<div class="subsubsection-level-extent" id="ms-Multiple-Columns">
<div class="nav-panel">
<p>
Next: <a href="#ms-TOC" accesskey="n" rel="next">Creating a table of contents</a>, Previous: <a href="#ms-Margins" accesskey="p" rel="prev">Margins</a>, Up: <a href="#ms-Page-Layout" accesskey="u" rel="up">Page layout</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Multiple-columns">4.6.6.4 Multiple columns</h4>
<a class="index-entry-id" id="index-ms-macros_002c-multiple-columns"></a>
<a class="index-entry-id" id="index-multiple-columns-_005bms_005d"></a>

<p><samp class="file">ms</samp> can set text in as many columns as reasonably fit on the page.
The following macros force a page break if a multi-column layout is
active when they are called.  The <code class="code">MINGW</code> register stores the
default minimum gutter width; it is a GNU extension.  When multiple
columns are in use, keeps and the <code class="code">HORPHANS</code> and <code class="code">PORPHANS</code>
registers work with respect to column breaks instead of page breaks.
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002e1C"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.1C</code></strong><a class="copiable-link" href='#index-_002e1C'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-1C-_005bms_005d"></a>
<p>Arrange page text in a single column (the default).
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002e2C"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.2C</code></strong><a class="copiable-link" href='#index-_002e2C'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-2C-_005bms_005d"></a>
<p>Arrange page text in two columns.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eMC"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.MC</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">column-width</i></span> [<span class="r"><i class="slanted">gutter-width</i></span>]]</var><a class="copiable-link" href='#index-_002eMC'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-MC-_005bms_005d"></a>
<p>Arrange page text in multiple columns.  If you specify no arguments, it
is equivalent to the <code class="code">2C</code> macro.  Otherwise, <var class="var">column-width</var> is
the width of each column and <var class="var">gutter-width</var> is the minimum distance
between columns.
</p></dd></dl>


<hr>
</div>
<div class="subsubsection-level-extent" id="ms-TOC">
<div class="nav-panel">
<p>
Next: <a href="#Differences-from-AT_0026T-ms" accesskey="n" rel="next">Differences from <abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp></a>, Previous: <a href="#ms-Multiple-Columns" accesskey="p" rel="prev">Multiple columns</a>, Up: <a href="#ms-Page-Layout" accesskey="u" rel="up">Page layout</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Creating-a-table-of-contents">4.6.6.5 Creating a table of contents</h4>
<a class="index-entry-id" id="index-ms-macros_002c-creating-table-of-contents"></a>
<a class="index-entry-id" id="index-table-of-contents_002c-creating-_005bms_005d"></a>

<p>Because <code class="code">roff</code> formatters process their input in a single pass,
material on page 50, for example, cannot influence what appears on
page&nbsp;1&mdash;this poses a challenge for a table of contents at its
traditional location in front matter, if you wish to avoid manually
maintaining it.  <samp class="file">ms</samp> enables the collection of material to be
presented in the table of contents as it appears, saving its page number
along with it, and then emitting the collected contents on demand toward
the end of the document.  The table of contents can then be resequenced
to its desired location by physically rearranging the pages of a printed
document, or as part of post-processing&mdash;with a <cite class="cite">sed<span class="r">(1)</span></cite>
script to reorder the pages in <code class="command">troff</code>&rsquo;s output, with
<cite class="cite">pdfjam<span class="r">(1)</span></cite>, or with <cite class="cite">gropdf<span class="r">(1)</span></cite>&rsquo;s
&lsquo;<samp class="samp">.pdfswitchtopage</samp>&rsquo; feature, for example.
</p>
<p>Define an entry to appear in the table of contents by bracketing its
text between calls to the <code class="code">XS</code> and <code class="code">XE</code> macros.  A typical
application is to call them immediately after <code class="code">NH</code> or <code class="code">SH</code> and
repeat the heading text within them.  The <code class="code">XA</code> macro, used within
&lsquo;<samp class="samp">.XS</samp>&rsquo;/&lsquo;<samp class="samp">.XE</samp>&rsquo; pairs, supplements an entry&mdash;for instance, when
it requires multiple output lines, whether because a heading is too long
to fit or because style dictates that page numbers not be repeated.  You
may wish to indent the text thus wrapped to correspond to its heading
depth; this can be done in the entry text by prefixing it with tabs or
horizontal motion escape sequences, or by providing a second argument to
the <code class="code">XA</code> macro.  <code class="code">XS</code> and <code class="code">XA</code> automatically associate
the page number where they are called with the text following them, but
they accept arguments to override this behavior.  At the end of the
document, call <code class="code">TC</code> or <code class="code">PX</code> to emit the table of contents;
<code class="code">TC</code> resets the page number to &lsquo;<samp class="samp">i</samp>&rsquo; (Roman numeral one), and
then calls <code class="code">PX</code>.  All of these macros are Berkeley extensions.
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eXS"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.XS</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">page-number</i></span>]</var><a class="copiable-link" href='#index-_002eXS'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-XS-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eXA"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.XA</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">page-number</i></span> [<span class="r"><i class="slanted">indentation</i></span>]]</var><a class="copiable-link" href='#index-_002eXA'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-XA-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eXE"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.XE</code></strong><a class="copiable-link" href='#index-_002eXE'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-XE-_005bms_005d"></a>
<p>Begin, supplement, and end a table of contents entry.  Each entry is
associated with <var class="var">page-number</var> (otherwise the current page number); a
<var class="var">page-number</var> of &lsquo;<samp class="samp">no</samp>&rsquo; prevents a leader and page number from
being emitted for that entry.  Use of <code class="code">XA</code> within
<code class="code">XS</code>/<code class="code">XE</code> is optional; it can be repeated.  If
<var class="var">indentation</var> is present, a supplemental entry is indented by that
amount; ens are assumed if no unit is indicated.  Text on input lines
between <code class="code">XS</code> and <code class="code">XE</code> is stored for later recall by <code class="code">PX</code>.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002ePX"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.PX</code></strong> <var class="def-var-arguments">[<code class="code">no</code>]</var><a class="copiable-link" href='#index-_002ePX'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-PX-_005bms_005d"></a>
<p>Switch to single-column layout.  Unless <code class="code">no</code> is specified, center
and interpolate the <code class="code">TOC</code> string in bold and two points larger than
the body text.  Emit the table of contents entries.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eTC"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.TC</code></strong> <var class="def-var-arguments">[<code class="code">no</code>]</var><a class="copiable-link" href='#index-_002eTC'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-TC-_005bms_005d"></a>
<p>Set the page number to&nbsp;1, the page number format to lowercase Roman
numerals, and call <code class="code">PX</code> (with a <code class="code">no</code> argument, if present).
</p></dd></dl>

<p>Here&rsquo;s an example of typical <samp class="file">ms</samp> table of contents preparation.
We employ horizontal escape sequences <code class="code">\h</code> to indent the entries by
sectioning depth.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.NH 1
Introduction
.XS
Introduction
.XE
<span class="r">&hellip;</span>
.NH 2
Methodology
.XS
\h'2n'Methodology
.XA
\h'4n'Fassbinder's Approach
\h'4n'Kahiu's Approach
.XE
<span class="r">&hellip;</span>
.NH 1
Findings
.XS
Findings
.XE
<span class="r">&hellip;</span>
.TC
</pre></div>
</td></tr></table>

<p>The remaining features in this subsubsection are GNU extensions.
<code class="code">groff</code> <samp class="file">ms</samp> obviates the need to repeat heading text after
<code class="code">XS</code> calls.  Call <code class="code">XN</code> and <code class="code">XH</code> after <code class="code">NH</code> and
<code class="code">SH</code>, respectively.
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eXN"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.XN</code></strong> <var class="def-var-arguments"><span class="r"><i class="slanted">heading-text</i></span></var><a class="copiable-link" href='#index-_002eXN'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-XN-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eXH"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.XH</code></strong> <var class="def-var-arguments"><span class="r"><i class="slanted">depth</i></span> <span class="r"><i class="slanted">heading-text</i></span></var><a class="copiable-link" href='#index-_002eXH'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-XH-_005bms_005d"></a>
<p>Format <var class="var">heading-text</var> and create a corresponding table of contents
entry.  <code class="code">XN</code> computes the indentation from the depth of the
preceding <code class="code">NH</code> call; <code class="code">XH</code> requires a <var class="var">depth</var> argument to
do so.
</p></dd></dl>

<p><code class="code">groff</code> <samp class="file">ms</samp> encourages customization of table of contents
entry production.
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eXN_002dREPLACEMENT"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.XN-REPLACEMENT</code></strong> <var class="def-var-arguments"><span class="r"><i class="slanted">heading-text</i></span></var><a class="copiable-link" href='#index-_002eXN_002dREPLACEMENT'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-XN_002dREPLACEMENT-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eXH_002dREPLACEMENT"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.XH-REPLACEMENT</code></strong> <var class="def-var-arguments"><span class="r"><i class="slanted">depth</i></span> <span class="r"><i class="slanted">heading-text</i></span></var><a class="copiable-link" href='#index-_002eXH_002dREPLACEMENT'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-XH_002dREPLACEMENT-_005bms_005d"></a>
<p>These hook macros implement <code class="code">XN</code> and <code class="code">XH</code>, respectively.
They call <code class="code">XN-INIT</code> and pass their <var class="var">heading-text</var> arguments to
<code class="code">XH-UPDATE-TOC</code>.
</p></dd></dl>

<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eXN_002dINIT"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.XN-INIT</code></strong><a class="copiable-link" href='#index-_002eXN_002dINIT'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-XN_002dINIT-_005bms_005d"></a>
</dd><dt class="deffnx defmacx-alias-deffnx def-cmd-deffn" id="index-_002eXH_002dUPDATE_002dTOC"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.XH-UPDATE-TOC</code></strong> <var class="def-var-arguments"><span class="r"><i class="slanted">depth</i></span> <span class="r"><i class="slanted">heading-text</i></span></var><a class="copiable-link" href='#index-_002eXH_002dUPDATE_002dTOC'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-XH_002dUPDATE_002dTOC-_005bms_005d"></a>
<p>The <code class="code">XN-INIT</code> hook macro does nothing by default.
<code class="code">XH-UPDATE-TOC</code> brackets <var class="var">heading-text</var> with <code class="code">XS</code> and
<code class="code">XE</code> calls, indenting it by 2 ens per level of <var class="var">depth</var> beyond
the first.
</p></dd></dl>

<p>We could therefore produce a table of contents similar to that in the
previous example with fewer macro calls.  (The difference is that this
input follows the &ldquo;Approach&rdquo; entries with leaders and page numbers.)
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.NH 1
.XN Introduction
<span class="r">&hellip;</span>
.NH 2
.XN Methodology
.XH 3 &quot;Fassbinder's Approach&quot;
.XH 3 &quot;Kahiu's Approach&quot;
<span class="r">&hellip;</span>
.NH 1
.XN Findings
<span class="r">&hellip;</span>
</pre></div>
</td></tr></table>

<p>To get the section number of the numbered headings into the table of
contents entries, we might define <code class="code">XN-REPLACEMENT</code> as follows.
(We obtain the heading depth from <code class="code">groff</code> <samp class="file">ms</samp>&rsquo;s internal
register <code class="code">nh*hl</code>.)
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.de XN-REPLACEMENT
.XN-INIT
.XH-UPDATE-TOC \\n[nh*hl] \\$@
\&amp;\\*[SN] \\$*
..
</pre></div>
</td></tr></table>

<p>You can change the style of the leader that bridges each table of
contents entry with its page number; define the <code class="code">TC-LEADER</code> special
character by using the <code class="code">char</code> request.  A typical leader combines
the dot glyph &lsquo;<samp class="samp">.</samp>&rsquo; with a horizontal motion escape sequence to
spread the dots.  The width of the page number field is stored in the
<code class="code">TC-MARGIN</code> register.
</p>

<hr>
</div>
</div>
<div class="subsection-level-extent" id="Differences-from-AT_0026T-ms">
<div class="nav-panel">
<p>
Next: <a href="#ms-Naming-Conventions" accesskey="n" rel="next">Naming Conventions</a>, Previous: <a href="#ms-Page-Layout" accesskey="p" rel="prev">Page layout</a>, Up: <a href="#ms" accesskey="u" rel="up"><samp class="file">ms</samp></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Differences-from-AT_0026T-ms-1">4.6.7 Differences from <abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp></h4>
<a class="index-entry-id" id="index-ms-macros_002c-groff-differences-from-AT_0026T"></a>
<a class="index-entry-id" id="index-AT_0026T-ms_002c-macro-package-differences"></a>

<p>The <code class="code">groff</code> <samp class="file">ms</samp> macros are an independent reimplementation,
using no <abbr class="acronym">AT&amp;T</abbr> code.  Since they take advantage of the extended
features of <code class="code">groff</code>, they cannot be used with <abbr class="acronym">AT&amp;T</abbr>
<code class="code">troff</code>.  <code class="code">groff</code> <samp class="file">ms</samp> supports features described above
as Berkeley and Tenth Edition Research Unix extensions, and adds several
of its own.
</p>
<ul class="itemize mark-bullet">
<li>The internals of <code class="code">groff</code> <samp class="file">ms</samp> differ from the internals of
<abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp>.  Documents that depend upon implementation
details of <abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp> may not format properly with
<code class="code">groff</code> <samp class="file">ms</samp>.  Such details include macros whose function was
not documented in the <abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp>
manual.<a class="footnote" id="DOCF14" href="#FOOT14"><sup>14</sup></a>

</li><li>The error-handling policy of <code class="code">groff</code> <samp class="file">ms</samp> is to detect and
report errors, rather than to ignore them silently.

</li><li>Tenth Edition Research Unix supported <code class="code">P1</code>/<code class="code">P2</code> macros to bracket code
examples; <code class="code">groff</code> <samp class="file">ms</samp> does not.

</li><li><code class="code">groff</code> <samp class="file">ms</samp> does not work in GNU <code class="code">troff</code>&rsquo;s
<abbr class="acronym">AT&amp;T</abbr> compatibility mode.  If loaded when that mode is enabled,
it aborts processing with a diagnostic message.

</li><li>Multiple line spacing is not supported.  Use a larger vertical spacing
instead.

</li><li><code class="code">groff</code> <samp class="file">ms</samp> uses the same header and footer defaults in both
<code class="code">nroff</code> and <code class="code">troff</code> modes as <abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp> does in
<code class="code">troff</code> mode; <abbr class="acronym">AT&amp;T</abbr>&rsquo;s default in <code class="code">nroff</code> mode is to
put the date, in U.S. traditional format (e.g., &ldquo;January 1, 2021&rdquo;),
in the center footer (the <code class="code">CF</code> string).

</li><li>Many <code class="code">groff</code> <samp class="file">ms</samp> macros, including those for paragraphs,
headings, and displays, cause a reset of paragraph rendering parameters,
and may change the indentation; they do so not by incrementing or
decrementing it, but by setting it absolutely.  This can cause problems
for documents that define additional macros of their own that try to
manipulate indentation.  Use the <samp class="file">ms</samp> <code class="code">RS</code> and <code class="code">RE</code>
macros instead of the <code class="code">in</code> request.

</li><li><a class="index-entry-id" id="index-fractional-type-sizes-in-ms-macros"></a>
<a class="index-entry-id" id="index-ms-macros_002c-fractional-type-sizes-in"></a>
<abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp> interpreted the values of the registers
<code class="code">PS</code> and <code class="code">VS</code> in points, and did not support the use of
scaling units with them.  <code class="code">groff</code> <samp class="file">ms</samp> interprets values of
the registers <code class="code">PS</code>, <code class="code">VS</code>, <code class="code">FPS</code>, and <code class="code">FVS</code> equal to
or larger than&nbsp;1,000 (one thousand) as decimal fractions multiplied
by&nbsp;1,000.<a class="footnote" id="DOCF15" href="#FOOT15"><sup>15</sup></a>  This threshold makes use of a
scaling unit with these parameters practical for high-resolution
devices while preserving backward compatibility.  It also permits
expression of non-integral type sizes.  For example, &lsquo;<samp class="samp">groff
-rPS=10.5p</samp>&rsquo; at the shell prompt is equivalent to placing &lsquo;<samp class="samp">.nr PS
10.5p</samp>&rsquo; at the beginning of the document.

</li><li><abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp>&rsquo;s <code class="code">AU</code> macro supported arguments used with
some document types; <code class="code">groff</code> <samp class="file">ms</samp> does not.

</li><li>Right-aligned displays are available.  The <abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp>
manual observes that &ldquo;it is tempting to assume that &lsquo;<samp class="samp">.DS R</samp>&rsquo; will
right adjust lines, but it doesn&rsquo;t work&rdquo;.  In <code class="code">groff</code> <samp class="file">ms</samp>,
it does.

</li><li>To make <code class="code">groff</code> <samp class="file">ms</samp> use the default page offset (which also
specifies the left margin), the <code class="code">PO</code> register must stay undefined
until the first <samp class="file">ms</samp> macro is called.

<p>This implies that &lsquo;<samp class="samp">\n[PO]</samp>&rsquo; should not be used early in the
document, unless it is changed also: accessing an undefined register
automatically defines it.
</p>
</li><li><code class="code">groff</code> <samp class="file">ms</samp> supports the <code class="code">PN</code> register, but it is not
necessary; you can access the page number via the usual <code class="code">%</code>
register and invoke the <code class="code">af</code> request to assign a different format
to it if desired.<a class="footnote" id="DOCF16" href="#FOOT16"><sup>16</sup></a>

</li><li>The <abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp> manual documents registers <code class="code">CW</code> and
<code class="code">GW</code> as setting the default column width and &ldquo;intercolumn gap&rdquo;,
respectively, and which applied when <code class="code">MC</code> was called with fewer
than two arguments.  <code class="code">groff</code> <samp class="file">ms</samp> instead treats <code class="code">MC</code>
without arguments as synonymous with <code class="code">2C</code>; there is thus no
occasion for a default column width register.  Further, the <code class="code">MINGW</code>
register and the second argument to <code class="code">MC</code> specify a <em class="emph">minimum</em>
space between columns, not the fixed gutter width of <abbr class="acronym">AT&amp;T</abbr>
<samp class="file">ms</samp>.

</li><li>The <abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp> manual did not document the <code class="code">QI</code>
register; Berkeley and <code class="code">groff</code> <samp class="file">ms</samp> do.
</li></ul>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bGS_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[GS]</code></strong><a class="copiable-link" href='#index-_005cn_005bGS_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-GS-_005bms_005d"></a>
<p>The register <code class="code">GS</code> is set to&nbsp;1 by the <code class="code">groff</code> <samp class="file">ms</samp>
macros, but is not used by the <abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp> package.
Documents that need to determine whether they are being formatted with
<code class="code">groff</code> <samp class="file">ms</samp> or another implementation should test this
register.
</p></dd></dl>



<ul class="mini-toc">
<li><a href="#Missing-Unix-Version-7-ms-Macros" accesskey="1">Unix Version 7 <samp class="file">ms</samp> macros not implemented by <code class="code">groff</code> <samp class="file">ms</samp></a></li>
</ul>
<hr>
<div class="subsubsection-level-extent" id="Missing-Unix-Version-7-ms-Macros">
<div class="nav-panel">
<p>
Previous: <a href="#Differences-from-AT_0026T-ms" accesskey="p" rel="prev">Differences from <abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp></a>, Up: <a href="#Differences-from-AT_0026T-ms" accesskey="u" rel="up">Differences from <abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Unix-Version-7-ms-macros-not-implemented-by-groff-ms">4.6.7.1 Unix Version 7 <samp class="file">ms</samp> macros not implemented by <code class="code">groff</code> <samp class="file">ms</samp></h4>

<p>Several macros described in the Unix Version&nbsp;7 <samp class="file">ms</samp>
documentation are unimplemented by <code class="code">groff</code> <samp class="file">ms</samp> because they
are specific to the requirements of documents produced internally by
Bell Laboratories, some of which also require a glyph for the Bell
System logo that <code class="code">groff</code> does not support.  These macros
implemented several document type formats
(<code class="code">EG</code>, <code class="code">IM</code>, <code class="code">MF</code>, <code class="code">MR</code>, <code class="code">TM</code>, <code class="code">TR</code>), were meaningful only in conjunction with the use of certain document
types
(<code class="code">AT</code>, <code class="code">CS</code>, <code class="code">CT</code>, <code class="code">OK</code>, <code class="code">SG</code>), stored the postal addresses of Bell Labs sites
(<code class="code">HO</code>, <code class="code">IH</code>, <code class="code">MH</code>, <code class="code">PY</code>, <code class="code">WH</code>), or lacked a stable definition over time
(<code class="code">UX</code>). To compatibly render historical <samp class="file">ms</samp> documents using these macros,
we advise your documents to invoke the <code class="code">rm</code> request to remove any
such macros it uses and then define replacements with an authentically
typeset original at hand.<a class="footnote" id="DOCF17" href="#FOOT17"><sup>17</sup></a>  For
informal purposes, a simple definition of <code class="code">UX</code> should maintain the
readability of the document&rsquo;s substance.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.rm UX
.ds UX Unix\&quot;
</pre></div>
</td></tr></table>


<hr>
</div>
</div>
<div class="subsection-level-extent" id="ms-Legacy-Features">
<div class="nav-panel">
<p>
Next: <a href="#ms-Naming-Conventions" accesskey="n" rel="next">Naming Conventions</a>, Previous: <a href="#Differences-from-AT_0026T-ms" accesskey="p" rel="prev">Differences from <abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp></a>, Up: <a href="#ms" accesskey="u" rel="up"><samp class="file">ms</samp></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Legacy-Features">4.6.8 Legacy Features</h4>
<a class="index-entry-id" id="index-ms-macros_002c-strings"></a>
<a class="index-entry-id" id="index-ms-macros_002c-special-characters"></a>
<a class="index-entry-id" id="index-ms-macros_002c-accent-marks"></a>
<a class="index-entry-id" id="index-accent-marks-_005bms_005d"></a>
<a class="index-entry-id" id="index-special-characters-_005bms_005d"></a>
<a class="index-entry-id" id="index-strings-_005bms_005d"></a>

<p><code class="code">groff</code> <samp class="file">ms</samp> retains some legacy features solely to support
formatting of historical documents; contemporary ones should not use
them because they can render poorly.  See the <cite class="cite">groff_char<span class="r">(7)</span></cite>
man page.
</p>
<ul class="mini-toc">
<li><a href="#AT_0026T-accent-mark-strings" accesskey="1">AT&amp;T accent mark strings</a></li>
<li><a href="#Berkeley-accent-mark-and-glyph-strings" accesskey="2">Berkeley accent mark and glyph strings</a></li>
</ul>
<div class="unnumberedsubsubsec-level-extent" id="AT_0026T-accent-mark-strings">
<h4 class="unnumberedsubsubsec">AT&amp;T accent mark strings</h4>

<p>AT&amp;T <samp class="file">ms</samp> defined accent mark strings as follows.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_0027_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[<code class="code">'</code>]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_0027_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_0027-_005bms_005d"></a>
<p>Apply acute accent to subsequent glyph.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_0060_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[<code class="code">`</code>]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_0060_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_0060-_005bms_005d"></a>
<p>Apply grave accent to subsequent glyph.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_003a_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[:]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_003a_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_003a-_005bms_005d"></a>
<p>Apply dieresis (umlaut) to subsequent glyph.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_005e_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[^]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_005e_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005e-_005bms_005d"></a>
<p>Apply circumflex accent to subsequent glyph.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_007e_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[~]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_007e_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_007e-_005bms_005d"></a>
<p>Apply tilde accent to subsequent glyph.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bC_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[C]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bC_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-C-_005bms_005d"></a>
<p>Apply caron to subsequent glyph.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_002c_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[,]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_002c_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002c-_005bms_005d"></a>
<p>Apply cedilla to subsequent glyph.
</p></dd></dl>

</div>
<div class="unnumberedsubsubsec-level-extent" id="Berkeley-accent-mark-and-glyph-strings">
<h4 class="unnumberedsubsubsec">Berkeley accent mark and glyph strings</h4>

<p>Berkeley <samp class="file">ms</samp> offered an <code class="code">AM</code> macro; calling it redefined the
AT&amp;T accent mark strings (except for &lsquo;<samp class="samp">\*C</samp>&rsquo;), applied them to the
<em class="emph">preceding</em> glyph, and defined additional strings, some for spacing
glyphs.
</p>
<dl class="first-deffn first-defmac-alias-first-deffn">
<dt class="deffn defmac-alias-deffn" id="index-_002eAM"><span class="category-def">Macro: </span><span><strong class="def-name"><code class="t">.AM</code></strong><a class="copiable-link" href='#index-_002eAM'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-AM-_005bms_005d"></a>
<p>Enable alternative accent mark and glyph-producing strings.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_0027_005d-1"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[<code class="code">'</code>]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_0027_005d-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_0027-_005bms_005d-1"></a>
<p>Apply acute accent to preceding glyph.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_0060_005d-1"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[<code class="code">`</code>]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_0060_005d-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_0060-_005bms_005d-1"></a>
<p>Apply grave accent to preceding glyph.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_003a_005d-1"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[:]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_003a_005d-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_003a-_005bms_005d-1"></a>
<p>Apply dieresis (umlaut) to preceding glyph.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_005e_005d-1"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[^]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_005e_005d-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005e-_005bms_005d-1"></a>
<p>Apply circumflex accent to preceding glyph.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_007e_005d-1"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[~]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_007e_005d-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_007e-_005bms_005d-1"></a>
<p>Apply tilde accent to preceding glyph.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_002c_005d-1"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[,]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_002c_005d-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002c-_005bms_005d-1"></a>
<p>Apply cedilla to preceding glyph.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_002f_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[/]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_002f_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002f-_005bms_005d"></a>
<p>Apply stroke (slash) to preceding glyph.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bv_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[v]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bv_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-v-_005bms_005d"></a>
<p>Apply caron to preceding glyph.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_005f_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[_]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_005f_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005f-_005bms_005d"></a>
<p>Apply macron to preceding glyph.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_002e_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[.]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_002e_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002e-_005bms_005d"></a>
<p>Apply underdot to preceding glyph.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bo_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[o]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bo_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-o-_005bms_005d"></a>
<p>Apply ring accent to preceding glyph.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_003f_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[?]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_003f_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_003f-_005bms_005d"></a>
<p>Interpolate inverted question mark.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_0021_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[!]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_0021_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_0021-_005bms_005d"></a>
<p>Interpolate inverted exclamation mark.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b8_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[8]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b8_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-8-_005bms_005d"></a>
<p>Interpolate small letter sharp s.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bq_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[q]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bq_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-q-_005bms_005d"></a>
<p>Interpolate small letter o with hook accent (ogonek).
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b3_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[3]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b3_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-3-_005bms_005d"></a>
<p>Interpolate small letter yogh.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bd_002d_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[d-]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bd_002d_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-d_002d-_005bms_005d"></a>
<p>Interpolate small letter eth.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bD_002d_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[D-]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bD_002d_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-D_002d-_005bms_005d"></a>
<p>Interpolate capital letter eth.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bth_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[th]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bth_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-th-_005bms_005d"></a>
<p>Interpolate small letter thorn.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bTh_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[Th]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bTh_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-Th-_005bms_005d"></a>
<p>Interpolate capital letter thorn.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bae_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[ae]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bae_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ae-_005bms_005d"></a>
<p>Interpolate small  ligature.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bAe_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[Ae]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bAe_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-Ae-_005bms_005d"></a>
<p>Interpolate capital  ligature.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005boe_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[oe]</code></strong><a class="copiable-link" href='#index-_005c_002a_005boe_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-oe-_005bms_005d"></a>
<p>Interpolate small oe ligature.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005bOE_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[OE]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bOE_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-OE-_005bms_005d"></a>
<p>Interpolate capital OE ligature.
</p></dd></dl>


<hr>
</div>
</div>
<div class="subsection-level-extent" id="ms-Naming-Conventions">
<div class="nav-panel">
<p>
Previous: <a href="#ms-Legacy-Features" accesskey="p" rel="prev">Legacy Features</a>, Up: <a href="#ms" accesskey="u" rel="up"><samp class="file">ms</samp></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Naming-Conventions">4.6.9 Naming Conventions</h4>
<a class="index-entry-id" id="index-ms-macros_002c-naming-conventions"></a>
<a class="index-entry-id" id="index-naming-conventions_002c-ms-macros"></a>

<p>The following conventions are used for names of macros, strings, and
registers.  External names available to documents that use the
<code class="code">groff</code> <samp class="file">ms</samp> macros contain only uppercase letters and digits.
</p>
<p>Internally, the macros are divided into modules.  Conventions for
identifier names are as follows.
</p>
<ul class="itemize mark-bullet">
<li>Names used only within one module are of the form
<var class="var">module</var><code class="code">*</code><var class="var">name</var>.

</li><li>Names used outside the module in which they are defined are of the form
<var class="var">module</var><code class="code">@</code><var class="var">name</var>.

</li><li>Names associated with a particular environment are of the form
<var class="var">environment</var><code class="code">:</code><var class="var">name</var>; these are used only within the
<code class="code">par</code> module.

</li><li><var class="var">name</var> does not have a module prefix.

</li><li>Constructed names used to implement arrays are of the form
<var class="var">array</var><code class="code">!</code><var class="var">index</var>.
</li></ul>

<p>Thus the <code class="code">groff</code> <samp class="file">ms</samp> macros reserve the following names.
</p>
<ul class="itemize mark-bullet">
<li>Names containing the characters <code class="code">*</code>, <code class="code">@</code>, and&nbsp;<code class="code">:</code>.

</li><li>Names containing only uppercase letters and digits.
</li></ul>



<hr>
</div>
</div>
</div>
<div class="chapter-level-extent" id="GNU-troff-Reference">
<div class="nav-panel">
<p>
Next: <a href="#File-Formats" accesskey="n" rel="next">File Formats</a>, Previous: <a href="#Major-Macro-Packages" accesskey="p" rel="prev">Macro Packages</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU <code class="code">troff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="chapter" id="GNU-troff-Reference-1">5 GNU <code class="code">troff</code> Reference</h2>
<a class="index-entry-id" id="index-reference_002c-gtroff"></a>
<a class="index-entry-id" id="index-gtroff_002c-reference"></a>

<p>This chapter covers <em class="emph">all</em> of the facilities of the GNU
<code class="code">troff</code> formatting engine.  Users of macro packages may skip it if
not interested in details.
</p>




<ul class="mini-toc">
<li><a href="#Text" accesskey="1">Text</a></li>
<li><a href="#Page-Geometry" accesskey="2">Page Geometry</a></li>
<li><a href="#Measurements" accesskey="3">Measurements</a></li>
<li><a href="#Numeric-Expressions" accesskey="4">Numeric Expressions</a></li>
<li><a href="#Identifiers" accesskey="5">Identifiers</a></li>
<li><a href="#Formatter-Instructions" accesskey="6">Formatter Instructions</a></li>
<li><a href="#Comments" accesskey="7">Comments</a></li>
<li><a href="#Registers" accesskey="8">Registers</a></li>
<li><a href="#Manipulating-Filling-and-Adjustment" accesskey="9">Manipulating Filling and Adjustment</a></li>
<li><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></li>
<li><a href="#Manipulating-Spacing">Manipulating Spacing</a></li>
<li><a href="#Tabs-and-Fields">Tabs and Fields</a></li>
<li><a href="#Character-Translations">Character Translations</a></li>
<li><a href="#troff-and-nroff-Modes"><code class="code">troff</code> and <code class="code">nroff</code> Modes</a></li>
<li><a href="#Line-Layout">Line Layout</a></li>
<li><a href="#Line-Continuation">Line Continuation</a></li>
<li><a href="#Page-Layout">Page Layout</a></li>
<li><a href="#Page-Control">Page Control</a></li>
<li><a href="#Using-Fonts">Using Fonts</a></li>
<li><a href="#Manipulating-Type-Size-and-Vertical-Spacing">Manipulating Type Size and Vertical Spacing</a></li>
<li><a href="#Colors">Colors</a></li>
<li><a href="#Strings">Strings</a></li>
<li><a href="#Conditionals-and-Loops">Conditionals and Loops</a></li>
<li><a href="#Writing-Macros">Writing Macros</a></li>
<li><a href="#Page-Motions">Page Motions</a></li>
<li><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></li>
<li><a href="#Deferring-Output">Deferring Output</a></li>
<li><a href="#Traps">Traps</a></li>
<li><a href="#Diversions">Diversions</a></li>
<li><a href="#Punning-Names">Punning Names</a></li>
<li><a href="#Environments">Environments</a></li>
<li><a href="#Suppressing-Output">Suppressing Output</a></li>
<li><a href="#I_002fO">I/O</a></li>
<li><a href="#Postprocessor-Access">Postprocessor Access</a></li>
<li><a href="#Miscellaneous">Miscellaneous</a></li>
<li><a href="#Gtroff-Internals"><code class="code">gtroff</code> Internals</a></li>
<li><a href="#Debugging">Debugging</a></li>
<li><a href="#Implementation-Differences">Implementation Differences</a></li>
</ul>
<hr>
<div class="section-level-extent" id="Text">
<div class="nav-panel">
<p>
Next: <a href="#Measurements" accesskey="n" rel="next">Measurements</a>, Previous: <a href="#GNU-troff-Reference" accesskey="p" rel="prev">GNU <code class="code">troff</code> Reference</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Text-1">5.1 Text</h3>
<a class="index-entry-id" id="index-text_002c-GNU-troff-processing"></a>

<p><abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> was designed to take input as it would be
composed on a typewriter, including the teletypewriters used as early
computer terminals, and relieve the user drafting a document of concern
with details like line length, hyphenation breaking, and the achievement
of straight margins.  Early in its development, the program gained the
ability to prepare output for a phototypesetter; a document could then
be prepared for output to either a teletypewriter, a phototypesetter, or
both.  GNU <code class="code">troff</code> continues this tradition of permitting an author
to compose a single master version of a document which can then be
rendered for a variety of output formats or devices.
</p>
<p><code class="code">roff</code> input files contain text interspersed with instructions to
control the formatter.  Even in the absence of such instructions, GNU
<code class="code">troff</code> still processes its input in several ways, by filling,
hyphenating, breaking, and adjusting it, and supplementing it with
inter-sentence space.
</p>


<ul class="mini-toc">
<li><a href="#Filling" accesskey="1">Filling</a></li>
<li><a href="#Sentences" accesskey="2">Sentences</a></li>
<li><a href="#Hyphenation" accesskey="3">Hyphenation</a></li>
<li><a href="#Breaking" accesskey="4">Breaking</a></li>
<li><a href="#Adjustment" accesskey="5">Adjustment</a></li>
<li><a href="#Tabs-and-Leaders" accesskey="6">Tabs and Leaders</a></li>
<li><a href="#Requests-and-Macros" accesskey="7">Requests and Macros</a></li>
<li><a href="#Macro-Packages" accesskey="8">Macro Packages</a></li>
<li><a href="#Input-Encodings" accesskey="9">Input Encodings</a></li>
<li><a href="#Input-Conventions">Input Conventions</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="Filling">
<div class="nav-panel">
<p>
Next: <a href="#Sentences" accesskey="n" rel="next">Sentences</a>, Previous: <a href="#Text" accesskey="p" rel="prev">Text</a>, Up: <a href="#Text" accesskey="u" rel="up">Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Filling-1">5.1.1 Filling</h4>

<p>When GNU <code class="code">troff</code> starts up, it obtains information about the device
for which it is preparing output.<a class="footnote" id="DOCF18" href="#FOOT18"><sup>18</sup></a>  An essential property is the length of the output
line, such as &ldquo;6.5 inches&rdquo;.
</p>
<a class="index-entry-id" id="index-word_002c-definition-of"></a>
<a class="index-entry-id" id="index-filling"></a>
<p>GNU <code class="code">troff</code> interprets plain text files employing the Unix
line-ending convention.  It reads input a character at a time,
collecting words as it goes, and fits as many words together on an
output line as it can&mdash;this is known as <em class="dfn">filling</em>.  To GNU
<code class="code">troff</code>, a <em class="dfn">word</em> is any sequence of one or more characters
that aren&rsquo;t spaces or newlines.  The exceptions separate
words.<a class="footnote" id="DOCF19" href="#FOOT19"><sup>19</sup></a>  To disable filling, see
<a class="ref" href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a>.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">It is a truth universally acknowledged
that a single man in possession of a
good fortune must be in want of a wife.
    &rArr; It is a truth universally acknowledged that a
    &rArr; single man in possession of a good fortune must
    &rArr; be in want of a wife.
</pre></div></div>


<hr>
</div>
<div class="subsection-level-extent" id="Sentences">
<div class="nav-panel">
<p>
Next: <a href="#Hyphenation" accesskey="n" rel="next">Hyphenation</a>, Previous: <a href="#Filling" accesskey="p" rel="prev">Filling</a>, Up: <a href="#Text" accesskey="u" rel="up">Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Sentences-1">5.1.2 Sentences</h4>
<a class="index-entry-id" id="index-sentences"></a>

<p>A passionate debate has raged for decades among writers of the English
language over whether more space should appear between adjacent
sentences than between words within a sentence, and if so, how much, and
what other circumstances should influence this spacing.<a class="footnote" id="DOCF20" href="#FOOT20"><sup>20</sup></a>
GNU <code class="code">troff</code> follows the example of <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>;
it attempts to detect the boundaries between sentences, and supplies
additional inter-sentence space between them.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">Hello, world!
Welcome to groff.
    &rArr; Hello, world!  Welcome to groff.
</pre></div></div>

<a class="index-entry-id" id="index-end_002dof_002dsentence-characters"></a>
<a class="index-entry-id" id="index-sentence-space"></a>
<a class="index-entry-id" id="index-space-between-sentences"></a>
<a class="index-entry-id" id="index-French-spacing"></a>
<p>GNU <code class="code">troff</code> flags certain characters (normally &lsquo;<samp class="samp">!</samp>&rsquo;, &lsquo;<samp class="samp">?</samp>&rsquo;,
and &lsquo;<samp class="samp">.</samp>&rsquo;) as potentially ending a sentence.  When GNU <code class="code">troff</code>
encounters one of these <em class="dfn">end-of-sentence characters</em> at the end of
an input line, or one of them is followed by two (unescaped) spaces on
the same input line, it appends an inter-word space followed by an
inter-sentence space in the output.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">R. Harper subscribes to a maxim of P. T. Barnum.
    &rArr; R. Harper subscribes to a maxim of P. T. Barnum.
</pre></div></div>

<p>In the above example, inter-sentence space is not added after &lsquo;<samp class="samp">P.</samp>&rsquo;
or &lsquo;<samp class="samp">T.</samp>&rsquo; because the periods do not occur at the end of an input
line, nor are they followed by two or more spaces.  Let&rsquo;s imagine that
we&rsquo;ve heard something about defamation from Mr. Harper&rsquo;s attorney,
recast the sentence, and reflowed it in our text editor.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">I submit that R. Harper subscribes to a maxim of P. T.
Barnum.
    &rArr; I submit that R. Harper subscribes to a maxim of
    &rArr; P. T.  Barnum.
</pre></div></div>

<p>&ldquo;Barnum&rdquo; doesn&rsquo;t begin a sentence!  What to do?  Let us meet our first
<em class="dfn">escape sequence</em>, a series of input characters that give
instructions to GNU <code class="code">troff</code> instead of being used to construct
output device glyphs.<a class="footnote" id="DOCF21" href="#FOOT21"><sup>21</sup></a> An escape sequence begins with the backslash character <code class="code">\</code>
by default, an uncommon character in natural language text, and is
<em class="emph">always</em> followed by at least one other character, hence the term
&ldquo;sequence&rdquo;.
</p>
<a class="index-entry-id" id="index-_005c_0026_002c-at-end-of-sentence"></a>
<p>The dummy character escape sequence <code class="code">\&amp;</code> can be used after an
end-of-sentence character to defeat end-of-sentence detection on a
per-instance basis.  We can therefore rewrite our input more
defensively.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">I submit that R.\&amp; Harper subscribes to a maxim of P.\&amp;
T.\&amp; Barnum.
    &rArr; I submit that R. Harper subscribes to a maxim of
    &rArr; P. T. Barnum.
</pre></div></div>

<p>Adding text caused our input to wrap; now, we don&rsquo;t need <code class="code">\&amp;</code> after
&lsquo;<samp class="samp">T.</samp>&rsquo; but we do after &lsquo;<samp class="samp">P.</samp>&rsquo;.  Consistent use of the escape
sequence ensures that potential sentence boundaries are robust to
editing activities.  Further advice along these lines will follow in
<a class="ref" href="#Input-Conventions">Input Conventions</a>.
</p>
<a class="index-entry-id" id="index-end_002dof_002dsentence-transparent-characters"></a>
<a class="index-entry-id" id="index-characters_002c-end_002dof_002dsentence-transparent"></a>
<a class="index-entry-id" id="index-dg-glyph_002c-at-end-of-sentence"></a>
<a class="index-entry-id" id="index-dd-glyph_002c-at-end-of-sentence"></a>
<a class="index-entry-id" id="index-rq-glyph_002c-at-end-of-sentence"></a>
<a class="index-entry-id" id="index-cq-glyph_002c-at-end-of-sentence"></a>
<a class="index-entry-id" id="index-_0022_002c-at-end-of-sentence"></a>
<a class="index-entry-id" id="index-_0027_002c-at-end-of-sentence"></a>
<a class="index-entry-id" id="index-_0029_002c-at-end-of-sentence"></a>
<a class="index-entry-id" id="index-_005d_002c-at-end-of-sentence"></a>
<a class="index-entry-id" id="index-_002a_002c-at-end-of-sentence"></a>
<a class="index-entry-id" id="index-special-characters"></a>
<a class="index-entry-id" id="index-characters_002c-special"></a>
<p>Normally, the occurrence of a visible non-end-of-sentence character (as
opposed to a space or tab) immediately after an end-of-sentence
character cancels detection of the end of a sentence.  For example, it
would be incorrect for GNU <code class="code">troff</code> to infer the end of a sentence
after the dot in &lsquo;<samp class="samp">3.14159</samp>&rsquo;.  However, several characters are
treated <em class="emph">transparently</em> after the occurrence of an end-of-sentence
character.  That is, GNU <code class="code">troff</code> does not cancel end-of-sentence
detection when it processes them.  This is because such characters are
often used as footnote markers or to close quotations and
parentheticals.  The default set is &lsquo;<samp class="samp">&quot;</samp>&rsquo;, &lsquo;<samp class="samp">'</samp>&rsquo;, &lsquo;<samp class="samp">)</samp>&rsquo;,
&lsquo;<samp class="samp">]</samp>&rsquo;, &lsquo;<samp class="samp">*</samp>&rsquo;, <code class="code">\[dg]</code>, <code class="code">\[dd]</code>, <code class="code">\[rq]</code>, and
<code class="code">\[cq]</code>.  The last four are examples of <em class="dfn">special characters</em>,
escape sequences whose purpose is to obtain glyphs that are not easily
typed at the keyboard, or which have special meaning to GNU <code class="code">troff</code>
(like <code class="code">\</code> itself).<a class="footnote" id="DOCF22" href="#FOOT22"><sup>22</sup></a>
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">\[lq]The idea that the poor should have leisure has always
been shocking to the rich.\[rq]
(Bertrand Russell, 1935)
    &rArr; &quot;The idea that the poor should have
    &rArr; leisure has always been shocking to
    &rArr; the rich.&quot;  (Bertrand Russell, 1935)
</pre></div></div>

<p>The sets of characters that potentially end sentences or are transparent
to sentence endings are configurable.  See the <code class="code">cflags</code> request in
<a class="ref" href="#Using-Symbols">Using Symbols</a>.  To change the additional inter-sentence space
amount&mdash;even to remove it entirely&mdash;see <a class="ref" href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a>.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Hyphenation">
<div class="nav-panel">
<p>
Next: <a href="#Breaking" accesskey="n" rel="next">Breaking</a>, Previous: <a href="#Sentences" accesskey="p" rel="prev">Sentences</a>, Up: <a href="#Text" accesskey="u" rel="up">Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Hyphenation-1">5.1.3 Hyphenation</h4>
<a class="index-entry-id" id="index-hyphenation"></a>

<p>When an output line is nearly full, it is uncommon for the next word
collected from the input to exactly fill it&mdash;typically, there is room
left over only for part of the next word.  The process of splitting a
word so that it appears partially on one line (with a hyphen to indicate
to the reader that the word has been broken) with its remainder on the
next is <em class="dfn">hyphenation</em>.  Hyphenation points can be manually
specified; GNU <code class="code">troff</code> also uses a hyphenation algorithm and
language-specific pattern files (based on those used in TeX) to
decide which words can be hyphenated and where.
</p>
<p>Hyphenation does not always occur even when the hyphenation rules for a
word allow it; it can be disabled, and when not disabled there are
several parameters that can prevent it in certain circumstances.
See <a class="xref" href="#Manipulating-Hyphenation">Manipulating Hyphenation</a>.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Breaking">
<div class="nav-panel">
<p>
Next: <a href="#Adjustment" accesskey="n" rel="next">Adjustment</a>, Previous: <a href="#Hyphenation" accesskey="p" rel="prev">Hyphenation</a>, Up: <a href="#Text" accesskey="u" rel="up">Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Breaking-1">5.1.4 Breaking</h4>
<a class="index-entry-id" id="index-break"></a>
<a class="index-entry-id" id="index-implicit-line-break"></a>
<a class="index-entry-id" id="index-line-break_002c-output"></a>
<a class="index-entry-id" id="index-output-line-break"></a>

<p>Once an output line is full, the next word (or remainder of a hyphenated
one) is placed on a different output line; this is called a <em class="dfn">break</em>.
In this manual and in <code class="code">roff</code> discussions generally, a &ldquo;break&rdquo; if
not further qualified always refers to the termination of an output
line.  When the formatter is filling text, it introduces breaks
automatically to keep output lines from exceeding the configured line
length.  After an automatic break, GNU <code class="code">troff</code> adjusts the line if
applicable (see below), and then resumes collecting and filling text on
the next output line.
</p>
<p>Sometimes, a line cannot be broken automatically.  This usually does
not happen with natural language text unless the output line length has
been manipulated to be extremely short, but it can with specialized
text like program source code.  We can use <code class="code">perl</code> at the shell
prompt to contrive an example of failure to break the line.  We also
employ the <samp class="option">-z</samp> option to suppress normal output.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">$ perl -e 'print &quot;#&quot; x 80, &quot;\n&quot;;' | nroff -z
    error&rarr; warning: cannot break line
</pre></div></div>

<p>The remedy for these cases is to tell GNU <code class="code">troff</code> where the line
may be broken without hyphens.  This is done with the non-printing break
point escape sequence &lsquo;<samp class="samp">\:</samp>&rsquo;; see <a class="ref" href="#Manipulating-Hyphenation">Manipulating Hyphenation</a>.
</p>
<a class="index-entry-id" id="index-blank-line"></a>
<a class="index-entry-id" id="index-empty-line"></a>
<a class="index-entry-id" id="index-line_002c-blank"></a>
<a class="index-entry-id" id="index-blank-line-macro-_0028blm_0029"></a>
<p>What if the document author wants to stop filling lines temporarily, for
instance to start a new paragraph?  There are several solutions.  A
blank input line not only causes a break, but by default it also outputs
a one-line vertical space (effectively a blank output line).  This
behavior can be modified; see <a class="ref" href="#Blank-Line-Traps">Blank Line Traps</a>.  Macro packages
may discourage or disable the blank line method of paragraphing in favor
of their own macros.
</p>
<a class="index-entry-id" id="index-leading-spaces"></a>
<a class="index-entry-id" id="index-spaces_002c-leading-and-trailing"></a>
<a class="index-entry-id" id="index-trailing-spaces-on-text-lines"></a>
<a class="index-entry-id" id="index-leading-space-macro-_0028lsm_0029"></a>
<p>A line that begins with one or more spaces causes a break.  The spaces
are output at the beginning of the next line without being
<em class="emph">adjusted</em> (see below); however, this behavior can be modified
(see <a class="pxref" href="#Leading-Space-Traps">Leading Space Traps</a>).  Again, macro packages may provide other
methods of producing indented paragraphs.  Trailing spaces on text lines
are discarded.<a class="footnote" id="DOCF23" href="#FOOT23"><sup>23</sup></a>
</p>
<p>What if the file ends before enough words have been collected to fill an
output line?  Or the output line is exactly full but not yet broken, and
there is no more input?  GNU <code class="code">troff</code> interprets the end of input as
a break.  Certain requests also cause breaks, implicitly or explicitly.
This is discussed in <a class="ref" href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a>.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Adjustment">
<div class="nav-panel">
<p>
Next: <a href="#Tabs-and-Leaders" accesskey="n" rel="next">Tabs and Leaders</a>, Previous: <a href="#Breaking" accesskey="p" rel="prev">Breaking</a>, Up: <a href="#Text" accesskey="u" rel="up">Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Adjustment-1">5.1.5 Adjustment</h4>

<a class="index-entry-id" id="index-extra-spaces-between-words"></a>
<p>After GNU <code class="code">troff</code> performs an automatic break, it may then
<em class="dfn">adjust</em> the line, widening inter-word spaces until the text reaches
the right margin.  Extra spaces between words are preserved.  Leading
and trailing spaces are handled as noted above.  Text can be aligned to
the left or right margin only, or centered; see <a class="ref" href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a>.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Tabs-and-Leaders">
<div class="nav-panel">
<p>
Next: <a href="#Input-Conventions" accesskey="n" rel="next">Input Conventions</a>, Previous: <a href="#Adjustment" accesskey="p" rel="prev">Adjustment</a>, Up: <a href="#Text" accesskey="u" rel="up">Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Tabs-and-Leaders-1">5.1.6 Tabs and Leaders</h4>

<a class="index-entry-id" id="index-horizontal-tab-character"></a>
<a class="index-entry-id" id="index-tab-character"></a>
<a class="index-entry-id" id="index-character_002c-horizontal-tab"></a>
<a class="index-entry-id" id="index-leader-character"></a>
<a class="index-entry-id" id="index-character_002c-leader"></a>
<a class="index-entry-id" id="index-tab-stops"></a>
<a class="index-entry-id" id="index-stops_002c-tab"></a>
<p>GNU <code class="code">troff</code> translates input horizontal tab characters (&ldquo;tabs&rdquo;)
and <kbd class="key">Control+A</kbd> characters (&ldquo;leaders&rdquo;) into movements to the next
tab stop.  Tabs simply move to the next tab stop; leaders place enough
periods to fill the space.  Tab stops are by default located every half
inch measured from the drawing position corresponding to the beginning
of the input line; see <a class="ref" href="#Page-Geometry">Page Geometry</a>.   Tabs and leaders do not
cause breaks and therefore do not interrupt filling.  Below, we use
arrows &rarr; and bullets &bull; to indicate input tabs and
leaders, respectively.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">1
&rarr; 2 &rarr; 3 &bull; 4
&rarr; &bull; 5
&rArr; 1         2       3.......4         ........5
</pre></div></div>

<p>Tabs and leaders lend themselves to table construction.<a class="footnote" id="DOCF24" href="#FOOT24"><sup>24</sup></a> The tab and leader glyphs can be
configured, and further facilities for sophisticated table composition
are available; see <a class="ref" href="#Tabs-and-Fields">Tabs and Fields</a>.  There are many details to
track when using such low-level features, so most users turn to the
<cite class="cite">tbl<span class="r">(1)</span></cite> preprocessor to lay out tables.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Requests-and-Macros">
<div class="nav-panel">
<p>
Next: <a href="#Macro-Packages" accesskey="n" rel="next">Macro Packages</a>, Previous: <a href="#Tabs-and-Leaders" accesskey="p" rel="prev">Tabs and Leaders</a>, Up: <a href="#Text" accesskey="u" rel="up">Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Requests-and-Macros-1">5.1.7 Requests and Macros</h4>

<p>We have now encountered almost all of the syntax there is in the
<code class="code">roff</code> language, with an exception already noted in passing.
<a class="index-entry-id" id="index-request"></a>
<a class="index-entry-id" id="index-control-character-_0028_002e_0029"></a>
<a class="index-entry-id" id="index-character_002c-control-_0028_002e_0029"></a>
<a class="index-entry-id" id="index-no_002dbreak-control-character-_0028_0027_0029"></a>
<a class="index-entry-id" id="index-character_002c-no_002dbreak-control-_0028_0027_0029"></a>
<a class="index-entry-id" id="index-control-character_002c-no_002dbreak-_0028_0027_0029"></a>
A <em class="dfn">request</em> is an instruction to the formatter that occurs after a
<em class="dfn">control character</em>, which is recognized at the beginning of an
input line.  The regular control character is a dot (<code class="code">.</code>).  Its
counterpart, the <em class="dfn">no-break control character</em>, a neutral apostrophe
(<code class="code">'</code>), suppresses the break that is implied by some requests.
These characters were chosen because it is uncommon for lines of text in
natural languages to begin with them.
<a class="index-entry-id" id="index-dummy-character-_0028_005c_0026_0029_002c-as-control-character-suppressor"></a>
<a class="index-entry-id" id="index-character_002c-dummy-_0028_005c_0026_0029_002c-as-control-character-suppressor"></a>
If you require a formatted period or apostrophe (closing single
quotation mark) where GNU <code class="code">troff</code> is expecting a control character,
prefix the dot or neutral apostrophe with the dummy character escape
sequence, &lsquo;<samp class="samp">\&amp;</samp>&rsquo;.
</p>
<a class="index-entry-id" id="index-control-line"></a>
<p>An input line beginning with a control character is called a
<em class="dfn">control line</em>.
<a class="index-entry-id" id="index-text-line"></a>
Every line of input that is not a control line is a <em class="dfn">text
line</em>.<a class="footnote" id="DOCF25" href="#FOOT25"><sup>25</sup></a>
</p>
<a class="index-entry-id" id="index-argument"></a>
<p>Requests often take <em class="dfn">arguments</em>, words (separated from the request
name and each other by spaces) that specify details of the action GNU
<code class="code">troff</code> is expected to perform.  If a request is meaningless
without arguments, it is typically ignored.
</p>
<p>GNU <code class="code">troff</code>&rsquo;s requests and escape sequences comprise the control
language of the formatter.  Of key importance are the requests that
define macros.  Macros are invoked like requests, enabling the request
repertoire to be extended or overridden.<a class="footnote" id="DOCF26" href="#FOOT26"><sup>26</sup></a>
</p>
<a class="index-entry-id" id="index-macro"></a>
<a class="index-entry-id" id="index-calling-a-macro"></a>
<a class="index-entry-id" id="index-interpolation"></a>
<p>A <em class="dfn">macro</em> can be thought of as an abbreviation you can define for a
collection of control and text lines.  When the macro is <em class="dfn">called</em> by
giving its name after a control character, it is replaced with what it
stands for.  The process of textual replacement is known as
<em class="dfn">interpolation</em>.<a class="footnote" id="DOCF27" href="#FOOT27"><sup>27</sup></a>  Interpolations are handled as soon as they are
recognized, and once performed, a <code class="code">roff</code> formatter scans the
replacement for further requests, macro calls, and escape sequences.
</p>
<p>In <code class="code">roff</code> systems, the <code class="code">de</code> request defines a
macro.<a class="footnote" id="DOCF28" href="#FOOT28"><sup>28</sup></a>
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de DATE
2020-11-14
..
</pre></div></div>

<p>The foregoing input produces no output by itself; all we have done is
store some information.  Observe the pair of dots that ends the macro
definition.  This is a default; you can specify your own terminator for
the macro definition as the second argument to the <code class="code">de</code> request.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de NAME ENDNAME
Heywood Jabuzzoff
.ENDNAME
</pre></div></div>

<p>In fact, the ending marker is itself the name of a macro to be
called, or a request to be invoked, if it is defined at the time its
control line is read.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de END
Big Rip
..
.de START END
Big Bang
.END
.START
    &rArr; Big Rip Big Bang
</pre></div></div>

<p>In the foregoing example, &ldquo;Big Rip&rdquo; printed before &ldquo;Big Bang&rdquo;
because its macro was <em class="emph">called</em> first.  Consider what would happen
if we dropped <code class="code">END</code> from the &lsquo;<samp class="samp">.de START</samp>&rsquo; line and added
<code class="code">..</code> after <code class="code">.END</code>.  Would the order change?
</p>
<p>Let us consider a more elaborate example.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de DATE
2020-10-05
..
.
.de BOSS
D.\&amp; Kruger,
J.\&amp; Peterman
..
.
.de NOTICE
Approved:
.DATE
by
.BOSS
..
.
Insert tedious regulatory compliance paragraph here.

.NOTICE

Insert tedious liability disclaimer paragraph here.

.NOTICE
    &rArr; Insert tedious regulatory compliance paragraph here.
    &rArr;
    &rArr; Approved: 2020-10-05 by D. Kruger, J. Peterman
    &rArr;
    &rArr; Insert tedious liability disclaimer paragraph here.
    &rArr;
    &rArr; Approved: 2020-10-05 by D. Kruger, J. Peterman
</pre></div></div>

<p>The above document started with a series of control lines.  Three macros
were defined, with a <code class="code">de</code> request declaring each macro&rsquo;s name, and
the &ldquo;body&rdquo; of the macro starting on the next line and continuing until
a line with two dots &lsquo;<samp class="samp"><code class="code">..</code></samp>&rsquo; marked its end.  The text proper
began only after the macros were defined; this is a common pattern.
Only the <code class="code">NOTICE</code> macro was called &ldquo;directly&rdquo; by the document;
<code class="code">DATE</code> and <code class="code">BOSS</code> were called only by <code class="code">NOTICE</code> itself.
Escape sequences were used in <code class="code">BOSS</code>, two levels of macro
interpolation deep.
</p>
<p>The advantage in typing and maintenance economy may not be obvious from
such a short example, but imagine a much longer document with dozens of
such paragraphs, each requiring a notice of managerial approval.
Consider what must happen if you are in charge of generating a new
version of such a document with a different date, for a different boss.
With well-chosen macros, you only have to change each datum in one
place.
</p>
<p>In practice, we would probably use strings (see <a class="pxref" href="#Strings">Strings</a>) instead of
macros for such simple interpolations; what is important here is to
glimpse the potential of macros and the power of recursive
interpolation.
</p>
<p>We could have defined <code class="code">DATE</code> and <code class="code">BOSS</code> in the opposite order;
perhaps less obviously, we could also have defined them <em class="emph">after</em>
<code class="code">NOTICE</code>.  &ldquo;Forward references&rdquo; like this are acceptable because
the body of a macro definition is not (completely) interpreted, but
stored instead (see <a class="pxref" href="#Copy-Mode">Copy Mode</a>).  While a macro is being defined (or
appended to), requests are not interpreted and macros not interpolated,
whereas some commonly used escape sequences <em class="emph">are</em> interpreted.
<code class="code">roff</code> systems also support recursive macro calls, as long as you
have a way to break the recursion (see <a class="pxref" href="#Conditionals-and-Loops">Conditionals and Loops</a>).
Maintainable <code class="code">roff</code> documents tend to arrange macro definitions to
minimize forward references.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Macro-Packages">
<div class="nav-panel">
<p>
Next: <a href="#Input-Encodings" accesskey="n" rel="next">Input Encodings</a>, Previous: <a href="#Requests-and-Macros" accesskey="p" rel="prev">Requests and Macros</a>, Up: <a href="#Text" accesskey="u" rel="up">Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Macro-Packages-3">5.1.8 Macro Packages</h4>
<a class="index-entry-id" id="index-macro-package"></a>
<a class="index-entry-id" id="index-package_002c-macro"></a>

<p>Macro definitions can be collected into <em class="dfn">macro files</em>, <code class="code">roff</code>
input files designed to produce no output themselves but instead ease
the preparation of other <code class="code">roff</code> documents.  There is no syntactical
difference between a macro file and any other <code class="code">roff</code> document; only
its purpose distinguishes it.  When a macro file is installed at a
standard location and suitable for use by a general audience, it is
often termed a <em class="dfn">macro package</em>.<a class="footnote" id="DOCF29" href="#FOOT29"><sup>29</sup></a>  Macro packages can be
loaded by supplying the <samp class="option">-m</samp> option to GNU <code class="command">troff</code> or a
<code class="code">groff</code> front end.  Alternatively, a document requiring a macro
package can load it with the <code class="code">mso</code> (&ldquo;macro source&rdquo;) request.
</p>


<hr>
</div>
<div class="subsection-level-extent" id="Input-Encodings">
<div class="nav-panel">
<p>
Next: <a href="#Input-Conventions" accesskey="n" rel="next">Input Conventions</a>, Previous: <a href="#Macro-Packages" accesskey="p" rel="prev">Macro Packages</a>, Up: <a href="#Text" accesskey="u" rel="up">Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Input-Encodings-1">5.1.9 Input Encodings</h4>

<p>The <code class="command">groff</code> command&rsquo;s <samp class="option">-k</samp> option calls the
<code class="command">preconv</code> preprocessor to perform input character encoding
conversions.  Input to the GNU <code class="code">troff</code> formatter itself, on the
other hand, must be in one of two encodings it can recognize.
</p>
<dl class="table">
<dt id='index-encoding_002c-input_002c-EBCDIC'><span><code class="code">cp1047</code><a class="copiable-link" href='#index-encoding_002c-input_002c-EBCDIC'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-EBCDIC_002c-input-encoding"></a>
<a class="index-entry-id" id="index-input-encoding_002c-EBCDIC"></a>
<a class="index-entry-id" id="index-encoding_002c-input_002c-code-page-1047"></a>
<a class="index-entry-id" id="index-code-page-1047_002c-input-encoding"></a>
<a class="index-entry-id" id="index-input-encoding_002c-code-page-1047"></a>
<a class="index-entry-id" id="index-IBM-code-page-1047-input-encoding"></a>
<a class="index-entry-id" id="index-cp1047_002etmac"></a>
<p>The code page 1047 input encoding works only on <abbr class="acronym">EBCDIC</abbr>
platforms (and conversely, the other input encodings don&rsquo;t work with
<abbr class="acronym">EBCDIC</abbr>); the file <samp class="file">cp1047.tmac</samp> is loaded at startup.
</p>
</dd>
<dt id='index-encoding_002c-input_002c-Latin_002d1-_0028ISO-8859_002d1_0029'><span><code class="code">latin1</code><a class="copiable-link" href='#index-encoding_002c-input_002c-Latin_002d1-_0028ISO-8859_002d1_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-Latin_002d1-_0028ISO-8859_002d1_0029_002c-input-encoding"></a>
<a class="index-entry-id" id="index-ISO-8859_002d1-_0028Latin_002d1_0029_002c-input-encoding"></a>
<a class="index-entry-id" id="index-input-encoding_002c-Latin_002d1-_0028ISO-8859_002d1_0029"></a>
<a class="index-entry-id" id="index-latin1_002etmac"></a>
<p>ISO <span class="w-nolinebreak-text">Latin-1</span><!-- /@w -->, an encoding for Western European languages, is the
default input encoding on non-<abbr class="acronym">EBCDIC</abbr> platforms; the file
<samp class="file">latin1.tmac</samp> is loaded at startup.
</p></dd>
</dl>

<p>Any document that is encoded in ISO 646:1991 (a descendant of USAS
<span class="w-nolinebreak-text">X3.4-1968</span><!-- /@w --> or &ldquo;US-ASCII&rdquo;), or, equivalently, uses only code points
from the &ldquo;C0 Controls&rdquo; and &ldquo;Basic Latin&rdquo; parts of the Unicode
character set is also a valid ISO <span class="w-nolinebreak-text">Latin-1</span><!-- /@w --> document; the standards
are interchangeable in their first 128 code points.<a class="footnote" id="DOCF30" href="#FOOT30"><sup>30</sup></a>
</p>
<p>Other encodings are supported by means of macro packages.
</p>
<dl class="table">
<dt id='index-encoding_002c-input_002c-Latin_002d2-_0028ISO-8859_002d2_0029'><span><code class="code">latin2</code><a class="copiable-link" href='#index-encoding_002c-input_002c-Latin_002d2-_0028ISO-8859_002d2_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-Latin_002d2-_0028ISO-8859_002d2_0029_002c-input-encoding"></a>
<a class="index-entry-id" id="index-ISO-8859_002d2-_0028Latin_002d2_0029_002c-input-encoding"></a>
<a class="index-entry-id" id="index-input-encoding_002c-Latin_002d2-_0028ISO-8859_002d2_0029"></a>
<a class="index-entry-id" id="index-latin2_002etmac"></a>
<p>To use ISO <span class="w-nolinebreak-text">Latin-2</span><!-- /@w -->, an encoding for Central and Eastern European
languages, invoke &lsquo;<samp class="samp">.mso&nbsp;latin2.tmac</samp>&rsquo;<!-- /@w --> at the beginning of your
document or supply &lsquo;<samp class="samp">-mlatin2</samp>&rsquo; as a command-line argument to
<code class="code">groff</code>.
</p>
</dd>
<dt id='index-encoding_002c-input_002c-Latin_002d5-_0028ISO-8859_002d9_0029'><span><code class="code">latin5</code><a class="copiable-link" href='#index-encoding_002c-input_002c-Latin_002d5-_0028ISO-8859_002d9_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-Latin_002d5-_0028ISO-8859_002d9_0029_002c-input-encoding"></a>
<a class="index-entry-id" id="index-ISO-8859_002d9-_0028Latin_002d5_0029_002c-input-encoding"></a>
<a class="index-entry-id" id="index-input-encoding_002c-Latin_002d5-_0028ISO-8859_002d9_0029"></a>
<a class="index-entry-id" id="index-latin5_002etmac"></a>
<p>To use ISO <span class="w-nolinebreak-text">Latin-5</span><!-- /@w -->, an encoding for the Turkish language, invoke
&lsquo;<samp class="samp">.mso&nbsp;latin5.tmac</samp>&rsquo;<!-- /@w --> at the beginning of your document or
supply &lsquo;<samp class="samp">-mlatin5</samp>&rsquo; as a command-line argument to <code class="code">groff</code>.
</p>
</dd>
<dt id='index-encoding_002c-input_002c-Latin_002d9-_0028ISO-8859_002d15_0029'><span><code class="code">latin9</code><a class="copiable-link" href='#index-encoding_002c-input_002c-Latin_002d9-_0028ISO-8859_002d15_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-Latin_002d9-_0028ISO-8859_002d15_0029_002c-input-encoding"></a>
<a class="index-entry-id" id="index-ISO-8859_002d15-_0028Latin_002d9_0029_002c-input-encoding"></a>
<a class="index-entry-id" id="index-input-encoding_002c-Latin_002d9-_0028ISO-8859_002d15_0029"></a>
<a class="index-entry-id" id="index-latin9_002etmac"></a>
<p>ISO <span class="w-nolinebreak-text">Latin-9</span><!-- /@w --> succeeds <span class="w-nolinebreak-text">Latin-1</span><!-- /@w -->; it includes a Euro sign and better
glyph coverage for French.  To use this encoding, invoke &lsquo;<samp class="samp">.mso&nbsp;latin9.tmac</samp>&rsquo;<!-- /@w --> at the beginning of your document or supply
&lsquo;<samp class="samp">-mlatin9</samp>&rsquo; as a command-line argument to <code class="code">groff</code>.
</p></dd>
</dl>

<p>Some characters from an input encoding may not be available with a
particular output driver, or their glyphs may not have representation in
the font used.  For terminal devices, fallbacks are defined, like
&lsquo;<samp class="samp">EUR</samp>&rsquo; for the Euro sign and &lsquo;<samp class="samp">(C)</samp>&rsquo; for the copyright sign.  For
typesetter devices, you may need to &ldquo;mount&rdquo; fonts that support glyphs
required by the document.  See <a class="xref" href="#Font-Positions">Font Positions</a>.
</p>
<a class="index-entry-id" id="index-freeeuro_002epfa"></a>
<a class="index-entry-id" id="index-ec_002etmac"></a>
<p>Because a Euro glyph was not historically defined in PostScript fonts,
<code class="code">groff</code> comes with a font called <samp class="file">freeeuro.pfa</samp> that provides
the Euro in several styles.  Standard PostScript fonts contain the
glyphs from <span class="w-nolinebreak-text">Latin-5</span><!-- /@w --> and <span class="w-nolinebreak-text">Latin-9</span><!-- /@w --> that <span class="w-nolinebreak-text">Latin-1</span><!-- /@w --> lacks, so these
encodings are supported for the <samp class="option">ps</samp> and <samp class="option">pdf</samp> output
devices as <code class="code">groff</code> ships, while <span class="w-nolinebreak-text">Latin-2</span><!-- /@w --> is not.
</p>
<p>Unicode supports characters from all other input encodings; the
<samp class="option">utf8</samp> output driver for terminals therefore does as well.  The
DVI output driver supports the <span class="w-nolinebreak-text">Latin-2</span><!-- /@w --> and <span class="w-nolinebreak-text">Latin-9</span><!-- /@w --> encodings if
the command-line option <samp class="option">-mec</samp> is used as well.  <a class="footnote" id="DOCF31" href="#FOOT31"><sup>31</sup></a>
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Input-Conventions">
<div class="nav-panel">
<p>
Previous: <a href="#Input-Encodings" accesskey="p" rel="prev">Input Encodings</a>, Up: <a href="#Text" accesskey="u" rel="up">Text</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Input-Conventions-1">5.1.10 Input Conventions</h4>
<a class="index-entry-id" id="index-input-conventions"></a>
<a class="index-entry-id" id="index-conventions-for-input"></a>

<p>Since GNU <code class="code">troff</code> fills text automatically, it is common practice
in the <code class="code">roff</code> language to avoid visual composition of text in input
files: the esthetic appeal of the formatted output is what matters.
Therefore, <code class="code">roff</code> input should be arranged such that it is easy for
authors and maintainers to compose and develop the document, understand
the syntax of <code class="code">roff</code> requests, macro calls, and preprocessor
languages used, and predict the behavior of the formatter.  Several
traditions have accrued in service of these goals.
</p>
<ul class="itemize mark-bullet">
<li>Follow sentence endings in the input with newlines to ease their
recognition (see <a class="pxref" href="#Sentences">Sentences</a>).  It is frequently convenient to end
text lines after colons and semicolons as well, as these typically
precede independent clauses.  Consider doing so after commas; they often
occur in lists that become easy to scan when itemized by line, or
constitute supplements to the sentence that are added, deleted, or
updated to clarify it.  Parenthetical and quoted phrases are also good
candidates for placement on text lines by themselves.

</li><li>Set your text editor&rsquo;s line length to 72 characters or
fewer.<a class="footnote" id="DOCF32" href="#FOOT32"><sup>32</sup></a>
This limit, combined with the previous item of advice, makes it less
common that an input line will wrap in your text editor, and thus will
help you perceive excessively long constructions in your text.  Recall
that natural languages originate in speech, not writing, and that
punctuation is correlated with pauses for breathing and changes in
prosody.

</li><li>Use <code class="code">\&amp;</code> after &lsquo;<samp class="samp">!</samp>&rsquo;, &lsquo;<samp class="samp">?</samp>&rsquo;, and &lsquo;<samp class="samp">.</samp>&rsquo; if they are
followed by space, tab, or newline characters and don&rsquo;t end a sentence.

</li><li>In filled text lines, use <code class="code">\&amp;</code> before &lsquo;<samp class="samp">.</samp>&rsquo; and &lsquo;<samp class="samp">'</samp>&rsquo; if they
are preceded by space, so that reflowing the input doesn&rsquo;t turn them
into control lines.

</li><li>Do not use spaces to perform indentation or align columns of a table.
Leading spaces are reliable when text is not being filled.

</li><li>Comment your document.  It is never too soon to apply comments to
record information of use to future document maintainers (including your
future self).  We thus introduce another escape sequence, <code class="code">\&quot;</code>,
which causes GNU <code class="code">troff</code> to ignore the remainder of the input line.

</li><li>Use the empty request&mdash;a control character followed immediately by a
newline&mdash;to visually manage separation of material in input files.
Many of the <code class="code">groff</code> project&rsquo;s own documents use an empty request
between sentences, after macro definitions, and where a break is
expected, and two empty requests between paragraphs or other requests or
macro calls that will introduce vertical space into the document.

<p>You can combine the empty request with the comment escape sequence to
include whole-line comments in your document, and even &ldquo;comment out&rdquo;
sections of it.
</p></li></ul>

<p>We conclude this section with an example sufficiently long to illustrate
most of the above suggestions in practice.  For the purpose of fitting
the example between the margins of this manual with the font used for
its typeset version, we have shortened the input line length to 56
columns.  As before, an arrow &rarr; indicates a tab character.
</p>
<table class="cartouche" border="1"><tr><td>
<div class="example">
<pre class="example-preformatted">.\&quot;   nroff this_file.roff | less
.\&quot;   groff -T ps this_file.roff &gt; this_file.ps
&rarr;The theory of relativity is intimately connected with
the theory of space and time.
.
I shall therefore begin with a brief investigation of
the origin of our ideas of space and time,
although in doing so I know that I introduce a
controversial subject.  \&quot; remainder of paragraph elided
.
.

&rarr;The experiences of an individual appear to us arranged
in a series of events;
in this series the single events which we remember
appear to be ordered according to the criterion of
\[lq]earlier\[rq] and \[lq]later\[rq], \&quot; punct swapped
which cannot be analysed further.
.
There exists,
therefore,
for the individual,
an I-time,
or subjective time.
.
This itself is not measurable.
.
I can,
indeed,
associate numbers with the events,
in such a way that the greater number is associated with
the later event than with an earlier one;
but the nature of this association may be quite
arbitrary.
.
This association I can define by means of a clock by
comparing the order of events furnished by the clock
with the order of a given series of events.
.
We understand by a clock something which provides a
series of events which can be counted,
and which has other properties of which we shall speak
later.
.\&quot; Albert Einstein, _The Meaning of Relativity_, 1922
</pre></div>
</td></tr></table>

<hr>
</div>
</div>
<div class="section-level-extent" id="Page-Geometry">
<div class="nav-panel">
<p>
Next: <a href="#Measurements" accesskey="n" rel="next">Measurements</a>, Previous: <a href="#Text" accesskey="p" rel="prev">Text</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Page-Geometry-1">5.2 Page Geometry</h3>
<a class="index-entry-id" id="index-page_002c-geometry-of"></a>
<a class="index-entry-id" id="index-geometry_002c-page"></a>

<p><code class="code">roff</code> systems format text under certain assumptions about the size
of the output medium, or page.  For the formatter to correctly break a
line it is filling, it must know the line length, which it derives from
the page width (see <a class="pxref" href="#Line-Layout">Line Layout</a>).  For it to decide whether to write
an output line to the current page or wait until the next one, it must
know the page length (see <a class="pxref" href="#Page-Layout">Page Layout</a>).
</p>
<a class="index-entry-id" id="index-device-resolution"></a>
<a class="index-entry-id" id="index-resolution_002c-device"></a>
<a class="index-entry-id" id="index-basic-units"></a>
<a class="index-entry-id" id="index-units_002c-basic"></a>
<a class="index-entry-id" id="index-machine-units"></a>
<a class="index-entry-id" id="index-units_002c-machine"></a>
<p>A device&rsquo;s <em class="dfn">resolution</em> converts practical units like inches or
centimeters to <em class="dfn">basic units</em>, a convenient length measure for the
output device or file format.  The formatter and output driver use basic
units to reckon page measurements.  The device description file defines
its resolution and page dimensions (see <a class="pxref" href="#DESC-File-Format"><samp class="file">DESC</samp> File Format</a>).
</p>
<a class="index-entry-id" id="index-page"></a>
<p>A <em class="dfn">page</em> is a two-dimensional structure upon which a <code class="code">roff</code>
system imposes a rectangular coordinate system with its upper left
corner as the origin.  Coordinate values are in basic units and increase
down and to the right.  Useful ones are therefore always positive and
within numeric ranges corresponding to the page boundaries.
</p>
<a class="index-entry-id" id="index-drawing-position"></a>
<a class="index-entry-id" id="index-position_002c-drawing"></a>
<p>While the formatter (and, later, output driver) is processing a page, it
keeps track of its <em class="dfn">drawing position</em>, which is the location at
which the next glyph will be written, from which the next motion will be
measured, or where a geometric object will commence rendering.
<a class="index-entry-id" id="index-text-baseline"></a>
<a class="index-entry-id" id="index-baseline_002c-text"></a>
Notionally, glyphs are drawn from the text baseline upward and to the
right.<a class="footnote" id="DOCF33" href="#FOOT33"><sup>33</sup></a>  The <em class="dfn">text baseline</em> is a (usually invisible) line upon
which the glyphs of a typeface are aligned.  A glyph therefore
&ldquo;starts&rdquo; at its bottom-left corner.  If drawn at the origin, a typical
letter glyph would lie partially or wholly off the page, depending on
whether, like &ldquo;g&rdquo;, it features a descender below the baseline.
</p>
<a class="index-entry-id" id="index-page-offset"></a>
<a class="index-entry-id" id="index-offset_002c-page"></a>
<p>Such a situation is nearly always undesirable.  It is furthermore
conventional not to write or draw at the extreme edges of the page.
Therefore the initial drawing position of a <code class="code">roff</code> formatter is not
at the origin, but below and to the right of it.  This rightward shift
from the left edge is known as the <em class="dfn">page
offset</em>.<a class="footnote" id="DOCF34" href="#FOOT34"><sup>34</sup></a>  The downward shift leaves room for a text output
line.
</p>
<p>Text is arranged on a one-dimensional lattice of text baselines from the
top to the bottom of the page.
<a class="index-entry-id" id="index-vertical-spacing"></a>
<a class="index-entry-id" id="index-spacing_002c-vertical"></a>
<a class="index-entry-id" id="index-vee"></a>
<em class="dfn">Vertical spacing</em> is the distance between adjacent text baselines.
Typographic tradition sets this quantity to 120% of the type size.  The
initial drawing position is one unit of vertical spacing below the page
top.  Typographers term this unit a <i class="slanted">vee</i>.
</p>
<a class="index-entry-id" id="index-page-break"></a>
<a class="index-entry-id" id="index-break_002c-page"></a>
<a class="index-entry-id" id="index-page-ejection"></a>
<a class="index-entry-id" id="index-ejection_002c-page"></a>
<p>Vertical spacing has an impact on page-breaking decisions.  Generally,
when a break occurs, the formatter moves the drawing position to the
next text baseline automatically.  If the formatter were already writing
to the last line that would fit on the page, advancing by one vee would
place the next text baseline off the page.  Rather than let that happen,
<code class="code">roff</code> formatters instruct the output driver to eject the page,
start a new one, and again set the drawing position to one vee below the
page top; this is a <em class="dfn">page break</em>.
</p>
<p>When the last line of input text corresponds to the last output line
that fits on the page, the break caused by the end of input will also
break the page, producing a useless blank one.  Macro packages keep
users from having to confront this difficulty by setting &ldquo;traps&rdquo;
(see <a class="pxref" href="#Traps">Traps</a>); moreover, all but the simplest page layouts tend to
have headers and footers, or at least bear vertical margins larger than
one vee.
</p>


<hr>
</div>
<div class="section-level-extent" id="Measurements">
<div class="nav-panel">
<p>
Next: <a href="#Numeric-Expressions" accesskey="n" rel="next">Numeric Expressions</a>, Previous: <a href="#Text" accesskey="p" rel="prev">Text</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Measurements-1">5.3 Measurements</h3>
<a class="index-entry-id" id="index-measurements"></a>
<a class="index-entry-id" id="index-scaling-indicator"></a>
<a class="index-entry-id" id="index-indicator_002c-scaling"></a>

<a class="index-entry-id" id="index-units-of-measurement"></a>
<a class="index-entry-id" id="index-measurement-units"></a>
<p>The formatter sometimes requires the input of numeric parameters to
specify measurements.  These are specified as integers or decimal
fractions with an optional <em class="dfn">scaling unit</em> suffixed.  A scaling unit
is a letter that immediately follows the last digit of a number.  Digits
after the decimal point are optional.  Measurement expressions include
&lsquo;<samp class="samp">10.5p</samp>&rsquo;, &lsquo;<samp class="samp">11i</samp>&rsquo;, and &lsquo;<samp class="samp">3.c</samp>&rsquo;.
</p>
<a class="index-entry-id" id="index-basic-units_002c-conversion-to"></a>
<a class="index-entry-id" id="index-units_002c-basic_002c-conversion-to"></a>
<a class="index-entry-id" id="index-conversion-to-basic-units"></a>
<p>Measurements are scaled by the scaling unit and stored internally (with
any fractional part discarded) in basic units.
<a class="index-entry-id" id="index-device-resolution_002c-obtaining-in-the-formatter"></a>
<a class="index-entry-id" id="index-resolution_002c-device_002c-obtaining-in-the-formatter"></a>
The device resolution can therefore be obtained by storing a value of
&lsquo;<samp class="samp">1i</samp>&rsquo; to a register.  The only constraint on the basic unit is that
it is at least as small as any other unit.
</p>
<dl class="table">
<dd><a class="index-entry-id" id="index-basic-scaling-unit-_0028u_0029"></a>
<a class="index-entry-id" id="index-u-scaling-unit"></a>
<a class="index-entry-id" id="index-unit_002c-scaling_002c-u"></a>
<a class="index-entry-id" id="index-scaling-unit-u"></a>
</dd>
<dt><code class="code">u</code></dt>
<dd><p>Basic unit.
</p>
</dd>
<dt id='index-inch-scaling-unit-_0028i_0029'><span><code class="code">i</code><a class="copiable-link" href='#index-inch-scaling-unit-_0028i_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-i-scaling-unit"></a>
<a class="index-entry-id" id="index-unit_002c-scaling_002c-i"></a>
<a class="index-entry-id" id="index-scaling-unit-i"></a>
<p>Inch; defined as 2.54&nbsp;centimeters.
</p>
</dd>
<dt id='index-centimeter-scaling-unit-_0028c_0029'><span><code class="code">c</code><a class="copiable-link" href='#index-centimeter-scaling-unit-_0028c_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-c-scaling-unit"></a>
<a class="index-entry-id" id="index-unit_002c-scaling_002c-c"></a>
<a class="index-entry-id" id="index-scaling-unit-c"></a>
<p>Centimeter; a centimeter is about 0.3937&nbsp;inches.
</p>
</dd>
<dt id='index-point-scaling-unit-_0028p_0029'><span><code class="code">p</code><a class="copiable-link" href='#index-point-scaling-unit-_0028p_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-p-scaling-unit"></a>
<a class="index-entry-id" id="index-unit_002c-scaling_002c-p"></a>
<a class="index-entry-id" id="index-scaling-unit-p"></a>
<p>Point; a typesetter&rsquo;s unit used for measuring type size.
There are 72&nbsp;points to an inch.
</p>
</dd>
<dt id='index-pica-scaling-unit-_0028P_0029'><span><code class="code">P</code><a class="copiable-link" href='#index-pica-scaling-unit-_0028P_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-P-scaling-unit"></a>
<a class="index-entry-id" id="index-unit_002c-scaling_002c-P"></a>
<a class="index-entry-id" id="index-scaling-unit-P"></a>
<p>Pica; another typesetter&rsquo;s unit.  There are 6&nbsp;picas to an inch and
12&nbsp;points to a pica.
</p>
</dd>
<dt><code class="code">s</code></dt>
<dt><code class="code">z</code></dt>
<dd><p>See <a class="xref" href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a>, for a discussion of these units.
</p>
</dd>
<dt><code class="code">f</code></dt>
<dd><p>GNU <code class="code">troff</code> defines this unit to scale decimal fractions in the
interval [0, 1] to 16-bit unsigned integers.  It multiplies a quantity
by 65,536.  See <a class="xref" href="#Colors">Colors</a>, for usage.
</p></dd>
</dl>

<p>The magnitudes of other scaling units depend on the text formatting
parameters in effect.  These are useful when specifying measurements
that need to scale with the typeface or vertical spacing.
</p>
<dl class="table">
<dt id='index-em-scaling-unit-_0028m_0029'><span><code class="code">m</code><a class="copiable-link" href='#index-em-scaling-unit-_0028m_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-m-scaling-unit"></a>
<a class="index-entry-id" id="index-unit_002c-scaling_002c-m"></a>
<a class="index-entry-id" id="index-scaling-unit-m"></a>
<p>Em; an em is equal to the current type size in points.  It is named thus
because it is approximately the width of the letter&nbsp;&lsquo;<samp class="samp">M</samp>&rsquo;.
</p>
</dd>
<dt id='index-en-scaling-unit-_0028n_0029'><span><code class="code">n</code><a class="copiable-link" href='#index-en-scaling-unit-_0028n_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-n-scaling-unit"></a>
<a class="index-entry-id" id="index-unit_002c-scaling_002c-n"></a>
<a class="index-entry-id" id="index-scaling-unit-n"></a>
<p>En; an en is one-half em.
</p>
</dd>
<dt id='index-vertical-space-unit-_0028v_0029'><span><code class="code">v</code><a class="copiable-link" href='#index-vertical-space-unit-_0028v_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-space_002c-vertical_002c-unit-_0028v_0029"></a>
<a class="index-entry-id" id="index-vee-scaling-unit-_0028v_0029"></a>
<a class="index-entry-id" id="index-v-scaling-unit"></a>
<a class="index-entry-id" id="index-unit_002c-scaling_002c-v"></a>
<a class="index-entry-id" id="index-scaling-unit-v"></a>
<p>Vee; recall <a class="ref" href="#Page-Geometry">Page Geometry</a>.
</p>
</dd>
<dt id='index-M-scaling-unit'><span><code class="code">M</code><a class="copiable-link" href='#index-M-scaling-unit'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-unit_002c-scaling_002c-M"></a>
<a class="index-entry-id" id="index-scaling-unit-M"></a>
<p>Hundredth of an em.
</p></dd>
</dl>



<ul class="mini-toc">
<li><a href="#Motion-Quanta" accesskey="1">Motion Quanta</a></li>
<li><a href="#Default-Units" accesskey="2">Default Units</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="Motion-Quanta">
<div class="nav-panel">
<p>
Next: <a href="#Default-Units" accesskey="n" rel="next">Default Units</a>, Previous: <a href="#Measurements" accesskey="p" rel="prev">Measurements</a>, Up: <a href="#Measurements" accesskey="u" rel="up">Measurements</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Motion-Quanta-1">5.3.1 Motion Quanta</h4>
<a class="index-entry-id" id="index-motion-quanta"></a>
<a class="index-entry-id" id="index-quanta_002c-motion"></a>

<p>An output device&rsquo;s basic unit <code class="code">u</code> is not necessarily its smallest
addressable length; <code class="code">u</code> can be smaller to avoid problems with
integer roundoff.  The minimum distances that a device can work with in
the horizontal and vertical directions are termed its <em class="dfn">motion
quanta</em>.  Measurements are rounded to applicable motion quanta.
Half-quantum fractions round toward zero.
</p>
<a class="index-entry-id" id="index-horizontal-motion-quantum-register-_0028_002eH_0029"></a>
<a class="index-entry-id" id="index-motion-quantum_002c-horizontal_002c-register-_0028_002eH_0029"></a>
<a class="index-entry-id" id="index-horizontal-resolution-register-_0028_002eH_0029"></a>
<a class="index-entry-id" id="index-resolution_002c-horizontal_002c-register-_0028_002eH_0029"></a>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005b_002eH_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.H]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002eH_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002eH"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002eV_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.V]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002eV_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002eV"></a>
<p>These read-only registers interpolate the horizontal and vertical motion
quanta, respectively, of the output device in basic units.
</p></dd></dl>

<p>For example, we might draw short baseline rules on a terminal device as
follows.  See <a class="xref" href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a>.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.tm \n[.H]
    error&rarr; 24
.nf
\l'36u' 36u
\l'37u' 37u
    &rArr; _ 36u
    &rArr; __ 37u
</pre></div></div>


<hr>
</div>
<div class="subsection-level-extent" id="Default-Units">
<div class="nav-panel">
<p>
Previous: <a href="#Motion-Quanta" accesskey="p" rel="prev">Motion Quanta</a>, Up: <a href="#Measurements" accesskey="u" rel="up">Measurements</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Default-Units-1">5.3.2 Default Units</h4>
<a class="index-entry-id" id="index-default-units"></a>
<a class="index-entry-id" id="index-units_002c-default"></a>

<p>A general-purpose register (one created or updated with the <code class="code">nr</code>
request; see see <a class="pxref" href="#Registers">Registers</a>) is implicitly dimensionless, or reckoned
in basic units if interpreted in a measurement context.  But it is
convenient for many requests and escape sequences to infer a scaling
unit for an argument if none is specified.  An explicit scaling unit
(not after a closing parenthesis) can override an undesirable default.
Effectively, the default unit is suffixed to the expression if a scaling
unit is not already present.  GNU <code class="code">troff</code>&rsquo;s use of integer
arithmetic should also be kept in mind (see <a class="pxref" href="#Numeric-Expressions">Numeric Expressions</a>).
</p>
<p>The <code class="code">ll</code> request interprets its argument in ems by default.
Consider several attempts to set a line length of 3.5&nbsp;inches when
the type size is 10&nbsp;points on a terminal device with a resolution
of 240 basic units and horizontal motion quantum of 24.  Some
expressions become zero; the request clamps them to that quantum.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ll 3.5i      \&quot; 3.5i (= 840u)
.ll 7/2       \&quot; 7u/2u -&gt; 3u -&gt; 3m -&gt; 0, clamped to 24u
.ll (7 / 2)u  \&quot; 7u/2u -&gt; as above
.ll 7/2i      \&quot; 7u/2i -&gt; 7u/480u -&gt; 0 -&gt; as above
.ll 7i/2      \&quot; 7i/2u -&gt; 1680u/2m -&gt; 1680u/24u -&gt; 35u
.ll 7i/2u     \&quot; 3.5i (= 840u)
</pre></div></div>

<a class="index-entry-id" id="index-measurements_002c-specifying-safely"></a>
<p>The safest way to specify measurements is to attach a scaling unit.  To
multiply or divide by a dimensionless quantity, use &lsquo;<samp class="samp">u</samp>&rsquo; as its
scaling unit.
</p>


<hr>
</div>
</div>
<div class="section-level-extent" id="Numeric-Expressions">
<div class="nav-panel">
<p>
Next: <a href="#Identifiers" accesskey="n" rel="next">Identifiers</a>, Previous: <a href="#Measurements" accesskey="p" rel="prev">Measurements</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Numeric-Expressions-1">5.4 Numeric Expressions</h3>
<a class="index-entry-id" id="index-numeric-expressions"></a>
<a class="index-entry-id" id="index-expressions_002c-numeric"></a>

<p>A <em class="dfn">numeric expression</em> evaluates to an integer: it can be as
simple as a literal &lsquo;<samp class="samp">0</samp>&rsquo; or it can be a complex sequence of register
and string interpolations interleaved with measurements and operators.
</p>
<p>GNU <code class="code">troff</code> provides a set of mathematical and logical operators
familiar to programmers&mdash;as well as some unusual ones&mdash;but supports
only integer arithmetic.<a class="footnote" id="DOCF35" href="#FOOT35"><sup>35</sup></a>  The internal data type
used for computing results is usually a 32-bit signed integer, which
suffices to represent magnitudes within a range of 2
billion.<a class="footnote" id="DOCF36" href="#FOOT36"><sup>36</sup></a>
</p>
<a class="index-entry-id" id="index-arithmetic-operators"></a>
<a class="index-entry-id" id="index-operators_002c-arithmetic"></a>
<a class="index-entry-id" id="index-truncating-division"></a>
<a class="index-entry-id" id="index-addition"></a>
<a class="index-entry-id" id="index-subtraction"></a>
<a class="index-entry-id" id="index-multiplication"></a>
<a class="index-entry-id" id="index-division_002c-truncating"></a>
<a class="index-entry-id" id="index-modulus"></a>
<a class="index-entry-id" id="index-_002b"></a>
<a class="index-entry-id" id="index-_002d"></a>
<a class="index-entry-id" id="index-_002a"></a>
<a class="index-entry-id" id="index-_002f"></a>
<a class="index-entry-id" id="index-_0025"></a>
<p>Arithmetic infix operators perform a function on the numeric expressions
to their left and right; they are <code class="code">+</code> (addition), <code class="code">-</code>
(subtraction), <code class="code">*</code> (multiplication), <code class="code">/</code> (truncating
division), and <code class="code">%</code> (modulus).  <em class="dfn">Truncating division</em> rounds to
the integer nearer to zero, no matter how large the fractional portion.
Overflow and division (or modulus) by zero are errors and abort
evaluation of a numeric expression.
<a class="index-entry-id" id="index-unary-arithmetic-operators"></a>
<a class="index-entry-id" id="index-operators_002c-unary-arithmetic"></a>
<a class="index-entry-id" id="index-negation"></a>
<a class="index-entry-id" id="index-assertion-_0028arithmetic-operator_0029"></a>
<a class="index-entry-id" id="index-_002d-1"></a>
<a class="index-entry-id" id="index-_002b-1"></a>
<a class="index-entry-id" id="index-if-request_002c-and-the-_0021-operator"></a>
<a class="index-entry-id" id="index-while-request_002c-and-the-_0021-operator"></a>
</p>
<p>Arithmetic unary operators operate on the numeric expression to their
right; they are <code class="code">-</code> (negation) and <code class="code">+</code> (assertion&mdash;for
completeness; it does nothing).  The unary minus must often be used
with parentheses to avoid confusion with the decrementation operator,
discussed below.
</p>
<p>Observe the rounding behavior and effect of negative operands on the
modulus and truncating division operators.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr T 199/100
.nr U 5/2
.nr V (-5)/2
.nr W 5/-2
.nr X 5%2
.nr Y (-5)%2
.nr Z 5%-2
T=\n[T] U=\n[U] V=\n[V] W=\n[W] X=\n[X] Y=\n[Y] Z=\n[Z]
    &rArr; T=1 U=2 V=-2 W=-2 X=1 Y=-1 Z=1
</pre></div></div>

<p>The sign of the modulus of operands of mixed signs is determined by the
sign of the first.  Division and modulus operators satisfy the following
property: given a dividend&nbsp;<var class="var">a</var> and a divisor&nbsp;<var class="var">b</var>, a
quotient&nbsp;<var class="var">q</var> formed by &lsquo;<samp class="samp">(a / b)</samp>&rsquo; and a
remainder&nbsp;<var class="var">r</var> by &lsquo;<samp class="samp">(a % b)</samp>&rsquo;, then <em class="math">qb + r = a</em>.
</p>
<a class="index-entry-id" id="index-scaling-operator"></a>
<a class="index-entry-id" id="index-operator_002c-scaling"></a>
<a class="index-entry-id" id="index-_003b"></a>
<p>GNU <code class="code">troff</code>&rsquo;s scaling operator, used with parentheses as
<code class="code">(<var class="var">c</var>;<var class="var">e</var>)</code>, evaluates a numeric expression&nbsp;<var class="var">e</var>
using&nbsp;<var class="var">c</var> as the default scaling unit.  If <var class="var">c</var> is omitted,
scaling units are ignored in the evaluation of&nbsp;<var class="var">e</var>.  This
operator can save typing by avoiding the attachment of scaling units to
every operand out of caution.  Your macros can select a sensible default
unit in case the user neglects to supply one.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.\&quot; Indent by amount given in first argument; assume ens.
.de Indent
.  in (n;\\$1)
..
</pre></div></div>

<p>Without the scaling operator, the foregoing macro would, if called with
a unitless argument, cause indentation by the <code class="code">in</code> request&rsquo;s
default scaling unit (ems).  The result would be twice as much
indentation as expected.
</p>
<a class="index-entry-id" id="index-extremum-operators-_0028_003e_003f_002c-_003c_003f_0029"></a>
<a class="index-entry-id" id="index-operators_002c-extremum-_0028_003e_003f_002c-_003c_003f_0029"></a>
<a class="index-entry-id" id="index-maximum-operator"></a>
<a class="index-entry-id" id="index-minimum-operator"></a>
<a class="index-entry-id" id="index-_003e_003f"></a>
<a class="index-entry-id" id="index-_003c_003f"></a>
<p>GNU <code class="code">troff</code> also provides a pair of operators to compute the
extrema of two operands: <code class="code">&gt;?</code> (maximum) and <code class="code">&lt;?</code> (minimum).
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr slots 5
.nr candidates 3
.nr salaries (\n[slots] &lt;? \n[candidates])
Looks like we'll end up paying \n[salaries] salaries.
    &rArr; Looks like we'll end up paying 3 salaries.
</pre></div></div>

<a class="index-entry-id" id="index-comparison-operators"></a>
<a class="index-entry-id" id="index-operators_002c-comparison"></a>
<a class="index-entry-id" id="index-greater-than-_0028or-equal-to_0029-operator"></a>
<a class="index-entry-id" id="index-less-than-_0028or-equal-to_0029-operator"></a>
<a class="index-entry-id" id="index-equality-operator"></a>
<a class="index-entry-id" id="index-_003c"></a>
<a class="index-entry-id" id="index-_003e"></a>
<a class="index-entry-id" id="index-_003e_003d"></a>
<a class="index-entry-id" id="index-_003c_003d"></a>
<a class="index-entry-id" id="index-_003d"></a>
<a class="index-entry-id" id="index-_003d_003d"></a>
<p>Comparison operators comprise <code class="code">&lt;</code> (less than), <code class="code">&gt;</code> (greater
than), <code class="code">&lt;=</code> (less than or equal), <code class="code">&gt;=</code> (greater than or
equal), and <code class="code">=</code> (equal).  <code class="code">==</code> is a synonym for <code class="code">=</code>.
When evaluated, a comparison is replaced with &lsquo;<samp class="samp">0</samp>&rsquo; if it is false
and &lsquo;<samp class="samp">1</samp>&rsquo; if true.  In the <code class="code">roff</code> language, positive values are
true, others false.
</p>
<a class="index-entry-id" id="index-logical-operators"></a>
<a class="index-entry-id" id="index-operators_002c-logical"></a>
<a class="index-entry-id" id="index-logical-_0060_0060and_0027_0027-operator"></a>
<a class="index-entry-id" id="index-logical-conjunction-operator"></a>
<a class="index-entry-id" id="index-logical-_0060_0060or_0027_0027-operator"></a>
<a class="index-entry-id" id="index-logical-disjunction-operator"></a>
<a class="index-entry-id" id="index-_0026"></a>
<a class="index-entry-id" id="index-_003a"></a>
<p>We can operate on truth values with the logical operators <code class="code">&amp;</code>
(logical conjunction or &ldquo;and&rdquo;) and <code class="code">:</code> (logical disjunction or
&ldquo;or&rdquo;).  They evaluate as comparison operators do.
</p>
<a class="index-entry-id" id="index-_0021"></a>
<a class="index-entry-id" id="index-complementation_002c-logical"></a>
<a class="index-entry-id" id="index-logical-complementation-operator"></a>
<a class="index-entry-id" id="index-logical-not_002c-limitation-in-expression"></a>
<a class="index-entry-id" id="index-expression_002c-limitation-of-logical-not-in"></a>
<p>A logical complementation (&ldquo;not&rdquo;) operator, <code class="code">!</code>, works only
within <code class="code">if</code>, <code class="code">ie</code>, and <code class="code">while</code> requests.
Furthermore, <code class="code">!</code> is recognized only at the beginning of a numeric
expression not contained by another numeric expression.  In other words,
it must be the &ldquo;outermost&rdquo; operator.  Including it elsewhere in the
expression produces a warning in the &lsquo;<samp class="samp">number</samp>&rsquo; category
(see <a class="pxref" href="#Warnings">Warnings</a>), and its expression evaluates false.  This
unfortunate limitation maintains compatibility with <abbr class="acronym">AT&amp;T</abbr>
<code class="code">troff</code>.  Test a numeric expression for falsity by
comparing it to a false value.<a class="footnote" id="DOCF37" href="#FOOT37"><sup>37</sup></a>
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr X 1
.nr Y 0
.\&quot; This does not work as expected.
.if (\n[X])&amp;(!\n[Y]) .nop A: X is true, Y is false
.
.\&quot; Use this construct instead.
.if (\n[X])&amp;(\n[Y]&lt;=0) .nop B: X is true, Y is false
    error&rarr; warning: expected numeric expression, got '!'
    &rArr; B: X is true, Y is false
</pre></div></div>

<a class="index-entry-id" id="index-parentheses"></a>
<a class="index-entry-id" id="index-order-of-evaluation-in-expressions"></a>
<a class="index-entry-id" id="index-expression_002c-order-of-evaluation"></a>
<a class="index-entry-id" id="index-_0028"></a>
<a class="index-entry-id" id="index-_0029"></a>
<p>The <code class="code">roff</code> language has no operator precedence: expressions are
evaluated strictly from left to right, in contrast to schoolhouse
arithmetic.  Use parentheses <code class="code">(</code> <code class="code">)</code> to impose a desired
precedence upon subexpressions.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr X 3+5*4
.nr Y (3+5)*4
.nr Z 3+(5*4)
X=\n[X] Y=\n[Y] Z=\n[Z]
    &rArr; X=32 Y=32 Z=23
</pre></div></div>

<a class="index-entry-id" id="index-_002b_002c-and-page-motion"></a>
<a class="index-entry-id" id="index-_002d_002c-and-page-motion"></a>
<a class="index-entry-id" id="index-motion-operators"></a>
<a class="index-entry-id" id="index-operators_002c-motion"></a>
<a class="index-entry-id" id="index-_002b-_0028unary_0029"></a>
<a class="index-entry-id" id="index-_002d-_0028unary_0029"></a>
<p>For many requests and escape sequences that cause motion on the page,
the unary operators <code class="code">+</code> and <code class="code">-</code> work differently when leading
a numeric expression.  They then indicate a motion relative to the
drawing position: positive is down in vertical contexts, right in
horizontal ones.
</p>
<a class="index-entry-id" id="index-bp-request_002c-using-_002b-and-_002d-with"></a>
<a class="index-entry-id" id="index-in-request_002c-using-_002b-and-_002d-with"></a>
<a class="index-entry-id" id="index-ll-request_002c-using-_002b-and-_002d-with"></a>
<a class="index-entry-id" id="index-lt-request_002c-using-_002b-and-_002d-with"></a>
<a class="index-entry-id" id="index-nm-request_002c-using-_002b-and-_002d-with"></a>
<a class="index-entry-id" id="index-nr-request_002c-using-_002b-and-_002d-with"></a>
<a class="index-entry-id" id="index-pl-request_002c-using-_002b-and-_002d-with"></a>
<a class="index-entry-id" id="index-pn-request_002c-using-_002b-and-_002d-with"></a>
<a class="index-entry-id" id="index-po-request_002c-using-_002b-and-_002d-with"></a>
<a class="index-entry-id" id="index-ps-request_002c-using-_002b-and-_002d-with"></a>
<a class="index-entry-id" id="index-pvs-request_002c-using-_002b-and-_002d-with"></a>
<a class="index-entry-id" id="index-rt-request_002c-using-_002b-and-_002d-with"></a>
<a class="index-entry-id" id="index-ti-request_002c-using-_002b-and-_002d-with"></a>
<a class="index-entry-id" id="index-_005cH_002c-using-_002b-and-_002d-with"></a>
<a class="index-entry-id" id="index-_005cR_002c-using-_002b-and-_002d-with"></a>
<a class="index-entry-id" id="index-_005cs_002c-using-_002b-and-_002d-with"></a>
<p><code class="code">+</code> and <code class="code">-</code> are also treated differently by the following
requests and escape sequences: <code class="code">bp</code>, <code class="code">in</code>, <code class="code">ll</code>,
<code class="code">lt</code>, <code class="code">nm</code>, <code class="code">nr</code>, <code class="code">pl</code>, <code class="code">pn</code>, <code class="code">po</code>,
<code class="code">ps</code>, <code class="code">pvs</code>, <code class="code">rt</code>, <code class="code">ti</code>, <code class="code">\H</code>, <code class="code">\R</code>, and
<code class="code">\s</code>.  Here, leading plus and minus signs serve as incrementation
and decrementation operators, respectively.  To negate an expression,
subtract it from zero or include the unary minus in parentheses with its
argument.  See <a class="xref" href="#Setting-Registers">Setting Registers</a>, for examples.
</p>
<a class="index-entry-id" id="index-_007c"></a>
<a class="index-entry-id" id="index-_007c_002c-and-page-motion"></a>
<a class="index-entry-id" id="index-absolute-_0028sic_0029-position-operator-_0028_007c_0029"></a>
<a class="index-entry-id" id="index-position_002c-absolute-_0028sic_0029-operator-_0028_007c_0029"></a>
<a class="index-entry-id" id="index-boundary_002drelative-motion-operator-_0028_007c_0029"></a>
<p>A leading <code class="code">|</code> operator indicates a motion relative not to the
drawing position but to a boundary.  For horizontal motions, the
measurement specifies a distance relative to a drawing position
corresponding to the beginning of the <em class="emph">input</em> line.  By default,
tab stops reckon movements in this way.  Most escape sequences do not;
<code class="code">|</code> tells them to do so.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">Mind the \h'1.2i'gap.
.br
Mind the \h'|1.2i'gap.
.br
Mind the
\h'|1.2i'gap.
    &rArr; Mind the             gap.
    &rArr; Mind the    gap.
    &rArr; Mind the             gap.
</pre></div></div>

<p>One use of this feature is to define macros whose scope is limited to
the output they format.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.\&quot; underline word $1 with trailing punctuation $2
.de Underline
.  nop \\$1\l'|0\[ul]'\\$2
..
Typographical emphasis is best used
.Underline sparingly .
</pre></div></div>

<p>In the above example, &lsquo;<samp class="samp">|0</samp>&rsquo; specifies a negative motion from the
current position (at the end of the argument just emitted, <code class="code">\$1</code>)
to the beginning of the input line.  Thus, the <code class="code">\l</code> escape sequence
in this case draws a line from right to left.  A macro call occurs at
the beginning of an input line;<a class="footnote" id="DOCF38" href="#FOOT38"><sup>38</sup></a> if the <code class="code">|</code>
operator were omitted, then the underline would be drawn at zero
distance from the current position, producing device-dependent, and
likely undesirable, results.  On the &lsquo;<samp class="samp">ps</samp>&rsquo; output device, it
underlines the period.
</p>
<p>For vertical motions, the <code class="code">|</code> operator specifies a distance from
the first text baseline on the page or in the current
diversion,<a class="footnote" id="DOCF39" href="#FOOT39"><sup>39</sup></a>  using the current vertical
spacing.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">A
.br
B \Z'C'\v'|0'D
    &rArr; A D
    &rArr; B C
</pre></div></div>

<p>In the foregoing example, we&rsquo;ve used the <code class="code">\Z</code> escape sequence
(see <a class="pxref" href="#Page-Motions">Page Motions</a>) to restore the drawing position after formatting
&lsquo;<samp class="samp">C</samp>&rsquo;, then moved vertically to the first text baseline on the page.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cB_0027anything_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\B<code class="code">'</code></code><span class="r"><i class="slanted">anything</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cB_0027anything_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cB"></a>
<a class="index-entry-id" id="index-numeric-expression_002c-valid"></a>
<a class="index-entry-id" id="index-valid-numeric-expression"></a>
<p>Interpolate&nbsp;1 if <var class="var">anything</var> is a valid numeric expression,
and&nbsp;0 otherwise.  The delimiter need not be a neutral apostrophe;
see <a class="ref" href="#Delimiters">Delimiters</a>.
</p></dd></dl>

<p>You might use <code class="code">\B</code> along with the <code class="code">if</code> request to filter out
invalid macro or string arguments.  See <a class="xref" href="#Conditionals-and-Loops">Conditionals and Loops</a>.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.\&quot; Indent by amount given in first argument; assume ens.
.de Indent
.  if \B'\\$1' .in (n;\\$1)
..
</pre></div></div>

<p>A register interpolated as an operand in a numeric expression must have
an Arabic format; luckily, this is the default.  See <a class="xref" href="#Assigning-Register-Formats">Assigning Register Formats</a>.
</p>
<a class="index-entry-id" id="index-space-characters_002c-in-expressions"></a>
<a class="index-entry-id" id="index-expressions_002c-and-space-characters"></a>
<p>Because spaces separate arguments to requests, spaces are not allowed in
numeric expressions unless the (sub)expression containing them is
surrounded by parentheses.  See <a class="xref" href="#Invoking-Requests">Invoking Requests</a>, and
<a class="ref" href="#Conditionals-and-Loops">Conditionals and Loops</a>.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nf
.nr a 1+2 + 2+1
\na
    error&rarr; expected numeric expression, got a space
    &rArr; 3
.nr a 1+(2 + 2)+1
\na
    &rArr; 6
</pre></div></div>

<p>The <code class="code">nr</code> request (see <a class="pxref" href="#Setting-Registers">Setting Registers</a>) expects its second and
optional third arguments to be numeric expressions; a bare <code class="code">+</code> does
not qualify, so our first attempt got a warning.
</p>


<hr>
</div>
<div class="section-level-extent" id="Identifiers">
<div class="nav-panel">
<p>
Next: <a href="#Formatter-Instructions" accesskey="n" rel="next">Formatter Instructions</a>, Previous: <a href="#Numeric-Expressions" accesskey="p" rel="prev">Numeric Expressions</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Identifiers-1">5.5 Identifiers</h3>
<a class="index-entry-id" id="index-identifiers"></a>

<p>An <em class="dfn">identifier</em> labels a GNU <code class="code">troff</code> datum such as a register,
name (macro, string, or diversion), typeface, color, special character,
character class, environment, or stream.  Valid identifiers consist of
one or more ordinary characters.
<a class="index-entry-id" id="index-ordinary-character"></a>
<a class="index-entry-id" id="index-character_002c-ordinary"></a>
An <i class="slanted">ordinary character</i> is an input character that is not the
escape character, a leader, tab, newline, or invalid as GNU <code class="code">troff</code>
input.
</p>
<a class="index-entry-id" id="index-invalid-input-characters"></a>
<a class="index-entry-id" id="index-input-characters_002c-invalid"></a>
<a class="index-entry-id" id="index-characters_002c-invalid-input"></a>
<a class="index-entry-id" id="index-Unicode"></a>
<p>Invalid input characters are a subset of control characters (from the
sets &ldquo;C0 Controls&rdquo; and &ldquo;C1 Controls&rdquo; as Unicode describes them).
When GNU <code class="code">troff</code> encounters one in an identifier, it produces a
warning in category &lsquo;<samp class="samp">input</samp>&rsquo; (see <a class="pxref" href="#Warnings">Warnings</a>).  They are removed
during interpretation: an identifier &lsquo;<samp class="samp">foo</samp>&rsquo;, followed by an invalid
character and then &lsquo;<samp class="samp">bar</samp>&rsquo;, is processed as &lsquo;<samp class="samp">foobar</samp>&rsquo;.
</p>
<p>On a machine using the ISO 646, 8859, or 10646 character encodings,
invalid input characters are <code class="code">0x00</code>, <code class="code">0x08</code>, <code class="code">0x0B</code>,
<code class="code">0x0D</code>&ndash;<code class="code">0x1F</code>, and <code class="code">0x80</code>&ndash;<code class="code">0x9F</code>.  On an
<abbr class="acronym">EBCDIC</abbr> host, they are <code class="code">0x00</code>&ndash;<code class="code">0x01</code>, <code class="code">0x08</code>,
<code class="code">0x09</code>, <code class="code">0x0B</code>, <code class="code">0x0D</code>&ndash;<code class="code">0x14</code>,
<code class="code">0x17</code>&ndash;<code class="code">0x1F</code>, and
<code class="code">0x30</code>&ndash;<code class="code">0x3F</code>.<a class="footnote" id="DOCF40" href="#FOOT40"><sup>40</sup></a>  Some of these code points are used
by GNU <code class="code">troff</code> internally, making it non-trivial to extend the
program to accept UTF-8 or other encodings that use characters from
these ranges.<a class="footnote" id="DOCF41" href="#FOOT41"><sup>41</sup></a>
</p>
<p>Thus, the identifiers &lsquo;<samp class="samp">br</samp>&rsquo;, &lsquo;<samp class="samp">PP</samp>&rsquo;, &lsquo;<samp class="samp">end-list</samp>&rsquo;,
&lsquo;<samp class="samp">ref*normal-print</samp>&rsquo;, &lsquo;<samp class="samp">|</samp>&rsquo;, &lsquo;<samp class="samp">@_</samp>&rsquo;, and &lsquo;<samp class="samp">!&quot;#$%'()*+,-./</samp>&rsquo;
are all valid.  Discretion should be exercised to prevent confusion.
Identifiers starting with &lsquo;<samp class="samp">(</samp>&rsquo; or &lsquo;<samp class="samp">[</samp>&rsquo; require care.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr x 9
.nr y 1
.nr (x 2
.nr [y 3
.nr sum1 (\n(x + \n[y])
    error&rarr; a space character is not allowed in an escape
    error&rarr;   sequence parameter
A:2+3=\n[sum1]
.nr sum2 (\n((x + \n[[y])
B:2+3=\n[sum2]
.nr sum3 (\n[(x] + \n([y)
C:2+3=\n[sum3]
    &rArr; A:2+3=1 B:2+3=5 C:2+3=5
</pre></div></div>

<a class="index-entry-id" id="index-_005d_002c-as-part-of-an-identifier"></a>
<p>An identifier with a closing bracket (&lsquo;<samp class="samp">]</samp>&rsquo;) in its name can&rsquo;t be
accessed with bracket-form escape sequences that expect an identifier as
a parameter.  For example, &lsquo;<samp class="samp">\[foo]]</samp>&rsquo; accesses the glyph &lsquo;<samp class="samp">foo</samp>&rsquo;,
followed by &lsquo;<samp class="samp">]</samp>&rsquo; in whatever the surrounding context is, whereas
&lsquo;<samp class="samp">\C'foo]'</samp>&rsquo; formats a glyph named &lsquo;<samp class="samp">foo]</samp>&rsquo;.  Similarly, the
identifier &lsquo;<samp class="samp">(</samp>&rsquo; can&rsquo;t be interpolated <em class="emph">except</em> with bracket
forms.
</p>
<a class="index-entry-id" id="index-refer_002c-and-macro-names-starting-with-_005b-or-_005d"></a>
<a class="index-entry-id" id="index-_005b_002c-macro-names-starting-with_002c-and-refer"></a>
<a class="index-entry-id" id="index-_005d_002c-macro-names-starting-with_002c-and-refer"></a>
<a class="index-entry-id" id="index-macro-names_002c-starting-with-_005b-or-_005d_002c-and-refer"></a>
<p>If you begin a macro, string, or diversion name with either of the
characters &lsquo;<samp class="samp">[</samp>&rsquo; or &lsquo;<samp class="samp">]</samp>&rsquo;, you foreclose use of the <code class="code">grefer</code>
preprocessor, which recognizes &lsquo;<samp class="samp">.[</samp>&rsquo; and &lsquo;<samp class="samp">.]</samp>&rsquo; as bibliographic
reference delimiters.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cA_0027anything_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\A<code class="code">'</code></code><span class="r"><i class="slanted">anything</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cA_0027anything_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cA"></a>
<p>Interpolate&nbsp;1 if <var class="var">anything</var> is a valid identifier, and&nbsp;0
otherwise.  The delimiter need not be a neutral apostrophe; see
<a class="ref" href="#Delimiters">Delimiters</a>.  Because invalid input characters are removed (see
above), invalid identifiers are empty or contain spaces, tabs, or
newlines.
</p>
<p>You can employ <code class="code">\A</code> to validate a macro argument before using it to
construct another escape sequence or identifier.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.\&quot; usage: .init-coordinate-pair name val1 val2
.\&quot; Create a coordinate pair where name!x=val1 and
.\&quot; name!y=val2.
.de init-coordinate-pair
.  if \A'\\$1' \{\
.    if \B'\\$2' .nr \\$1!x \\$2
.    if \B'\\$3' .nr \\$1!y \\$3
.  \}
..
.init-coordinate-pair center 5 10
The center is at (\n[center!x], \n[center!y]).
.init-coordinate-pair &quot;poi&rarr;nt&quot; trash garbage \&quot; ignored
.init-coordinate-pair point trash garbage \&quot; ignored
    &rArr; The center is at (5, 10).
</pre></div></div>

<p>In this example, we also validated the numeric arguments; the registers
&lsquo;<samp class="samp">point!x</samp>&rsquo; and &lsquo;<samp class="samp">point!y</samp>&rsquo; remain undefined.  See <a class="xref" href="#Numeric-Expressions">Numeric Expressions</a> for the <code class="code">\B</code> escape sequence.
</p></dd></dl>

<a class="index-entry-id" id="index-undefined-identifiers"></a>
<a class="index-entry-id" id="index-identifiers_002c-undefined"></a>
<p>How GNU <code class="code">troff</code> handles the interpretation of an undefined
identifier depends on the context.  There is no way to invoke an
undefined request; such syntax is interpreted as a macro call instead.
If the identifier is interpreted as a string, macro, or diversion, GNU
<code class="code">troff</code> emits a warning in category &lsquo;<samp class="samp">mac</samp>&rsquo;, defines it as
empty, and interpolates nothing.  If the identifier is interpreted as a
register, GNU <code class="code">troff</code> emits a warning in category &lsquo;<samp class="samp">reg</samp>&rsquo;,
initializes it to zero, and interpolates that value.  See <a class="xref" href="#Warnings">Warnings</a>,
<a class="ref" href="#Interpolating-Registers">Interpolating Registers</a>, and <a class="ref" href="#Strings">Strings</a>.  Attempting to use an
undefined typeface, special character, color, character class,
environment, or stream generally provokes an error diagnostic.
</p>
<a class="index-entry-id" id="index-name-space_002c-common_002c-of-macros_002c-diversions_002c-and-strings"></a>
<a class="index-entry-id" id="index-common-name-space-of-macros_002c-diversions_002c-and-strings"></a>
<a class="index-entry-id" id="index-macros_002c-shared-name-space-with-strings-and-diversions"></a>
<a class="index-entry-id" id="index-strings_002c-shared-name-space-with-macros-and-diversions"></a>
<a class="index-entry-id" id="index-diversions_002c-shared-name-space-with-macros-and-strings"></a>
<p>Identifiers for requests, macros, strings, and diversions share one name
space; special characters and character classes another.  No other
object types do.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de xxx
.  nop foo
..
.di xxx
bar
.br
.di
.
.xxx
    &rArr; bar
</pre></div></div>

<p>The foregoing example shows that GNU <code class="code">troff</code> reuses the identifier
&lsquo;<samp class="samp">xxx</samp>&rsquo;, changing it from a macro to a diversion.  No warning is
emitted, and the previous contents of &lsquo;<samp class="samp">xxx</samp>&rsquo; are lost.
</p>


<hr>
</div>
<div class="section-level-extent" id="Formatter-Instructions">
<div class="nav-panel">
<p>
Next: <a href="#Registers" accesskey="n" rel="next">Registers</a>, Previous: <a href="#Identifiers" accesskey="p" rel="prev">Identifiers</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Formatter-Instructions-1">5.6 Formatter Instructions</h3>
<a class="index-entry-id" id="index-formatter-instructions"></a>
<a class="index-entry-id" id="index-instructing-the-formatter"></a>

<p>To support documents that require more than filling, automatic line
breaking and hyphenation, adjustment, and supplemental inter-sentence
space, the <code class="code">roff</code> language offers two means of embedding
instructions to the formatter.
</p>
<a class="index-entry-id" id="index-request-1"></a>
<p>One is a <em class="dfn">request</em>, which begins with a control character and takes
up the remainder of the input line.  Requests often perform relatively
large-scale operations such as setting the page length, breaking the
line, or starting a new page.  They also conduct internal operations
like defining macros.
</p>
<a class="index-entry-id" id="index-escape-sequence"></a>
<a class="index-entry-id" id="index-sequence_002c-escape"></a>
<p>The other is an <em class="dfn">escape sequence</em>, which begins with the escape
character and can be embedded anywhere in the input, even in arguments
to requests and other escape sequences.  Escape sequences interpolate
special characters, strings, or registers, and handle comparatively
minor formatting tasks like sub- and superscripting.
</p>
<p>Some operations, such as font selection and type size alteration, are
available via both requests and escape sequences.
</p>


<ul class="mini-toc">
<li><a href="#Control-Characters" accesskey="1">Control Characters</a></li>
<li><a href="#Invoking-Requests" accesskey="2">Invoking Requests</a></li>
<li><a href="#Calling-Macros" accesskey="3">Calling Macros</a></li>
<li><a href="#Using-Escape-Sequences" accesskey="4">Using Escape Sequences</a></li>
<li><a href="#Delimiters" accesskey="5">Delimiters</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="Control-Characters">
<div class="nav-panel">
<p>
Next: <a href="#Invoking-Requests" accesskey="n" rel="next">Invoking Requests</a>, Previous: <a href="#Formatter-Instructions" accesskey="p" rel="prev">Formatter Instructions</a>, Up: <a href="#Formatter-Instructions" accesskey="u" rel="up">Formatter Instructions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Control-Characters-1">5.6.1 Control Characters</h4>
<a class="index-entry-id" id="index-control-characters"></a>
<a class="index-entry-id" id="index-configuring-control-characters"></a>
<a class="index-entry-id" id="index-changing-control-characters"></a>

<p>The mechanism of using <code class="code">roff</code>&rsquo;s control characters to invoke
requests and call macros was introduced in <a class="ref" href="#Requests-and-Macros">Requests and Macros</a>.
Control characters are recognized only at the beginning of an input
line, or at the beginning of the branch of a control structure request;
see <a class="ref" href="#Conditionals-and-Loops">Conditionals and Loops</a>.
</p>
<p>A few requests cause a break implicitly; use the no-break control
character to prevent the break.  Break suppression is its sole
behavioral distinction.  Employing the no-break control character to
invoke requests that don&rsquo;t cause breaks is harmless but poor style.
See <a class="xref" href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a>.
</p>
<a class="index-entry-id" id="index-control-character_002c-changing-_0028cc_0029"></a>
<a class="index-entry-id" id="index-character_002c-control_002c-changing-_0028cc_0029"></a>
<a class="index-entry-id" id="index-no_002dbreak-control-character_002c-changing-_0028c2_0029"></a>
<a class="index-entry-id" id="index-character_002c-no_002dbreak-control_002c-changing-_0028c2_0029"></a>
<a class="index-entry-id" id="index-control-character_002c-no_002dbreak_002c-changing-_0028c2_0029"></a>
<p>The control &lsquo;<samp class="samp">.</samp>&rsquo; and no-break control &lsquo;<samp class="samp">'</samp>&rsquo; characters can each
be changed to any ordinary character<a class="footnote" id="DOCF42" href="#FOOT42"><sup>42</sup></a>
with the <code class="code">cc</code> and <code class="code">c2</code> requests, respectively.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002ecc"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.cc</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">o</i></span>]</var><a class="copiable-link" href='#index-_002ecc'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-cc"></a>
<p>Recognize the ordinary character&nbsp;<var class="var">o</var> as the control character.
If&nbsp;<var class="var">o</var> is absent or invalid, the default control character
&lsquo;<samp class="samp">.</samp>&rsquo; is selected.  The identity of the control character is
associated with the environment (see <a class="pxref" href="#Environments">Environments</a>).
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ec2"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.c2</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">o</i></span>]</var><a class="copiable-link" href='#index-_002ec2'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-c2"></a>
<p>Recognize the ordinary character&nbsp;<var class="var">o</var> as the no-break control
character.  If&nbsp;<var class="var">o</var> is absent or invalid, the default no-break
control character &lsquo;<samp class="samp">'</samp>&rsquo; is selected.  The identity of the no-break
control character is associated with the environment
(see <a class="pxref" href="#Environments">Environments</a>).
</p></dd></dl>

<p>When writing a macro, you might wish to know which control character was
used to call it.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005b_002ebr_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.br]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ebr_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ebr-1"></a>
<p>This read-only register interpolates&nbsp;1 if the currently executing
macro was called using the normal control character and&nbsp;0
otherwise.  If a macro is interpolated as a string, the <code class="code">.br</code>
register&rsquo;s value is inherited from the context of the string
interpolation.  See <a class="xref" href="#Strings">Strings</a>.
</p>
<a class="index-entry-id" id="index-intercepting-requests"></a>
<a class="index-entry-id" id="index-requests_002c-intercepting"></a>
<a class="index-entry-id" id="index-modifying-requests"></a>
<a class="index-entry-id" id="index-requests_002c-modifying"></a>
<p>Use this register to reliably intercept requests that imply breaks.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.als bp*orig bp
.de bp
.  ie \\n[.br] .bp*orig
.  el          'bp*orig
..
</pre></div></div>

<p>Testing the <code class="code">.br</code> register outside of a macro definition makes no
sense.
</p></dd></dl>


<hr>
</div>
<div class="subsection-level-extent" id="Invoking-Requests">
<div class="nav-panel">
<p>
Next: <a href="#Calling-Macros" accesskey="n" rel="next">Calling Macros</a>, Previous: <a href="#Control-Characters" accesskey="p" rel="prev">Control Characters</a>, Up: <a href="#Formatter-Instructions" accesskey="u" rel="up">Formatter Instructions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Invoking-Requests-1">5.6.2 Invoking Requests</h4>
<a class="index-entry-id" id="index-invoking-requests"></a>
<a class="index-entry-id" id="index-requests_002c-invoking"></a>

<p>A control character is optionally followed by tabs and/or spaces and
then an identifier naming a request or macro.  The invocation of an
unrecognized request is interpreted as a macro call.  Defining a macro
with the same name as a request replaces the request.  Deleting a
request name with the <code class="code">rm</code> request makes it unavailable.  The
<code class="code">als</code> request can alias requests, permitting them to be wrapped or
non-destructively replaced.  See <a class="xref" href="#Strings">Strings</a>.
</p>
<a class="index-entry-id" id="index-request-arguments"></a>
<a class="index-entry-id" id="index-arguments-to-requests"></a>
<a class="index-entry-id" id="index-tabs_002c-and-macro-arguments"></a>
<a class="index-entry-id" id="index-macro-arguments_002c-and-tabs"></a>
<a class="index-entry-id" id="index-arguments-to-macros_002c-and-tabs"></a>
<a class="index-entry-id" id="index-tabs_002c-and-request-arguments"></a>
<a class="index-entry-id" id="index-request-arguments_002c-and-tabs"></a>
<a class="index-entry-id" id="index-arguments-to-requests_002c-and-tabs"></a>
<p>There is no inherent limit on argument length or quantity.  Most
requests take one or more arguments, and ignore any they do not expect.
A request may be separated from its arguments by tabs or spaces, but
only spaces can separate an argument from its successor.  Only one
between arguments is necessary; any excess is ignored.  GNU <code class="code">troff</code>
does not allow tabs for argument separation.<a class="footnote" id="DOCF43" href="#FOOT43"><sup>43</sup></a>
</p>
<p>Generally, a space <em class="emph">within</em> a request argument is not relevant, not
meaningful, or is supported by bespoke provisions, as with the <code class="code">tl</code>
request&rsquo;s delimiters (see <a class="pxref" href="#Page-Layout">Page Layout</a>).  Some requests, like
<code class="code">ds</code>, interpret the remainder of the control line as a single
argument.  See <a class="xref" href="#Strings">Strings</a>.
</p>
<a class="index-entry-id" id="index-structuring-source-code-of-documents-or-macro-packages"></a>
<a class="index-entry-id" id="index-documents_002c-structuring-the-source-of"></a>
<a class="index-entry-id" id="index-macro-package_002c-structuring-the-source-of"></a>
<a class="index-entry-id" id="index-package_002c-package_002c-structuring-the-source-of"></a>
<a class="index-entry-id" id="index-indentation_002c-of-roff-source-code"></a>
<p>Spaces and tabs immediately after a control character are ignored.
Commonly, authors structure the source of documents or macro files with
them.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de center
.  if \\n[.br] \
.    br
.  ce \\$1
..
.
.
.de right-align
.&rarr;if \\n[.br] \
.&rarr;&rarr;br
.&rarr;rj \\$1
..
</pre></div></div>

<a class="index-entry-id" id="index-blank-line-trap-_0028blm_0029"></a>
<a class="index-entry-id" id="index-blank-line-macro-_0028blm_0029-1"></a>
<p>If you assign an empty blank line trap, you can separate macro
definitions (or any input lines) with blank lines.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de do-nothing
..
.blm do-nothing  \&quot; activate blank line trap

.de center
.  if \\n[.br] \
.    br
.  ce \\$1
..


.de right-align
.&rarr;if \\n[.br] \
.&rarr;&rarr;br
.&rarr;rj \\$1
..

.blm             \&quot; deactivate blank line trap
</pre></div></div>

<p>See <a class="xref" href="#Blank-Line-Traps">Blank Line Traps</a>.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Calling-Macros">
<div class="nav-panel">
<p>
Next: <a href="#Using-Escape-Sequences" accesskey="n" rel="next">Using Escape Sequences</a>, Previous: <a href="#Invoking-Requests" accesskey="p" rel="prev">Invoking Requests</a>, Up: <a href="#Formatter-Instructions" accesskey="u" rel="up">Formatter Instructions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Calling-Macros-1">5.6.3 Calling Macros</h4>
<a class="index-entry-id" id="index-calling-macros"></a>
<a class="index-entry-id" id="index-macro-arguments"></a>
<a class="index-entry-id" id="index-arguments-to-macros"></a>

<p>If a macro of the desired name does not exist when called, it is
created, assigned an empty definition, and a warning in category
&lsquo;<samp class="samp">mac</samp>&rsquo; is emitted.  Calling an undefined macro <em class="emph">does</em> end a
macro definition naming it as its end macro (see <a class="pxref" href="#Writing-Macros">Writing Macros</a>).
</p>
<a class="index-entry-id" id="index-spaces_002c-in-a-macro-argument"></a>
<p>To embed spaces <em class="emph">within</em> a macro argument, enclose the argument in
neutral double quotes <code class="code">&quot;</code>.  Horizontal motion escape sequences are
sometimes a better choice for arguments to be formatted as text.
</p>
<p>Consider calls to a hypothetical section heading macro &lsquo;<samp class="samp">uh</samp>&rsquo;.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.uh The Mouse Problem
.uh &quot;The Mouse Problem&quot;
.uh The\~Mouse\~Problem
.uh The\ Mouse\ Problem
</pre></div></div>

<a class="index-entry-id" id="index-_005c_007e_002c-difference-from-_005cSP"></a>
<a class="index-entry-id" id="index-_005cSP_002c-difference-from-_005c_007e"></a>
<p>The first line calls <code class="code">uh</code> with three arguments: &lsquo;<samp class="samp">The</samp>&rsquo;,
&lsquo;<samp class="samp">Mouse</samp>&rsquo;, and &lsquo;<samp class="samp">Problem</samp>&rsquo;.  The remainder call the <code class="code">uh</code>
macro with one argument, &lsquo;<samp class="samp">The Mouse Problem</samp>&rsquo;.  The last solution,
using escaped spaces, can be found in documents prepared for
<abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>.  It can cause surprise when text is
adjusted, because <code class="code">\<kbd class="key">SP</kbd></code> inserts a <em class="emph">fixed-width</em>,
non-breaking space.  GNU <code class="code">troff</code>&rsquo;s <code class="code">\~</code> escape sequence
inserts an adjustable, non-breaking space.<a class="footnote" id="DOCF44" href="#FOOT44"><sup>44</sup></a>
</p>
<a class="index-entry-id" id="index-_0022_002c-embedding-in-a-macro-argument"></a>
<a class="index-entry-id" id="index-double-quote_002c-embedding-in-a-macro-argument"></a>
<a class="index-entry-id" id="index-_005c_002c-embedding-in-a-macro-argument"></a>
<a class="index-entry-id" id="index-backslash_002c-embedding-in-a-macro-argument"></a>
<p>The foregoing raises the question of how to embed neutral double quotes
or backslashes in macro arguments when <em class="emph">those</em> characters are
desired as literals.  In GNU <code class="code">troff</code>, the special character escape
sequence <code class="code">\[rs]</code> produces a backslash and <code class="code">\[dq]</code> a neutral
double quote.
</p>
<p>In GNU <code class="code">troff</code>&rsquo;s <abbr class="acronym">AT&amp;T</abbr> compatibility mode, these
characters remain available as <code class="code">\(rs</code> and <code class="code">\(dq</code>,
respectively.  <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> did not consistently define
these special characters,
but its descendants can be made to support them.  See <a class="xref" href="#Device-and-Font-Description-Files">Device and Font Description Files</a>.
</p>
<p>If even that is not feasible, options remain.  To obtain a literal
escape character in a macro argument, you can simply type it if you
change or disable the escape character first.  See <a class="xref" href="#Using-Escape-Sequences">Using Escape Sequences</a>.  Otherwise, you must escape the escape character repeatedly
to a context-dependent extent.  See <a class="xref" href="#Copy-Mode">Copy Mode</a>.
</p>
<p>For the (neutral) double quote, you have recourse to an obscure
syntactical feature of <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>.  Because a double
quote can begin a macro argument, the formatter keeps track of whether
the current argument was started thus, and doesn&rsquo;t require a space after
the double quote that ends it.<a class="footnote" id="DOCF45" href="#FOOT45"><sup>45</sup></a>  In
the argument list to a macro, a double quote that <em class="emph">isn&rsquo;t</em> preceded
by a space <em class="emph">doesn&rsquo;t</em> start a macro argument.  If not preceded by a
double quote that began an argument, this double quote becomes part of
the argument.  Furthermore, within a quoted argument, a pair of adjacent
double quotes becomes a literal double quote.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de eq
.  tm arg1:\\$1 arg2:\\$2 arg3:\\$3
.  tm arg4:\\$4 arg5:\\$5 arg6:\\$6
.. \&quot; 4 backslashes on the next line
.eq a&quot; &quot;b c&quot; &quot;de&quot;f\\\\g&quot; h&quot;&quot;i &quot;j&quot;&quot;k&quot;
    error&rarr; arg1:a&quot; arg2:b c arg3:de
    error&rarr; arg4:f\g&quot; arg5:h&quot;&quot;i arg6:j&quot;k
</pre></div></div>

<p>Apart from the complexity of the rules, this traditional solution has
the disadvantage that double quotes don&rsquo;t survive repeated argument
expansion in <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> or GNU <code class="code">troff</code>&rsquo;s
compatibility mode.  This can frustrate efforts to pass such arguments
intact through multiple macro calls.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.cp 1
.de eq
.  tm arg1:\\$1 arg2:\\$2 arg3:\\$3
.  tm arg4:\\$4 arg5:\\$5 arg6:\\$6
..
.de xe
.  eq \\$1 \\$2 \\$3 \\$4 \\$5 \\$6
.. \&quot; 8 backslashes on the next line
.xe a&quot; &quot;b c&quot; &quot;de&quot;f\\\\\\\\g&quot; h&quot;&quot;i &quot;j&quot;&quot;k&quot;
    error&rarr; arg1:a&quot; arg2:b arg3:c
    error&rarr; arg4:de arg5:f\g&quot; arg6:h&quot;&quot;i
</pre></div></div>

<a class="index-entry-id" id="index-input-level"></a>
<a class="index-entry-id" id="index-level_002c-input"></a>
<a class="index-entry-id" id="index-interpolation-depth"></a>
<a class="index-entry-id" id="index-depth_002c-interpolation"></a>
<p>Outside of compatibility mode, GNU <code class="code">troff</code> doesn&rsquo;t exhibit this
problem because it tracks the nesting depth of interpolations.
See <a class="xref" href="#Implementation-Differences">Implementation Differences</a>.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Using-Escape-Sequences">
<div class="nav-panel">
<p>
Next: <a href="#Delimiters" accesskey="n" rel="next">Delimiters</a>, Previous: <a href="#Calling-Macros" accesskey="p" rel="prev">Calling Macros</a>, Up: <a href="#Formatter-Instructions" accesskey="u" rel="up">Formatter Instructions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Using-Escape-Sequences-1">5.6.4 Using Escape Sequences</h4>
<a class="index-entry-id" id="index-using-escape-sequences"></a>
<a class="index-entry-id" id="index-escape-sequences"></a>

<p>Whereas requests must occur on control lines, escape sequences can occur
intermixed with text and may appear in arguments to requests, macros,
and other escape sequences.
<a class="index-entry-id" id="index-_005c"></a>
An escape sequence is introduced by the escape character, a backslash
<code class="code">\</code> (but see the <code class="code">ec</code> request below).  The next character
selects the escape&rsquo;s function.
</p>
<p>Escape sequences vary in length.  Some take an argument, and of those,
some have different syntactical forms for a one-character,
two-character, or arbitrary-length argument.  Others accept <em class="emph">only</em>
an arbitrary-length argument.  In the former scheme, a one-character
argument follows the function character immediately, an opening
parenthesis &lsquo;<samp class="samp">(</samp>&rsquo; introduces a two-character argument (no closing
parenthesis is used), and an argument of arbitrary length is enclosed in
brackets &lsquo;<samp class="samp">[]</samp>&rsquo;.  In the latter scheme, the user selects a delimiter
character.  A few escape sequences are idiosyncratic, and support both
of the foregoing conventions (<code class="code">\s</code>), designate their own
termination sequence (<code class="code">\?</code>), consume input until the next newline
(<code class="code">\!</code>, <code class="code">\&quot;</code>, <code class="code">\#</code>), or support an additional modifier
character (<code class="code">\s</code> again, and <code class="code">\n</code>).  As with requests, use of
some escape sequences in source documents may interact poorly with a
macro package you use; consult its documentation to learn of &ldquo;safe&rdquo;
sequences or alternative facilities it provides to achieve the desired
result.
</p>
<p>If an escape character is followed by a character that does not
identify a defined operation, the escape character is ignored (producing
a diagnostic of the &lsquo;<samp class="samp">escape</samp>&rsquo; warning category, which is not enabled
by default) and the following character is processed normally.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">$ groff -Tps -ww
.nr N 12
.ds co white
.ds animal elephant
I have \fI\nN \*(co \*[animal]s,\f[]
said \P.\&amp;\~Pseudo Pachyderm.
    error&rarr; warning: escape character ignored before 'P'
    &rArr; I have <i class="slanted">12 white elephants,</i> said P. Pseudo Pachyderm.
</pre></div></div>

<p>Escape sequence interpolation is of higher precedence than escape
sequence argument interpretation.  This rule affords flexibility in
using escape sequences to construct parameters to other escape
sequences.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds family C\&quot; Courier
.ds style I\&quot; oblique
Choice a typeface \f(\*[family]\*[style]wisely.
    &rArr; Choose a typeface <i class="slanted">wisely.</i>
</pre></div></div>

<p>In the above, the syntax form &lsquo;<samp class="samp">\f(</samp>&rsquo; accepts only two characters for
an argument; the example works because the subsequent escape sequences
are interpolated before the selection escape sequence argument is
processed, and strings <code class="code">family</code> and <code class="code">style</code> interpolate one
character each.<a class="footnote" id="DOCF46" href="#FOOT46"><sup>46</sup></a>
</p>
<p>The escape character is nearly always interpreted when encountered; it
is therefore desirable to have a way to interpolate it, disable it, or
change it.
</p>
<a class="index-entry-id" id="index-formatting-the-escape-character-_0028_005ce_0029"></a>
<a class="index-entry-id" id="index-escape-character_002c-formatting-_0028_005ce_0029"></a>
<dl class="first-deffn">
<dt class="deffn" id="index-_005ce-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\e</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005ce-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005ce"></a>
<p>Interpolate the escape character.
</p></dd></dl>

<a class="index-entry-id" id="index-formatting-a-backslash-glyph-_0028_005c_005brs_005d_0029"></a>
<a class="index-entry-id" id="index-backslash-glyph_002c-formatting-_0028_005c_005brs_005d_0029"></a>
<p>The <code class="code">\[rs]</code> special character escape sequence formats a backslash
glyph.  In macro and string definitions, the input sequences <code class="code">\\</code>
and <code class="code">\E</code> defer interpretation of escape sequences.  See <a class="xref" href="#Copy-Mode">Copy Mode</a>.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002eeo"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.eo</code></strong><a class="copiable-link" href='#index-_002eeo'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-eo"></a>
<a class="index-entry-id" id="index-disabling-_005c-_0028eo_0029"></a>
<a class="index-entry-id" id="index-_005c_002c-disabling-_0028eo_0029"></a>
<p>Disable the escape mechanism except in copy mode.  Once this request is
invoked, no input character is recognized as starting an escape
sequence in interpretation mode.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eec"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ec</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">o</i></span>]</var><a class="copiable-link" href='#index-_002eec'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ec"></a>
<a class="index-entry-id" id="index-escape-character_002c-changing-_0028ec_0029"></a>
<a class="index-entry-id" id="index-character_002c-escape_002c-changing-_0028ec_0029"></a>
<p>Recognize the ordinary character&nbsp;<var class="var">o</var> as the escape character.
If&nbsp;<var class="var">o</var> is absent or invalid, the default escape character
&lsquo;<samp class="samp">\</samp>&rsquo; is selected.
</p></dd></dl>

<p>Switching escape sequence interpretation off to define a macro and back
on afterward can obviate the need to double the escape character within
the definition.  See <a class="xref" href="#Writing-Macros">Writing Macros</a>.  This technique is not available
if your macro needs to interpolate values at the time it is
<em class="emph">defined</em>&mdash;but many do not.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.\&quot; simplified `BR` macro from the man(7) macro package
.eo
.de BR
.  ds result \&amp;
.  while (\n[.$] &gt;= 2) \{\
.    as result \fB\$1\fR\$2\&quot;
.    shift 2
.  \}
.  if \n[.$] .as result \fB\$1\&quot;
\*[result]
.  rm result
.  ft R
..
.ec
</pre></div></div>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eecs"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ecs</code></strong><a class="copiable-link" href='#index-_002eecs'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ecs"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002eecr"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ecr</code></strong><a class="copiable-link" href='#index-_002eecr'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ecr"></a>
<p>The <code class="code">ecs</code> request stores the escape character for recall with
<code class="code">ecr</code>.  <code class="code">ecr</code> sets the escape character to &lsquo;<samp class="samp">\</samp>&rsquo; if none
has been saved.
</p>
<p>Use these requests together to temporarily change the escape character.
</p></dd></dl>

<p>Using a different escape character, or disabling it, when calling macros
not under your control will likely cause errors, since GNU <code class="code">troff</code>
has no mechanism to &ldquo;intern&rdquo; macros&mdash;that is, to convert a macro
definition into a form independent of its
representation.<a class="footnote" id="DOCF47" href="#FOOT47"><sup>47</sup></a>  When a
macro is called, its contents are interpreted literally.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Delimiters">
<div class="nav-panel">
<p>
Previous: <a href="#Using-Escape-Sequences" accesskey="p" rel="prev">Using Escape Sequences</a>, Up: <a href="#Formatter-Instructions" accesskey="u" rel="up">Formatter Instructions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Delimiters-1">5.6.5 Delimiters</h4>
<a class="index-entry-id" id="index-delimiting-escape-sequence-arguments"></a>
<a class="index-entry-id" id="index-escape-sequence-argument-delimiters"></a>
<a class="index-entry-id" id="index-delimiters_002c-for-escape-sequence-arguments"></a>
<a class="index-entry-id" id="index-arguments_002c-to-escape-sequences_002c-delimiting"></a>

<a class="index-entry-id" id="index-_0027_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_0022_002c-as-delimiter"></a>
<p>Some escape sequences that require parameters use delimiters.  The
neutral apostrophe <code class="code">'</code> is a popular choice and shown in this
document.  The neutral double quote <code class="code">&quot;</code> is also commonly seen.
Letters, numerals, and leaders can be used.  Punctuation characters
are likely better choices, except for those defined as infix operators
in numeric expressions; see below.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">\l'1.5i\[bu]' \&quot; draw 1.5 inches of bullet glyphs
</pre></div></div>

<a class="index-entry-id" id="index-_005c_0025_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005cSP_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005c_007c_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005c_005e_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005c_007b_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005c_007d_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005c_0027_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005c_0060_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005c_002d_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005c_005f_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005c_0021_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005c_003f_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005c_0029_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005c_002f_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005c_002c_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005c_0026_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005c_003a_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005c_007e_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005c0_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005ca_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005cc_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005cd_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005ce_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005cE_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005cp_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005cr_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005ct_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_005cu_002c-as-delimiter"></a>
<p>The following escape sequences don&rsquo;t take arguments and thus are allowed
as delimiters:
<code class="code">\<kbd class="key">SP</kbd></code>, <code class="code">\%</code>, <code class="code">\|</code>, <code class="code">\^</code>, <code class="code">\{</code>,
<code class="code">\}</code>, <code class="code">\'</code>, <code class="code">\`</code>, <code class="code">\-</code>, <code class="code">\_</code>, <code class="code">\!</code>,
<code class="code">\?</code>, <code class="code">\)</code>, <code class="code">\/</code>, <code class="code">\,</code>, <code class="code">\&amp;</code>, <code class="code">\:</code>,
<code class="code">\~</code>, <code class="code">\0</code>, <code class="code">\a</code>, <code class="code">\c</code>, <code class="code">\d</code>, <code class="code">\e</code>,
<code class="code">\E</code>, <code class="code">\p</code>, <code class="code">\r</code>, <code class="code">\t</code>, and <code class="code">\u</code>.  However,
using them this way is discouraged; they can make the input confusing to
read.
</p>
<a class="index-entry-id" id="index-_005cA_002c-delimiters-allowed-by"></a>
<a class="index-entry-id" id="index-_005cb_002c-delimiters-allowed-by"></a>
<a class="index-entry-id" id="index-_005co_002c-delimiters-allowed-by"></a>
<a class="index-entry-id" id="index-_005cw_002c-delimiters-allowed-by"></a>
<a class="index-entry-id" id="index-_005cX_002c-delimiters-allowed-by"></a>
<a class="index-entry-id" id="index-_005cZ_002c-delimiters-allowed-by"></a>
<a class="index-entry-id" id="index-newline_002c-as-delimiter"></a>
<p>A few escape sequences,
<code class="code">\A</code>,
<code class="code">\b</code>,
<code class="code">\o</code>,
<code class="code">\w</code>,
<code class="code">\X</code>,
and <code class="code">\Z</code>, accept a newline as a delimiter.  Newlines that serve
as delimiters continue to be recognized as input line terminators.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">A caf\o
e\(aa
in Paris
    &rArr; A caf in Paris
</pre></div></div>

<p>Use of newlines as delimiters in escape sequences is also discouraged.
</p>
<a class="index-entry-id" id="index-_005cD_002c-delimiters-allowed-by"></a>
<a class="index-entry-id" id="index-_005ch_002c-delimiters-allowed-by"></a>
<a class="index-entry-id" id="index-_005cH_002c-delimiters-allowed-by"></a>
<a class="index-entry-id" id="index-_005cl_002c-delimiters-allowed-by"></a>
<a class="index-entry-id" id="index-_005cL_002c-delimiters-allowed-by"></a>
<a class="index-entry-id" id="index-_005cN_002c-delimiters-allowed-by"></a>
<a class="index-entry-id" id="index-_005cR_002c-delimiters-allowed-by"></a>
<a class="index-entry-id" id="index-_005cs_002c-delimiters-allowed-by"></a>
<a class="index-entry-id" id="index-_005cS_002c-delimiters-allowed-by"></a>
<a class="index-entry-id" id="index-_005cv_002c-delimiters-allowed-by"></a>
<a class="index-entry-id" id="index-_005cx_002c-delimiters-allowed-by"></a>
<p>Finally, the escape sequences <code class="code">\D</code>, <code class="code">\h</code>, <code class="code">\H</code>,
<code class="code">\l</code>, <code class="code">\L</code>, <code class="code">\N</code>, <code class="code">\R</code>, <code class="code">\s</code>, <code class="code">\S</code>,
<code class="code">\v</code>, and <code class="code">\x</code> prohibit many delimiters.
</p>
<ul class="itemize mark-bullet">
<li><a class="index-entry-id" id="index-numerals_002c-as-delimiters"></a>
<a class="index-entry-id" id="index-digits_002c-as-delimiters"></a>
<a class="index-entry-id" id="index-_002e_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-decimal-point_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-dot_002c-as-delimiter"></a>
the numerals <code class="code">0</code>-<code class="code">9</code> and the decimal point <code class="code">.</code>

</li><li><a class="index-entry-id" id="index-operators_002c-as-delimiters"></a>
<a class="index-entry-id" id="index-_002b_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_002d_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_002f_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_002a_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_0025_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_003c_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_003e_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_003d_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_0026_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_003a_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_0028_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-_0029_002c-as-delimiter"></a>
the (single-character) operators &lsquo;<samp class="samp">+-/*%&lt;&gt;=&amp;:()</samp>&rsquo;

</li><li><a class="index-entry-id" id="index-space-character_002c-as-delimiter"></a>
<a class="index-entry-id" id="index-tab-character_002c-as-delimiter"></a>
the space and tab characters

</li><li><a class="index-entry-id" id="index-_005c_0025_002c-as-delimiter-1"></a>
<a class="index-entry-id" id="index-_005c_003a_002c-as-delimiter-1"></a>
<a class="index-entry-id" id="index-_005c_007b_002c-as-delimiter-1"></a>
<a class="index-entry-id" id="index-_005c_007d_002c-as-delimiter-1"></a>
<a class="index-entry-id" id="index-_005c_0027_002c-as-delimiter-1"></a>
<a class="index-entry-id" id="index-_005c_0060_002c-as-delimiter-1"></a>
<a class="index-entry-id" id="index-_005c_002d_002c-as-delimiter-1"></a>
<a class="index-entry-id" id="index-_005c_005f_002c-as-delimiter-1"></a>
<a class="index-entry-id" id="index-_005c_0021_002c-as-delimiter-1"></a>
<a class="index-entry-id" id="index-_005c_002f_002c-as-delimiter-1"></a>
<a class="index-entry-id" id="index-_005cc_002c-as-delimiter-1"></a>
<a class="index-entry-id" id="index-_005ce_002c-as-delimiter-1"></a>
<a class="index-entry-id" id="index-_005cp_002c-as-delimiter-1"></a>
any escape sequences other than <code class="code">\%</code>, <code class="code">\:</code>, <code class="code">\{</code>,
<code class="code">\}</code>, <code class="code">\'</code>, <code class="code">\`</code>, <code class="code">\-</code>, <code class="code">\_</code>, <code class="code">\!</code>,
<code class="code">\/</code>, <code class="code">\c</code>, <code class="code">\e</code>, and <code class="code">\p</code>
</li></ul>

<p>Delimiter syntax is complex and flexible primarily for historical
reasons; the foregoing restrictions need be kept in mind mainly when
using <code class="code">groff</code> in <abbr class="acronym">AT&amp;T</abbr> compatibility mode.  GNU
<code class="code">troff</code> keeps track of the nesting depth of escape sequence
interpolations, so the only characters you need to avoid using as
delimiters are those that appear in the arguments you input, not any
that result from interpolation. Typically, <code class="code">'</code> works fine.
See <a class="xref" href="#Implementation-Differences">Implementation Differences</a>.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">$ groff -Tps
.de Mw
.  nr wd \w'\\$1'
.  tm &quot;\\$1&quot; is \\n(wd units wide.
..
.Mw Wet'suwet'en
.Mw Wet+200i
.cp 1 \&quot; turn on compatibility mode
.Mw Wet'suwet'en
.Mw Wet'
.Mw Wet+200i
    error&rarr; &quot;Wet'suwet'en&quot; is 54740 units wide.
    error&rarr; &quot;Wet'+200i&quot; is 42610 units wide.
    error&rarr; &quot;Wet'suwet'en&quot; is 15860 units wide.
    error&rarr; &quot;Wet'&quot; is 15860 units wide.
    error&rarr; &quot;Wet'+200i&quot; is 14415860 units wide.
</pre></div></div>

<p>We see here that in compatibility mode, the part of the argument after
the <code class="code">'</code> delimiter escapes from its context and, if nefariously
crafted, influences the computation of the <var class="var">wd</var> register&rsquo;s value in
a surprising way.
</p>
<hr>
</div>
</div>
<div class="section-level-extent" id="Comments">
<div class="nav-panel">
<p>
Next: <a href="#Registers" accesskey="n" rel="next">Registers</a>, Previous: <a href="#Formatter-Instructions" accesskey="p" rel="prev">Formatter Instructions</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Comments-1">5.7 Comments</h3>
<a class="index-entry-id" id="index-comments"></a>

<p>One of the most common forms of escape sequence is the
comment.<a class="footnote" id="DOCF48" href="#FOOT48"><sup>48</sup></a>
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_0022-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\&quot;</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_0022-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_0022"></a>
<p>Start a comment.  Everything up to the next newline is ignored.
</p>
<p>This may sound simple, but it can be tricky to keep the comments from
interfering with the appearance of the output.
<a class="index-entry-id" id="index-ds_002c-ds1-requests_002c-and-comments"></a>
<a class="index-entry-id" id="index-as_002c-as1-requests_002c-and-comments"></a>
If the escape sequence is to the right of some text or a request, that
portion of the line is ignored, but spaces preceding it are processed
normally by GNU <code class="code">troff</code>.  This affects only the <code class="code">ds</code> and
<code class="code">as</code> requests and their variants.
</p>
<a class="index-entry-id" id="index-tabs_002c-before-comments"></a>
<a class="index-entry-id" id="index-comments_002c-lining-up-with-tabs"></a>
<p>One possibly irritating idiosyncrasy is that tabs should not be used to
vertically align comments in the source document.  Tab characters are
not treated as separators between a request name and its first argument,
nor between arguments.
</p>
<a class="index-entry-id" id="index-undefined-request"></a>
<a class="index-entry-id" id="index-request_002c-undefined"></a>
<p>A comment on a line by itself is treated as a blank line, because after
eliminating the comment, that is all that remains.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">Test
\&quot; comment
Test
    &rArr; Test
    &rArr;
    &rArr; Test
</pre></div></div>

<p>To avoid this, it is common to combine the empty request with the
comment escape sequence as &lsquo;<samp class="samp">.\&quot;</samp>&rsquo;, causing the input line to be
ignored.
</p>
<a class="index-entry-id" id="index-_0027_002c-as-a-comment"></a>
<p>Another commenting scheme sometimes seen is three consecutive single
quotes (<code class="code">'''</code>) at the beginning of a line.  This works, but GNU
<code class="code">troff</code> emits a warning diagnostic (if enabled) about an undefined
macro (namely &lsquo;<samp class="samp">''</samp>&rsquo;).
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_0023-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\#</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_0023-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_0023"></a>
<p>Start a comment; everything up to and including the next newline is
ignored.  This <code class="code">groff</code> extension was introduced to avoid the
problems described above.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">Test
\# comment
Test
    &rArr; Test Test
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eig"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ig</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">end</i></span>]</var><a class="copiable-link" href='#index-_002eig'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ig"></a>
<p>Ignore input until, in the current conditional block (if
any),<a class="footnote" id="DOCF49" href="#FOOT49"><sup>49</sup></a> the macro <var class="var">end</var> is called
at the start of a control line, or the control line &lsquo;<samp class="samp">..</samp>&rsquo; is
encountered if <var class="var">end</var> is not specified.  <code class="code">ig</code> is parsed as if it
were a macro definition, but its contents are discarded, not
stored.<a class="footnote" id="DOCF50" href="#FOOT50"><sup>50</sup></a>
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">hand\c
.de TX
fasting
..
.ig TX
This is part of a large block of input that has been
temporarily(?) commented out.
We can restore it simply by removing the .ig request and
the call of its end macro.
.TX
</pre></div></div>
<div class="example">
<div class="group"><pre class="example-preformatted">    &rArr; handfasting
</pre></div></div>
</dd></dl>



<hr>
</div>
<div class="section-level-extent" id="Registers">
<div class="nav-panel">
<p>
Next: <a href="#Manipulating-Filling-and-Adjustment" accesskey="n" rel="next">Manipulating Filling and Adjustment</a>, Previous: <a href="#Formatter-Instructions" accesskey="p" rel="prev">Formatter Instructions</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Registers-1">5.8 Registers</h3>
<a class="index-entry-id" id="index-registers"></a>

<p>In the <code class="code">roff</code> language, numbers can be stored in <em class="dfn">registers</em>.
Many built-in registers exist, supplying anything from the date to
details of formatting parameters.  You can also define your own.
See <a class="xref" href="#Identifiers">Identifiers</a>, for information on constructing a valid name for a
register.
</p>


<ul class="mini-toc">
<li><a href="#Setting-Registers" accesskey="1">Setting Registers</a></li>
<li><a href="#Interpolating-Registers" accesskey="2">Interpolating Registers</a></li>
<li><a href="#Auto_002dincrement" accesskey="3">Auto-increment</a></li>
<li><a href="#Assigning-Register-Formats" accesskey="4">Assigning Register Formats</a></li>
<li><a href="#Built_002din-Registers" accesskey="5">Built-in Registers</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="Setting-Registers">
<div class="nav-panel">
<p>
Next: <a href="#Interpolating-Registers" accesskey="n" rel="next">Interpolating Registers</a>, Previous: <a href="#Registers" accesskey="p" rel="prev">Registers</a>, Up: <a href="#Registers" accesskey="u" rel="up">Registers</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Setting-Registers-1">5.8.1 Setting Registers</h4>
<a class="index-entry-id" id="index-setting-registers-_0028nr_002c-_005cR_0029"></a>
<a class="index-entry-id" id="index-registers_002c-setting-_0028nr_002c-_005cR_0029"></a>

<p>Define registers and update their values with the <code class="code">nr</code> request or
the <code class="code">\R</code> escape sequence.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002enr-1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.nr</code></strong> <var class="def-var-arguments">ident value</var><a class="copiable-link" href='#index-_002enr-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-nr-1"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cR_0027ident-value_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\R<code class="code">'</code></code><span class="r"><i class="slanted">ident value</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cR_0027ident-value_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cR"></a>
<p>Set register <var class="var">ident</var> to <var class="var">value</var>.  If <var class="var">ident</var> doesn&rsquo;t exist,
GNU <code class="code">troff</code> creates it.  In the <code class="code">\R</code> escape sequence, the
delimiter need not be a neutral apostrophe; see <a class="ref" href="#Delimiters">Delimiters</a>.  It
also does not produce an input token in GNU <code class="code">troff</code>.  See <a class="xref" href="#Gtroff-Internals"><code class="code">gtroff</code> Internals</a>.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr a (((17 + (3 * 4))) % 4)
\n[a]
.\R'a (((17 + (3 * 4))) % 4)'
\n[a]
    &rArr; 1 1
</pre></div></div>

<p>(Later, we will discuss additional forms of <code class="code">nr</code> and <code class="code">\R</code> that
can change a register&rsquo;s value after it is dereferenced but before it is
interpolated.  See <a class="xref" href="#Auto_002dincrement">Auto-increment</a>.)
</p>
<p>The complete transparency of <code class="code">\R</code> can cause surprising effects if
you use registers like <code class="code">.k</code>, which get evaluated at the time they
are accessed.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ll 1.6i
.
aaa bbb ccc ddd eee fff ggg hhh\R':k \n[.k]'
.tm :k == \n[:k]
    &rArr; :k == 126950
.
.br
.
aaa bbb ccc ddd eee fff ggg hhh\h'0'\R':k \n[.k]'
.tm :k == \n[:k]
    &rArr; :k == 15000
</pre></div></div>

<p>If you process this with the PostScript device (<code class="code">-Tps</code>), there will
be a line break eventually after <code class="code">ggg</code> in both input lines.
However, after processing the space after <code class="code">ggg</code>, the partially
collected line is not overfull yet, so GNU <code class="code">troff</code> continues to
collect input until it sees the space (or in this case, the newline)
after <code class="code">hhh</code>.  At this point, the line is longer than the line
length, and the line gets broken.
</p>
<p>In the first input line, since the <code class="code">\R</code> escape sequence leaves no
traces, the check for the overfull line hasn&rsquo;t been done yet at the
point where <code class="code">\R</code> gets handled, and you get a value for the
<code class="code">.k</code> register that is even greater than the current line length.
</p>
<p>In the second input line, the insertion of <code class="code">\h'0'</code> to cause a
zero-width motion forces GNU <code class="code">troff</code> to check the line length,
which in turn causes the start of a new output line.  Now <code class="code">.k</code>
returns the expected value.
</p></dd></dl>

<p><code class="code">nr</code> and <code class="code">\R</code> each have two additional special forms to
increment or decrement a register.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002enr-2"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.nr</code></strong> <var class="def-var-arguments">ident <code class="t">+</code><span class="r"><i class="slanted">value</i></span></var><a class="copiable-link" href='#index-_002enr-2'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-nr-2"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002enr-3"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.nr</code></strong> <var class="def-var-arguments">ident <code class="t">-</code><span class="r"><i class="slanted">value</i></span></var><a class="copiable-link" href='#index-_002enr-3'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cR_0027ident-_002bvalue_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\R<code class="code">'</code></code><span class="r"><i class="slanted">ident <code class="t">+</code>value</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cR_0027ident-_002bvalue_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cR-1"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cR_0027ident-_002dvalue_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\R<code class="code">'</code></code><span class="r"><i class="slanted">ident <code class="t">-</code>value</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cR_0027ident-_002dvalue_0027'> &para;</a></span></dt>
<dd><p>Increment (decrement) register <var class="var">ident</var> by <var class="var">value</var>.  In the
<code class="code">\R</code> escape sequence, the delimiter need not be a neutral
apostrophe; see <a class="ref" href="#Delimiters">Delimiters</a>.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr a 1
.nr a +1
\na
    &rArr; 2
</pre></div></div>

<a class="index-entry-id" id="index-negating-register-values"></a>
<p>A leading minus sign in <var class="var">value</var> is always interpreted as a
decrementation operator, not an algebraic sign.  To assign a register a
negative value or the negated value of another register, you can
force GNU <code class="code">troff</code> to interpret &lsquo;<samp class="samp">-</samp>&rsquo; as a negation or minus,
rather than decrementation, operator: enclose it with its operand in
parentheses or subtract it from zero.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr a 7
.nr b 3
.nr a -\nb
\na
    &rArr; 4
.nr a (-\nb)
\na
    &rArr; -3
.nr a 0-\nb
\na
    &rArr; -3
</pre></div></div>

<p>If a register&rsquo;s prior value does not exist (the register was undefined),
an increment or decrement is applied as if to&nbsp;0.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002err"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.rr</code></strong> <var class="def-var-arguments">ident</var><a class="copiable-link" href='#index-_002err'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-rr"></a>
<a class="index-entry-id" id="index-removing-a-register-_0028rr_0029"></a>
<a class="index-entry-id" id="index-register_002c-removing-_0028rr_0029"></a>
<p>Remove register <var class="var">ident</var>.  If <var class="var">ident</var> doesn&rsquo;t exist, the request
is ignored.  Technically, only the name is removed; the register&rsquo;s
contents are still accessible under aliases created with <code class="code">aln</code>, if
any.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ernn"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.rnn</code></strong> <var class="def-var-arguments">ident1 ident2</var><a class="copiable-link" href='#index-_002ernn'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-rnn"></a>
<a class="index-entry-id" id="index-renaming-a-register-_0028rnn_0029"></a>
<a class="index-entry-id" id="index-register_002c-renaming-_0028rnn_0029"></a>
<p>Rename register <var class="var">ident1</var> to <var class="var">ident2</var>.  If <var class="var">ident1</var> doesn&rsquo;t
exist, the request is ignored.  Renaming a built-in register does not
otherwise alter its properties.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ealn"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.aln</code></strong> <var class="def-var-arguments">new old</var><a class="copiable-link" href='#index-_002ealn'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-aln"></a>
<a class="index-entry-id" id="index-alias_002c-register_002c-creating-_0028aln_0029"></a>
<a class="index-entry-id" id="index-creating-alias-for-register-_0028aln_0029"></a>
<a class="index-entry-id" id="index-register_002c-creating-alias-for-_0028aln_0029"></a>
<p>Create an alias <var class="var">new</var> for an existing register <var class="var">old</var>, causing
the names to refer to the same stored object.  If <var class="var">old</var> is
undefined, a warning in category &lsquo;<samp class="samp">reg</samp>&rsquo; is produced and the request
is ignored.  See <a class="xref" href="#Warnings">Warnings</a>, for information about the enablement and
suppression of warnings.
</p>
<a class="index-entry-id" id="index-alias_002c-register_002c-removing-_0028rr_0029"></a>
<a class="index-entry-id" id="index-removing-alias-for-register-_0028rr_0029"></a>
<a class="index-entry-id" id="index-register_002c-removing-alias-for-_0028rr_0029"></a>
<p>To remove a register alias, invoke <code class="code">rr</code> on its name.  A register&rsquo;s
contents do not become inaccessible until it has no more names.
</p></dd></dl>


<hr>
</div>
<div class="subsection-level-extent" id="Interpolating-Registers">
<div class="nav-panel">
<p>
Next: <a href="#Auto_002dincrement" accesskey="n" rel="next">Auto-increment</a>, Previous: <a href="#Setting-Registers" accesskey="p" rel="prev">Setting Registers</a>, Up: <a href="#Registers" accesskey="u" rel="up">Registers</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Interpolating-Registers-1">5.8.2 Interpolating Registers</h4>
<a class="index-entry-id" id="index-interpolating-registers-_0028_005cn_0029"></a>
<a class="index-entry-id" id="index-registers_002c-interpolating-_0028_005cn_0029"></a>

<p>Register contents are interpolated with the <code class="code">\n</code> escape sequence.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cni"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\n</code><span class="r"><i class="slanted">i</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cni'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cn"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_0028id"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\n(</code><span class="r"><i class="slanted">id</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cn_0028id'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_005bident_005d"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\n[</code><span class="r"><i class="slanted">ident</i></span><code class="t">]</code></strong><a class="copiable-link" href='#index-_005cn_005bident_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-nested-assignments"></a>
<a class="index-entry-id" id="index-assignments_002c-nested"></a>
<a class="index-entry-id" id="index-indirect-assignments"></a>
<a class="index-entry-id" id="index-assignments_002c-indirect"></a>
<p>Interpolate register with name <var class="var">ident</var> (one-character
name&nbsp;<var class="var">i</var>, two-character name <var class="var">id</var>).  <code class="code">\n</code> is
interpreted even in copy mode (see <a class="pxref" href="#Copy-Mode">Copy Mode</a>).  If the register is
undefined, it is created and assigned a value of&nbsp;&lsquo;<samp class="samp">0</samp>&rsquo;, that
value is interpolated, and a warning in category &lsquo;<samp class="samp">reg</samp>&rsquo; is emitted.
See <a class="xref" href="#Warnings">Warnings</a>, for information about the enablement and suppression of
warnings.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr a 5
.nr as \na+\na
\n(as
    &rArr; 10
</pre></div></div>

<div class="example">
<div class="group"><pre class="example-preformatted">.nr a1 5
.nr ab 6
.ds str b
.ds num 1
\n[a\n[num]]
    &rArr; 5
\n[a\*[str]]
    &rArr; 6
</pre></div></div>
</dd></dl>


<hr>
</div>
<div class="subsection-level-extent" id="Auto_002dincrement">
<div class="nav-panel">
<p>
Next: <a href="#Assigning-Register-Formats" accesskey="n" rel="next">Assigning Register Formats</a>, Previous: <a href="#Interpolating-Registers" accesskey="p" rel="prev">Interpolating Registers</a>, Up: <a href="#Registers" accesskey="u" rel="up">Registers</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Auto_002dincrement-1">5.8.3 Auto-increment</h4>
<a class="index-entry-id" id="index-auto_002dincrementation-of-a-register"></a>
<a class="index-entry-id" id="index-incrementation_002c-automatic_002c-of-a-register"></a>
<a class="index-entry-id" id="index-decrementation_002c-automatic_002c-of-a-register"></a>

<p>Registers can also be incremented or decremented by a configured amount
at the time they are interpolated.  The value of the increment is
specified with a third argument to the <code class="code">nr</code> request, and a special
interpolation syntax is used to alter and then retrieve the register&rsquo;s
value.  Together, these features are called
<em class="dfn">auto-increment</em>.<a class="footnote" id="DOCF51" href="#FOOT51"><sup>51</sup></a>
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002enr-4"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.nr</code></strong> <var class="def-var-arguments">ident value incr</var><a class="copiable-link" href='#index-_002enr-4'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-nr-3"></a>
<a class="index-entry-id" id="index-_005cR_002c-difference-from-nr"></a>
<p>Set register <var class="var">ident</var> to <var class="var">value</var> and its auto-incrementation
amount to to <var class="var">incr</var>.  The <code class="code">\R</code> escape sequence doesn&rsquo;t support
an <var class="var">incr</var> argument.
</p></dd></dl>

<p>Auto-incrementation is not <em class="emph">completely</em> automatic; the <code class="code">\n</code>
escape sequence in its basic form never alters the value of a register.
To apply auto-incrementation to a register, interpolate it with
&lsquo;<samp class="samp">\n</samp>&rsquo;.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_002bi"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\n+</code><span class="r"><i class="slanted">i</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cn_002bi'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cn-1"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_002di"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\n-</code><span class="r"><i class="slanted">i</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cn_002di'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_002b_0028id"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\n+(</code><span class="r"><i class="slanted">id</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cn_002b_0028id'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_002d_0028id"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\n-(</code><span class="r"><i class="slanted">id</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cn_002d_0028id'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_002b_005bident_005d"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\n+[</code><span class="r"><i class="slanted">ident</i></span><code class="t">]</code></strong><a class="copiable-link" href='#index-_005cn_002b_005bident_005d'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_002d_005bident_005d"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\n-[</code><span class="r"><i class="slanted">ident</i></span><code class="t">]</code></strong><a class="copiable-link" href='#index-_005cn_002d_005bident_005d'> &para;</a></span></dt>
<dd><p>Increment or decrement <var class="var">ident</var> (one-character
name&nbsp;<var class="var">i</var>, two-character name <var class="var">id</var>) by the register&rsquo;s
auto-incrementation value and then interpolate the new register value.
If <var class="var">ident</var> has no auto-incrementation value, interpolate as with
<code class="code">\n</code>.
</p></dd></dl>

<div class="example">
<div class="group"><pre class="example-preformatted">.nr a 0 1
.nr xx 0 5
.nr foo 0 -2
\n+a, \n+a, \n+a, \n+a, \n+a
.br
\n-(xx, \n-(xx, \n-(xx, \n-(xx, \n-(xx
.br
\n+[foo], \n+[foo], \n+[foo], \n+[foo], \n+[foo]
    &rArr; 1, 2, 3, 4, 5
    &rArr; -5, -10, -15, -20, -25
    &rArr; -2, -4, -6, -8, -10
</pre></div></div>

<a class="index-entry-id" id="index-increment-value-without-changing-the-register"></a>
<a class="index-entry-id" id="index-value_002c-incrementing-without-changing-the-register"></a>
<p>To change the increment value without changing the value of a register,
assign the register&rsquo;s value to itself by interpolating it, and specify
the desired increment normally.  Apply an increment of &lsquo;<samp class="samp">0</samp>&rsquo; to
disable auto-incrementation of the register.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Assigning-Register-Formats">
<div class="nav-panel">
<p>
Next: <a href="#Built_002din-Registers" accesskey="n" rel="next">Built-in Registers</a>, Previous: <a href="#Auto_002dincrement" accesskey="p" rel="prev">Auto-increment</a>, Up: <a href="#Registers" accesskey="u" rel="up">Registers</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Assigning-Register-Formats-1">5.8.4 Assigning Register Formats</h4>
<a class="index-entry-id" id="index-assign-number-format-to-register-_0028af_0029"></a>
<a class="index-entry-id" id="index-number-formats_002c-assigning-to-register-_0028af_0029"></a>
<a class="index-entry-id" id="index-register_002c-assigning-number-format-to-_0028af_0029"></a>

<p>A writable register&rsquo;s value can be interpolated in several number
formats.  By default, conventional Arabic numerals are used.
Other formats see use in sectioning and outlining schemes and
alternative page numbering arrangements.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002eaf"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.af</code></strong> <var class="def-var-arguments">reg fmt</var><a class="copiable-link" href='#index-_002eaf'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-af"></a>
<p>Use number format <var class="var">fmt</var> when interpolating register <var class="var">reg</var>.
Valid number formats are as follows.
</p>
<dl class="table">
<dt><code class="code">0<span class="r">&hellip;</span></code></dt>
<dd><p>Arabic numerals 0, 1, 2, and so on.
Any decimal digit is equivalent to &lsquo;<samp class="samp">0</samp>&rsquo;; the formatter merely counts
the digits specified.  Multiple Arabic numerals in <var class="var">fmt</var> cause
interpolations to be zero-padded on the left if necessary to at least as
many digits as specified (interpolations never truncate a register
value).  A register with format &lsquo;<samp class="samp">00</samp>&rsquo; interpolates values 1, 2, 3 as
&lsquo;<samp class="samp">01</samp>&rsquo;, &lsquo;<samp class="samp">02</samp>&rsquo;, &lsquo;<samp class="samp">03</samp>&rsquo;.  The default format for all writable
registers is &lsquo;<samp class="samp">0</samp>&rsquo;.
</p>
</dd>
<dt id='index-Roman-numerals'><span><code class="code">I</code><a class="copiable-link" href='#index-Roman-numerals'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-numerals_002c-Roman"></a>
<p>Uppercase Roman numerals: 0, I, II, III, IV,&nbsp;<small class="enddots">...</small>
</p>
</dd>
<dt><code class="code">i</code></dt>
<dd><p>Lowercase Roman numerals: 0, i, ii, iii, iv,&nbsp;<small class="enddots">...</small>
</p>
</dd>
<dt><code class="code">A</code></dt>
<dd><p>Uppercase letters: 0, A, B, C, &hellip;,&nbsp;Z, AA, AB,&nbsp;<small class="enddots">...</small>
</p>
</dd>
<dt><code class="code">a</code></dt>
<dd><p>Lowercase letters: 0, a, b, c, &hellip;,&nbsp;z, aa, ab,&nbsp;<small class="enddots">...</small>
</p></dd>
</dl>

<p>Omitting <var class="var">fmt</var> causes a warning in category &lsquo;<samp class="samp">missing</samp>&rsquo;.
See <a class="xref" href="#Warnings">Warnings</a>, for information about the enablement and suppression of
warnings.  Specifying an unrecognized format is an error.
</p>
<p>Zero values are interpolated as &lsquo;<samp class="samp">0</samp>&rsquo; in non-Arabic formats.
Negative quantities are prefixed with &lsquo;<samp class="samp">-</samp>&rsquo; irrespective of format.
In Arabic formats, the sign supplements the field width.  If <var class="var">reg</var>
doesn&rsquo;t exist, it is created with a zero value.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr a 10
.af a 0           \&quot; the default format
\na,
.af a I
\na,
.af a 321
.nr a (-\na)
\na,
.af a a
\na
    &rArr; 10, X, -010, -j
</pre></div></div>

<a class="index-entry-id" id="index-Roman-numerals_002c-extrema-_0028maximum-and-minimum_0029"></a>
<a class="index-entry-id" id="index-extreme-values-representable-with-Roman-numerals"></a>
<a class="index-entry-id" id="index-maximum-value-representable-with-Roman-numerals"></a>
<a class="index-entry-id" id="index-minimum-value-representable-with-Roman-numerals"></a>
<p>The representable extrema in the &lsquo;<samp class="samp">i</samp>&rsquo; and &lsquo;<samp class="samp">I</samp>&rsquo; formats
correspond to Arabic 39,999.  GNU <code class="code">troff</code> uses &lsquo;<samp class="samp">w</samp>&rsquo; and
&lsquo;<samp class="samp">z</samp>&rsquo; to represent 5,000 and 10,000 in Roman numerals, respectively,
following the convention of <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>&mdash;currently, the
correct glyphs for Roman numerals five thousand (<code class="code">U+2181</code>) and ten
thousand (<code class="code">U+2182</code>) are not used.
</p>
<a class="index-entry-id" id="index-read_002donly-register_002c-changing-format"></a>
<a class="index-entry-id" id="index-changing-format_002c-and-read_002donly-registers"></a>
<p>Assigning the format of a read-only register is an error.  Instead, copy
the read-only register&rsquo;s value to, and assign the format of, a writable
register.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cgr"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\g</code><span class="r"><i class="slanted">r</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cgr'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cg"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cg_0028rg"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\g(</code><span class="r"><i class="slanted">rg</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cg_0028rg'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cg_005breg_005d"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\g[</code><span class="r"><i class="slanted">reg</i></span><code class="t">]</code></strong><a class="copiable-link" href='#index-_005cg_005breg_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-format-of-register-_0028_005cg_0029"></a>
<a class="index-entry-id" id="index-register_002c-format-_0028_005cg_0029"></a>
<p>Interpolate the format of the register <var class="var">reg</var> (one-character
name&nbsp;<var class="var">r</var>, two-character name <var class="var">rg</var>).  Zeroes represent
Arabic formats.  If <var class="var">reg</var> is not defined, <var class="var">reg</var> is not created
and nothing is interpolated.  <code class="code">\g</code> is interpreted even in copy mode
(see <a class="pxref" href="#Copy-Mode">Copy Mode</a>).
</p></dd></dl>

<a class="index-entry-id" id="index-register-format_002c-in-expressions"></a>
<a class="index-entry-id" id="index-expressions_002c-and-register-format"></a>
<p>GNU <code class="code">troff</code> interprets only Arabic numerals.  The Roman numeral or
alphabetic formats cannot be used as operands to arithmetic operators in
expressions (see <a class="pxref" href="#Numeric-Expressions">Numeric Expressions</a>).  For instance, it may be
desirable to test the page number independently of its format.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.af % i \&quot; front matter
.de header-trap
.  \&quot; To test the page number, we need it in Arabic.
.  ds saved-page-number-format \\g%\&quot;
.  af % 0
.  nr page-number-in-decimal \\n%
.  af % \\*[saved-page-number-format]
.  ie \\n[page-number-in-decimal]=1 .do-first-page-stuff
.  el \{\
.    ie o .do-odd-numbered-page-stuff
.    el   .do-even-numbered-page-stuff
.  \}
.  rm saved-page-number-format
..
.wh 0 header-trap
</pre></div></div>


<hr>
</div>
<div class="subsection-level-extent" id="Built_002din-Registers">
<div class="nav-panel">
<p>
Previous: <a href="#Assigning-Register-Formats" accesskey="p" rel="prev">Assigning Register Formats</a>, Up: <a href="#Registers" accesskey="u" rel="up">Registers</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Built_002din-Registers-1">5.8.5 Built-in Registers</h4>
<a class="index-entry-id" id="index-built_002din-registers"></a>
<a class="index-entry-id" id="index-registers_002c-built_002din"></a>

<p>Predefined registers whose identifiers start with a dot are read-only.
Many are Boolean-valued, interpolating a true or false value testable
with the <code class="code">if</code>, <code class="code">ie</code>, or <code class="code">while</code> requests.  Some read-only
registers are string-valued, meaning that they interpolate text.
</p>
<a class="index-entry-id" id="index-removing-a-built_002din-register"></a>
<a class="index-entry-id" id="index-register_002c-built_002din_002c-removing"></a>
<a class="index-entry-id" id="index-built_002din-register_002c-removing"></a>
<p><strong class="strong">Caution:</strong> Built-in registers are subject to removal like
others; once removed, they can be recreated only as normal writable
registers and will not reflect formatter state.
</p>
<p>A register name (without the dot) is often associated with a request of
the same name.  A complete listing of all built-in registers can be
found in <a class="ref" href="#Register-Index">Register Index</a>.
</p>
<p>We present here a few built-in registers that are not described
elsewhere in this manual; they have to do with invariant properties of
GNU <code class="code">troff</code>, or obtain information about the formatter&rsquo;s
command-line options, processing progress, or the operating environment.
</p>
<dl class="table">
<dt id='index-_002eA'><span><code class="code">\n[.A]</code><a class="copiable-link" href='#index-_002eA'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-approximation-output-register-_0028_002eA_0029"></a>
<a class="index-entry-id" id="index-plain-text-approximation-output-register-_0028_002eA_0029-1"></a>
<p>Approximate output is being formatted (Boolean-valued); see
<code class="command">groff</code> <samp class="option">-a</samp> option (<a class="ref" href="#Groff-Options">Options</a>).
</p>
</dd>
<dt id='index-c_002e'><span><code class="code">\n[.c]</code><a class="copiable-link" href='#index-c_002e'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ec"></a>
</dd>
<dt><code class="code">\n[c.]</code></dt>
<dd><a class="index-entry-id" id="index-input-line-number-register-_0028_002ec_002c-c_002e_0029"></a>
<a class="index-entry-id" id="index-line-number_002c-input_002c-register-_0028_002ec_002c-c_002e_0029"></a>
<p>Input line number.  &lsquo;<samp class="samp">c.</samp>&rsquo; is a writable synonym,
affecting subsequent interpolations of both &lsquo;<samp class="samp">.c</samp>&rsquo; and &lsquo;<samp class="samp">c.</samp>&rsquo;.
</p>
</dd>
<dt id='index-current-input-file-name-register-_0028_002eF_0029'><span><code class="code">\n[.F]</code><a class="copiable-link" href='#index-current-input-file-name-register-_0028_002eF_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-input-file-name_002c-current_002c-register-_0028_002eF_0029"></a>
<a class="index-entry-id" id="index-_002eF"></a>
<p>Name of input file (string-valued).
</p>
</dd>
<dt id='index-_002eg'><span><code class="code">\n[.g]</code><a class="copiable-link" href='#index-_002eg'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-GNU-troff_002c-identification-register-_0028_002eg_0029"></a>
<a class="index-entry-id" id="index-GNU_002dspecific-register-_0028_002eg_0029"></a>
<p>Always true in GNU <code class="code">troff</code> (Boolean-valued).  Documents can use
this to ask the formatter if it claims <code class="code">groff</code> compatibility.
</p>
</dd>
<dt id='index-_002eP'><span><code class="code">\n[.P]</code><a class="copiable-link" href='#index-_002eP'> &para;</a></span></dt>
<dd><p>Output page selection status (Boolean-valued); see <code class="command">groff</code>
<samp class="option">-o</samp> option (<a class="ref" href="#Groff-Options">Options</a>).
</p>
</dd>
<dt id='index-number-of-registers-register-_0028_002eR_0029'><span><code class="code">\n[.R]</code><a class="copiable-link" href='#index-number-of-registers-register-_0028_002eR_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-registers_002c-number-of_002c-register-_0028_002eR_0029"></a>
<a class="index-entry-id" id="index-_002eR-2"></a>
<p>Count of available unused registers; always 10,000 in GNU
<code class="code">troff</code>.<a class="footnote" id="DOCF52" href="#FOOT52"><sup>52</sup></a>
</p>
</dd>
<dt id='index-_002eT-2'><span><code class="code">\n[.T]</code><a class="copiable-link" href='#index-_002eT-2'> &para;</a></span></dt>
<dd><p>Indicator of output device selection (Boolean-valued); see
<code class="command">groff</code> <samp class="option">-T</samp> option (<a class="ref" href="#Groff-Options">Options</a>).
</p>
</dd>
<dt id='index-safer-mode-2'><span><code class="code">\n[.U]</code><a class="copiable-link" href='#index-safer-mode-2'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-mode_002c-safer-2"></a>
<a class="index-entry-id" id="index-unsafe-mode-2"></a>
<a class="index-entry-id" id="index-mode_002c-unsafe-2"></a>
<a class="index-entry-id" id="index-_002eU"></a>
<p>Unsafe mode enablement status (Boolean-valued); see <code class="command">groff</code>
<samp class="option">-U</samp> option (<a class="ref" href="#Groff-Options">Options</a>).
</p>
</dd>
<dt id='index-_002ex'><span><code class="code">\n[.x]</code><a class="copiable-link" href='#index-_002ex'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-major-version-number-register-_0028_002ex_0029"></a>
<a class="index-entry-id" id="index-version-number_002c-major_002c-register-_0028_002ex_0029"></a>
<p>Major version number of the running GNU <code class="code">troff</code> formatter.  For
example, if the version number is 1.23.0, then <code class="code">.x</code>
contains&nbsp;&lsquo;<samp class="samp">1</samp>&rsquo;.
</p>
</dd>
<dt id='index-_002ey'><span><code class="code">\n[.y]</code><a class="copiable-link" href='#index-_002ey'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-minor-version-number-register-_0028_002ey_0029"></a>
<a class="index-entry-id" id="index-version-number_002c-minor_002c-register-_0028_002ey_0029"></a>
<p>Minor version number of the running GNU <code class="code">troff</code> formatter.  For
example, if the version number is 1.23.0, then <code class="code">.y</code>
contains&nbsp;&lsquo;<samp class="samp">23</samp>&rsquo;.
</p>
</dd>
<dt id='index-_002eY'><span><code class="code">\n[.Y]</code><a class="copiable-link" href='#index-_002eY'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-revision-number-register-_0028_002eY_0029"></a>
<p>Revision number of the running GNU <code class="code">troff</code> formatter.  For example,
if the version number is 1.23.0, then <code class="code">.Y</code> contains&nbsp;&lsquo;<samp class="samp">0</samp>&rsquo;.
</p>
</dd>
<dt id='index-_0024_0024'><span><code class="code">\n[$$]</code><a class="copiable-link" href='#index-_0024_0024'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-process-ID-of-GNU-troff-register-_0028_0024_0024_0029"></a>
<a class="index-entry-id" id="index-PID-of-GNU-troff-register-_0028_0024_0024_0029"></a>
<a class="index-entry-id" id="index-GNU-troff_002c-process-ID-register-_0028_0024_0024_0029"></a>
<a class="index-entry-id" id="index-GNU-troff_002c-PID-register-_0028_0024_0024_0029"></a>
<p>Process identifier (PID) of the GNU <code class="code">troff</code> program in its
operating environment.
</p></dd>
</dl>

<p>Date- and time-related registers are set per the local time as
determined by <cite class="cite">localtime<span class="r">(3)</span></cite> when the formatter launches.  This
initialization can be overridden by <code class="env">SOURCE_DATE_EPOCH</code> and
<code class="env">TZ</code>; see <a class="ref" href="#Environment">Environment</a>.
</p>
<dl class="table">
<dt id='index-seconds_002c-current-time-_0028seconds_0029'><span><code class="code">\n[seconds]</code><a class="copiable-link" href='#index-seconds_002c-current-time-_0028seconds_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-time_002c-current_002c-seconds-_0028seconds_0029"></a>
<a class="index-entry-id" id="index-current-time_002c-seconds-_0028seconds_0029"></a>
<a class="index-entry-id" id="index-seconds"></a>
<p>Count of seconds elapsed in the minute (0&ndash;60). </p>
</dd>
<dt id='index-minutes_002c-current-time-_0028minutes_0029'><span><code class="code">\n[minutes]</code><a class="copiable-link" href='#index-minutes_002c-current-time-_0028minutes_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-time_002c-current_002c-minutes-_0028minutes_0029"></a>
<a class="index-entry-id" id="index-current-time_002c-minutes-_0028minutes_0029"></a>
<a class="index-entry-id" id="index-minutes"></a>
<p>Count of minutes elapsed in the hour (0&ndash;59).
</p>
</dd>
<dt id='index-hours_002c-current-time-_0028hours_0029'><span><code class="code">\n[hours]</code><a class="copiable-link" href='#index-hours_002c-current-time-_0028hours_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-time_002c-current_002c-hours-_0028hours_0029"></a>
<a class="index-entry-id" id="index-current-time_002c-hours-_0028hours_0029"></a>
<a class="index-entry-id" id="index-hours"></a>
<p>Count of hours elapsed since midnight (0&ndash;23).
</p>
</dd>
<dt id='index-day-of-the-week-register-_0028dw_0029'><span><code class="code">\n[dw]</code><a class="copiable-link" href='#index-day-of-the-week-register-_0028dw_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-date_002c-day-of-the-week-register-_0028dw_0029"></a>
<a class="index-entry-id" id="index-dw"></a>
<p>Day of the week (1&ndash;7; 1 is Sunday).
</p>
</dd>
<dt id='index-day-of-the-month-register-_0028dy_0029'><span><code class="code">\n[dy]</code><a class="copiable-link" href='#index-day-of-the-month-register-_0028dy_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-date_002c-day-of-the-month-register-_0028dy_0029"></a>
<a class="index-entry-id" id="index-dy"></a>
<p>Day of the month (1&ndash;31).
</p>
</dd>
<dt id='index-month-of-the-year-register-_0028mo_0029'><span><code class="code">\n[mo]</code><a class="copiable-link" href='#index-month-of-the-year-register-_0028mo_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-date_002c-month-of-the-year-register-_0028mo_0029"></a>
<a class="index-entry-id" id="index-mo"></a>
<p>Month of the year (1&ndash;12).
</p>
</dd>
<dt id='index-date_002c-year-register-_0028year_002c-yr_0029'><span><code class="code">\n[year]</code><a class="copiable-link" href='#index-date_002c-year-register-_0028year_002c-yr_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-year_002c-current_002c-register-_0028year_002c-yr_0029"></a>
<a class="index-entry-id" id="index-year"></a>
<p>Gregorian year.
</p>
<a class="index-entry-id" id="index-CSTR-_002354-errata"></a>
<a class="index-entry-id" id="index-CSTR-_002354-erratum_002c-yr-register"></a>
</dd>
<dt id='index-yr'><span><code class="code">\n[yr]</code><a class="copiable-link" href='#index-yr'> &para;</a></span></dt>
<dd><p>Gregorian year minus&nbsp;1900.  This register is incorrectly documented
in the <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> manual as storing the last two digits
of the current year.  That claim stopped being true in 2000.  Old
<code class="code">troff</code> input that looks like:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">'\&quot; The year number is a surprise after 1999.
This document was formatted in 19\n(yr.
</pre></div></div>

<p>can be corrected to:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">This document was formatted in \n[year].
</pre></div></div>

<p>or, for portability across many <code class="code">roff</code> programs, to the following.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr y4 1900+\n(yr
This document was formatted in \n(y4.
</pre></div></div>
</dd>
</dl>



<hr>
</div>
</div>
<div class="section-level-extent" id="Manipulating-Filling-and-Adjustment">
<div class="nav-panel">
<p>
Next: <a href="#Manipulating-Hyphenation" accesskey="n" rel="next">Manipulating Hyphenation</a>, Previous: <a href="#Registers" accesskey="p" rel="prev">Registers</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Manipulating-Filling-and-Adjustment-1">5.9 Manipulating Filling and Adjustment</h3>
<a class="index-entry-id" id="index-manipulating-filling-and-adjustment"></a>
<a class="index-entry-id" id="index-filling-and-adjustment_002c-manipulating"></a>
<a class="index-entry-id" id="index-adjustment-and-filling_002c-manipulating"></a>
<a class="index-entry-id" id="index-justifying-text"></a>
<a class="index-entry-id" id="index-text_002c-justifying"></a>

<a class="index-entry-id" id="index-break-1"></a>
<a class="index-entry-id" id="index-line-break"></a>
<a class="index-entry-id" id="index-bp-request_002c-causing-implicit-break"></a>
<a class="index-entry-id" id="index-ce-request_002c-causing-implicit-break"></a>
<a class="index-entry-id" id="index-cf-request_002c-causing-implicit-break"></a>
<a class="index-entry-id" id="index-fi-request_002c-causing-implicit-break"></a>
<a class="index-entry-id" id="index-fl-request_002c-causing-implicit-break"></a>
<a class="index-entry-id" id="index-in-request_002c-causing-implicit-break"></a>
<a class="index-entry-id" id="index-nf-request_002c-causing-implicit-break"></a>
<a class="index-entry-id" id="index-rj-request_002c-causing-implicit-break"></a>
<a class="index-entry-id" id="index-sp-request_002c-causing-implicit-break"></a>
<a class="index-entry-id" id="index-ti-request_002c-causing-implicit-break"></a>
<a class="index-entry-id" id="index-trf-request_002c-causing-implicit-break"></a>
<p>When an output line is pending (see below), a break moves the drawing
position to the beginning of the next text baseline, interrupting
filling.  Various ways of causing breaks were shown in <a class="ref" href="#Breaking">Breaking</a>.
The <code class="code">br</code> request likewise causes a break.  Several other requests
imply breaks: <code class="code">bp</code>, <code class="code">ce</code>, <code class="code">cf</code>, <code class="code">fi</code>, <code class="code">fl</code>,
<code class="code">in</code>, <code class="code">nf</code>, <code class="code">rj</code>, <code class="code">sp</code>, <code class="code">ti</code>, and <code class="code">trf</code>.
If the no-break control character is used with any of these requests,
GNU <code class="code">troff</code> suppresses the break; instead the requested operation
takes effect at the next break.  &lsquo;<samp class="samp">'br</samp>&rsquo; does nothing.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ll 55n
This line is normally filled and adjusted.
.br
A line's alignment is decided
'ce \&quot; Center the next input line (no break).
when it is output.
This line returns to normal filling and adjustment.
    &rArr; This line is normally filled and adjusted.
    &rArr;    A line's alignment is decided when it is output.
    &rArr; This line returns to normal filling and adjustment.
</pre></div></div>

<a class="index-entry-id" id="index-pending-output-line"></a>
<a class="index-entry-id" id="index-partially-collected-line"></a>
<a class="index-entry-id" id="index-output-line-properties"></a>
<a class="index-entry-id" id="index-properties-of-output-lines"></a>
<p>Output line properties like page offset, indentation, adjustment, and
even the location of its text baseline, are not determined until the
line has been broken.  An output line is said to be <em class="dfn">pending</em> if
some input has been collected but an output line corresponding to it has
not yet been written; such an output line is also termed <em class="dfn">partially
collected</em>.  If no output line is pending, it is as if a break has
already happened; additional breaks, whether explicit or implicit, have
no effect.  If the vertical drawing position is negative&mdash;as it is when
the formatter starts up&mdash;a break starts a new page (even if no output
line is pending) unless an end-of-input macro is being interpreted.
See <a class="xref" href="#End_002dof_002dinput-Traps">End-of-input Traps</a>.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002ebr"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.br</code></strong><a class="copiable-link" href='#index-_002ebr'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-br"></a>
<p>Break the line: emit any pending output line without adjustment.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">foo bar
.br
baz
'br
qux
    &rArr; foo bar
    &rArr; baz qux
</pre></div></div>
</dd></dl>

<p>Sometimes you want to prevent a break within a phrase or between a
quantity and its units.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_007e-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\~</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_007e-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_007e"></a>
<a class="index-entry-id" id="index-unbreakable-space-_0028_005c_007e_0029"></a>
<a class="index-entry-id" id="index-space_002c-unbreakable-_0028_005c_007e_0029"></a>
<p>Insert an unbreakable space that is adjustable like an ordinary space.
It is discarded from the end of an output line if a break is forced.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">Set the output speed to\~1.
There are 1,024\~bytes in 1\~KiB.
J.\~F.\~Ossanna wrote the original CSTR\~#54.
</pre></div></div>
</dd></dl>

<p>By default, GNU <code class="code">troff</code> fills text and adjusts it to reach the
output line length.  The <code class="code">nf</code> request disables filling; the
<code class="code">fi</code> request renables it.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002efi"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.fi</code></strong><a class="copiable-link" href='#index-_002efi'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-fi"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002eu_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.u]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002eu_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002eu"></a>
<a class="index-entry-id" id="index-filling-of-output_002c-enabling-_0028fi_0029"></a>
<a class="index-entry-id" id="index-output_002c-filling_002c-enablement-of-_0028fi_0029"></a>
<a class="index-entry-id" id="index-fill-mode-_0028fi_0029_002c-enabling"></a>
<a class="index-entry-id" id="index-mode_002c-fill-_0028fi_0029_002c-enabling"></a>
<p>Enable filling of output lines; a pending output line is broken.  The
read-only register <code class="code">.u</code> is set to&nbsp;1.  The filling enablement
status, sometimes called <em class="dfn">fill mode</em>, is associated with the
environment (see <a class="pxref" href="#Environments">Environments</a>).  See <a class="xref" href="#Line-Continuation">Line Continuation</a>, for
interaction with the <code class="code">\c</code> escape sequence.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002enf"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.nf</code></strong><a class="copiable-link" href='#index-_002enf'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-nf"></a>
<a class="index-entry-id" id="index-filling-of-output_002c-disabling-_0028nf_0029"></a>
<a class="index-entry-id" id="index-output_002c-filling_002c-disablement-of-_0028nf_0029"></a>
<a class="index-entry-id" id="index-no_002dfill-mode"></a>
<a class="index-entry-id" id="index-mode_002c-no_002dfill"></a>
<a class="index-entry-id" id="index-fill-mode_002c-disabling"></a>
<a class="index-entry-id" id="index-mode_002c-fill_002c-disabling"></a>
<p>Disable filling of output lines: the output line length (see <a class="pxref" href="#Line-Layout">Line Layout</a>) is ignored and output lines are broken where the input lines
are.  A pending output line is broken and adjustment is suppressed.  The
read-only register <code class="code">.u</code> is set to&nbsp;0.  The filling enablement
status is associated with the environment (see <a class="pxref" href="#Environments">Environments</a>).  See
<a class="ref" href="#Line-Continuation">Line Continuation</a>, for interaction with the <code class="code">\c</code> escape
sequence.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ead"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ad</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">mode</i></span>]</var><a class="copiable-link" href='#index-_002ead'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ad"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ej_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.j]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ej_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ej"></a>
<p>Enable output line adjustment in <var class="var">mode</var>, taking effect when the
pending (or next) output line is broken.  Adjustment is suppressed when
filling is.  <var class="var">mode</var> can have one of the following values.
</p>
<dl class="table">
<dt><code class="code">b</code></dt>
<dt><code class="code">n</code></dt>
<dd><p>Adjust &ldquo;normally&rdquo;: if the output line does not consume the distance
between the indentation and the configured output line length, GNU
<code class="code">troff</code> stretches adjustable spaces within the line until that
length is reached.  When the indentation is zero, this mode spreads the
line to both the left and right margins.  This is the GNU <code class="code">troff</code>
default.
</p>
</dd>
<dt id='index-centered-text-_0028filled_0029'><span><code class="code">c</code><a class="copiable-link" href='#index-centered-text-_0028filled_0029'> &para;</a></span></dt>
<dd><p>Center filled text.  Contrast with the <code class="code">ce</code> request, which centers
text <em class="emph">without</em> filling it.
</p>
</dd>
<dt id='index-ragged_002dright-text'><span><code class="code">l</code><a class="copiable-link" href='#index-ragged_002dright-text'> &para;</a></span></dt>
<dd><p>Align text to the left without adjusting it.
</p>
</dd>
<dt id='index-ragged_002dleft-text'><span><code class="code">r</code><a class="copiable-link" href='#index-ragged_002dleft-text'> &para;</a></span></dt>
<dd><p>Align text to the right without adjusting it.
</p></dd>
</dl>

<p><var class="var">mode</var> can also be a value previously stored in the <code class="code">.j</code>
register.  Using <code class="code">ad</code> without an argument is the same as &lsquo;<samp class="samp">.ad
\n[.j]</samp>&rsquo;; unless filling is disabled, GNU <code class="code">troff</code> resumes adjusting
lines in the same way it did before adjustment was disabled by
invocation of the <code class="code">na</code> request.
</p>
<a class="index-entry-id" id="index-adjustment-mode-register-_0028_002ej_0029"></a>
<p>The adjustment mode and enablement status are encoded in the read-only
register <code class="code">.j</code>.  These parameters are associated with the
environment (see <a class="pxref" href="#Environments">Environments</a>).
</p>
<p>The value of <code class="code">.j</code> for any adjustment mode is an implementation
detail and should not be relied upon as a programmer&rsquo;s interface.  Do
not write logic to interpret or perform arithmetic on it.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ll 48n
.de AD
.  br
.  ad \\$1
..
.de NA
.  br
.  na
..
left
.AD r
.nr ad \n(.j
right
.AD c
center
.NA
left
.AD
center
.AD \n(ad
right
</pre></div></div>
<div class="example">
<div class="group"><pre class="example-preformatted">    &rArr; left
    &rArr;                                            right
    &rArr;                      center
    &rArr; left
    &rArr;                      center
    &rArr;                                            right
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ena"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.na</code></strong><a class="copiable-link" href='#index-_002ena'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-na"></a>
<p>Disable output line adjustment.  This produces the same output as
left-alignment, but the value of the adjustment mode register <code class="code">.j</code>
is altered differently.  The adjustment mode and enablement status are
associated with the environment (see <a class="pxref" href="#Environments">Environments</a>).
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ebrp"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.brp</code></strong><a class="copiable-link" href='#index-_002ebrp'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-brp"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cp-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\p</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cp-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cp"></a>
<p>Break, adjusting the line per the current adjustment mode.  <code class="code">\p</code>
schedules a break with adjustment at the next word boundary.  The escape
sequence is itself neither a break nor a space of any kind; it can thus
be placed in the middle of a word to cause a break at the end of that
word.
</p>
<p>Breaking with immediate adjustment can produce ugly results since GNU
<code class="code">troff</code> doesn&rsquo;t have a sophisticated paragraph-building algorithm,
as TeX has, for example.  Instead, GNU <code class="code">troff</code> fills and adjusts
a paragraph line by line.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ll 4.5i
This is an uninteresting sentence.
This is an uninteresting sentence.\p
This is an uninteresting sentence.
</pre></div></div>

<p>is formatted as follows.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">This  is  an uninteresting sentence.  This is
an          uninteresting           sentence.
This is an uninteresting sentence.
</pre></div></div>
</dd></dl>

<a class="index-entry-id" id="index-productive-input-line"></a>
<a class="index-entry-id" id="index-input-line_002c-productive"></a>
<a class="index-entry-id" id="index-line_002c-productive-input"></a>
<p>To clearly present the next couple of requests, we must introduce the
concept of &ldquo;productive&rdquo; input lines.  A <em class="dfn">productive input line</em> is
one that directly produces formatted output.  Text lines produce
output,<a class="footnote" id="DOCF53" href="#FOOT53"><sup>53</sup></a> as do control
lines containing requests like <code class="code">tl</code> or escape sequences like
<code class="code">\D</code>.  Macro calls are not <em class="emph">directly</em> productive, and thus not
counted, but their interpolated contents can be.  Empty requests, and
requests and escape sequences that define registers or strings or alter
the formatting environment (as with changes to the size, face, height,
slant, or color of the type) are not productive.  We will also preview
the output line continuation escape sequence, <code class="code">\c</code>, which
&ldquo;connects&rdquo; two input lines that would otherwise be counted separately.
<a class="footnote" id="DOCF54" href="#FOOT54"><sup>54</sup></a>
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de hello
Hello, world!
..
.ce \&quot; center output of next productive input line
.
.nr junk-reg 1
.ft I
Chorus: \c
.ft
.hello
Went the day well?
  &rArr;                  <i class="slanted">Chorus:</i> Hello, world!
  &rArr; Went the day well?
</pre></div></div>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ece"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ce</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">n</i></span>]</var><a class="copiable-link" href='#index-_002ece'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ce"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ece_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.ce]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ece_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ece-1"></a>
<a class="index-entry-id" id="index-centered-text-_0028unfilled_0029"></a>
<a class="index-entry-id" id="index-centering-lines-_0028ce_0029"></a>
<a class="index-entry-id" id="index-lines_002c-centering-_0028ce_0029"></a>
<p>Break (unless the no-break control character is used), center the output
of the next <var class="var">n</var> productive input lines with respect to the line
length and indentation without filling, then break again regardless of
the invoking control character.
If the argument is not positive, centering is disabled.  Omitting the
argument implies an <var class="var">n</var> of &lsquo;<samp class="samp">1</samp>&rsquo;.  The count of lines remaining
to be centered is stored in the read-only register <code class="code">.ce</code> and is
associated with the environment (see <a class="pxref" href="#Environments">Environments</a>).
</p>
<a class="index-entry-id" id="index-ce-request_002c-difference-from-_002ead-c"></a>
<p>While the &lsquo;<samp class="samp">.ad&nbsp;c</samp>&rsquo;<!-- /@w --> request also centers text, it fills the text
as well.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de FR
This is a small text fragment that shows the differences
between the `.ce' and the `.ad c' requests.
..
.ll 4i
.ce 1000
.FR
.ce 0

.ad c
.FR
    &rArr; This is a small text fragment that shows
    &rArr;              the differences
    &rArr; between the &lsquo;.ce&rsquo; and the &lsquo;.ad c&rsquo; requests.
    &rArr;
    &rArr; This is a small text fragment that shows
    &rArr;  the differences between the &lsquo;.ce&rsquo; and
    &rArr;         the &lsquo;.ad c&rsquo; requests.
</pre></div></div>

<p>The previous example illustrates a common idiom of turning centering on
for a quantity of lines far in excess of what is required, and off again
after the text to be centered.  This technique relieves humans of
counting lines for requests that take a count of input lines as an
argument.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002erj"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.rj</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">n</i></span>]</var><a class="copiable-link" href='#index-_002erj'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-rj"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002erj_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.rj]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002erj_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002erj-1"></a>
<a class="index-entry-id" id="index-justifying-text-_0028rj_0029"></a>
<a class="index-entry-id" id="index-text_002c-justifying-_0028rj_0029"></a>
<a class="index-entry-id" id="index-right_002djustifying-_0028rj_0029"></a>
<p>Break (unless the no-break control character is used), align the output
of the next <var class="var">n</var> productive input lines to the right margin without
filling, then break again regardless of the control character.
If the argument is not positive, right-alignment is disabled.  Omitting
the argument implies an <var class="var">n</var> of &lsquo;<samp class="samp">1</samp>&rsquo;.  The count of lines
remaining to be right-aligned is stored in the read-only register
<code class="code">.rj</code> and is associated with the environment
(see <a class="pxref" href="#Environments">Environments</a>).
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ll 49n
.rj 3
At first I hoped that such a technically unsound
project would collapse but I soon realized it was
doomed to success. \[em] C. A. R. Hoare
    &rArr;  At first I hoped that such a technically unsound
    &rArr; project would collapse but I soon realized it was
    &rArr;              doomed to success. -- C. A. R. Hoare
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ess"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ss</code></strong> <var class="def-var-arguments">word-space-size [<span class="r"><i class="slanted">additional-sentence-space-size</i></span>]</var><a class="copiable-link" href='#index-_002ess'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ss"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ess_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.ss]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ess_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ess-1"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002esss_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.sss]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002esss_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002esss"></a>
<a class="index-entry-id" id="index-word-space-size-register-_0028_002ess_0029"></a>
<a class="index-entry-id" id="index-size-of-word-space-register-_0028_002ess_0029"></a>
<a class="index-entry-id" id="index-space-between-words-register-_0028_002ess_0029"></a>
<a class="index-entry-id" id="index-inter_002dsentence-space-size-register-_0028_002esss_0029"></a>
<a class="index-entry-id" id="index-sentence-space-size-register-_0028_002esss_0029"></a>
<a class="index-entry-id" id="index-size-of-sentence-space-register-_0028_002esss_0029"></a>
<a class="index-entry-id" id="index-space-between-sentences-register-_0028_002esss_0029"></a>
<p>Set the sizes of spaces between words and
sentences<a class="footnote" id="DOCF55" href="#FOOT55"><sup>55</sup></a> in twelfths
of font&rsquo;s space width (typically one-fourth to one-third em for Western
scripts).  The default for both parameters is&nbsp;12.  Negative values
are erroneous.
<a class="index-entry-id" id="index-inter_002dword-spacing_002c-minimal"></a>
<a class="index-entry-id" id="index-minimal-inter_002dword-spacing"></a>
<a class="index-entry-id" id="index-space_002c-between-words"></a>
The first argument is a minimum; if an output line undergoes adjustment,
such spaces may increase in width.
<a class="index-entry-id" id="index-inter_002dsentence-space_002c-additional"></a>
<a class="index-entry-id" id="index-additional-inter_002dsentence-space"></a>
<a class="index-entry-id" id="index-space_002c-between-sentences"></a>
The optional second argument sets the amount of additional space
separating sentences on the same output line.  If omitted, this amount
is set to <var class="var">word-space-size</var>.  The request is ignored if there are no
parameters.
</p>
<a class="index-entry-id" id="index-filling_002c-and-inter_002dsentence-space"></a>
<a class="index-entry-id" id="index-mode_002c-fill_002c-and-inter_002dsentence-space"></a>
<p>Additional inter-sentence space is used only if the output line is not
full when the end of a sentence occurs in the input.  If a sentence ends
at the end of an input line, then both an inter-word space and an
inter-sentence space are added to the output; if two spaces follow the
end of a sentence in the middle of an input line, then the second space
becomes an inter-sentence space in the output.  Additional
inter-sentence space is not adjusted, but the inter-word space that
always precedes it may be.  Further input spaces after the second, if
present, are adjusted as normal.
</p>
<p>The read-only registers <code class="code">.ss</code> and <code class="code">.sss</code> hold the minimal
inter-word space and additional inter-sentence space amounts,
respectively.  These parameters are part of the environment
(see <a class="pxref" href="#Environments">Environments</a>), and rounded down to the nearest multiple
of&nbsp;12 on terminals.
</p>
<a class="index-entry-id" id="index-discardable-horizontal-space"></a>
<a class="index-entry-id" id="index-space_002c-discardable_002c-horizontal"></a>
<a class="index-entry-id" id="index-horizontal-discardable-space"></a>
<p>The <code class="code">ss</code> request can insert discardable horizontal space; that is,
space that is discarded at a break.  For example, some footnote styles
collect the notes into a single paragraph with large gaps between
each note.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ll 48n
1.\~J. Fict. Ch. Soc. 6 (2020), 3\[en]14.
.ss 12 48 \&quot; applies to next sentence ending
Reprints no longer available through FCS.
.ss 12 \&quot; go back to normal
2.\~Better known for other work.
    &rArr; 1.  J.  Fict. Ch. Soc. 6 (2020), 3-14.  Reprints
    &rArr; no longer available through FCS.      2.  Better
    &rArr; known for other work.
</pre></div></div>

<p>If <em class="emph">undiscardable</em> space is required, use the <code class="code">\h</code> escape
sequence.
</p></dd></dl>



<hr>
</div>
<div class="section-level-extent" id="Manipulating-Hyphenation">
<div class="nav-panel">
<p>
Next: <a href="#Manipulating-Spacing" accesskey="n" rel="next">Manipulating Spacing</a>, Previous: <a href="#Manipulating-Filling-and-Adjustment" accesskey="p" rel="prev">Manipulating Filling and Adjustment</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Manipulating-Hyphenation-1">5.10 Manipulating Hyphenation</h3>
<a class="index-entry-id" id="index-manipulating-hyphenation"></a>
<a class="index-entry-id" id="index-hyphenation_002c-manipulating"></a>

<a class="index-entry-id" id="index-hyphenation_002c-automatic"></a>
<a class="index-entry-id" id="index-automatic-hyphenation"></a>
<p>When filling, GNU <code class="code">troff</code> hyphenates words as needed at
user-specified and automatically determined hyphenation points.  The
machine-driven determination of hyphenation points in words requires
algorithms and data, and is susceptible to conventions and preferences.
Before tackling such <em class="dfn">automatic hyphenation</em>, let us consider how
hyphenation points can be set explicitly.
</p>
<a class="index-entry-id" id="index-hyphenation_002c-explicit"></a>
<a class="index-entry-id" id="index-explicit-hyphenation"></a>
<a class="index-entry-id" id="index-hyphenation_002c-manual"></a>
<a class="index-entry-id" id="index-manual-hyphenation"></a>
<p>Explicitly hyphenated words such as &ldquo;mother-in-law&rdquo; are eligible for
breaking after each of their hyphens.  Relatively few words in a
language offer such obvious break points, however, and automatic
detection of syllabic (or phonetic) boundaries for hyphenation is not
perfect,<a class="footnote" id="DOCF56" href="#FOOT56"><sup>56</sup></a> particularly for
unusual words found in technical literature.  We can instruct GNU
<code class="code">troff</code> how to hyphenate specific words if the need arises.
</p>
<a class="index-entry-id" id="index-hyphenation-exceptions"></a>
<dl class="first-deffn">
<dt class="deffn" id="index-_002ehw"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.hw</code></strong> <var class="def-var-arguments">word &hellip;</var><a class="copiable-link" href='#index-_002ehw'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-hw"></a>
<p>Define each <em class="dfn">hyphenation exception</em> <var class="var">word</var> with each hyphen &lsquo;-&rsquo;
in the word indicating a hyphenation point.  For example, the request
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.hw in-sa-lub-rious alpha
</pre></div></div>

<p>marks potential hyphenation points in &ldquo;insalubrious&rdquo;, and prevents
&ldquo;alpha&rdquo; from being hyphenated at all.
</p>
<p>Besides the space character, any character whose hyphenation code is
zero can be used to separate the arguments of <code class="code">hw</code> (see the
<code class="code">hcode</code> request below).  In addition, this request can be used more
than once.
</p>
<a class="index-entry-id" id="index-hw-request_002c-and-hy-restrictions"></a>
<p>Hyphenation points specified with <code class="code">hw</code> are not subject to the
within-word placement restrictions imposed by the <code class="code">hy</code> request (see
below).
</p>
<p>Hyphenation exceptions specified with the <code class="code">hw</code> request are
associated with the hyphenation language (see the <code class="code">hla</code> request
below) and environment (see <a class="pxref" href="#Environments">Environments</a>); invoking the <code class="code">hw</code>
request in the absence of a hyphenation language is an error.
</p>
<p>The request is ignored if there are no parameters.
</p></dd></dl>

<p>These are known as hyphenation <i class="slanted">exceptions</i> in the expectation
that most users will avail themselves of automatic hyphenation; these
exceptions override any rules that would normally apply to a word
matching a hyphenation exception defined with <code class="code">hw</code>.
</p>
<p>Situations also arise when only a specific occurrence of a word needs
its hyphenation altered or suppressed, or when a URL or similar string
needs to be breakable in sensible places without hyphenation.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_0025-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\%</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_0025-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_0025"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_003a-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\:</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_003a-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_003a"></a>
<a class="index-entry-id" id="index-hyphenation-character-_0028_005c_0025_0029"></a>
<a class="index-entry-id" id="index-character_002c-hyphenation-_0028_005c_0025_0029"></a>
<a class="index-entry-id" id="index-disabling-hyphenation-_0028_005c_0025_0029"></a>
<a class="index-entry-id" id="index-hyphenation_002c-disabling-_0028_005c_0025_0029"></a>
<p>To tell GNU <code class="code">troff</code> how to hyphenate words as they occur in input,
use the <code class="code">\%</code> escape sequence; it is the default <em class="dfn">hyphenation
character</em>.  Each instance within a word indicates to GNU <code class="code">troff</code>
that the word may be hyphenated at that point, while prefixing a word
with this escape sequence prevents it from being otherwise hyphenated.
This mechanism affects only that occurrence of the word; to change the
hyphenation of a word for the remainder of input processing, use the
<code class="code">hw</code> request.
</p>
<a class="index-entry-id" id="index-_005cX_002c-followed-by-_005c_0025"></a>
<a class="index-entry-id" id="index-_005cY_002c-followed-by-_005c_0025"></a>
<a class="index-entry-id" id="index-_005c_0025_002c-following-_005cX-or-_005cY"></a>
<p>GNU <code class="code">troff</code> regards the escape sequences <code class="code">\X</code> and <code class="code">\Y</code> as
starting a word; that is, the <code class="code">\%</code> escape sequence in, say,
&lsquo;<samp class="samp">\X'...'\%foobar</samp>&rsquo;<!-- /@w --> or &lsquo;<samp class="samp">\Y'...'\%foobar</samp>&rsquo;<!-- /@w --> no longer
prevents hyphenation of &lsquo;<samp class="samp">foobar</samp>&rsquo; but inserts a hyphenation point
just prior to it; most likely this isn&rsquo;t what you want.
See <a class="xref" href="#Postprocessor-Access">Postprocessor Access</a>.
</p>
<a class="index-entry-id" id="index-non_002dprinting-break-point-_0028_005c_003a_0029"></a>
<a class="index-entry-id" id="index-breaking-without-hyphens-_0028_005c_003a_0029"></a>
<a class="index-entry-id" id="index-file-names_002c-breaking-_0028_005c_003a_0029"></a>
<a class="index-entry-id" id="index-breaking-file-names-_0028_005c_003a_0029"></a>
<a class="index-entry-id" id="index-URLs_002c-breaking-_0028_005c_003a_0029"></a>
<a class="index-entry-id" id="index-breaking-URLs-_0028_005c_003a_0029"></a>
<p><code class="code">\:</code> inserts a non-printing break point; that is, a word can break
there, but the soft hyphen glyph (see below) is not written to the
output if it does.  This escape sequence is an input word boundary, so
the remainder of the word is subject to hyphenation as normal.
</p>
<p>You can combine <code class="code">\:</code> and <code class="code">\%</code> to control breaking of a file
name or URL, or to permit hyphenation only after certain explicit
hyphens within a word.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">The \%Lethbridge-Stewart-\:\%Sackville-Baggins divorce
was, in retrospect, inevitable once the contents of
\%/var/log/\:\%httpd/\:\%access_log on the family web
server came to light, revealing visitors from Hogwarts.
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ehc"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.hc</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">char</i></span>]</var><a class="copiable-link" href='#index-_002ehc'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-hc"></a>
<p>Change the hyphenation character to <var class="var">char</var>.  This character then
works as the <code class="code">\%</code> escape sequence normally does, and thus no longer
appears in the output.<a class="footnote" id="DOCF57" href="#FOOT57"><sup>57</sup></a>  Without an
argument, <code class="code">hc</code> resets the hyphenation character to <code class="code">\%</code> (the
default).  The hyphenation character is associated with the environment
(see <a class="pxref" href="#Environments">Environments</a>).
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eshc"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.shc</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">c</i></span>]</var><a class="copiable-link" href='#index-_002eshc'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-shc"></a>
<a class="index-entry-id" id="index-soft-hyphen-character_002c-setting-_0028shc_0029"></a>
<a class="index-entry-id" id="index-character_002c-soft-hyphen_002c-setting-_0028shc_0029"></a>
<a class="index-entry-id" id="index-glyph_002c-soft-hyphen-_0028hy_0029"></a>
<a class="index-entry-id" id="index-soft-hyphen-glyph-_0028hy_0029"></a>
<a class="index-entry-id" id="index-char-request_002c-and-soft-hyphen-character"></a>
<a class="index-entry-id" id="index-tr-request_002c-and-soft-hyphen-character"></a>
<p>Set the <em class="dfn">soft hyphen character</em>, inserted when a word is hyphenated
automatically or at a hyphenation character, to the ordinary or special
character&nbsp;<var class="var">c</var>.<a class="footnote" id="DOCF58" href="#FOOT58"><sup>58</sup></a>  If the argument is omitted, the soft
hyphen character is set to the default, <code class="code">\[hy]</code>.  If no glyph for
<var class="var">c</var> exists in the font in use at a potential hyphenation point, then
the line is not broken there.  Neither character definitions (specified
with the <code class="code">char</code> and similar requests) nor translations (specified
with the <code class="code">tr</code> request) are applied to <var class="var">c</var>.
</p></dd></dl>

<a class="index-entry-id" id="index-hyphenation-parameters_002c-automatic"></a>
<a class="index-entry-id" id="index-automatic-hyphenation-parameters"></a>
<p>Several requests influence automatic hyphenation.  Because conventions
vary, a variety of hyphenation modes is available to the <code class="code">hy</code>
request; these determine whether hyphenation will apply to a
word prior to breaking a line at the end of a page (more or less; see
below for details), and at which positions within that word
automatically determined hyphenation points are permissible.  The places
within a word that are eligible for hyphenation are determined by
language-specific data and lettercase relationships.  Furthermore,
hyphenation of a word might be suppressed due to a limit on
consecutive hyphenated lines (<code class="code">hlm</code>), a minimum line length
threshold (<code class="code">hym</code>), or because the line can instead be adjusted with
additional inter-word space (<code class="code">hys</code>).
</p>
<a class="index-entry-id" id="index-hyphenation-mode-register-_0028_002ehy_0029"></a>
<dl class="first-deffn">
<dt class="deffn" id="index-_002ehy"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.hy</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">mode</i></span>]</var><a class="copiable-link" href='#index-_002ehy'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-hy"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ehy_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.hy]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ehy_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ehy-1"></a>
<p>Set automatic hyphenation mode to <var class="var">mode</var>, an integer encoding
conditions for hyphenation; if omitted, &lsquo;<samp class="samp">1</samp>&rsquo; is implied.  The
hyphenation mode is available in the read-only register &lsquo;<samp class="samp">.hy</samp>&rsquo;; it
is associated with the environment (see <a class="pxref" href="#Environments">Environments</a>).  The default
hyphenation mode depends on the localization file loaded when GNU
<code class="code">troff</code> starts up; see the <code class="code">hpf</code> request below.
</p>
<p>Typesetting practice generally does not avail itself of every
opportunity for hyphenation, but the details differ by language and site
mandates.  The hyphenation modes of <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> were
implemented with English-language publishing practices of the 1970s in
mind, not a scrupulous enumeration of conceivable parameters.  GNU
<code class="code">troff</code> extends those modes such that finer-grained control is
possible, favoring compatibility with older implementations over a more
intuitive arrangement.  The means of hyphenation mode control is a set
of numbers that can be added up to encode the behavior
sought.<a class="footnote" id="DOCF59" href="#FOOT59"><sup>59</sup></a>  The entries in the
following table are termed <em class="dfn">values</em>; the sum of the desired
values is the <em class="dfn">mode</em>.
</p>
<dl class="table">
<dt><code class="code">0</code></dt>
<dd><p>disables hyphenation.
</p>
</dd>
<dt><code class="code">1</code></dt>
<dd><p>enables hyphenation except after the first and before the last character
of a word.
</p></dd>
</dl>

<p>The remaining values &ldquo;imply&rdquo; 1; that is, they enable hyphenation
under the same conditions as &lsquo;<samp class="samp">.hy 1</samp>&rsquo;, and then apply or lift
restrictions relative to that basis.
</p>
<dl class="table">
<dt><code class="code">2</code></dt>
<dd><p>disables hyphenation of the last word on a page,<a class="footnote" id="DOCF60" href="#FOOT60"><sup>60</sup></a> even for explicitly hyphenated words.
</p>
</dd>
<dt><code class="code">4</code></dt>
<dd><p>disables hyphenation before the last two characters of a word.
</p>
</dd>
<dt><code class="code">8</code></dt>
<dd><p>disables hyphenation after the first two characters of a word.
</p>
</dd>
<dt><code class="code">16</code></dt>
<dd><p>enables hyphenation before the last character of a word.
</p>
</dd>
<dt><code class="code">32</code></dt>
<dd><p>enables hyphenation after the first character of a word.
</p></dd>
</dl>

<p>Apart from value&nbsp;2, restrictions imposed by the hyphenation mode
are <em class="emph">not</em> respected for words whose hyphenations have been
specified with the hyphenation character (&lsquo;<samp class="samp">\%</samp>&rsquo; by default) or the
<code class="code">hw</code> request.
</p>
<p>Nonzero values in the previous table are additive.  For example,
mode&nbsp;12 causes GNU <code class="code">troff</code> to hyphenate neither the last two
nor the first two characters of a word.  Some values cannot be used
together because they contradict; for instance, values 4 and&nbsp;16,
and values 8 and&nbsp;32.  As noted, it is superfluous to add 1 to any
non-zero even mode.
</p>
<a class="index-entry-id" id="index-hyphenation-pattern-files"></a>
<a class="index-entry-id" id="index-pattern-files_002c-for-hyphenation"></a>
<p>The automatic placement of hyphens in words is determined by
<em class="dfn">pattern files</em>, which are derived from TeX and available for
several languages.  The number of characters at the beginning of a word
after which the first hyphenation point should be inserted is determined
by the patterns themselves; it can&rsquo;t be reduced further without
introducing additional, invalid hyphenation points (unfortunately, this
information is not part of a pattern file&mdash;you have to know it in
advance).  The same is true for the number of characters at the end of
a word before the last hyphenation point should be inserted.  For
example, you can supply the following input to &lsquo;<samp class="samp">echo $(nroff)</samp>&rsquo;.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ll 1
.hy 48
splitting
</pre></div></div>

<p>You will get
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">s- plit- t- in- g
</pre></div></div>

<p>instead of the correct &lsquo;split- ting&rsquo;.  English patterns as distributed
with GNU <code class="code">troff</code> need two characters at the beginning and three
characters at the end; this means that value&nbsp;4 of <code class="code">hy</code> is
mandatory.  Value&nbsp;8 is possible as an additional restriction, but
values&nbsp;16 and&nbsp;32 should be avoided, as should mode&nbsp;1.
Modes&nbsp;4 and&nbsp;6 are typical.
</p>
<p>A table of left and right minimum character counts for hyphenation as
needed by the patterns distributed with GNU <code class="code">troff</code> follows; see
the <cite class="cite">groff_tmac<span class="r">(5)</span></cite> man page for more information on GNU
<code class="code">troff</code>&rsquo;s language macro files.
</p>
<table class="multitable">
<thead><tr><th>language</th><th>pattern name</th><th>left min</th><th>right min</th></tr></thead>
<tbody><tr><td>Czech</td><td>cs</td><td>2</td><td>2</td></tr>
<tr><td>English</td><td>en</td><td>2</td><td>3</td></tr>
<tr><td>French</td><td>fr</td><td>2</td><td>3</td></tr>
<tr><td>German traditional</td><td>det</td><td>2</td><td>2</td></tr>
<tr><td>German reformed</td><td>den</td><td>2</td><td>2</td></tr>
<tr><td>Italian</td><td>it</td><td>2</td><td>2</td></tr>
<tr><td>Swedish</td><td>sv</td><td>1</td><td>2</td></tr>
</tbody>
</table>

<p>Hyphenation exceptions within pattern files (i.e., the words within a
TeX <code class="code">\hyphenation</code> group) obey the hyphenation restrictions
given by <code class="code">hy</code>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002enh"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.nh</code></strong><a class="copiable-link" href='#index-_002enh'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-nh"></a>
<p>Disable automatic hyphenation; i.e., set the hyphenation mode to&nbsp;0
(see above).  The hyphenation mode of the last call to <code class="code">hy</code> is not
remembered.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ehpf"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.hpf</code></strong> <var class="def-var-arguments">pattern-file</var><a class="copiable-link" href='#index-_002ehpf'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-hpf"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002ehpfa"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.hpfa</code></strong> <var class="def-var-arguments">pattern-file</var><a class="copiable-link" href='#index-_002ehpfa'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-hpfa"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002ehpfcode"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.hpfcode</code></strong> <var class="def-var-arguments">a b [c d] &hellip;</var><a class="copiable-link" href='#index-_002ehpfcode'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-hpfcode"></a>
<a class="index-entry-id" id="index-hyphenation-patterns-_0028hpf_0029"></a>
<a class="index-entry-id" id="index-patterns-for-hyphenation-_0028hpf_0029"></a>
<p>Read hyphenation patterns from <var class="var">pattern-file</var>, which is sought
in the same way that macro files are with the <code class="code">mso</code> request or the
<samp class="option">-m<var class="var">name</var></samp> command-line option to <code class="code">groff</code>.  The
<var class="var">pattern-file</var> should have the same format as (simple) TeX
pattern files.  More specifically, the following scanning rules are
implemented.
</p>
<ul class="itemize mark-bullet">
<li>A percent sign starts a comment (up to the end of the line) even if
preceded by a backslash.

</li><li>&ldquo;Digraphs&rdquo; like <code class="code">\$</code> are not supported.

</li><li><code class="code">^^<var class="var">xx</var></code> (where each <var class="var">x</var> is 0&ndash;9 or a&ndash;f) and
<code class="code">^^<var class="var">c</var></code> (character <var class="var">c</var> in the code point range 0&ndash;127
decimal) are recognized; other uses of <code class="code">^</code> cause an error.

</li><li>No macro expansion is performed.

</li><li><code class="code">hpf</code> checks for the expression <code class="code">\patterns{&hellip;}</code>
(possibly with whitespace before or after the braces).  Everything
between the braces is taken as hyphenation patterns.  Consequently,
<code class="code">{</code> and <code class="code">}</code> are not allowed in patterns.

</li><li>Similarly, <code class="code">\hyphenation{&hellip;}</code> gives a list of hyphenation
exceptions.

</li><li><code class="code">\endinput</code> is recognized also.

</li><li>For backward compatibility, if <code class="code">\patterns</code> is missing, the whole
file is treated as a list of hyphenation patterns (except that the
<code class="code">%</code> character is recognized as the start of a comment).
</li></ul>

<p>The <code class="code">hpfa</code> request appends a file of patterns to the current list.
</p>
<p>The <code class="code">hpfcode</code> request defines mapping values for character codes in
pattern files.  It is an older mechanism no longer used by GNU
<code class="code">troff</code>&rsquo;s own macro files; for its successor, see <code class="code">hcode</code>
below.  <code class="code">hpf</code> or <code class="code">hpfa</code> apply the mapping after reading the
patterns but before replacing or appending to the active list of
patterns.  Its arguments are pairs of character codes&mdash;integers from 0
to&nbsp;255.  The request maps character code&nbsp;<var class="var">a</var> to
code&nbsp;<var class="var">b</var>, code&nbsp;<var class="var">c</var> to code&nbsp;<var class="var">d</var>, and so on.
Character codes that would otherwise be invalid in GNU <code class="code">troff</code> can
be used.  By default, every code maps to itself except those for letters
&lsquo;A&rsquo; to &lsquo;Z&rsquo;, which map to those for &lsquo;a&rsquo; to &lsquo;z&rsquo;.
</p>
<a class="index-entry-id" id="index-localization"></a>
<a class="index-entry-id" id="index-troffrc-2"></a>
<a class="index-entry-id" id="index-cs_002etmac"></a>
<a class="index-entry-id" id="index-de_002etmac"></a>
<a class="index-entry-id" id="index-en_002etmac"></a>
<a class="index-entry-id" id="index-fr_002etmac"></a>
<a class="index-entry-id" id="index-it_002etmac"></a>
<a class="index-entry-id" id="index-ja_002etmac"></a>
<a class="index-entry-id" id="index-sv_002etmac"></a>
<a class="index-entry-id" id="index-zh_002etmac"></a>
<p>The set of hyphenation patterns is associated with the language set by
the <code class="code">hla</code> request (see below).  The <code class="code">hpf</code> request is usually
invoked by a localization file loaded by the <samp class="file">troffrc</samp>
file.<a class="footnote" id="DOCF61" href="#FOOT61"><sup>61</sup></a>
</p>
<p>A second call to <code class="code">hpf</code> (for the same language) replaces the
hyphenation patterns with the new ones.  Invoking <code class="code">hpf</code> or
<code class="code">hpfa</code> causes an error if there is no hyphenation language.  If no
<code class="code">hpf</code> request is specified (either in the document, in a file
loaded at startup, or in a macro package), GNU <code class="code">troff</code> won&rsquo;t
automatically hyphenate at all.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ehcode"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.hcode</code></strong> <var class="def-var-arguments">c1 code1 [c2 code2] &hellip;</var><a class="copiable-link" href='#index-_002ehcode'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-hcode"></a>
<a class="index-entry-id" id="index-hyphenation-code-_0028hcode_0029"></a>
<a class="index-entry-id" id="index-code_002c-hyphenation-_0028hcode_0029"></a>
<p>Set the hyphenation code of character <var class="var">c1</var> to <var class="var">code1</var>, that of
<var class="var">c2</var> to <var class="var">code2</var>, and so on.  A hyphenation code must be an
ordinary character (not a special character escape sequence) other than
a digit or a space.  The request is ignored if given no arguments.
</p>
<p>For hyphenation to work, hyphenation codes must be set up.  At
startup, GNU <code class="code">troff</code> assigns hyphenation codes to the letters
&lsquo;<samp class="samp">a</samp>&rsquo;&ndash;&lsquo;<samp class="samp">z</samp>&rsquo; (mapped to themselves), to the letters
&lsquo;<samp class="samp">A</samp>&rsquo;&ndash;&lsquo;<samp class="samp">Z</samp>&rsquo; (mapped to &lsquo;<samp class="samp">a</samp>&rsquo;&ndash;&lsquo;<samp class="samp">z</samp>&rsquo;), and zero to all other
characters.  Normally, hyphenation patterns contain only lowercase
letters which should be applied regardless of case.  In other words,
they assume that the words &lsquo;FOO&rsquo; and &lsquo;Foo&rsquo; should be hyphenated exactly
as &lsquo;foo&rsquo; is.  The <code class="code">hcode</code> request extends this principle to letters
outside the Unicode basic Latin alphabet; without it, words containing
such letters won&rsquo;t be hyphenated properly even if the corresponding
hyphenation patterns contain them.
</p>
<p>For example, the following <code class="code">hcode</code> requests are necessary to assign
hyphenation codes to the letters &lsquo;<samp class="samp"></samp>&rsquo;, needed for German.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.hcode     
.hcode     
.hcode     
.hcode  
</pre></div></div>

<p>Without these assignments, GNU <code class="code">troff</code> treats the German word
&lsquo;Kindergrten&rsquo;<!-- /@w --> (the plural form of &lsquo;kindergarten&rsquo;) as two words
&lsquo;kinderg&rsquo;<!-- /@w --> and &lsquo;rten&rsquo;<!-- /@w --> because the hyphenation code of the
umlaut&nbsp;a is zero by default, just like a space.  There is a German
hyphenation pattern that covers &lsquo;kinder&rsquo;<!-- /@w -->, so GNU <code class="code">troff</code> finds
the hyphenation &lsquo;kin-der&rsquo;.  The other two hyphenation points
(&lsquo;kin-der-gr-ten&rsquo;) are missed.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ehla"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.hla</code></strong> <var class="def-var-arguments">lang</var><a class="copiable-link" href='#index-_002ehla'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-hla"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ehla_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.hla]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ehla_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ehla-1"></a>
<a class="index-entry-id" id="index-hpf-request_002c-and-hyphenation-language"></a>
<a class="index-entry-id" id="index-hw-request_002c-and-hyphenation-language"></a>
<a class="index-entry-id" id="index-troffrc-3"></a>
<a class="index-entry-id" id="index-troffrc_002dend-1"></a>
<p>Set the hyphenation language to <var class="var">lang</var>.  Hyphenation exceptions
specified with the <code class="code">hw</code> request and hyphenation patterns and
exceptions specified with the <code class="code">hpf</code> and <code class="code">hpfa</code> requests are
associated with the hyphenation language.  The <code class="code">hla</code> request is
usually invoked by a localization file, which is turn loaded by the
<samp class="file">troffrc</samp> or <samp class="file">troffrc-end</samp> file; see the <code class="code">hpf</code> request
above.
</p>
<a class="index-entry-id" id="index-hyphenation-language-register-_0028_002ehla_0029"></a>
<p>The hyphenation language is available in the read-only string-valued
register &lsquo;<samp class="samp">.hla</samp>&rsquo;; it is associated with the environment
(see <a class="pxref" href="#Environments">Environments</a>).
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ehlm"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.hlm</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">n</i></span>]</var><a class="copiable-link" href='#index-_002ehlm'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-hlm"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ehlm_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.hlm]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ehlm_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ehlm-1"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ehlc_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.hlc]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ehlc_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ehlc"></a>
<a class="index-entry-id" id="index-explicit-hyphen-_0028_005c_0025_0029"></a>
<a class="index-entry-id" id="index-hyphen_002c-explicit-_0028_005c_0025_0029"></a>
<a class="index-entry-id" id="index-consecutive-hyphenated-lines-_0028hlm_0029"></a>
<a class="index-entry-id" id="index-lines_002c-consecutive-hyphenated-_0028hlm_0029"></a>
<a class="index-entry-id" id="index-hyphenated-lines_002c-consecutive-_0028hlm_0029"></a>
<p>Set the maximum quantity of consecutive hyphenated lines to <var class="var">n</var>.  If
<var class="var">n</var> is negative, there is no maximum.  If omitted, <var class="var">n</var>
is&nbsp;&minus;1.  This value is associated with the environment
(see <a class="pxref" href="#Environments">Environments</a>).  Only lines output from a given environment
count toward the maximum associated with that environment.  Hyphens
resulting from <code class="code">\%</code> are counted; explicit hyphens are not.
</p>
<a class="index-entry-id" id="index-hyphenation-consecutive-line-limit-register-_0028_002ehlm_0029"></a>
<a class="index-entry-id" id="index-hyphenation-consecutive-line-count-register-_0028_002ehlc_0029"></a>
<p>The <code class="code">.hlm</code> read-only register stores this maximum.  The count of
immediately preceding consecutive hyphenated lines is available in the
read-only register <code class="code">.hlc</code>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ehym"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.hym</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">length</i></span>]</var><a class="copiable-link" href='#index-_002ehym'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-hym"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ehym_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.hym]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ehym_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ehym-1"></a>
<a class="index-entry-id" id="index-hyphenation-margin-_0028hym_0029"></a>
<a class="index-entry-id" id="index-margin-for-hyphenation-_0028hym_0029"></a>
<a class="index-entry-id" id="index-ad-request_002c-and-hyphenation-margin"></a>
<p>Set the (right) hyphenation margin to <var class="var">length</var>.  If the adjustment
mode is not &lsquo;<samp class="samp">b</samp>&rsquo; or &lsquo;<samp class="samp">n</samp>&rsquo;, the line is not hyphenated if it is
shorter than <var class="var">length</var>.  Without an argument, the hyphenation margin
is reset to its default value, 0.  The default scaling unit is &lsquo;<samp class="samp">m</samp>&rsquo;.
The hyphenation margin is associated with the environment
(see <a class="pxref" href="#Environments">Environments</a>).
</p>
<p>A negative argument resets the hyphenation margin to zero, emitting a
warning in category &lsquo;<samp class="samp">range</samp>&rsquo;.
</p>
<a class="index-entry-id" id="index-hyphenation-margin-register-_0028_002ehym_0029"></a>
<p>The hyphenation margin is available in the <code class="code">.hym</code> read-only
register.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ehys"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.hys</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">hyphenation-space</i></span>]</var><a class="copiable-link" href='#index-_002ehys'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-hys"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ehys_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.hys]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ehys_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ehys-1"></a>
<a class="index-entry-id" id="index-hyphenation-space-_0028hys_0029"></a>
<a class="index-entry-id" id="index-hyphenation-space-adjustment-threshold"></a>
<a class="index-entry-id" id="index-ad-request_002c-and-hyphenation-space"></a>
<p>Suppress hyphenation of the line in adjustment modes &lsquo;<samp class="samp">b</samp>&rsquo; or
&lsquo;<samp class="samp">n</samp>&rsquo; if it can be justified by adding no more than
<var class="var">hyphenation-space</var> extra space to each inter-word space.  Without
an argument, the hyphenation space adjustment threshold is set to its
default value, 0.  The default scaling unit is &lsquo;<samp class="samp">m</samp>&rsquo;.  The
hyphenation space adjustment threshold is associated with the
environment (see <a class="pxref" href="#Environments">Environments</a>).
</p>
<p>A negative argument resets the hyphenation space adjustment threshold to
zero, emitting a warning in category &lsquo;<samp class="samp">range</samp>&rsquo;.
</p>
<a class="index-entry-id" id="index-hyphenation-space-adjustment-threshold-register-_0028_002ehys_0029"></a>
<p>The hyphenation space adjustment threshold is available in the
<code class="code">.hys</code> read-only register.
</p></dd></dl>



<hr>
</div>
<div class="section-level-extent" id="Manipulating-Spacing">
<div class="nav-panel">
<p>
Next: <a href="#Tabs-and-Fields" accesskey="n" rel="next">Tabs and Fields</a>, Previous: <a href="#Manipulating-Hyphenation" accesskey="p" rel="prev">Manipulating Hyphenation</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Manipulating-Spacing-1">5.11 Manipulating Spacing</h3>
<a class="index-entry-id" id="index-manipulating-spacing"></a>
<a class="index-entry-id" id="index-spacing_002c-manipulating"></a>

<p>A break causes the formatter to update the vertical drawing position at
which the new text baseline is aligned.  You can alter this location.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002esp"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.sp</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">distance</i></span>]</var><a class="copiable-link" href='#index-_002esp'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-sp"></a>
<p>Break and move the next text baseline down by <var class="var">distance</var>, or until
springing a page location trap.<a class="footnote" id="DOCF62" href="#FOOT62"><sup>62</sup></a>
If invoked with the no-break control character, <code class="code">sp</code> moves the
pending output line&rsquo;s text baseline by <var class="var">distance</var>.  A negative
<var class="var">distance</var> will not reduce the position of the text baseline below
zero.  Inside a diversion, any <var class="var">distance</var> argument is ignored.  The
default scaling unit is &lsquo;<samp class="samp">v</samp>&rsquo;.  If <var class="var">distance</var> is not specified,
&lsquo;<samp class="samp">1v</samp>&rsquo; is assumed.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.pl 5v \&quot; Set page length to 5 vees.
.de xx
\-\-\-
.  br
..
.wh 0 xx \&quot; Set a trap at the top of the page.
foo on page \n%
.sp 2v
bar on page \n%
.sp 50v \&quot; This will cause a page break.
baz on page \n%
.pl \n(nlu \&quot; Truncate page to current position.
    &rArr; ---
    &rArr; foo on page 1
    &rArr;
    &rArr;
    &rArr; bar on page 1
    &rArr; ---
    &rArr; baz on page 2
</pre></div></div>

<p>You might use the following macros to set the baseline of the next
output text at a given distance from the top or the bottom of the page.
We subtract one line height (<code class="code">\n[.v]</code>) because the <code class="code">|</code>
operator moves to one vee below the page top (recall <a class="ref" href="#Numeric-Expressions">Numeric Expressions</a>).
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de y-from-top-down
.  sp |\\$1-\\n[.v]u
..
.
.de y-from-bot-up
.  sp |\\n[.p]u-\\$1-\\n[.v]u
..
</pre></div></div>

<p>A call to &lsquo;<samp class="samp">.y-from-bot-up 10c</samp>&rsquo; means that the next text baseline
will be 10&nbsp;cm from the bottom edge of the paper.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002els"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ls</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">count</i></span>]</var><a class="copiable-link" href='#index-_002els'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ls"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002eL_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.L]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002eL_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002eL"></a>
<a class="index-entry-id" id="index-double_002dspacing-_0028ls_0029"></a>
<p>Set the line spacing; add <var class="var">count</var>&minus;1<!-- /@w --> blank lines after each
line of text.  With no argument, GNU <code class="code">troff</code> uses the previous
value before the last <code class="code">ls</code> call.  The default is <code class="code">1</code>.
</p>

<a class="index-entry-id" id="index-line-spacing-register-_0028_002eL_0029"></a>
<p>The read-only register <code class="code">.L</code> contains the current line spacing; it
is associated with the environment (see <a class="pxref" href="#Environments">Environments</a>).
</p></dd></dl>

<p>The <code class="code">ls</code> request is a coarse mechanism.  See <a class="xref" href="#Changing-the-Type-Size">Changing the Type Size</a>, for the requests <code class="code">vs</code> and <code class="code">pvs</code> as alternatives to
<code class="code">ls</code>.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cx_0027spacing_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\x<code class="code">'</code></code><span class="r"><i class="slanted">spacing</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cx_0027spacing_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cx"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ea_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.a]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ea_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ea"></a>
<p>Sometimes, an output line requires additional vertical spacing, for
instance to allow room for a tall construct like an inline equation with
exponents or subscripts (particularly if they are iterated).  The
<code class="code">\x</code> escape sequence takes a delimited measurement (like
&lsquo;<samp class="samp">\x'3p'</samp>&rsquo;) to increase the vertical spacing of the pending output
line.  The default scaling unit is &lsquo;<samp class="samp">v</samp>&rsquo;.  If the measurement is
positive, extra vertical space is inserted below the current line; a
negative measurement adds space above.  If <code class="code">\x</code> is applied to the
pending output line multiple times, the maxima of the positive and
negative adjustments are separately applied.  The delimiter need not be
a neutral apostrophe; see <a class="ref" href="#Delimiters">Delimiters</a>.
</p>
<a class="index-entry-id" id="index-extra-post_002dvertical-line-space-register-_0028_002ea_0029"></a>
<p>The <code class="code">.a</code> read-only register contains the extra vertical spacing
<em class="emph">after</em> the text baseline of the most recently emitted output line.
(In other words, it is the largest positive argument to <code class="code">\x</code>
encountered on that line.)  This quantity is exposed via a register
because if an output line requires this &ldquo;extra post-vertical line
spacing&rdquo;, and the subsequent output line requires &ldquo;extra pre-vertical
line spacing&rdquo; (a negative argument to <code class="code">\x</code>), then applying both
can lead to excessive spacing between the output lines.  Text that is
piling high on line <var class="var">n</var> might not require (as much) extra
pre-vertical line spacing if line <var class="var">n</var>&minus;1 carries extra
post-vertical line spacing.
</p>
<p>Use of <code class="code">\x</code> can be necessary in combination with the
bracket-building escape sequence <code class="code">\b</code>,<a class="footnote" id="DOCF63" href="#FOOT63"><sup>63</sup></a> as the following example shows.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nf
This is a test of \[rs]b (1).
This is a test of \[rs]b (2).
This is a test of \b'xyz'\x'-1m'\x'1m' (3).
This is a test of \[rs]b (4).
This is a test of \[rs]b (5).
    &rArr; This is a test of \b (1).
    &rArr; This is a test of \b (2).
    &rArr;                   x
    &rArr; This is a test of y (3).
    &rArr;                   z
    &rArr; This is a test of \b (4).
    &rArr; This is a test of \b (5).
</pre></div></div>
</dd></dl>

<p>Without <code class="code">\x</code>, the backslashes on the lines marked &lsquo;<samp class="samp">(2)</samp>&rsquo; and
&lsquo;<samp class="samp">(4)</samp>&rsquo; would be overprinted.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002ens"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ns</code></strong><a class="copiable-link" href='#index-_002ens'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ns"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002ers"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.rs</code></strong><a class="copiable-link" href='#index-_002ers'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-rs"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ens_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.ns]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ens_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ens-1"></a>
<a class="index-entry-id" id="index-sp-request_002c-and-no_002dspace-mode"></a>
<a class="index-entry-id" id="index-no_002dspace-mode-_0028ns_0029"></a>
<a class="index-entry-id" id="index-mode_002c-no_002dspace-_0028ns_0029"></a>
<a class="index-entry-id" id="index-blank-lines_002c-disabling"></a>
<a class="index-entry-id" id="index-lines_002c-blank_002c-disabling"></a>
<p>Enable <em class="dfn">no-space mode</em>.  Vertical spacing, whether by <code class="code">sp</code>
requests or blank input lines, is disabled.  The <code class="code">bp</code> request to
advance to the next page is also disabled, unless it is accompanied by a
page number (see <a class="pxref" href="#Page-Control">Page Control</a>).  No-space mode ends automatically
when text<a class="footnote" id="DOCF64" href="#FOOT64"><sup>64</sup></a> is formatted for output <a class="footnote" id="DOCF65" href="#FOOT65"><sup>65</sup></a> or the <code class="code">rs</code> request is invoked, which ends
no-space mode.  The read-only register <code class="code">.ns</code> interpolates a Boolean
value indicating the enablement of no-space mode.
</p>
<p>A paragraphing macro might ordinarily insert vertical space to separate
paragraphs.  A section heading macro could invoke <code class="code">ns</code> to suppress
this spacing for the first paragraph in a section.
</p></dd></dl>



<hr>
</div>
<div class="section-level-extent" id="Tabs-and-Fields">
<div class="nav-panel">
<p>
Next: <a href="#Character-Translations" accesskey="n" rel="next">Character Translations</a>, Previous: <a href="#Manipulating-Spacing" accesskey="p" rel="prev">Manipulating Spacing</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Tabs-and-Fields-1">5.12 Tabs and Fields</h3>
<a class="index-entry-id" id="index-tabs_002c-and-fields"></a>
<a class="index-entry-id" id="index-fields_002c-and-tabs"></a>

<a class="index-entry-id" id="index-tab-character-encoding"></a>
<p>A tab character (<abbr class="acronym">ISO</abbr> code point&nbsp;9, <abbr class="acronym">EBCDIC</abbr>
code point&nbsp;5) causes a horizontal movement to the next tab stop, if
any.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005ct-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\t</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005ct-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005ct"></a>
<a class="index-entry-id" id="index-tab-character_002c-non_002dinterpreted-_0028_005ct_0029"></a>
<a class="index-entry-id" id="index-character_002c-tab_002c-non_002dinterpreted-_0028_005ct_0029"></a>
<a class="index-entry-id" id="index-_005ct_002c-and-copy-mode"></a>
<a class="index-entry-id" id="index-copy-mode_002c-and-_005ct"></a>
<a class="index-entry-id" id="index-mode_002c-copy_002c-and-_005ct"></a>
<p>Interpolate a tab in copy mode; see <a class="ref" href="#Copy-Mode">Copy Mode</a>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eta"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ta</code></strong> <var class="def-var-arguments">[[<span class="r"><i class="slanted">n1</i></span> <span class="r"><i class="slanted">n2</i></span> &hellip; <span class="r"><i class="slanted">nn</i></span> ]<code class="t">T</code> <span class="r"><i class="slanted">r1</i></span>  <span class="r"><i class="slanted">r2</i></span> &hellip; <span class="r"><i class="slanted">rn</i></span>]</var><a class="copiable-link" href='#index-_002eta'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ta"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002etabs_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.tabs]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002etabs_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002etabs"></a>
<p>Change tab stop positions.  This request takes a series of tab
specifiers as arguments (optionally divided into two groups with the
letter &lsquo;<samp class="samp">T</samp>&rsquo;) that indicate where each tab stop is to be, overriding
any previous settings.  The default scaling unit is &lsquo;<samp class="samp">m</samp>&rsquo;.  Invoking
<code class="code">ta</code> without an argument removes all tab stops.
<a class="index-entry-id" id="index-default-tab-stops"></a>
<a class="index-entry-id" id="index-tab-stops_002c-default"></a>
GNU <code class="code">troff</code>&rsquo;s startup value is &lsquo;<samp class="samp">T&nbsp;0.5i</samp>&rsquo;<!-- /@w -->.
</p>
<p>Tab stops can be specified absolutely&mdash;as distances from the left
margin.  The following example sets six tab stops, one every inch.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ta 1i 2i 3i 4i 5i 6i
</pre></div></div>

<p>Tab stops can also be specified using a leading &lsquo;<samp class="samp">+</samp>&rsquo;, which means
that the specified tab stop is set relative to the previous tab stop.
For example, the following is equivalent to the previous example.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ta 1i +1i +1i +1i +1i +1i
</pre></div></div>

<p>GNU <code class="code">troff</code> supports an extended syntax to specify repeating tab
stops.  These stops appear after a &lsquo;<samp class="samp">T</samp>&rsquo; argument.  Their values are
always taken as distances relative to the previous tab stop.  This is
the idiomatic way to specify tab stops at equal intervals in
<code class="code">groff</code>.  The following is, yet again, the same as the previous
examples.  It does more, in fact, since it defines an infinite number of
tab stops at one-inch intervals.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ta T 1i
</pre></div></div>

<p>Now we are ready to interpret the full syntax given above.  The
<code class="code">ta</code> request sets tabs at positions <var class="var">n1</var>, <var class="var">n2</var>, &hellip;,
<var class="var">nn</var>, then at <var class="var">nn</var>+<var class="var">r1</var>, <var class="var">nn</var>+<var class="var">r2</var>, &hellip;,
<var class="var">nn</var>+<var class="var">rn</var>, then at <var class="var">nn</var>+<var class="var">rn</var>+<var class="var">r1</var>,
<var class="var">nn</var>+<var class="var">rn</var>+<var class="var">r2</var>, &hellip;, <var class="var">nn</var>+<var class="var">rn</var>+<var class="var">rn</var>, and so
on.
</p>
<p>For example, &lsquo;<samp class="samp">4c +6c T 3c 5c 2c</samp>&rsquo; is equivalent to &lsquo;<samp class="samp">4c 10c 13c
18c 20c 23c 28c 30c &hellip;</samp>&rsquo;.
</p>
<p>Text written to a tab column (i.e., between two tab stops, or between a
tab stop and an output line boundary) may be aligned to the right or
left, or centered in the column.  This alignment is determined by
appending &lsquo;<samp class="samp">R</samp>&rsquo;, &lsquo;<samp class="samp">L</samp>&rsquo;, or &lsquo;<samp class="samp">C</samp>&rsquo; to the tab specifier.  The
default is &lsquo;<samp class="samp">L</samp>&rsquo;.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ta 1i 2iC 3iR
</pre></div></div>

<p>The beginning of an output line is not a tab stop; the text that begins
an output line is placed according to the configured alignment and
indentation; see <a class="ref" href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a> and <a class="ref" href="#Line-Layout">Line Layout</a>.
</p>
<p>A tab stop is converted into a non-breakable horizontal movement that
cannot be adjusted.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ll 2i
.ds foo a\tb\tc
.ta T 1i
\*[foo]
    error&rarr; warning: cannot break line
    &rArr; a         b         c
</pre></div></div>

<p>The above creates a single output line that is a bit longer than two
inches (we use a string to show exactly where the tab stops are).
Now consider the following.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ll 2i
.ds bar a\tb c\td
.ta T 1i
\*[bar]
    error&rarr; warning: cannot adjust line
    &rArr; a         b
    &rArr; c       d
</pre></div></div>

<p>GNU <code class="code">troff</code> first converts the line&rsquo;s tab stops into unbreakable
horizontal movements, then breaks after &lsquo;<samp class="samp">b</samp>&rsquo;.  This usually isn&rsquo;t
what you want.
</p>
<p>Superfluous tab characters&mdash;those that do not correspond to a tab
stop&mdash;are ignored except for the first, which delimits the characters
belonging to the last tab stop for right-alignment or centering.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds Z   foo\tbar\tbaz
.ds ZZ  foo\tbar\tbazqux
.ds ZZZ foo\tbar\tbaz\tqux
.ta 2i 4iR
\*[Z]
.br
\*[ZZ]
.br
\*[ZZZ]
.br
    &rArr; foo                 bar              baz
    &rArr; foo                 bar           bazqux
    &rArr; foo                 bar              bazqux
</pre></div></div>

<p>The first line right-aligns &ldquo;baz&rdquo; within the second tab stop.  The
second line right-aligns &ldquo;bazqux&rdquo; within it.  The third line
right-aligns only &ldquo;baz&rdquo; because of the additional tab character, which
marks the end of the text occupying the last tab stop defined.
</p>
<p>Tab stops are associated with the environment (see <a class="pxref" href="#Environments">Environments</a>).
</p>
<a class="index-entry-id" id="index-tab-stop-settings-register-_0028_002etabs_0029"></a>
<a class="index-entry-id" id="index-_002eS-register_002c-Plan-9-alias-for-_002etabs"></a>
<a class="index-entry-id" id="index-_002etabs-register_002c-Plan-9-alias-_0028_002eS_0029"></a>
<p>The read-only register <code class="code">.tabs</code> contains a string
representation of the current tab settings suitable for use as an
argument to the <code class="code">ta</code> request.<a class="footnote" id="DOCF66" href="#FOOT66"><sup>66</sup></a>
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds tab-string \n[.tabs]
\*[tab-string]
    &rArr; T120u
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002etc"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.tc</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">c</i></span>]</var><a class="copiable-link" href='#index-_002etc'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-tc"></a>
<a class="index-entry-id" id="index-tab-repetition-character-_0028tc_0029"></a>
<a class="index-entry-id" id="index-character_002c-tab-repetition-_0028tc_0029"></a>
<a class="index-entry-id" id="index-glyph_002c-tab-repetition-_0028tc_0029"></a>
<p>Set the tab repetition character to the ordinary or special character
<var class="var">c</var>; normally, no glyph is written when moving to a tab stop (and
some output devices may output space characters to achieve this motion).
A <em class="dfn">tab repetition character</em> causes the formatter to write as many
instances of <var class="var">c</var> as are necessary to occupy the interval from the
horizontal drawing position to the next tab stop.  With no argument, GNU
<code class="code">troff</code> reverts to the default behavior.  The tab repetition
character is associated with the environment (see <a class="pxref" href="#Environments">Environments</a>).
Only a single character of <var class="var">c</var> is recognized; any excess is ignored.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002elinetabs"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.linetabs</code></strong> <var class="def-var-arguments">n</var><a class="copiable-link" href='#index-_002elinetabs'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-linetabs"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002elinetabs_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.linetabs]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002elinetabs_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002elinetabs-1"></a>
<a class="index-entry-id" id="index-tab_002c-line_002dtabs-mode"></a>
<a class="index-entry-id" id="index-line_002dtabs-mode"></a>
<a class="index-entry-id" id="index-mode_002c-line_002dtabs"></a>
<p>If <var class="var">n</var> is missing or non-zero, activate <em class="dfn">line-tabs</em>; deactivate
it otherwise (the default).  Active line-tabs cause GNU <code class="code">troff</code>
to compute tab distances relative to the start of the output line
instead of the input line.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de Tabs
.  ds x a\t\c
.  ds y b\t\c
.  ds z c
.  ta 1i 3i
\\*x
\\*y
\\*z
..
.Tabs
.br
.linetabs
.Tabs
    &rArr; a         b         c
    &rArr; a         b                   c
</pre></div></div>

<p>Line-tabs activation is associated with the environment
(see <a class="pxref" href="#Environments">Environments</a>).  The read-only register <code class="code">.linetabs</code>
interpolates&nbsp;1 if line-tabs are active, and 0 otherwise.
</p></dd></dl>



<ul class="mini-toc">
<li><a href="#Leaders" accesskey="1">Leaders</a></li>
<li><a href="#Fields" accesskey="2">Fields</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="Leaders">
<div class="nav-panel">
<p>
Next: <a href="#Fields" accesskey="n" rel="next">Fields</a>, Previous: <a href="#Tabs-and-Fields" accesskey="p" rel="prev">Tabs and Fields</a>, Up: <a href="#Tabs-and-Fields" accesskey="u" rel="up">Tabs and Fields</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Leaders-1">5.12.1 Leaders</h4>
<a class="index-entry-id" id="index-leaders"></a>

<p>Sometimes it is desirable to fill a tab stop with a given glyph,
but also use tab stops normally on the same output line.  An example is
a table of contents entry that uses dots to bridge the entry name with
its page number, which is itself aligned between tab stops.  The
<code class="code">roff</code> language provides <em class="dfn">leaders</em> for this
purpose.<a class="footnote" id="DOCF67" href="#FOOT67"><sup>67</sup></a>
</p>
<a class="index-entry-id" id="index-leader-character-1"></a>
<p>A leader character (<abbr class="acronym">ISO</abbr> and <abbr class="acronym">EBCDIC</abbr> code
point&nbsp;1, also known as <abbr class="acronym">SOH</abbr> or &ldquo;start of heading&rdquo;),
behaves similarly to a tab character: it moves to the next tab stop.
The difference is that for this movement, the default fill character is
a period &lsquo;<samp class="samp">.</samp>&rsquo;.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005ca-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\a</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005ca-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005ca"></a>
<a class="index-entry-id" id="index-leader-character_002c-non_002dinterpreted-_0028_005ca_0029"></a>
<a class="index-entry-id" id="index-character_002c-leader_002c-non_002dinterpreted-_0028_005ca_0029"></a>
<a class="index-entry-id" id="index-_005ca_002c-and-copy-mode"></a>
<a class="index-entry-id" id="index-copy-mode_002c-and-_005ca"></a>
<a class="index-entry-id" id="index-mode_002c-copy_002c-and-_005ca"></a>
<p>Interpolate a leader in copy mode; see <a class="ref" href="#Copy-Mode">Copy Mode</a>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002elc"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.lc</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">c</i></span>]</var><a class="copiable-link" href='#index-_002elc'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-lc"></a>
<a class="index-entry-id" id="index-leader-repetition-character-_0028lc_0029"></a>
<a class="index-entry-id" id="index-character_002c-leader-repetition-_0028lc_0029"></a>
<a class="index-entry-id" id="index-glyph_002c-leader-repetition-_0028lc_0029"></a>
<p>Set the leader repetition character to the ordinary or special character
<var class="var">c</var>.  Recall <a class="ref" href="#Tabs-and-Leaders">Tabs and Leaders</a>: when encountering a leader
character in the input, the formatter writes as many dots &lsquo;<samp class="samp">.</samp>&rsquo; as
are necessary until
reaching the next tab stop; this is the <em class="dfn">leader definition
character</em>.  Omitting <var class="var">c</var> unsets the leader
character.  With no argument, GNU <code class="code">troff</code> treats leaders the same
as tabs.  The leader repetition character is associated with the
environment (see <a class="pxref" href="#Environments">Environments</a>).  Only a single <var class="var">c</var> is
recognized; any excess is ignored.
</p></dd></dl>

<a class="index-entry-id" id="index-table-of-contents-1"></a>
<a class="index-entry-id" id="index-contents_002c-table-of-1"></a>
<p>A table of contents, for example, may define tab stops after a section
number, a title, and a gap to be filled with leader dots.  The page
number follows the leader, after a right-aligned final tab stop wide
enough to house the largest page number occurring in the document.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds entry1 19.\tThe Prophet\a\t98
.ds entry2 20.\tAll Astir\a\t101
.ta .5i 4.5i +.5iR
.nf
\*[entry1]
\*[entry2]
    &rArr; 19.  The Prophet.............................   98
    &rArr; 20.  All Astir...............................  101
</pre></div></div>


<hr>
</div>
<div class="subsection-level-extent" id="Fields">
<div class="nav-panel">
<p>
Previous: <a href="#Leaders" accesskey="p" rel="prev">Leaders</a>, Up: <a href="#Tabs-and-Fields" accesskey="u" rel="up">Tabs and Fields</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Fields-1">5.12.2 Fields</h4>
<a class="index-entry-id" id="index-fields"></a>

<a class="index-entry-id" id="index-field-delimiting-character-_0028fc_0029"></a>
<a class="index-entry-id" id="index-delimiting-character_002c-for-fields-_0028fc_0029"></a>
<a class="index-entry-id" id="index-character_002c-field-delimiting-_0028fc_0029"></a>
<a class="index-entry-id" id="index-field-padding-character-_0028fc_0029"></a>
<a class="index-entry-id" id="index-padding-character_002c-for-fields-_0028fc_0029"></a>
<a class="index-entry-id" id="index-character_002c-field-padding-_0028fc_0029"></a>
<p><em class="dfn">Fields</em> are a more general way of laying out tabular data.  A field
is defined as the data between a pair of <em class="dfn">delimiting characters</em>.
It contains substrings that are separated by <em class="dfn">padding characters</em>.
The width of a field is the distance on the <em class="emph">input</em> line from the
position where the field starts to the next tab stop.  A padding
character inserts an adjustable space similar to TeX&rsquo;s <code class="code">\hss</code>
command (thus it can even be negative) to make the sum of all substring
lengths plus the adjustable space equal to the field width.  If more
than one padding character is inserted, the available space is evenly
distributed among them.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002efc"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.fc</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">delim-char</i></span> [<span class="r"><i class="slanted">padding-char</i></span>]]</var><a class="copiable-link" href='#index-_002efc'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-fc"></a>
<p>Define a delimiting and a padding character for fields.  If the latter
is missing, the padding character defaults to a space character.  If
there is no argument at all, the field mechanism is disabled (which is
the default).  In contrast to, e.g., the tab repetition character,
delimiting and padding characters are <em class="emph">not</em> associated with the
environment (see <a class="pxref" href="#Environments">Environments</a>).
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.fc # ^
.ta T 3i
#foo^bar^smurf#
.br
#foo^^bar^smurf#
    &rArr; foo         bar          smurf
    &rArr; foo            bar       smurf
</pre></div></div>
</dd></dl>



<hr>
</div>
</div>
<div class="section-level-extent" id="Character-Translations">
<div class="nav-panel">
<p>
Next: <a href="#troff-and-nroff-Modes" accesskey="n" rel="next"><code class="code">troff</code> and <code class="code">nroff</code> Modes</a>, Previous: <a href="#Tabs-and-Fields" accesskey="p" rel="prev">Tabs and Fields</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Character-Translations-1">5.13 Character Translations</h3>
<a class="index-entry-id" id="index-character-translations"></a>
<a class="index-entry-id" id="index-translations-of-characters"></a>

<p>A <em class="dfn">translation</em> is a mapping of an input character to an output
glyph.  The mapping occurs at output time, i.e., the input character
gets assigned the metric information of the mapped output character
right before input tokens are converted to nodes (see <a class="pxref" href="#Gtroff-Internals"><code class="code">gtroff</code> Internals</a>, for more on this process).
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002etr"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.tr</code></strong> <var class="def-var-arguments"><span class="r"><i class="slanted">a</i></span><span class="r"><i class="slanted">b</i></span><span class="r"><i class="slanted">c</i></span><span class="r"><i class="slanted">d</i></span>&hellip;</var><a class="copiable-link" href='#index-_002etr'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-tr"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002etrin"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.trin</code></strong> <var class="def-var-arguments"><span class="r"><i class="slanted">a</i></span><span class="r"><i class="slanted">b</i></span><span class="r"><i class="slanted">c</i></span><span class="r"><i class="slanted">d</i></span>&hellip;</var><a class="copiable-link" href='#index-_002etrin'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-trin"></a>
<p>Translate character <var class="var">a</var> to glyph&nbsp;<var class="var">b</var>, character <var class="var">c</var> to
glyph&nbsp;<var class="var">d</var>, and so on.  If there is an odd number of characters
in the argument, the last one is translated to a fixed-width space (the
same one obtained by the <code class="code">\<kbd class="key">SP</kbd></code> escape sequence).
</p>
<p>The <code class="code">trin</code> request is identical to <code class="code">tr</code>, but when you unformat
a diversion with <code class="code">asciify</code> it ignores the translation.
See <a class="xref" href="#Diversions">Diversions</a>, for details about the <code class="code">asciify</code> request.
</p>
<p>Some notes:
</p>
<ul class="itemize mark-bullet">
<li><a class="index-entry-id" id="index-_005c_0028_002c-and-translations"></a>
<a class="index-entry-id" id="index-_005c_005b_002c-and-translations"></a>
<a class="index-entry-id" id="index-_005c_0027_002c-and-translations"></a>
<a class="index-entry-id" id="index-_005c_0060_002c-and-translations"></a>
<a class="index-entry-id" id="index-_005c_002d_002c-and-translations"></a>
<a class="index-entry-id" id="index-_005c_005f_002c-and-translations"></a>
<a class="index-entry-id" id="index-_005cC_002c-and-translations"></a>
<a class="index-entry-id" id="index-_005cN_002c-and-translations"></a>
<a class="index-entry-id" id="index-char-request_002c-and-translations"></a>
<a class="index-entry-id" id="index-special-characters-1"></a>
<a class="index-entry-id" id="index-character_002c-special"></a>
<a class="index-entry-id" id="index-numbered-glyph-_0028_005cN_0029"></a>
<a class="index-entry-id" id="index-glyph_002c-numbered-_0028_005cN_0029"></a>
Special characters (<code class="code">\(<var class="var">xx</var></code>, <code class="code">\[<var class="var">xxx</var>]</code>,
<code class="code">\C'<var class="var">xxx</var>'</code>, <code class="code">\'</code>, <code class="code">\`</code>, <code class="code">\-</code>, <code class="code">\_</code>),
glyphs defined with the <code class="code">char</code> request, and numbered glyphs
(<code class="code">\N'<var class="var">xxx</var>'</code>) can be translated also.

</li><li><a class="index-entry-id" id="index-_005ce_002c-and-translations"></a>
The <code class="code">\e</code> escape can be translated also.

</li><li><a class="index-entry-id" id="index-_005c_0025_002c-and-translations"></a>
<a class="index-entry-id" id="index-_005c_007e_002c-and-translations"></a>
Characters can be mapped onto the <code class="code">\%</code> and <code class="code">\~</code> escape
sequences (but <code class="code">\%</code> and <code class="code">\~</code> can&rsquo;t be mapped onto another
glyph).

</li><li><a class="index-entry-id" id="index-backspace-character_002c-and-translations"></a>
<a class="index-entry-id" id="index-character_002c-backspace_002c-and-translations"></a>
<a class="index-entry-id" id="index-leader-character_002c-and-translations"></a>
<a class="index-entry-id" id="index-character_002c-leader_002c-and-translations"></a>
<a class="index-entry-id" id="index-newline-character_002c-and-translations"></a>
<a class="index-entry-id" id="index-character_002c-newline_002c-and-translations"></a>
<a class="index-entry-id" id="index-tab-character_002c-and-translations"></a>
<a class="index-entry-id" id="index-character_002c-tab_002c-and-translations"></a>
<a class="index-entry-id" id="index-_005ca_002c-and-translations"></a>
<a class="index-entry-id" id="index-_005ct_002c-and-translations"></a>
The following characters can&rsquo;t be translated: space (with one exception,
see below), backspace, newline, leader (and <code class="code">\a</code>), tab (and
<code class="code">\t</code>).

</li><li><a class="index-entry-id" id="index-shc-request_002c-and-translations"></a>
Translations are not considered for finding the soft hyphen character
set with the <code class="code">shc</code> request.

</li><li><a class="index-entry-id" id="index-_005c_0026_002c-and-translations"></a>
The pair &lsquo;<samp class="samp"><var class="var">c</var>\&amp;</samp>&rsquo; (an arbitrary character&nbsp;<var class="var">c</var> followed
by the dummy character) maps this character to &ldquo;nothing&rdquo;.

<div class="example">
<div class="group"><pre class="example-preformatted">.tr a\&amp;
foo bar
    &rArr; foo br
</pre></div></div>

<p>Even the space character can be mapped to the dummy character.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.tr aa \&amp;
foo bar
    &rArr; foobar
</pre></div></div>

<p>As shown in the example, the space character can&rsquo;t be the first
character/glyph pair as an argument of <code class="code">tr</code>.  Additionally, it is
not possible to map the space character to any other glyph; requests
like &lsquo;<samp class="samp">.tr&nbsp;aa&nbsp;x</samp>&rsquo;<!-- /@w --> undo &lsquo;<samp class="samp">.tr&nbsp;aa&nbsp;\&amp;</samp>&rsquo;<!-- /@w --> instead.
</p>
<p>If justification is active, lines are justified in spite of the &lsquo;empty&rsquo;
space character (but there is no minimal distance, i.e., the space
character, between words).
</p>
</li><li>After an output glyph has been constructed (this happens at the moment
immediately before the glyph is appended to an output glyph list, either
by direct output, in a macro, diversion, or string), it is no longer
affected by <code class="code">tr</code>.

</li><li>Translating character to glyphs where one of them or both are undefined
is possible also; <code class="code">tr</code> does not check whether the elements of its
argument exist.

<p>See <a class="xref" href="#Gtroff-Internals"><code class="code">gtroff</code> Internals</a>.
</p>
</li><li>Without an argument, the <code class="code">tr</code> request is ignored.
</li></ul>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002etrnt"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.trnt</code></strong> <var class="def-var-arguments"><span class="r"><i class="slanted">a</i></span><span class="r"><i class="slanted">b</i></span><span class="r"><i class="slanted">c</i></span><span class="r"><i class="slanted">d</i></span>&hellip;</var><a class="copiable-link" href='#index-_002etrnt'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-trnt"></a>
<a class="index-entry-id" id="index-_005c_0021_002c-and-trnt"></a>
<p><code class="code">trnt</code> is the same as the <code class="code">tr</code> request except that the
translations do not apply to text that is transparently throughput into
a diversion with <code class="code">\!</code>.  See <a class="xref" href="#Diversions">Diversions</a>.
</p>
<p>For example,
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.tr ab
.di x
\!.tm a
.di
.x
</pre></div></div>

<p>prints &lsquo;<samp class="samp">b</samp>&rsquo; to the standard error stream; if <code class="code">trnt</code> is used
instead of <code class="code">tr</code> it prints &lsquo;<samp class="samp">a</samp>&rsquo;.
</p></dd></dl>



<hr>
</div>
<div class="section-level-extent" id="troff-and-nroff-Modes">
<div class="nav-panel">
<p>
Next: <a href="#Line-Layout" accesskey="n" rel="next">Line Layout</a>, Previous: <a href="#Character-Translations" accesskey="p" rel="prev">Character Translations</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="troff-and-nroff-Modes-1">5.14 <code class="code">troff</code> and <code class="code">nroff</code> Modes</h3>
<a class="index-entry-id" id="index-troff-mode"></a>
<a class="index-entry-id" id="index-mode_002c-troff"></a>
<a class="index-entry-id" id="index-nroff-mode"></a>
<a class="index-entry-id" id="index-mode_002c-nroff"></a>

<p>Historically, <code class="code">nroff</code> and <code class="code">troff</code> were two separate programs;
the former for terminal output, the latter for typesetters.  GNU
<code class="code">troff</code> merges both functions into one executable<a class="footnote" id="DOCF68" href="#FOOT68"><sup>68</sup></a> that sends its output to a
device driver (<code class="code">grotty</code> for terminal devices, <code class="code">grops</code> for
PostScript, and so on) which interprets this intermediate output format.
When discussing <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>, it makes sense to talk
about <em class="dfn"><code class="code">nroff</code> mode</em> and <em class="dfn"><code class="code">troff</code> mode</em> since the
differences are hard-coded.  GNU <code class="code">troff</code> takes information from
device and font description files without handling requests specially if
a terminal output device is used, so such a strong distinction is
unnecessary.
</p>
<p>Usually, a macro package can be used with all output devices.
Nevertheless, it is sometimes necessary to make a distinction between
terminal and non-terminal devices: GNU <code class="code">troff</code> provides two
built-in conditions &lsquo;<samp class="samp">n</samp>&rsquo; and &lsquo;<samp class="samp">t</samp>&rsquo; for the <code class="code">if</code>, <code class="code">ie</code>,
and <code class="code">while</code> requests to decide whether GNU <code class="code">troff</code> shall
behave like <code class="code">nroff</code> or like <code class="code">troff</code>.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002etroff"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.troff</code></strong><a class="copiable-link" href='#index-_002etroff'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-troff"></a>
<a class="index-entry-id" id="index-troffrc-4"></a>
<a class="index-entry-id" id="index-troffrc_002dend-2"></a>
<p>Make the &lsquo;<samp class="samp">t</samp>&rsquo; built-in condition true (and the &lsquo;<samp class="samp">n</samp>&rsquo; built-in
condition false) for <code class="code">if</code>, <code class="code">ie</code>, and <code class="code">while</code> conditional
requests.  This is the default if GNU <code class="code">troff</code> (<em class="emph">not</em>
<code class="code">groff</code>) is started with the <samp class="option">-R</samp> switch to avoid loading of
the startup files <samp class="file">troffrc</samp> and <samp class="file">troffrc-end</samp>.  Without
<samp class="option">-R</samp>, GNU <code class="code">troff</code> stays in <code class="code">troff</code> mode if the output
device is not a terminal (e.g., &lsquo;ps&rsquo;).
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002enroff"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.nroff</code></strong><a class="copiable-link" href='#index-_002enroff'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-nroff"></a>
<a class="index-entry-id" id="index-tty_002etmac"></a>
<p>Make the &lsquo;<samp class="samp">n</samp>&rsquo; built-in condition true (and the &lsquo;<samp class="samp">t</samp>&rsquo; built-in
condition false) for <code class="code">if</code>, <code class="code">ie</code>, and <code class="code">while</code> conditional
requests.  This is the default if GNU <code class="code">troff</code> uses a terminal
output device; the code for switching to <code class="code">nroff</code> mode is in the
file <samp class="file">tty.tmac</samp>, which is loaded by the startup file
<code class="code">troffrc</code>.
</p></dd></dl>

<p>See <a class="xref" href="#Conditionals-and-Loops">Conditionals and Loops</a>, for more details on built-in conditions.
</p>


<hr>
</div>
<div class="section-level-extent" id="Line-Layout">
<div class="nav-panel">
<p>
Next: <a href="#Line-Continuation" accesskey="n" rel="next">Line Continuation</a>, Previous: <a href="#troff-and-nroff-Modes" accesskey="p" rel="prev"><code class="code">troff</code> and <code class="code">nroff</code> Modes</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Line-Layout-1">5.15 Line Layout</h3>
<a class="index-entry-id" id="index-line-layout"></a>
<a class="index-entry-id" id="index-layout_002c-line"></a>

<a class="index-entry-id" id="index-dimensions_002c-line"></a>
<a class="index-entry-id" id="index-line-dimensions"></a>
<p>The following drawing shows the dimensions that <code class="code">gtroff</code> uses for
placing a line of output onto the page.  They are labeled with the
request that manipulates each dimension.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">     --&gt;| in |&lt;--
        |&lt;-----------ll------------&gt;|
   +----+----+----------------------+----+
   |    :    :                      :    |
   +----+----+----------------------+----+
--&gt;| po |&lt;--
   |&lt;--------paper width----------------&gt;|
</pre></div></div>

<p>These dimensions are:
</p>
<dl class="ftable">
<dt id='index-po'><span><code class="code">po</code><a class="copiable-link" href='#index-po'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-left-margin-_0028po_0029"></a>
<a class="index-entry-id" id="index-margin_002c-left-_0028po_0029"></a>
<a class="index-entry-id" id="index-page-offset-_0028po_0029"></a>
<a class="index-entry-id" id="index-offset_002c-page-_0028po_0029"></a>
<p><em class="dfn">Page offset</em>&mdash;this is the leftmost position of text on the final
output, defining the <em class="dfn">left margin</em>.
</p>
</dd>
<dt id='index-in'><span><code class="code">in</code><a class="copiable-link" href='#index-in'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-indentation-_0028in_0029"></a>
<a class="index-entry-id" id="index-line-indentation-_0028in_0029"></a>
<p><em class="dfn">Indentation</em>&mdash;this is the distance from the left margin where
text is printed.
</p>
</dd>
<dt id='index-ll'><span><code class="code">ll</code><a class="copiable-link" href='#index-ll'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-line-length-_0028ll_0029"></a>
<a class="index-entry-id" id="index-length-of-line-_0028ll_0029"></a>
<p><em class="dfn">Line length</em>&mdash;this is the distance from the left margin to right
margin.
</p></dd>
</dl>

<a class="index-entry-id" id="index-margin_002c-right"></a>
<a class="index-entry-id" id="index-right-margin"></a>
<p>The right margin is not explicitly configured; the combination of page
offset and line length provides the information necessary to derive it.
</p>
<p>A simple demonstration:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ll 3i
This is text without indentation.
The line length has been set to 3\~inches.
.in +.5i
.ll -.5i
Now the left and right margins are both increased.
.in
.ll
Calling .in and .ll without parameters restores
the previous values.
</pre></div></div>

<div class="example">
<div class="group"><pre class="example-preformatted">    &rArr; This  is text without indenta-
    &rArr; tion.   The  line  length  has
    &rArr; been set to 3 inches.
    &rArr;      Now   the  left  and
    &rArr;      right  margins   are
    &rArr;      both increased.
    &rArr; Calling  .in  and  .ll without
    &rArr; parameters restores the previ-
    &rArr; ous values.
</pre></div></div>

<dl class="first-deffn">
<dt class="deffn" id="index-_002epo"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.po</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">offset</i></span>]</var><a class="copiable-link" href='#index-_002epo'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-po-1"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002epo-1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.po</code></strong> <var class="def-var-arguments"><code class="t">+</code><span class="r"><i class="slanted">offset</i></span></var><a class="copiable-link" href='#index-_002epo-1'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_002epo-2"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.po</code></strong> <var class="def-var-arguments"><code class="t">-</code><span class="r"><i class="slanted">offset</i></span></var><a class="copiable-link" href='#index-_002epo-2'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002eo_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.o]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002eo_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002eo"></a>
<a class="index-entry-id" id="index-tty_002etmac-1"></a>
<p>Set page offset to <var class="var">offset</var> (or increment or decrement its current
value by <var class="var">offset</var>).  If invoked without an argument, the page offset
is restored to the value before the previous <code class="code">po</code> request.
This request does not cause a break; the page offset in effect when an
output line is broken prevails (see <a class="pxref" href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a>).  The initial value is 1<span class="dmn">i</span> and the default scaling
unit is &lsquo;<samp class="samp">m</samp>&rsquo;.  On terminal devices, the page offset is set to zero
by a driver-specific macro file, <samp class="file">tty.tmac</samp>.  The current page
offset can be found in the read-only register &lsquo;<samp class="samp">.o</samp>&rsquo;.
<a class="index-entry-id" id="index-CSTR-_002354-errata-1"></a>
<a class="index-entry-id" id="index-CSTR-_002354-erratum_002c-po-request"></a>
This request is incorrectly documented in the <abbr class="acronym">AT&amp;T</abbr>
<code class="code">troff</code> manual as using a default scaling unit of &lsquo;<samp class="samp">v</samp>&rsquo;.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.po 3i
\n[.o]
    &rArr; 720
.po -1i
\n[.o]
    &rArr; 480
.po
\n[.o]
    &rArr; 720
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ein"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.in</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">indent</i></span>]</var><a class="copiable-link" href='#index-_002ein'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-in-1"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002ein-1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.in</code></strong> <var class="def-var-arguments"><code class="t">+</code><span class="r"><i class="slanted">indent</i></span></var><a class="copiable-link" href='#index-_002ein-1'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_002ein-2"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.in</code></strong> <var class="def-var-arguments"><code class="t">-</code><span class="r"><i class="slanted">indent</i></span></var><a class="copiable-link" href='#index-_002ein-2'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ei_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.i]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ei_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ei"></a>
<p>Set indentation to <var class="var">indent</var> (or increment or decrement the current
value by <var class="var">indent</var>).  This request causes a break.  Initially, there
is no indentation.
</p>
<p>If <code class="code">in</code> is called without an argument, the indentation is reset to
the previous value before the last call to <code class="code">in</code>.  The default
scaling unit is &lsquo;<samp class="samp">m</samp>&rsquo;.
</p>
<p>If a negative indentation value is specified (which is not allowed),
<code class="code">gtroff</code> emits a warning in category &lsquo;<samp class="samp">range</samp>&rsquo; and sets the
indentation to zero.
</p>
<p>The effect of <code class="code">in</code> is delayed until a partially collected line (if
it exists) is output.  A temporary indentation value is reset to zero
also.
</p>
<p>The current indentation (as set by <code class="code">in</code>) can be found in the
read-only register &lsquo;<samp class="samp">.i</samp>&rsquo;.  The indentation is associated with the
environment (see <a class="pxref" href="#Environments">Environments</a>).
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eti"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ti</code></strong> <var class="def-var-arguments">offset</var><a class="copiable-link" href='#index-_002eti'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ti"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002eti-1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ti</code></strong> <var class="def-var-arguments"><code class="t">+</code><span class="r"><i class="slanted">offset</i></span></var><a class="copiable-link" href='#index-_002eti-1'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_002eti-2"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ti</code></strong> <var class="def-var-arguments"><code class="t">-</code><span class="r"><i class="slanted">offset</i></span></var><a class="copiable-link" href='#index-_002eti-2'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ein_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.in]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ein_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ein-3"></a>
<p>Temporarily indent the next output line by <var class="var">offset</var>.  If an
increment or decrement value is specified, adjust the temporary
indentation relative to the value set by the <code class="code">in</code> request.
</p>
<p>This request causes a break; its value is associated with the
environment (see <a class="pxref" href="#Environments">Environments</a>).  The default scaling unit is
&lsquo;<samp class="samp">m</samp>&rsquo;.  A call of <code class="code">ti</code> without an argument is ignored.
</p>
<p>If the total indentation value is negative (which is not allowed),
<code class="code">gtroff</code> emits a warning in category &lsquo;<samp class="samp">range</samp>&rsquo; and sets the
temporary indentation to zero.  &lsquo;Total indentation&rsquo; is either
<var class="var">offset</var> if specified as an absolute value, or the temporary plus
normal indentation, if <var class="var">offset</var> is given as a relative value.
</p>
<p>The effect of <code class="code">ti</code> is delayed until a partially collected line (if
it exists) is output.
</p>
<p>The read-only register <code class="code">.in</code> is the indentation that applies to the
current output line.
</p>
<p>The difference between <code class="code">.i</code> and <code class="code">.in</code> is that the latter takes
into account whether a partially collected line still uses the old
indentation value or a temporary indentation value is active.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ell"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ll</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">length</i></span>]</var><a class="copiable-link" href='#index-_002ell'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ll-1"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002ell-1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ll</code></strong> <var class="def-var-arguments"><code class="t">+</code><span class="r"><i class="slanted">length</i></span></var><a class="copiable-link" href='#index-_002ell-1'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_002ell-2"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ll</code></strong> <var class="def-var-arguments"><code class="t">-</code><span class="r"><i class="slanted">length</i></span></var><a class="copiable-link" href='#index-_002ell-2'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002el_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.l]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002el_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002el"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ell_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.ll]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ell_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ell-3"></a>
<p>Set the line length to <var class="var">length</var> (or increment or decrement the
current value by <var class="var">length</var>).  Initially, the line length is set to
6.5<span class="dmn">i</span>.  The effect of <code class="code">ll</code> is delayed until a partially
collected line (if it exists) is output.  The default scaling unit is
&lsquo;<samp class="samp">m</samp>&rsquo;.
</p>
<p>If <code class="code">ll</code> is called without an argument, the line length is reset to
the previous value before the last call to <code class="code">ll</code>.  If a negative
line length is specified (which is not allowed), <code class="code">gtroff</code> emits a
warning in category &lsquo;<samp class="samp">range</samp>&rsquo; and sets the line length to zero.  The
line length is associated with the environment (see <a class="pxref" href="#Environments">Environments</a>).
</p>
<a class="index-entry-id" id="index-line-length-register-_0028_002el_0029"></a>
<p>The current line length (as set by <code class="code">ll</code>) can be found in the
read-only register &lsquo;<samp class="samp">.l</samp>&rsquo;.  The read-only register <code class="code">.ll</code> is the
line length that applies to the current output line.
</p>
<p>Similar to <code class="code">.i</code> and <code class="code">.in</code>, the difference between <code class="code">.l</code>
and <code class="code">.ll</code> is that the latter takes into account whether a partially
collected line still uses the old line length value.
</p></dd></dl>



<hr>
</div>
<div class="section-level-extent" id="Line-Continuation">
<div class="nav-panel">
<p>
Next: <a href="#Page-Layout" accesskey="n" rel="next">Page Layout</a>, Previous: <a href="#Line-Layout" accesskey="p" rel="prev">Line Layout</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Line-Continuation-1">5.16 Line Continuation</h3>
<a class="index-entry-id" id="index-line-control"></a>
<a class="index-entry-id" id="index-control_002c-line"></a>

<p>When filling is enabled, input and output line breaks generally do not
correspond.  The <code class="code">roff</code> language therefore distinguishes input and
output line continuation.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cRET-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\<kbd class="key">RET</kbd></code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cRET-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cRET"></a>
<a class="index-entry-id" id="index-input-line-continuation-_0028_005cRET_0029"></a>
<a class="index-entry-id" id="index-line_002c-input_002c-continuation-_0028_005cRET_0029"></a>
<a class="index-entry-id" id="index-continuation_002c-input-line-_0028_005cRET_0029"></a>
<a class="index-entry-id" id="index-_005cnewline"></a>
<p><code class="code">\<kbd class="key">RET</kbd></code> (a backslash immediately followed by a newline)
suppresses the effects of that newline in the input.  The next input
line thus retains the classification of its predecessor as a control or
text line.  <code class="code">\<kbd class="key">RET</kbd></code> is useful for managing line lengths in the
input during document maintenance; you can break an input line in the
middle of a request invocation, macro call, or escape sequence.  Input
line continuation is invisible to the formatter, with two exceptions:
the <code class="code">|</code> operator recognizes the new input line
(see <a class="pxref" href="#Numeric-Expressions">Numeric Expressions</a>), and the input line counter register
<code class="code">.c</code> is incremented.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ll 50n
.de I
.  ft I
.  nop \\$*
.  ft
..
Our film class watched
.I The Effect of Gamma Rays on Man-in-the-Moon
Marigolds. \&quot; whoops, the input line wrapped
.br
.I My own opus begins on line \n[.c] \
and ends on line \n[.c].
</pre></div></div>
<div class="example">
<div class="group"><pre class="example-preformatted">    &rArr; Our film class watched <i class="i">The Effect of Gamma Rays on</i>
    &rArr; <i class="i">Man-in-the-Moon</i> Marigolds.
    &rArr; <i class="i">My own opus begins on line 11 and ends on line 12.</i>
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cc-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\c</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cc-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cc"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002eint_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.int]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002eint_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002eint"></a>
<a class="index-entry-id" id="index-output-line_002c-continuation-_0028_005cc_0029"></a>
<a class="index-entry-id" id="index-line_002c-output_002c-continuation-_0028_005cc_0029"></a>
<a class="index-entry-id" id="index-continuation_002c-output-line-_0028_005cc_0029"></a>
<a class="index-entry-id" id="index-interrupted-line"></a>
<a class="index-entry-id" id="index-line_002c-interrupted"></a>
<a class="index-entry-id" id="index-_005cR_002c-after-_005cc"></a>
<p><code class="code">\c</code> continues an output line.  Nothing after it on the input line
is formatted.  In contrast to <code class="code">\<kbd class="key">RET</kbd></code>, a line after <code class="code">\c</code>
remains a new input line, so a control character is recognized at its
beginning.  The visual results depend on whether filling is enabled; see
<a class="ref" href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a>.
</p>
<ul class="itemize mark-bullet">
<li><a class="index-entry-id" id="index-_005cc_002c-when-filling-enabled"></a>
<a class="index-entry-id" id="index-fill-mode_002c-and-_005cc"></a>
<a class="index-entry-id" id="index-mode_002c-fill_002c-and-_005cc"></a>
If filling is enabled, a word interrupted with <code class="code">\c</code> is continued
with the text on the next input text line, without an intervening space.

<div class="example">
<div class="group"><pre class="example-preformatted">This is a te\c
st.
    &rArr; This is a test.
</pre></div></div>

</li><li><a class="index-entry-id" id="index-_005cc_002c-when-filling-disabled"></a>
<a class="index-entry-id" id="index-no_002dfill-mode_002c-and-_005cc"></a>
<a class="index-entry-id" id="index-mode_002c-no_002dfill_002c-and-_005cc"></a>
If filling is disabled, the next input text line after <code class="code">\c</code> is
handled as a continuation of the same input text line.

<div class="example">
<div class="group"><pre class="example-preformatted">.nf
This is a \c
test.
    &rArr; This is a test.
</pre></div></div>
</li></ul>

<p>An intervening control line that causes a break overrides <code class="code">\c</code>,
flushing out the pending output line in the usual way.
</p>
<a class="index-entry-id" id="index-interrupted-line-register-_0028_002eint_0029"></a>
<a class="index-entry-id" id="index-continued-output-line-register-_0028_002eint_0029"></a>
<p>The <code class="code">.int</code> register contains a positive value if the last output
line was continued with <code class="code">\c</code>; this datum is associated with the
environment (see <a class="pxref" href="#Environments">Environments</a>).<a class="footnote" id="DOCF69" href="#FOOT69"><sup>69</sup></a>
</p></dd></dl>



<hr>
</div>
<div class="section-level-extent" id="Page-Layout">
<div class="nav-panel">
<p>
Next: <a href="#Page-Control" accesskey="n" rel="next">Page Control</a>, Previous: <a href="#Line-Continuation" accesskey="p" rel="prev">Line Continuation</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Page-Layout-2">5.17 Page Layout</h3>
<a class="index-entry-id" id="index-page-layout"></a>
<a class="index-entry-id" id="index-layout_002c-page"></a>

<p>The formatter permits configuration of the page length and page number.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002epl"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.pl</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">length</i></span>]</var><a class="copiable-link" href='#index-_002epl'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-pl"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002epl-1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.pl</code></strong> <var class="def-var-arguments"><code class="t">+</code><span class="r"><i class="slanted">length</i></span></var><a class="copiable-link" href='#index-_002epl-1'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_002epl-2"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.pl</code></strong> <var class="def-var-arguments"><code class="t">-</code><span class="r"><i class="slanted">length</i></span></var><a class="copiable-link" href='#index-_002epl-2'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ep_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.p]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ep_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ep"></a>
<a class="index-entry-id" id="index-page-length_002c-configuring-_0028pl_0029"></a>
<a class="index-entry-id" id="index-length-of-the-page_002c-configuring-_0028pl_0029"></a>
<a class="index-entry-id" id="index-configuring-the-page-length-_0028pl_0029"></a>
<a class="index-entry-id" id="index-setting-the-page-length-_0028pl_0029"></a>
<p>Change (increase or decrease) the page length per the numeric expression
<var class="var">length</var>.  The default scaling unit is &lsquo;<samp class="samp">v</samp>&rsquo;.  A negative
<var class="var">length</var> is valid, but an uncommon application: it prevents page
location traps from being sprung,<a class="footnote" id="DOCF70" href="#FOOT70"><sup>70</sup></a> and each
output line is placed on a new page.  If <var class="var">length</var> is invalid, GNU
<code class="code">troff</code> emits a warning in category &lsquo;<samp class="samp">number</samp>&rsquo;.  If <var class="var">length</var>
is absent or invalid, &lsquo;<samp class="samp">11i</samp>&rsquo; is assumed.
</p>
<a class="index-entry-id" id="index-page-length-register-_0028_002ep_0029"></a>
<p>The read-only register &lsquo;<samp class="samp">.p</samp>&rsquo; interpolates the current page length.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002epn"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.pn</code></strong> <var class="def-var-arguments">num</var><a class="copiable-link" href='#index-_002epn'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-pn"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002epn-1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.pn</code></strong> <var class="def-var-arguments"><code class="t">+</code><span class="r"><i class="slanted">num</i></span></var><a class="copiable-link" href='#index-_002epn-1'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_002epn-2"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.pn</code></strong> <var class="def-var-arguments"><code class="t">-</code><span class="r"><i class="slanted">num</i></span></var><a class="copiable-link" href='#index-_002epn-2'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002epn_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.pn]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002epn_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002epn-3"></a>
<a class="index-entry-id" id="index-page-number_002c-configuring-next-_0028pn_0029"></a>
<a class="index-entry-id" id="index-next-page-number_002c-configuring-_0028pn_0029"></a>
<a class="index-entry-id" id="index-number_002c-page_002c-next_002c-configuring-_0028pn_0029"></a>
<p>Change (increase or decrease) the page number of the <em class="emph">next</em> page
per the numeric expression <var class="var">num</var>.  If <var class="var">num</var> is invalid, GNU
<code class="code">troff</code> emits a warning in category &lsquo;<samp class="samp">number</samp>&rsquo; and ignores the
request.  Without an argument, <code class="code">pn</code> is ignored.
</p>
<a class="index-entry-id" id="index-next-page-number-register-_0028_002epn_0029"></a>
<a class="index-entry-id" id="index-page-number_002c-next_002c-register-_0028_002epn_0029"></a>
<p>The read-only register <code class="code">.pn</code> interpolates <var class="var">num</var> if set by
<code class="code">pn</code> on the current page, or the current page number plus&nbsp;1.
</p></dd></dl>

<a class="index-entry-id" id="index-headers"></a>
<a class="index-entry-id" id="index-footers"></a>
<a class="index-entry-id" id="index-titles"></a>
<p>The formatter offers special support for typesetting headers and
footers, collectively termed <em class="dfn">titles</em>.  Titles have an independent
line length, and their placement on the page is not restricted.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002etl"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.tl</code></strong> <var class="def-var-arguments"><code class="code">'</code><span class="r"><i class="slanted">left</i></span><code class="code">'</code><span class="r"><i class="slanted">center</i></span><code class="code">'</code><span class="r"><i class="slanted">right</i></span><code class="code">'</code></var><a class="copiable-link" href='#index-_002etl'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-tl"></a>
<a class="index-entry-id" id="index-title-line_002c-formatting-_0028tl_0029"></a>
<a class="index-entry-id" id="index-formatting-a-title-line-_0028tl_0029"></a>
<a class="index-entry-id" id="index-three_002dpart-title-_0028tl_0029"></a>
<a class="index-entry-id" id="index-page-number-character-_0028_0025_0029"></a>
<p>Format an output line as a title consisting of <var class="var">left</var>, <var class="var">center</var>,
and <var class="var">right</var>, each aligned accordingly.  The delimiter need not be a
neutral apostrophe: <code class="code">tl</code> accepts the same delimiters as most escape
sequences; see <a class="ref" href="#Delimiters">Delimiters</a>.  If not used as the delimiter, any
<em class="dfn">page number character</em> character is replaced with the current page
number; the default is &lsquo;<samp class="samp">%</samp>&rsquo;; see the the <code class="code">pc</code> request below.
Without an argument, <code class="code">tl</code> is ignored.  <code class="code">tl</code> writes the title
line immediately, ignoring any partially collected line.
</p>
<p>It is not an error to omit delimiters after the first.  For example,
&lsquo;<samp class="samp">.tl&nbsp;/Thesis</samp>&rsquo;<!-- /@w --> is interpreted as &lsquo;<samp class="samp">.tl&nbsp;/Thesis///</samp>&rsquo;<!-- /@w -->: it
sets a title line comprising only the left-aligned word &lsquo;<samp class="samp">Thesis</samp>&rsquo;.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002elt"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.lt</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">length</i></span>]</var><a class="copiable-link" href='#index-_002elt'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-lt"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002elt-1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.lt</code></strong> <var class="def-var-arguments"><code class="t">+</code><span class="r"><i class="slanted">length</i></span></var><a class="copiable-link" href='#index-_002elt-1'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_002elt-2"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.lt</code></strong> <var class="def-var-arguments"><code class="t">-</code><span class="r"><i class="slanted">length</i></span></var><a class="copiable-link" href='#index-_002elt-2'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002elt_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.lt]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002elt_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002elt-3"></a>
<a class="index-entry-id" id="index-length-of-title-line_002c-configuring-_0028lt_0029"></a>
<a class="index-entry-id" id="index-title-length_002c-configuring-_0028lt_0029"></a>
<p>Change (increase or decrease) the line length used by titles per the
numeric expression <var class="var">length</var>.  The default scaling unit is &lsquo;<samp class="samp">m</samp>&rsquo;.
If <var class="var">length</var> is negative, GNU emits a warning in category
&lsquo;<samp class="samp">range</samp>&rsquo; and treats <var class="var">length</var> as &lsquo;<samp class="samp">0</samp>&rsquo;.  If <var class="var">length</var> is
invalid, GNU <code class="code">troff</code> emits a warning in category &lsquo;<samp class="samp">number</samp>&rsquo; and
ignores the request.  The formatter&rsquo;s default title length is
&lsquo;<samp class="samp">6.5i</samp>&rsquo;.  With no argument, the title length is restored to the
previous value.  The title length is is associated with the environment
(see <a class="pxref" href="#Environments">Environments</a>).
</p>
<a class="index-entry-id" id="index-title-line-length-register-_0028_002elt_0029"></a>
<p>The read-only register &lsquo;<samp class="samp">.lt</samp>&rsquo; interpolates the title line length.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002epc"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.pc</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">char</i></span>]</var><a class="copiable-link" href='#index-_002epc'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-pc"></a>
<a class="index-entry-id" id="index-changing-the-page-number-character-_0028pc_0029"></a>
<a class="index-entry-id" id="index-page-number-character_002c-changing-_0028pc_0029"></a>
<a class="index-entry-id" id="index-_0025-1"></a>
<p>Set the page number character to <var class="var">char</var>.  With no argument, the page
number character is disabled.  <code class="code">pc</code> does not affect the
register&nbsp;<code class="code">%</code>.
</p></dd></dl>

<p>The following example exercises title features.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.lt 50n
This is my partially collected
.tl 'Isomers 2023'%'Dextrose Edition'
line.
    &rArr; Isomers 2023             1        Dextrose Edition
    &rArr; This is my partially collected line.
</pre></div></div>

<p>We most often see titles used in page header and footer traps.
See <a class="xref" href="#Traps">Traps</a>.
</p>

<hr>
</div>
<div class="section-level-extent" id="Page-Control">
<div class="nav-panel">
<p>
Next: <a href="#Using-Fonts" accesskey="n" rel="next">Using Fonts</a>, Previous: <a href="#Page-Layout" accesskey="p" rel="prev">Page Layout</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Page-Control-1">5.18 Page Control</h3>
<a class="index-entry-id" id="index-page-control"></a>
<a class="index-entry-id" id="index-control_002c-page"></a>

<a class="index-entry-id" id="index-page-break-1"></a>
<a class="index-entry-id" id="index-break_002c-page-1"></a>
<a class="index-entry-id" id="index-page-ejection-1"></a>
<a class="index-entry-id" id="index-ejection_002c-page-1"></a>
<p>Discretionary page breaks can prevent the unwanted separation of
content.  A new page number takes effect during page ejection; see
<a class="ref" href="#The-Implicit-Page-Trap">The Implicit Page Trap</a>.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002ebp"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.bp</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">page-number</i></span>]</var><a class="copiable-link" href='#index-_002ebp'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-bp"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002ebp-1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.bp</code></strong> <var class="def-var-arguments"><code class="t">+</code><span class="r"><i class="slanted">page-number</i></span></var><a class="copiable-link" href='#index-_002ebp-1'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_002ebp-2"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.bp</code></strong> <var class="def-var-arguments"><code class="t">-</code><span class="r"><i class="slanted">page-number</i></span></var><a class="copiable-link" href='#index-_002ebp-2'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_0025_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[%]</code></strong><a class="copiable-link" href='#index-_005cn_005b_0025_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_0025-2"></a>
<a class="index-entry-id" id="index-new-page-_0028bp_0029"></a>
<a class="index-entry-id" id="index-page_002c-new-_0028bp_0029"></a>
<p>Break the page and change (increase or decrease) the next page number
per the numeric expression <var class="var">page-number</var>.  If <var class="var">page-number</var> is
invalid, GNU <code class="code">troff</code> emits a warning in category &lsquo;<samp class="samp">number</samp>&rsquo; and
ignores the argument.  This request causes a break.  A page break
advances the vertical drawing position to the bottom of the page,
springing traps.  See <a class="xref" href="#Page-Location-Traps">Page Location Traps</a>.
<a class="index-entry-id" id="index-bp-request_002c-and-top_002dlevel-diversion"></a>
<a class="index-entry-id" id="index-top_002dlevel-diversion_002c-and-bp"></a>
<a class="index-entry-id" id="index-diversion_002c-top_002dlevel_002c-and-bp"></a>
<code class="code">bp</code> has effect only if invoked within the top-level
diversion.<a class="footnote" id="DOCF71" href="#FOOT71"><sup>71</sup></a>
<a class="index-entry-id" id="index-CSTR-_002354-errata-2"></a>
<a class="index-entry-id" id="index-CSTR-_002354-erratum_002c-bp-request"></a>
This request is incorrectly documented in the <abbr class="acronym">AT&amp;T</abbr>
<code class="code">troff</code> manual as having a default scaling unit of &lsquo;<samp class="samp">v</samp>&rsquo;.
</p>
<a class="index-entry-id" id="index-page-number-register-_0028_0025_0029"></a>
<a class="index-entry-id" id="index-current-page-number-_0028_0025_0029"></a>
<p>The register <code class="code">%</code> interpolates the current page number.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de BP
'  bp \&quot; schedule page break once current line is output
..
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ene"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ne</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">space</i></span>]</var><a class="copiable-link" href='#index-_002ene'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ne"></a>
<a class="index-entry-id" id="index-orphan-lines_002c-preventing-with-ne"></a>
<a class="index-entry-id" id="index-conditional-page-break-_0028ne_0029"></a>
<a class="index-entry-id" id="index-page-break_002c-conditional-_0028ne_0029"></a>
<p>Force a page break if insufficient vertical space is available (assert
&ldquo;needed&rdquo; space).  <code class="code">ne</code> tests the distance to the next page
location trap; see <a class="ref" href="#Page-Location-Traps">Page Location Traps</a>, and breaks the page if
that amount is less than <var class="var">space</var>.  The default scaling unit is
&lsquo;<samp class="samp">v</samp>&rsquo;.  If <var class="var">space</var> is invalid, GNU <code class="code">troff</code> emits a warning
in category &lsquo;<samp class="samp">number</samp>&rsquo; and ignores the argument.  If <var class="var">space</var> is
not specified, &lsquo;<samp class="samp">1v</samp>&rsquo; is assumed.
</p>
<a class="index-entry-id" id="index-widow"></a>
<p>We can require space for at least the first two output lines of a
paragraph, preventing its first line from being <i class="slanted">widowed</i> at the
page bottom.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ne 2v
Considering how common illness is,
how tremendous the spiritual change that it brings,
how astonishing,
when the lights of health go down,
the undiscovered countries that are then disclosed,
what wastes and deserts of the soul a slight attack
of influenza brings to view,
</pre></div></div>

<p>This method is reliable only if no output line is pending when <code class="code">ne</code>
is invoked.  When macro packages are used, this is often not the case:
their paragraphing macros perform the break.  You may need to experiment
with placing the <code class="code">ne</code> after the paragraphing macro, or <code class="code">br</code>
and <code class="code">ne</code> before it.
</p>
<a class="index-entry-id" id="index-orphan"></a>
<a class="index-entry-id" id="index-widow-1"></a>
<p><code class="code">ne</code> is also useful to force grouping of section headings with
their subsequent paragraphs, or tables with their captions and/or
explanations.  Macro packages often use <code class="code">ne</code> with diversions to
implement keeps and displays; see <a class="ref" href="#Diversions">Diversions</a>.  They may also offer
parameters for widow and orphan management.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002esv"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.sv</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">space</i></span>]</var><a class="copiable-link" href='#index-_002esv'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-sv"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002eos"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.os</code></strong><a class="copiable-link" href='#index-_002eos'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-os"></a>
<a class="index-entry-id" id="index-ne-request_002c-comparison-with-sv"></a>
<p>Require vertical space as <code class="code">ne</code> does, but also <i class="slanted">save</i> it for
later output by the <code class="code">os</code> request.  If <var class="var">space</var> is available
before the next page location trap, it is output immediately.  Both
requests ignore a partially collected line, taking effect at the next
break.
<a class="index-entry-id" id="index-sv-request_002c-and-no_002dspace-mode"></a>
<a class="index-entry-id" id="index-os-request_002c-and-no_002dspace-mode"></a>
<code class="code">sv</code> and <code class="code">os</code> ignore no-space mode (recall <a class="ref" href="#Manipulating-Spacing">Manipulating Spacing</a>).  While the <code class="code">sv</code> request allows negative values for
<var class="var">space</var>, <code class="code">os</code> ignores them.  The default scaling unit is
&lsquo;<samp class="samp">v</samp>&rsquo;.  If <var class="var">space</var> is not specified, &lsquo;<samp class="samp">1v</samp>&rsquo; is assumed.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bnl_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[nl]</code></strong><a class="copiable-link" href='#index-_005cn_005bnl_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-nl"></a>
<a class="index-entry-id" id="index-vertical-drawing-position-_0028nl_0029"></a>
<a class="index-entry-id" id="index-vertical-position_002c-drawing-_0028nl_0029"></a>
<a class="index-entry-id" id="index-drawing-position_002c-vertical-_0028nl_0029"></a>
<p><code class="code">nl</code> interpolates or sets the vertical drawing position.  When the
formatter starts, the first page transition hasn&rsquo;t happened yet, and
<code class="code">nl</code> is negative.  If a header trap has been planted on the page
(typically at vertical position <code class="code">0</code>), you can assign a negative
value to <code class="code">nl</code> to spring it if that page has already started
(see <a class="pxref" href="#Page-Location-Traps">Page Location Traps</a>).
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de HD
.  sp
.  tl ''Goldbach Solution''
.  sp
..
.
First page.
.bp
.wh 0 HD \&quot; plant header trap at top of page
.nr nl (-1)
Second page.
    &rArr; First page.
    &rArr;
    &rArr; <span class="r"><i class="i">(blank lines elided)</i></span>
    &rArr;
    &rArr;                         Goldbach Solution
    &rArr;
    &rArr; <span class="r"><i class="i">(blank lines elided)</i></span>
    &rArr;
    &rArr; Second page.
</pre></div></div>

<p>Without resetting <code class="code">nl</code> to a negative value, the trap just planted
would be active beginning with the <em class="emph">next</em> page, not the current
one.
</p>
<p>See <a class="xref" href="#Diversions">Diversions</a>, for a comparison of <code class="code">nl</code> with the <code class="code">.h</code> and
<code class="code">.d</code> registers.
</p></dd></dl>



<hr>
</div>
<div class="section-level-extent" id="Using-Fonts">
<div class="nav-panel">
<p>
Next: <a href="#Manipulating-Type-Size-and-Vertical-Spacing" accesskey="n" rel="next">Manipulating Type Size and Vertical Spacing</a>, Previous: <a href="#Page-Control" accesskey="p" rel="prev">Page Control</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Using-Fonts-1">5.19 Using Fonts</h3>
<a class="index-entry-id" id="index-font"></a>

<a class="index-entry-id" id="index-typeface"></a>
<a class="index-entry-id" id="index-font-family"></a>
<a class="index-entry-id" id="index-font-style"></a>
<a class="index-entry-id" id="index-style_002c-font"></a>
<a class="index-entry-id" id="index-family_002c-font"></a>
<a class="index-entry-id" id="index-text-font"></a>
<a class="index-entry-id" id="index-special-font"></a>
<a class="index-entry-id" id="index-unstyled-font"></a>
<a class="index-entry-id" id="index-font_002c-text"></a>
<a class="index-entry-id" id="index-font_002c-special"></a>
<a class="index-entry-id" id="index-font_002c-unstyled"></a>
<p>In digital typography, a <em class="dfn">font</em> is a collection of characters in a
specific typeface that a device can render as glyphs at a desired
size.<a class="footnote" id="DOCF72" href="#FOOT72"><sup>72</sup></a>  A <code class="code">roff</code> formatter can change typefaces at any
point in the text.  The basic faces are a set of <em class="dfn">styles</em> combining
upright and slanted shapes with normal and heavy stroke weights:
&lsquo;<samp class="samp">R</samp>&rsquo;, &lsquo;<samp class="samp">I</samp>&rsquo;, &lsquo;<samp class="samp">B</samp>&rsquo;, and &lsquo;<samp class="samp">BI</samp>&rsquo;&mdash;these stand for
<i class="slanted">roman</i>, <i class="slanted">italic</i>, <i class="slanted">bold</i>, and
<i class="slanted">bold-italic</i>.  For linguistic text, GNU <code class="code">troff</code> groups
typefaces into <em class="dfn">families</em> containing each of these
styles.<a class="footnote" id="DOCF73" href="#FOOT73"><sup>73</sup></a>  A <em class="dfn">text font</em> is thus often a family
combined with a style, but it need not be: consider the <code class="code">ps</code> and
<code class="code">pdf</code> devices&rsquo; <code class="code">ZCMI</code> (Zapf Chancery Medium italic)&mdash;often,
no other style of Zapf Chancery Medium is provided.  On typesetting
devices, at least one <em class="dfn">special font</em> is available, comprising
<em class="dfn">unstyled</em> glyphs for mathematical operators and other purposes.
</p>
<a class="index-entry-id" id="index-font-description-file"></a>
<a class="index-entry-id" id="index-description-file_002c-font"></a>
<a class="index-entry-id" id="index-file_002c-font-description"></a>
<a class="index-entry-id" id="index-font-metrics"></a>
<a class="index-entry-id" id="index-metrics_002c-font"></a>
<a class="index-entry-id" id="index-mounting-position"></a>
<a class="index-entry-id" id="index-mounting-position-1"></a>
<a class="index-entry-id" id="index-position_002c-mounting"></a>
<p>Like <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>, GNU <code class="code">troff</code> does not itself load
or manipulate a digital font file;<a class="footnote" id="DOCF74" href="#FOOT74"><sup>74</sup></a> instead it
works with a <em class="dfn">font description file</em> that characterizes it,
including its glyph repertoire and the <em class="dfn">metrics</em> (dimensions) of
each glyph.<a class="footnote" id="DOCF75" href="#FOOT75"><sup>75</sup></a>  This
information permits the formatter to accurately place glyphs with
respect to each other.  Before using a font description, the formatter
associates it with a <em class="dfn">mounting position</em>, a place in an ordered list
of available typefaces.
<a class="index-entry-id" id="index-abstract-font-style"></a>
<a class="index-entry-id" id="index-font-style_002c-abstract"></a>
<a class="index-entry-id" id="index-style_002c-font_002c-abstract"></a>
So that a document need not be strongly coupled to a specific font
family, in GNU <code class="code">troff</code> an output device can associate a style in
the abstract sense with a mounting position.  Thus the default family
can be combined with a style dynamically, producing a <em class="dfn">resolved font
name</em>.
</p>
<p>Fonts often have trademarked names, and even Free Software fonts can
require renaming upon modification.  <code class="code">groff</code> maintains a
convention that a device&rsquo;s serif font family is given the name &lsquo;<samp class="samp">T</samp>&rsquo;
(&ldquo;Times&rdquo;), its sans-serif family &lsquo;<samp class="samp">H</samp>&rsquo; (&ldquo;Helvetica&rdquo;), and its
monospaced family &lsquo;<samp class="samp">C</samp>&rsquo; (&ldquo;Courier&rdquo;).  Historical inertia has driven
<code class="code">groff</code>&rsquo;s font identifiers to short uppercase abbreviations of font
names, as with &lsquo;<samp class="samp">TR</samp>&rsquo;, &lsquo;<samp class="samp">TI</samp>&rsquo;, &lsquo;<samp class="samp">TB</samp>&rsquo;, &lsquo;<samp class="samp">TBI</samp>&rsquo;, and a
special font &lsquo;<samp class="samp">S</samp>&rsquo;.
</p>
<p>The default family used with abstract styles can be changed at any time;
initially, it is &lsquo;<samp class="samp">T</samp>&rsquo;.  Typically, abstract styles are arranged in
the first four mounting positions in the order shown above.  The default
mounting position, and therefore style, is always &lsquo;<samp class="samp">1</samp>&rsquo; (&lsquo;<samp class="samp">R</samp>&rsquo;).
By issuing appropriate formatter instructions, you can override these
defaults before your document writes its first glyph.
</p>
<a class="index-entry-id" id="index-graphic-renditions"></a>
<a class="index-entry-id" id="index-renditions_002c-graphic"></a>
<a class="index-entry-id" id="index-character-cell-attributes"></a>
<a class="index-entry-id" id="index-attributes_002c-character-cell"></a>
<a class="index-entry-id" id="index-cell_002c-character_002c-attributes"></a>
<p>Terminal output devices cannot change font families and lack special
fonts.  They support style changes by overstriking, or by altering
ISO&nbsp;6429/ECMA-48 <em class="dfn">graphic renditions</em> (character cell
attributes).
</p>


<ul class="mini-toc">
<li><a href="#Selecting-Fonts" accesskey="1">Selecting Fonts</a></li>
<li><a href="#Font-Families" accesskey="2">Font Families</a></li>
<li><a href="#Font-Positions" accesskey="3">Font Positions</a></li>
<li><a href="#Using-Symbols" accesskey="4">Using Symbols</a></li>
<li><a href="#Character-Classes" accesskey="5">Character Classes</a></li>
<li><a href="#Special-Fonts" accesskey="6">Special Fonts</a></li>
<li><a href="#Artificial-Fonts" accesskey="7">Artificial Fonts</a></li>
<li><a href="#Ligatures-and-Kerning" accesskey="8">Ligatures and Kerning</a></li>
<li><a href="#Italic-Corrections" accesskey="9">Italic Corrections</a></li>
<li><a href="#Dummy-Characters">Dummy Characters</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="Selecting-Fonts">
<div class="nav-panel">
<p>
Next: <a href="#Font-Families" accesskey="n" rel="next">Font Families</a>, Previous: <a href="#Using-Fonts" accesskey="p" rel="prev">Using Fonts</a>, Up: <a href="#Using-Fonts" accesskey="u" rel="up">Using Fonts</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Selecting-Fonts-1">5.19.1 Selecting Fonts</h4>
<a class="index-entry-id" id="index-font_002c-selection"></a>

<p>We use <em class="dfn">font</em> to refer to any of several means of identifying a
font: by mounting position (&lsquo;<samp class="samp">3</samp>&rsquo;), by abstract style (&lsquo;<samp class="samp">B</samp>&rsquo;), or
by its identifier (&lsquo;<samp class="samp">TB</samp>&rsquo;).
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002eft"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ft</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">font</i></span>]</var><a class="copiable-link" href='#index-_002eft'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ft"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cff"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\f</code><span class="r"><i class="slanted">f</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cff'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cf"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cf_0028fn"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\f(</code><span class="r"><i class="slanted">fn</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cf_0028fn'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cf_005bfont_005d"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\f[</code><span class="r"><i class="slanted">font</i></span><code class="t">]</code></strong><a class="copiable-link" href='#index-_005cf_005bfont_005d'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002efn_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.fn]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002efn_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002efn"></a>
<a class="index-entry-id" id="index-changing-fonts-_0028ft_002c-_005cf_0029"></a>
<a class="index-entry-id" id="index-fonts_002c-changing-_0028ft_002c-_005cf_0029"></a>
<a class="index-entry-id" id="index-sty-request_002c-and-changing-fonts"></a>
<a class="index-entry-id" id="index-fam-request_002c-and-changing-fonts"></a>
<a class="index-entry-id" id="index-_005cF_002c-and-changing-fonts"></a>
<a class="index-entry-id" id="index-styles"></a>
<a class="index-entry-id" id="index-family"></a>
<a class="index-entry-id" id="index-DESC"></a>
<a class="index-entry-id" id="index-selecting-the-previous-font-_0028ft_0029"></a>
<a class="index-entry-id" id="index-previous-font_002c-selecting-_0028ft_0029"></a>
<a class="index-entry-id" id="index-font_002c-previous_002c-slecting-_0028ft_0029"></a>
<p>The <code class="code">ft</code> request selects the typeface <var class="var">font</var>.  If the argument
is absent or &lsquo;<samp class="samp">P</samp>&rsquo;, it selects the previously chosen font.  If
<var class="var">font</var> is a non-negative integer, it is interpreted as mounting
position; the font mounted there is selected.  If that position refers
to an abstract style, it is combined with the default family (see
<code class="code">fam</code> and <code class="code">\F</code> below) to make a resolved font name.  If the
mounting position is not a style and no font is mounted there, GNU
<code class="code">troff</code> emits a warning in category &lsquo;<samp class="samp">font</samp>&rsquo; and ignores the
request.
</p>
<p>If <var class="var">font</var> matches a style name, it is combined with the current
family to make a resolved font name.  Otherwise, <var class="var">font</var> is assumed
to already be a resolved font name.
</p>
<a class="index-entry-id" id="index-automatic-font-mounting"></a>
<a class="index-entry-id" id="index-font-mounting_002c-automatic"></a>
<a class="index-entry-id" id="index-mounting_002c-font_002c-automatic"></a>
<p>The resolved font name is subject to translation (see request <code class="code">ftr</code>
below).  Next, the (possibly translated) font name&rsquo;s mounting position
is looked up; if not mounted, <var class="var">font</var> is sought on the file system as
a font description file and, if located, automatically mounted at the
next available position (see register <code class="code">.fp</code> below).  If the font
was mounted using an identifier different from its font description file
name (see request <code class="code">fp</code> below), that file name is then looked up.
If a font description file for the resolved font name is not found, GNU
<code class="code">troff</code> emits a warning in category &lsquo;<samp class="samp">font</samp>&rsquo; and ignores the
request.
</p>
<p>The <code class="code">\f</code> escape sequence is similar, using one-character name (or
mounting position) <var class="var">f</var>, two-character name <var class="var">fn</var>, or a name
<var class="var">font</var> of arbitrary length.
<a class="index-entry-id" id="index-previous-font_002c-selecting-_0028_005cf_005b_005d_002c-_005cfP_0029"></a>
<a class="index-entry-id" id="index-font_002c-previous_002c-selecting-_0028_005cf_005b_005d_002c-_005cfP_0029"></a>
&lsquo;<samp class="samp">\f[]</samp>&rsquo; selects the previous font.  The syntax form &lsquo;<samp class="samp">\fP</samp>&rsquo; is
supported for backward compatibility, and &lsquo;<samp class="samp">\f[P]</samp>&rsquo; for consistency.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">eggs, bacon,
.ft I
spam,
.ft
and sausage.
.br
eggs, bacon, \fIspam,\fP and sausage.
    &rArr; eggs, bacon, <i class="slanted">spam,</i> and sausage
    &rArr; eggs, bacon, <i class="slanted">spam,</i> and sausage
</pre></div></div>

<p>The current and previously selected fonts are properties of the
environment (see <a class="pxref" href="#Environments">Environments</a>).
</p>
<p>The read-only string-valued register <code class="code">.fn</code> contains the resolved
font name of the selected font.
</p>
<p><code class="code">\f</code> doesn&rsquo;t produce an input token in GNU <code class="code">troff</code>; it thus
can be used in requests that expect a single-character argument.  We can
assign a font to a margin character as follows (see <a class="pxref" href="#Miscellaneous">Miscellaneous</a>).
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.mc \f[I]x\f[]
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eftr"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ftr</code></strong> <var class="def-var-arguments">f [<span class="r"><i class="slanted">g</i></span>]</var><a class="copiable-link" href='#index-_002eftr'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ftr"></a>
<a class="index-entry-id" id="index-font-translation-_0028ftr_0029"></a>
<a class="index-entry-id" id="index-ft-request_002c-and-font-translations"></a>
<a class="index-entry-id" id="index-ul-request_002c-and-font-translations"></a>
<a class="index-entry-id" id="index-bd-request_002c-and-font-translations"></a>
<a class="index-entry-id" id="index-_005cf_002c-and-font-translations"></a>
<a class="index-entry-id" id="index-cs-request_002c-and-font-translations"></a>
<a class="index-entry-id" id="index-tkf-request_002c-and-font-translations"></a>
<a class="index-entry-id" id="index-special-request_002c-and-font-translations"></a>
<a class="index-entry-id" id="index-fspecial-request_002c-and-font-translations"></a>
<a class="index-entry-id" id="index-fp-request_002c-and-font-translations"></a>
<a class="index-entry-id" id="index-sty-request_002c-and-font-translations"></a>
<a class="index-entry-id" id="index-if-request_002c-and-font-translations"></a>
<a class="index-entry-id" id="index-ie-request_002c-and-font-translations"></a>
<a class="index-entry-id" id="index-while-request_002c-and-font-translations"></a>
<p>Translate font&nbsp;<var class="var">f</var> to font&nbsp;<var class="var">g</var>.  Whenever a font
named&nbsp;<var class="var">f</var> is referred to in a <code class="code">\f</code> escape sequence, in the
<code class="code">F</code> and <code class="code">S</code> conditional operators, or in the <code class="code">ft</code>,
<code class="code">ul</code>, <code class="code">bd</code>, <code class="code">cs</code>, <code class="code">tkf</code>, <code class="code">special</code>,
<code class="code">fspecial</code>, <code class="code">fp</code>, or <code class="code">sty</code> requests, font&nbsp;<var class="var">g</var> is
used.  If <var class="var">g</var> is missing or equal to&nbsp;<var class="var">f</var> the translation is
undone.
</p>
<p>Font translations cannot be chained.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ftr XXX TR
.ftr XXX YYY
.ft XXX
    error&rarr; warning: can't find font 'XXX'
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002efzoom"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.fzoom</code></strong> <var class="def-var-arguments">f [<span class="r"><i class="slanted">zoom</i></span>]</var><a class="copiable-link" href='#index-_002efzoom'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-fzoom"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ezoom_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.zoom]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ezoom_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ezoom"></a>
<a class="index-entry-id" id="index-magnification-of-a-font-_0028fzoom_0029"></a>
<a class="index-entry-id" id="index-font_002c-magnification-_0028fzoom_0029"></a>
<a class="index-entry-id" id="index-zoom-factor-of-a-font-_0028fzoom_0029"></a>
<a class="index-entry-id" id="index-factor_002c-zoom_002c-of-a-font-_0028fzoom_0029"></a>
<a class="index-entry-id" id="index-font_002c-zoom-factor-_0028fzoom_0029"></a>
<a class="index-entry-id" id="index-optical-size-of-a-font"></a>
<a class="index-entry-id" id="index-font_002c-optical-size"></a>
<a class="index-entry-id" id="index-size_002c-optical_002c-of-a-font"></a>
<p>Set magnification of font&nbsp;<var class="var">f</var> to factor <var class="var">zoom</var>, which must
be a non-negative integer multiple of 1/1000th.  This request is useful
to adjust the optical size of a font in relation to the others.  In the
example below, font <code class="code">CR</code> is magnified by 10% (the zoom factor is
thus 1.1).
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.fam P
.fzoom CR 1100
.ps 12
Palatino and \f[CR]Courier\f[]
</pre></div></div>

<p>A missing or zero value of <var class="var">zoom</var> is the same as a value of 1000,
which means no magnification.  <var class="var">f</var>&nbsp;must be a resolved font
name, not an abstract style.
</p>
<p>The magnification of a font is completely transparent to GNU
<code class="code">troff</code>; a change of the zoom factor doesn&rsquo;t cause any effect
except that the dimensions of glyphs, (word) spaces, kerns, etc., of the
affected font are adjusted accordingly.
</p>
<p>The zoom factor of the current font is available in the read-only
register &lsquo;<samp class="samp">.zoom</samp>&rsquo;, in multiples of 1/1000th.  It returns zero if
there is no magnification.
</p></dd></dl>


<hr>
</div>
<div class="subsection-level-extent" id="Font-Families">
<div class="nav-panel">
<p>
Next: <a href="#Font-Positions" accesskey="n" rel="next">Font Positions</a>, Previous: <a href="#Selecting-Fonts" accesskey="p" rel="prev">Selecting Fonts</a>, Up: <a href="#Using-Fonts" accesskey="u" rel="up">Using Fonts</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Font-Families-1">5.19.2 Font Families</h4>
<a class="index-entry-id" id="index-font-families"></a>
<a class="index-entry-id" id="index-families_002c-font"></a>
<a class="index-entry-id" id="index-font-styles"></a>
<a class="index-entry-id" id="index-styles_002c-font"></a>

<p>To accommodate the wide variety of fonts available, GNU <code class="code">troff</code>
distinguishes <em class="dfn">font families</em> and <em class="dfn">font styles</em>.  A resolved
font name is the catenation of a font family and a style.  Selecting an
abstract style causes GNU <code class="code">troff</code> to combine it with the default
font family.
</p>
<p>You can thus compose a document using abstract styles exclusively for
its body or running text, selecting a specific family only for titles or
examples, for instance, and change the default family on the command
line (recall <a class="ref" href="#Groff-Options">Options</a>).
</p>
<p>Fonts for the devices <code class="code">ps</code>, <code class="code">pdf</code>, <code class="code">dvi</code>, <code class="code">lj4</code>,
<code class="code">lbp</code>, and the X11 devices support this mechanism.  By default,
GNU <code class="code">troff</code> uses the Times family with the four styles &lsquo;<samp class="samp">R</samp>&rsquo;,
&lsquo;<samp class="samp">I</samp>&rsquo;, &lsquo;<samp class="samp">B</samp>&rsquo;, and &lsquo;<samp class="samp">BI</samp>&rsquo;.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002efam"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.fam</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">family</i></span>]</var><a class="copiable-link" href='#index-_002efam'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-fam"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002efam_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.fam]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002efam_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002efam-1"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cFf"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\F</code><span class="r"><i class="slanted">f</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cFf'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cF"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cF_0028fm"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\F(</code><span class="r"><i class="slanted">fm</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cF_0028fm'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cF_005bfamily_005d"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\F[</code><span class="r"><i class="slanted">family</i></span><code class="t">]</code></strong><a class="copiable-link" href='#index-_005cF_005bfamily_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-changing-font-family-_0028fam_002c-_005cF_0029"></a>
<a class="index-entry-id" id="index-font-family_002c-changing-_0028fam_002c-_005cF_0029"></a>
<p>Set the default font family, used in combination with abstract styles to
construct a resolved font name, to <var class="var">family</var> (one-character
name&nbsp;<var class="var">f</var>, two-character name <var class="var">fm</var>).  If no argument is
given, GNU <code class="code">troff</code> selects the previous font family; if there none,
is it falls back to the device&rsquo;s default<a class="footnote" id="DOCF76" href="#FOOT76"><sup>76</sup></a> or its own (&lsquo;<samp class="samp">T</samp>&rsquo;).
</p>
<p>The <code class="code">\F</code> escape sequence works similarly.  In disanalogy to
<code class="code">\f</code>, &lsquo;<samp class="samp">\FP</samp>&rsquo; makes &lsquo;<samp class="samp">P</samp>&rsquo; the default family.  Use
&lsquo;<samp class="samp">\F[]</samp>&rsquo; to select the previous default family.  The default font
family is available in the read-only string-valued register <code class="code">.fam</code>;
it is associated with the environment (see <a class="pxref" href="#Environments">Environments</a>).
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">spam,     \&quot; startup defaults are T (Times) R (roman)
.fam H    \&quot; make Helvetica the default family
spam,     \&quot; family H + style R = HR
.ft B     \&quot; family H + style B = HB
spam,
.ft CR    \&quot; Courier roman (default family not changed)
spam,
.ft       \&quot; back to Helvetica bold
spam,
.fam T    \&quot; make Times the default family
spam,     \&quot; family T + style B = TB
.ft AR    \&quot; font AR (not a style)
baked beans,
.ft R     \&quot; family T + style R = TR
and spam.
</pre></div></div>

<p><code class="code">\F</code> doesn&rsquo;t produce an input token in GNU <code class="code">troff</code>.  As a
consequence, it can be used in requests like <code class="code">mc</code> (which expects
a single character as an argument) to change the font family on the fly.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.mc \F[P]x\F[]
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002esty"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.sty</code></strong> <var class="def-var-arguments">n style</var><a class="copiable-link" href='#index-_002esty'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-sty"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002esty_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.sty]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002esty_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002esty-1"></a>
<a class="index-entry-id" id="index-setting-up-an-abstract-font-style-_0028sty_0029"></a>
<a class="index-entry-id" id="index-abstract-font-style_002c-setting-up-_0028sty_0029"></a>
<a class="index-entry-id" id="index-font-style_002c-abstract_002c-setting-up-_0028sty_0029"></a>
<a class="index-entry-id" id="index-style_002c-font_002c-abstract_002c-setting-up-_0028sty_0029"></a>
<a class="index-entry-id" id="index-cs-request_002c-and-font-styles"></a>
<a class="index-entry-id" id="index-bd-request_002c-and-font-styles"></a>
<a class="index-entry-id" id="index-tkf-request_002c-and-font-styles"></a>
<a class="index-entry-id" id="index-uf-request_002c-and-font-styles"></a>
<a class="index-entry-id" id="index-fspecial-request_002c-and-font-styles"></a>
<p>Associate an abstract style <var class="var">style</var> with mounting
position&nbsp;<var class="var">n</var>, which must be a non-negative integer.  If the
requests <code class="code">cs</code>, <code class="code">bd</code>, <code class="code">tkf</code>, <code class="code">uf</code>, or <code class="code">fspecial</code>
are applied to an abstract style, they are instead applied to the member
of the current family corresponding to that style.
</p>
<a class="index-entry-id" id="index-DESC-1"></a>
<a class="index-entry-id" id="index-styles-1"></a>
<p>The default family can be set with the <samp class="option">-f</samp> option (see <a class="pxref" href="#Groff-Options">Options</a>).  The <code class="code">styles</code> command in the <samp class="file">DESC</samp> file controls
which font positions (if any) are initially associated with abstract
styles rather than fonts.
</p>
<p><strong class="strong">Caution:</strong> The <var class="var">style</var> argument is not validated.
Errors may occur later, when the formatter attempts to construct a
resolved font name, or format a character for output.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr BarPos \n[.fp]
.sty \n[.fp] Bar
.fam Foo
.ft \n[BarPos]
.tm .f=\n[.f]
A
    error&rarr; error: no font family named 'Foo' exists
    error&rarr; .f=41
    error&rarr; error: cannot format glyph: no current font
</pre></div></div>

<p>When an abstract style has been selected, the read-only string-valued
register &lsquo;<samp class="samp">.sty</samp>&rsquo; interpolates its name; this datum is associated
with the environment (see <a class="pxref" href="#Environments">Environments</a>).  Otherwise, &lsquo;<samp class="samp">.sty</samp>&rsquo;
interpolates nothing.
</p></dd></dl>


<hr>
</div>
<div class="subsection-level-extent" id="Font-Positions">
<div class="nav-panel">
<p>
Next: <a href="#Using-Symbols" accesskey="n" rel="next">Using Symbols</a>, Previous: <a href="#Font-Families" accesskey="p" rel="prev">Font Families</a>, Up: <a href="#Using-Fonts" accesskey="u" rel="up">Using Fonts</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Font-Positions-1">5.19.3 Font Positions</h4>
<a class="index-entry-id" id="index-font-positions"></a>
<a class="index-entry-id" id="index-positions_002c-font"></a>

<p>To support typeface indirection through abstract styles, and for
compatibility with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>, the formatter maintains
a list of font <em class="dfn">positions</em> at which fonts required by a document are
<em class="dfn">mounted</em>.  An output device&rsquo;s description file <samp class="file">DESC</samp>
typically configures a set of pre-mounted fonts; see <a class="ref" href="#Device-and-Font-Description-Files">Device and Font Description Files</a>.  A font need not be explicitly mounted before
it is selected; GNU <code class="code">troff</code> will search <code class="env">GROFF_FONT_PATH</code> for
it by name and mount it at the first free mounting position on demand.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002efp"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.fp</code></strong> <var class="def-var-arguments">pos id [<span class="r"><i class="slanted">font-description-file-name</i></span>]</var><a class="copiable-link" href='#index-_002efp'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-fp"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ef_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.f]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ef_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ef"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002efp_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.fp]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002efp_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002efp-1"></a>
<a class="index-entry-id" id="index-mounting-a-font-_0028fp_0029"></a>
<a class="index-entry-id" id="index-font_002c-mounting-_0028fp_0029"></a>
<p>Mount a font under the name <var class="var">id</var> at mounting position <var class="var">pos</var>, a
non-negative integer.  When the formatter starts up, it reads the output
device&rsquo;s description to mount an initial set of faces, and selects font
position&nbsp;1.  Position&nbsp;0 is unused by default.  Unless the
<var class="var">font-description-file-name</var> argument is given, <var class="var">id</var> should be
the name of a font description file stored in a directory corresponding
to the selected output device.  GNU <code class="code">troff</code> does not traverse
directories to locate the font description file.
</p>
<a class="index-entry-id" id="index-font-aliasing-with-third-argument-to-fp-request"></a>
<a class="index-entry-id" id="index-aliasing-fonts-with-third-argument-to-fp-request"></a>
<p>The optional third argument enables font names to be aliased, which can
be necessary in compatibility mode since AT&amp;T <code class="code">troff</code> syntax
affords no means of identifying fonts with names longer than two
characters, like &lsquo;<samp class="samp">TBI</samp>&rsquo; or &lsquo;<samp class="samp">ZCMI</samp>&rsquo;, in a font selection escape
sequence.  See <a class="xref" href="#Compatibility-Mode">Compatibility Mode</a>.  You can also alias fonts on
mounting for convenience or abstraction.  (See below regarding the
<code class="code">.fp</code> register.)
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.fp \n[.fp] SC ZCMI
Send a \f(SChand-written\fP thank-you note.
.fp \n[.fp] Emph TI
.fp \n[.fp] Strong TB
Are \f[Emph]these names\f[] \f[Strong]comfortable\f[]?
</pre></div></div>

<p>&lsquo;<samp class="samp">DESC</samp>&rsquo;, &lsquo;<samp class="samp">P</samp>&rsquo;, and non-negative integers are not usable as font
identifiers.
</p>
<a class="index-entry-id" id="index-font-position-register-_0028_002ef_0029"></a>
<p>The position of the currently selected font (or abstract style) is
available in the read-only register &lsquo;<samp class="samp">.f</samp>&rsquo;.  It is associated with
the environment (see <a class="pxref" href="#Environments">Environments</a>).
</p>
<p>You can copy the value of <code class="code">.f</code> to another register to save it for
later use.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr saved-font \n[.f]
<span class="r">&hellip; <i class="i">text involving many font changes</i> &hellip;</span>
.ft \n[saved-font]
</pre></div></div>

<a class="index-entry-id" id="index-next-free-font-position-register-_0028_002efp_0029"></a>
<p>The index of the next (non-zero) free font position is available in the
read-only register &lsquo;<samp class="samp">.fp</samp>&rsquo;.
<a class="index-entry-id" id="index-DESC-file_002c-and-font-mounting"></a>
Fonts not listed in the <samp class="file">DESC</samp> file are automatically mounted at
position &lsquo;<samp class="samp">\n[.fp]</samp>&rsquo; when selected with the <code class="code">ft</code> request or
<code class="code">\f</code> escape sequence.  When mounting a font at a position
explicitly with the <code class="code">fp</code> request, this same practice should be
followed, although GNU <code class="code">troff</code> does not enforce this strictly.
</p></dd></dl>


<hr>
</div>
<div class="subsection-level-extent" id="Using-Symbols">
<div class="nav-panel">
<p>
Next: <a href="#Character-Classes" accesskey="n" rel="next">Character Classes</a>, Previous: <a href="#Font-Positions" accesskey="p" rel="prev">Font Positions</a>, Up: <a href="#Using-Fonts" accesskey="u" rel="up">Using Fonts</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Using-Symbols-1">5.19.4 Using Symbols</h4>
<a class="index-entry-id" id="index-using-symbols"></a>
<a class="index-entry-id" id="index-symbols_002c-using"></a>

<a class="index-entry-id" id="index-glyph"></a>
<a class="index-entry-id" id="index-character"></a>
<a class="index-entry-id" id="index-glyph_002c-distinguished-from-character"></a>
<a class="index-entry-id" id="index-character_002c-distinguished-from-glyph"></a>
<a class="index-entry-id" id="index-ligature"></a>
<p>A <em class="dfn">glyph</em> is a graphical representation of a <em class="dfn">character</em>.  While
a character is an abstraction of semantic information, a glyph is
something that can be seen on screen or paper.  A character has many
possible representation forms (for example, the character &lsquo;A&rsquo; can be
written in an upright or slanted typeface, producing distinct
glyphs).  Sometimes, a sequence of characters map to a single glyph:
this is a <em class="dfn">ligature</em>&mdash;the most common is &lsquo;fi&rsquo;.
</p>
<p>Space characters never become glyphs in GNU <code class="code">troff</code>.  If not
discarded (as when trailing on text lines), they are represented by
horizontal motions in the output.
</p>
<a class="index-entry-id" id="index-symbol"></a>
<a class="index-entry-id" id="index-special-fonts"></a>
<a class="index-entry-id" id="index-fonts"></a>
<a class="index-entry-id" id="index-DESC-2"></a>
<a class="index-entry-id" id="index-special-request_002c-and-glyph-search-order"></a>
<a class="index-entry-id" id="index-fspecial-request_002c-and-glyph-search-order"></a>
<p>A <em class="dfn">symbol</em> is simply a named glyph.  Within <code class="code">gtroff</code>, all glyph
names of a particular font are defined in its font file.  If the user
requests a glyph not available in this font, <code class="code">gtroff</code> looks up an
ordered list of <em class="dfn">special fonts</em>.  By default, the PostScript output
device supports the two special fonts &lsquo;<samp class="samp">SS</samp>&rsquo; (slanted symbols) and
&lsquo;<samp class="samp">S</samp>&rsquo; (symbols) (the former is looked up before the latter).  Other
output devices use different names for special fonts.  Fonts mounted
with the <code class="code">fonts</code> keyword in the <samp class="file">DESC</samp> file are globally
available.  To install additional special fonts locally (i.e., for a
particular font), use the <code class="code">fspecial</code> request.
</p>
<p>Here are the exact rules how <code class="code">gtroff</code> searches a given symbol:
</p>
<ul class="itemize mark-bullet">
<li>If the symbol has been defined with the <code class="code">char</code> request, use it.
This hides a symbol with the same name in the current font.

</li><li>Check the current font.

</li><li>If the symbol has been defined with the <code class="code">fchar</code> request, use it.

</li><li>Check whether the current font has a font-specific list of special
fonts; test all fonts in the order of appearance in the last
<code class="code">fspecial</code> call if appropriate.

</li><li>If the symbol has been defined with the <code class="code">fschar</code> request for the
current font, use it.

</li><li>Check all fonts in the order of appearance in the last <code class="code">special</code>
call.

</li><li>If the symbol has been defined with the <code class="code">schar</code> request, use it.

</li><li>As a last resort, consult all fonts loaded up to now for special fonts
and check them, starting with the lowest font number.  This can
sometimes lead to surprising results since the <code class="code">fonts</code> line in
the <samp class="file">DESC</samp> file often contains empty positions, which are filled
later on.  For example, consider the following:

<div class="example">
<div class="group"><pre class="example-preformatted">fonts 3 0 0 FOO
</pre></div></div>

<p>This mounts font <code class="code">foo</code> at font position&nbsp;3.  We assume that
<code class="code">FOO</code> is a special font, containing glyph <code class="code">foo</code>, and that no
font has been loaded yet.  The line
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.fspecial BAR BAZ
</pre></div></div>

<p>makes font <code class="code">BAZ</code> special only if font <code class="code">BAR</code> is active.  We
further assume that <code class="code">BAZ</code> is really a special font, i.e., the font
description file contains the <code class="code">special</code> keyword, and that it also
contains glyph <code class="code">foo</code> with a special shape fitting to font
<code class="code">BAR</code>.  After executing <code class="code">fspecial</code>, font <code class="code">BAR</code> is loaded
at font position&nbsp;1, and <code class="code">BAZ</code> at position&nbsp;2.
</p>
<p>We now switch to a new font <code class="code">XXX</code>, trying to access glyph
<code class="code">foo</code> that is assumed to be missing.  There are neither
font-specific special fonts for <code class="code">XXX</code> nor any other fonts made
special with the <code class="code">special</code> request, so <code class="code">gtroff</code> starts the
search for special fonts in the list of already mounted fonts, with
increasing font positions.  Consequently, it finds <code class="code">BAZ</code> before
<code class="code">FOO</code> even for <code class="code">XXX</code>, which is not the intended behaviour.
</p></li></ul>

<p>See <a class="xref" href="#Device-and-Font-Description-Files">Device and Font Description Files</a>, and <a class="ref" href="#Special-Fonts">Special Fonts</a>, for
more details.
</p>
<a class="index-entry-id" id="index-list-of-special-characters-_0028groff_005fchar_00287_0029-man-page_0029"></a>
<a class="index-entry-id" id="index-special-characters_002c-list-of-_0028groff_005fchar_00287_0029-man-page_0029"></a>
<a class="index-entry-id" id="index-characters_002c-special_002c-list-of-_0028groff_005fchar_00287_0029-man-page_0029"></a>
<a class="index-entry-id" id="index-available-glyphs_002c-list-of-_0028groff_005fchar_00287_0029-man-page_0029"></a>
<a class="index-entry-id" id="index-glyphs_002c-available_002c-list-of-_0028groff_005fchar_00287_0029-man-page_0029"></a>
<p>The <cite class="cite">groff_char<span class="r">(7)</span></cite> man page houses a complete list of
predefined special character names, but the availability of any as a
glyph is device- and font-dependent.  For example, say
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">man -Tdvi groff_char &gt; groff_char.dvi
</pre></div></div>

<p>to obtain those available with the DVI device and default font
configuration.<a class="footnote" id="DOCF77" href="#FOOT77"><sup>77</sup></a>  If you want to use an additional macro package to change
the fonts used, <code class="code">groff</code> (or <code class="code">gtroff</code>) must be run directly.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">groff -Tdvi -mec -man groff_char.7 &gt; groff_char.dvi
</pre></div></div>

<a class="index-entry-id" id="index-composite-glyph-names"></a>
<a class="index-entry-id" id="index-glyph-names_002c-composite"></a>
<a class="index-entry-id" id="index-groff-glyph-list-_0028GGL_0029"></a>
<a class="index-entry-id" id="index-GGL-_0028groff-glyph-list_0029"></a>
<a class="index-entry-id" id="index-Adobe-Glyph-List-_0028AGL_0029"></a>
<p>Special character names not listed in <cite class="cite">groff_char<span class="r">(7)</span></cite> are
derived algorithmically, using a simplified version of the Adobe Glyph
List (AGL) algorithm, which is described in
<a class="uref" href="https://github.com/adobe-type-tools/agl-aglfn">https://github.com/adobe-type-tools/agl-aglfn</a>.  The (frozen)
set of names that can&rsquo;t be derived algorithmically is called the
<em class="dfn"><code class="code">groff</code> glyph list (GGL)</em>.
</p>
<ul class="itemize mark-bullet">
<li>A glyph for Unicode character U+<var class="var">XXXX</var>[<var class="var">X</var>[<var class="var">X</var>]], which is
not a composite character is named
<code class="code">u<var class="var">XXXX</var><span class="r">[</span><var class="var">X</var><span class="r">[</span><var class="var">X</var><span class="r">]]</span></code>.  <var class="var">X</var> must be an
uppercase hexadecimal digit.  Examples: <code class="code">u1234</code>, <code class="code">u008E</code>,
<code class="code">u12DB8</code>.  The largest Unicode value is 0x10FFFF.  There must be at
least four <code class="code">X</code> digits; if necessary, add leading zeroes (after the
&lsquo;<samp class="samp">u</samp>&rsquo;).  No zero padding is allowed for character codes greater than
0xFFFF.  Surrogates (i.e., Unicode values greater than 0xFFFF
represented with character codes from the surrogate area U+D800-U+DFFF)
are not allowed either.

</li><li>A glyph representing more than a single input character is named

<div class="display">
<pre class="display-preformatted">&lsquo;<samp class="samp">u</samp>&rsquo; <var class="var">component1</var> &lsquo;<samp class="samp">_</samp>&rsquo; <var class="var">component2</var> &lsquo;<samp class="samp">_</samp>&rsquo; <var class="var">component3</var> &hellip;
</pre></div>

<p>Example: <code class="code">u0045_0302_0301</code>.
</p>
<p>For simplicity, all Unicode characters that are composites must be
maximally decomposed to NFD;<a class="footnote" id="DOCF78" href="#FOOT78"><sup>78</sup></a> for example,
<code class="code">u00CA_0301</code> is not a valid glyph name since U+00CA (<small class="sc">LATIN
CAPITAL LETTER E WITH CIRCUMFLEX</small>) can be further decomposed into U+0045
(<small class="sc">LATIN CAPITAL LETTER E</small>) and U+0302 (<small class="sc">COMBINING CIRCUMFLEX
ACCENT</small>).  <code class="code">u0045_0302_0301</code> is thus the glyph name for U+1EBE,
<small class="sc">LATIN CAPITAL LETTER E WITH CIRCUMFLEX AND ACUTE</small>.
</p>
</li><li>groff maintains a table to decompose all algorithmically derived glyph
names that are composites itself.  For example, <code class="code">u0100</code> (<small class="sc">LATIN
LETTER A WITH MACRON</small>) is automatically decomposed into
<code class="code">u0041_0304</code>.  Additionally, a glyph name of the GGL is preferred
to an algorithmically derived glyph name; <code class="code">groff</code> also
automatically does the mapping.  Example: The glyph <code class="code">u0045_0302</code> is
mapped to <code class="code">^E</code>.

</li><li>glyph names of the GGL can&rsquo;t be used in composite glyph names; for
example, <code class="code">^E_u0301</code> is invalid.
</li></ul>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_0028nm"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\(</code><span class="r"><i class="slanted">nm</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_0028nm'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c-1"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_005bname_005d"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\[</code><span class="r"><i class="slanted">name</i></span><code class="t">]</code></strong><a class="copiable-link" href='#index-_005c_005bname_005d'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005c_005bbase_002dglyph-combining_002dcomponent-_2026_005d"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\[</code><span class="r"><i class="slanted">base-glyph combining-component &hellip;</i></span><code class="t">]</code></strong><a class="copiable-link" href='#index-_005c_005bbase_002dglyph-combining_002dcomponent-_2026_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_0028"></a>
<a class="index-entry-id" id="index-_005c_005b"></a>
<p>Typeset a special character <var class="var">name</var> (two-character name <var class="var">nm</var>) or
a composite glyph consisting of <var class="var">base-glyph</var> overlaid with one or
more <var class="var">combining-component</var>s.  For example, &lsquo;<samp class="samp">\[A ho]</samp>&rsquo; is a
capital letter &ldquo;A&rdquo; with a &ldquo;hook accent&rdquo; (ogonek).
</p>
<p>There is no special syntax for one-character names&mdash;the analogous form
&lsquo;<samp class="samp">\<var class="var">n</var></samp>&rsquo; would collide with other escape sequences.  However, the
four escape sequences <code class="code">\'</code>, <code class="code">\-</code>, <code class="code">\_</code>, and <code class="code">\`</code>,
are translated on input to the special character escape sequences
<code class="code">\[aa]</code>, <code class="code">\[-]</code>, <code class="code">\[ul]</code>, and <code class="code">\[ga]</code>, respectively.
</p>
<p>A special character name of length one is not the same thing as an
ordinary character: that is, the character <code class="code">a</code> is not the same as
<code class="code">\[a]</code>.
</p>
<p>If <var class="var">name</var> is undefined, a warning in category &lsquo;<samp class="samp">char</samp>&rsquo; is
produced and the escape is ignored.  See <a class="xref" href="#Warnings">Warnings</a>, for information
about the enablement and suppression of warnings.
</p>
<p>GNU <code class="code">troff</code> resolves <code class="code">\[<span class="r">&hellip;</span>]</code> with more than a single
component as follows:
</p>
<ul class="itemize mark-bullet">
<li>Any component that is found in the GGL is converted to the
<code class="code">u<var class="var">XXXX</var></code> form.

</li><li>Any component <code class="code">u<var class="var">XXXX</var></code> that is found in the list of
decomposable glyphs is decomposed.

</li><li>The resulting elements are then concatenated with &lsquo;<samp class="samp">_</samp>&rsquo; in between,
dropping the leading &lsquo;<samp class="samp">u</samp>&rsquo; in all elements but the first.
</li></ul>

<p>No check for the existence of any component (similar to <code class="code">tr</code>
request) is done.
</p>
<p>Examples:
</p>
<dl class="table">
<dt><code class="code">\[A ho]</code></dt>
<dd><p>&lsquo;<samp class="samp">A</samp>&rsquo; maps to <code class="code">u0041</code>, &lsquo;<samp class="samp">ho</samp>&rsquo; maps to <code class="code">u02DB</code>, thus the
final glyph name would be <code class="code">u0041_02DB</code>.  This is not the expected
result: the ogonek glyph &lsquo;<samp class="samp">ho</samp>&rsquo; is a spacing ogonek, but for a
proper composite a non-spacing ogonek (U+0328) is necessary.  Looking
into the file <samp class="file">composite.tmac</samp>, one can find &lsquo;<samp class="samp">.composite&nbsp;ho&nbsp;u0328</samp>&rsquo;<!-- /@w -->, which changes the mapping of &lsquo;<samp class="samp">ho</samp>&rsquo; while a composite glyph
name is constructed, causing the final glyph name to be
<code class="code">u0041_0328</code>.
</p>
</dd>
<dt><code class="code">\[^E u0301]</code></dt>
<dt><code class="code">\[^E aa]</code></dt>
<dt><code class="code">\[E a^ aa]</code></dt>
<dt><code class="code">\[E ^ <code class="code">'</code>]</code></dt>
<dd><p>&lsquo;<samp class="samp">^E</samp>&rsquo; maps to <code class="code">u0045_0302</code>, thus the final glyph name is
<code class="code">u0045_0302_0301</code> in all forms (assuming proper calls of the
<code class="code">composite</code> request).
</p></dd>
</dl>

<p>It is not possible to define glyphs with names like &lsquo;<samp class="samp">A&nbsp;ho</samp>&rsquo;<!-- /@w -->
within a <code class="code">groff</code> font file.  This is not really a limitation;
instead, you have to define <code class="code">u0041_0328</code>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cC_0027xxx_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\C<code class="code">'</code></code><span class="r"><i class="slanted">xxx</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cC_0027xxx_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cC"></a>
<a class="index-entry-id" id="index-named-character-_0028_005cC_0029"></a>
<a class="index-entry-id" id="index-character_002c-named-_0028_005cC_0029"></a>
<p>Typeset the glyph of the special character <var class="var">xxx</var>.  Normally, it is
more convenient to use <code class="code">\[<var class="var">xxx</var>]</code>, but <code class="code">\C</code> has some
advantages: it is compatible with <abbr class="acronym">AT&amp;T</abbr> device-independent
<code class="code">troff</code> (and therefore available in compatibility
mode<a class="footnote" id="DOCF79" href="#FOOT79"><sup>79</sup></a>) and can interpolate special
characters with &lsquo;<samp class="samp">]</samp>&rsquo; in their names.  The delimiter need not be
a neutral apostrophe; see <a class="ref" href="#Delimiters">Delimiters</a>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ecomposite"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.composite</code></strong> <var class="def-var-arguments">id1 id2</var><a class="copiable-link" href='#index-_002ecomposite'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-composite"></a>
<a class="index-entry-id" id="index-composite_002etmac"></a>
<p>Map special character name <var class="var">id1</var> to <var class="var">id2</var> if <var class="var">id1</var> is used
in <code class="code">\[...]</code> with more than one component.  See above for examples.
This is a strict rewriting of the special character name; no check is
performed for the existence of a glyph for either.  A set of default
mappings for many accents can be found in the file
<samp class="file">composite.tmac</samp>, loaded by the default <samp class="file">troffrc</samp> at startup.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cN_0027n_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\N<code class="code">'</code></code><span class="r"><i class="slanted">n</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cN_0027n_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cN"></a>
<a class="index-entry-id" id="index-numbered-glyph-_0028_005cN_0029-1"></a>
<a class="index-entry-id" id="index-glyph_002c-numbered-_0028_005cN_0029-1"></a>
<a class="index-entry-id" id="index-char-request_002c-used-with-_005cN"></a>
<a class="index-entry-id" id="index-Unicode-1"></a>
<p>Typeset the glyph with code&nbsp;<var class="var">n</var> in the current font
(<code class="code">n</code>&nbsp;is <em class="emph">not</em> the input character code).  The number
<var class="var">n</var>&nbsp;can be any non-negative decimal integer.  Most devices only
have glyphs with codes between 0 and&nbsp;255; the Unicode output device
uses codes in the range 0&ndash;65535.  If the current font does not contain
a glyph with that code, special fonts are <em class="emph">not</em> searched.  The
<code class="code">\N</code> escape sequence can be conveniently used in conjunction with
the <code class="code">char</code> request:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.char \[phone] \f[ZD]\N'37'
</pre></div></div>

<a class="index-entry-id" id="index-DESC-3"></a>
<a class="index-entry-id" id="index-unnamed-glyphs"></a>
<a class="index-entry-id" id="index-glyphs_002c-unnamed"></a>
<p>The code of each glyph is given in the fourth column in the font
description file after the <code class="code">charset</code> command.  It is possible to
include unnamed glyphs in the font description file by using a name of
&lsquo;<samp class="samp">---</samp>&rsquo;; the <code class="code">\N</code> escape sequence is the only way to use these.
</p>
<p>No kerning is applied to glyphs accessed with <code class="code">\N</code>.  The delimiter
need not be a neutral apostrophe; see <a class="ref" href="#Delimiters">Delimiters</a>.
</p></dd></dl>

<p>A few escape sequences are also special characters.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_0027-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\<code class="code">'</code></code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_0027-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_0027"></a>
<p>An escaped neutral apostrophe is a synonym for <code class="code">\[aa]</code> (acute
accent).
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_0060-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\<code class="code">`</code></code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_0060-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_0060"></a>
<p>An escaped grave accent is a synonym for <code class="code">\[ga]</code> (grave accent).
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002d-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\-</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_002d-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_002d"></a>
<p>An escaped hyphen-minus is a synonym for <code class="code">\[-]</code> (minus sign).
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_005f-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\_</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_005f-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_005f"></a>
<p>An escaped underscore (&ldquo;low line&rdquo;) is a synonym for <code class="code">\[ul]</code>
(underrule).  On typesetting devices, the underrule is font-invariant
and drawn lower than the underscore &lsquo;<samp class="samp">_</samp>&rsquo;.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ecflags"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.cflags</code></strong> <var class="def-var-arguments">n c1 c2 &hellip;</var><a class="copiable-link" href='#index-_002ecflags'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-cflags"></a>
<a class="index-entry-id" id="index-glyph-properties-_0028cflags_0029"></a>
<a class="index-entry-id" id="index-character-properties-_0028cflags_0029"></a>
<a class="index-entry-id" id="index-properties-of-glyphs-_0028cflags_0029"></a>
<a class="index-entry-id" id="index-properties-of-characters-_0028cflags_0029"></a>
<p>Assign properties encoded by the number <var class="var">n</var> to characters <var class="var">c1</var>,
<var class="var">c2</var>, and so on.
</p>
<p>Input characters, including special characters introduced by an escape,
have certain properties associated with them.<a class="footnote" id="DOCF80" href="#FOOT80"><sup>80</sup></a>
These properties can be modified with this request.  The first argument
is the sum of the desired flags and the remaining arguments are the
characters to be assigned those properties.  Spaces between the <var class="var">cn</var>
arguments are optional.  Any argument <var class="var">cn</var> can be a character class
defined with the <code class="code">class</code> request rather than an individual
character.  See <a class="xref" href="#Character-Classes">Character Classes</a>.
</p>
<p>The non-negative integer <var class="var">n</var> is the sum of any of the following.
Some combinations are nonsensical, such as &lsquo;<samp class="samp">33</samp>&rsquo; (1 + 32).
</p>
<dl class="table">
<dt id='index-end_002dof_002dsentence-characters-1'><span><code class="code">1</code><a class="copiable-link" href='#index-end_002dof_002dsentence-characters-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-characters_002c-end_002dof_002dsentence"></a>
<p>Recognize the character as ending a sentence if followed by a newline
or two spaces.  Initially, characters &lsquo;<samp class="samp">.?!</samp>&rsquo; have this property.
</p>
</dd>
<dt id='index-hyphenating-characters'><span><code class="code">2</code><a class="copiable-link" href='#index-hyphenating-characters'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-characters_002c-hyphenation"></a>
<p>Enable breaks before the character.  A line is not broken at a character
with this property unless the characters on each side both have non-zero
hyphenation codes.  This exception can be overridden by adding 64.
Initially, no characters have this property.
</p>
</dd>
<dt id='index-_005c_002d-glyph_002c-and-cflags'><span><code class="code">4</code><a class="copiable-link" href='#index-_005c_002d-glyph_002c-and-cflags'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-hy-glyph_002c-and-cflags"></a>
<a class="index-entry-id" id="index-em-glyph_002c-and-cflags"></a>
<p>Enable breaks after the character.  A line is not broken at a character
with this property unless the characters on each side both have non-zero
hyphenation codes.  This exception can be overridden by adding 64.
Initially, characters &lsquo;<samp class="samp">\-\[hy]\[em]</samp>&rsquo; have this property.
</p>
</dd>
<dt id='index-overlapping-characters'><span><code class="code">8</code><a class="copiable-link" href='#index-overlapping-characters'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-characters_002c-overlapping"></a>
<a class="index-entry-id" id="index-ul-glyph_002c-and-cflags"></a>
<a class="index-entry-id" id="index-rn-glyph_002c-and-cflags"></a>
<a class="index-entry-id" id="index-ru-glyph_002c-and-cflags"></a>
<a class="index-entry-id" id="index-radicalex-glyph_002c-and-cflags"></a>
<a class="index-entry-id" id="index-sqrtex-glyph_002c-and-cflags"></a>
<p>Mark the glyph associated with this character as overlapping other
instances of itself horizontally.  Initially, characters
&lsquo;<samp class="samp">\[ul]\[rn]\[ru]\[radicalex]\[sqrtex]</samp>&rsquo; have this property.
</p>
</dd>
<dt id='index-br-glyph_002c-and-cflags'><span><code class="code">16</code><a class="copiable-link" href='#index-br-glyph_002c-and-cflags'> &para;</a></span></dt>
<dd><p>Mark the glyph associated with this character as overlapping other
instances of itself vertically.  Initially, the character &lsquo;<samp class="samp">\[br]</samp>&rsquo;
has this property.
</p>
</dd>
<dt id='index-transparent-characters'><span><code class="code">32</code><a class="copiable-link" href='#index-transparent-characters'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-character_002c-transparent"></a>
<a class="index-entry-id" id="index-_0022_002c-at-end-of-sentence-1"></a>
<a class="index-entry-id" id="index-_0027_002c-at-end-of-sentence-1"></a>
<a class="index-entry-id" id="index-_0029_002c-at-end-of-sentence-1"></a>
<a class="index-entry-id" id="index-_005d_002c-at-end-of-sentence-1"></a>
<a class="index-entry-id" id="index-_002a_002c-at-end-of-sentence-1"></a>
<a class="index-entry-id" id="index-dg-glyph_002c-at-end-of-sentence-1"></a>
<a class="index-entry-id" id="index-dd-glyph_002c-at-end-of-sentence-1"></a>
<a class="index-entry-id" id="index-rq-glyph_002c-at-end-of-sentence-1"></a>
<a class="index-entry-id" id="index-cq-glyph_002c-at-end-of-sentence-1"></a>
<p>Mark the character as transparent for the purpose of end-of-sentence
recognition.  In other words, an end-of-sentence character followed by
any number of characters with this property is treated as the end of a
sentence if followed by a newline or two spaces.  This is the same as
having a zero space factor in TeX.  Initially, characters
&lsquo;<samp class="samp">&quot;')]*\[dg]\[dd]\[rq]\[cq]</samp>&rsquo; have this property.
</p>
</dd>
<dt><code class="code">64</code></dt>
<dd><p>Ignore hyphenation codes of the surrounding characters.  Use this in
combination with values 2 and&nbsp;4 (initially, no characters have this
property).
</p>
<p>For example, if you need an automatic break point after the en-dash in
numeric ranges like &ldquo;3000&ndash;5000&rdquo;, insert
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.cflags 68 \[en]
</pre></div></div>

<p>into your document.  However, this practice can lead to bad layout if
done thoughtlessly; in most situations, a better solution instead of
changing the <code class="code">cflags</code> value is to insert <code class="code">\:</code> right after the
hyphen at the places that really need a break point.
</p></dd>
</dl>

<p>The remaining values were implemented for East Asian language support;
those who use alphabetic scripts exclusively can disregard them.
</p>
<dl class="table">
<dt><code class="code">128</code></dt>
<dd><p>Prohibit a line break before the character, but allow a line break after
the character.  This works only in combination with flags 256 and 512
and has no effect otherwise.  Initially, no characters have this
property.
</p>
</dd>
<dt><code class="code">256</code></dt>
<dd><p>Prohibit a line break after the character, but allow a line break before
the character.  This works only in combination with flags 128 and 512
and has no effect otherwise.  Initially, no characters have this
property.
</p>
</dd>
<dt><code class="code">512</code></dt>
<dd><p>Allow line break before or after the character.  This works only in
combination with flags 128 and 256 and has no effect otherwise.
Initially, no characters have this property.
</p></dd>
</dl>

<p>In contrast to values 2 and&nbsp;4, the values 128, 256, and 512 work
pairwise.  If, for example, the left character has value 512, and the
right character 128, no break will be automatically inserted between
them.  If we use value&nbsp;6 instead for the left character, a break
after the character can&rsquo;t be suppressed since the neighboring character
on the right doesn&rsquo;t get examined.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002echar"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.char</code></strong> <var class="def-var-arguments">c [<span class="r"><i class="slanted">contents</i></span>]</var><a class="copiable-link" href='#index-_002echar'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-char"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002efchar"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.fchar</code></strong> <var class="def-var-arguments">c [<span class="r"><i class="slanted">contents</i></span>]</var><a class="copiable-link" href='#index-_002efchar'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-fchar"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002efschar"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.fschar</code></strong> <var class="def-var-arguments">f c [<span class="r"><i class="slanted">contents</i></span>]</var><a class="copiable-link" href='#index-_002efschar'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-fschar"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002eschar"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.schar</code></strong> <var class="def-var-arguments">c [<span class="r"><i class="slanted">contents</i></span>]</var><a class="copiable-link" href='#index-_002eschar'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-schar"></a>
<a class="index-entry-id" id="index-defining-character-_0028char_0029"></a>
<a class="index-entry-id" id="index-defining-fallback-character-_0028fchar_002c-fschar_002c-schar_0029"></a>
<a class="index-entry-id" id="index-character_002c-defining-_0028char_0029"></a>
<a class="index-entry-id" id="index-character_002c-defining-fallback-_0028fchar_002c-fschar_002c-schar_0029"></a>
<a class="index-entry-id" id="index-fallback-character_002c-defining-_0028fchar_002c-fschar_002c-schar_0029"></a>
<a class="index-entry-id" id="index-creating-new-characters-_0028char_0029"></a>
<a class="index-entry-id" id="index-defining-symbol-_0028char_0029"></a>
<a class="index-entry-id" id="index-symbol_002c-defining-_0028char_0029"></a>
<a class="index-entry-id" id="index-defining-glyph-_0028char_0029"></a>
<a class="index-entry-id" id="index-glyph_002c-defining-_0028char_0029"></a>
<a class="index-entry-id" id="index-escape-character_002c-while-defining-glyph"></a>
<a class="index-entry-id" id="index-character_002c-escape_002c-while-defining-glyph"></a>
<a class="index-entry-id" id="index-tr-request_002c-and-glyph-definitions"></a>
<a class="index-entry-id" id="index-cp-request_002c-and-glyph-definitions"></a>
<a class="index-entry-id" id="index-rc-request_002c-and-glyph-definitions"></a>
<a class="index-entry-id" id="index-lc-request_002c-and-glyph-definitions"></a>
<a class="index-entry-id" id="index-_005cl_002c-and-glyph-definitions"></a>
<a class="index-entry-id" id="index-_005cL_002c-and-glyph-definitions"></a>
<a class="index-entry-id" id="index-_005c_0026_002c-and-glyph-definitions"></a>
<a class="index-entry-id" id="index-_005ce_002c-and-glyph-definitions"></a>
<a class="index-entry-id" id="index-hcode-request_002c-and-glyph-definitions"></a>
<p>Define a new character or glyph&nbsp;<var class="var">c</var> to be <var class="var">contents</var>, which
can be empty.  More precisely, <code class="code">char</code> defines a <code class="code">groff</code> object
(or redefines an existing one) that is accessed with the
name&nbsp;<var class="var">c</var> on input, and produces <var class="var">contents</var> on output.
Every time glyph&nbsp;<var class="var">c</var> needs to be printed, <var class="var">contents</var> is
processed in a temporary environment and the result is wrapped up into a
single object.  Compatibility mode is turned off and the escape
character is set to&nbsp;<code class="code">\</code> while <var class="var">contents</var> is processed.
Any emboldening, constant spacing, or track kerning is applied to this
object rather than to individual glyphs in <var class="var">contents</var>.
</p>
<p>An object defined by these requests can be used just like a normal glyph
provided by the output device.  In particular, other characters can be
translated to it with the <code class="code">tr</code> or <code class="code">trin</code> requests; it can be
made the leader character with the <code class="code">lc</code> request; repeated patterns
can be drawn with it using the <code class="code">\l</code> and <code class="code">\L</code> escape sequences;
and words containing&nbsp;<var class="var">c</var> can be hyphenated correctly if the
<code class="code">hcode</code> request is used to give the object a hyphenation code.
</p>
<p>There is a special anti-recursion feature: use of the object within its
own definition is handled like a normal character (not
defined with <code class="code">char</code>).
</p>
<p>The <code class="code">tr</code> and <code class="code">trin</code> requests take precedence if <code class="code">char</code>
accesses the same symbol.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.tr XY
X
    &rArr; Y
.char X Z
X
    &rArr; Y
.tr XX
X
    &rArr; Z
</pre></div></div>

<p>The <code class="code">fchar</code> request defines a fallback glyph: <code class="code">gtroff</code> only
checks for glyphs defined with <code class="code">fchar</code> if it cannot find the glyph
in the current font.  <code class="code">gtroff</code> carries out this test before
checking special fonts.
</p>
<p><code class="code">fschar</code> defines a fallback glyph for font&nbsp;<var class="var">f</var>:
<code class="code">gtroff</code> checks for glyphs defined with <code class="code">fschar</code> after the
list of fonts declared as font-specific special fonts with the
<code class="code">fspecial</code> request, but before the list of fonts declared as global
special fonts with the <code class="code">special</code> request.
</p>
<p>Finally, the <code class="code">schar</code> request defines a global fallback glyph:
<code class="code">gtroff</code> checks for glyphs defined with <code class="code">schar</code> after the list
of fonts declared as global special fonts with the <code class="code">special</code>
request, but before the already mounted special fonts.
</p>
<p>See <a class="xref" href="#Character-Classes">Character Classes</a>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002erchar"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.rchar</code></strong> <var class="def-var-arguments">c &hellip;</var><a class="copiable-link" href='#index-_002erchar'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-rchar"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002erfschar"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.rfschar</code></strong> <var class="def-var-arguments">f c &hellip;</var><a class="copiable-link" href='#index-_002erfschar'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-rfschar"></a>
<a class="index-entry-id" id="index-removing-glyph-definition-_0028rchar_002c-rfschar_0029"></a>
<a class="index-entry-id" id="index-glyph_002c-removing-definition-_0028rchar_002c-rfschar_0029"></a>
<a class="index-entry-id" id="index-fallback-glyph_002c-removing-definition-_0028rchar_002c-rfschar_0029"></a>
<p>Remove definition of each ordinary or special character <var class="var">c</var>,
undoing the effect of a <code class="code">char</code>, <code class="code">fchar</code>, or <code class="code">schar</code>
request.  Those supplied by font description files cannot be removed.
Spaces and tabs may separate <var class="var">c</var>&nbsp;arguments.
</p>
<p>The request <code class="code">rfschar</code> removes glyph definitions defined with
<code class="code">fschar</code> for font&nbsp;<var class="var">f</var>.
</p></dd></dl>


<hr>
</div>
<div class="subsection-level-extent" id="Character-Classes">
<div class="nav-panel">
<p>
Next: <a href="#Special-Fonts" accesskey="n" rel="next">Special Fonts</a>, Previous: <a href="#Using-Symbols" accesskey="p" rel="prev">Using Symbols</a>, Up: <a href="#Using-Fonts" accesskey="u" rel="up">Using Fonts</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Character-Classes-1">5.19.5 Character Classes</h4>
<a class="index-entry-id" id="index-character-classes"></a>
<a class="index-entry-id" id="index-classes_002c-character"></a>

<p>Classes are particularly useful for East Asian languages such as
Chinese, Japanese, and Korean, where the number of needed characters is
much larger than in European languages, and where large sets of
characters share the same properties.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002eclass"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.class</code></strong> <var class="def-var-arguments">name c1 c2 &hellip;</var><a class="copiable-link" href='#index-_002eclass'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-class"></a>
<a class="index-entry-id" id="index-character-class-_0028class_0029"></a>
<a class="index-entry-id" id="index-defining-character-class-_0028class_0029"></a>
<a class="index-entry-id" id="index-class-of-characters-_0028class_0029"></a>
<p>Define a character class (or simply &ldquo;class&rdquo;) <var class="var">name</var> comprising
the characters <var class="var">c1</var>, <var class="var">c2</var>, and so on.
</p>
<p>A class thus defined can then be referred to in lieu of listing all the
characters within it.  Currently, only the <code class="code">cflags</code> request can
handle references to character classes.
</p>
<p>In the request&rsquo;s simplest form, each <var class="var">cn</var> is a character (or special
character).
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.class [quotes] ' \[aq] \[dq] \[oq] \[cq] \[lq] \[rq]
</pre></div></div>

<p>Since class and glyph names share the same name space, it is recommended
to start and end the class name with <code class="code">[</code> and <code class="code">]</code>,
respectively, to avoid collisions with existing character names defined
by GNU <code class="code">troff</code> or the user (with <code class="code">char</code> and related requests).
This practice applies the presence of <code class="code">]</code> in the class name to
prevent the use of the special character escape form
<code class="code">\[<span class="r">&hellip;</span>]</code>, thus you must use the <code class="code">\C</code> escape to access
a class with such a name.
</p>
<a class="index-entry-id" id="index-GGL-_0028groff-glyph-list_0029-1"></a>
<a class="index-entry-id" id="index-groff-glyph-list-_0028GGL_0029-1"></a>
<p>You can also use a character range notation consisting of a
start character followed by &lsquo;<samp class="samp">-</samp>&rsquo; and then an end character.
Internally, GNU <code class="code">troff</code> converts these two symbol names to
Unicode code points (according to the <code class="code">groff</code> glyph list [GGL]),
which then give the start and end value of the range.  If that fails,
the class definition is skipped.
</p>
<p>Furthermore, classes can be nested.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.class [prepunct] , : ; &gt; }
.class [prepunctx] \C'[prepunct]' \[u2013]-\[u2016]
</pre></div></div>

<p>The class &lsquo;<samp class="samp">[prepunctx]</samp>&rsquo; thus contains the contents of the class
<code class="code">[prepunct]</code> as defined above (the set &lsquo;<samp class="samp">, : ; &gt; }</samp>&rsquo;), and
characters in the range between <code class="code">U+2013</code> and <code class="code">U+2016</code>.
</p>
<p>If you want to include &lsquo;<samp class="samp">-</samp>&rsquo; in a class, it must be the first
character value in the argument list, otherwise it gets misinterpreted
as part of the range syntax.
</p>
<p>It is not possible to use class names as end points of range
definitions.
</p>
<p>A typical use of the <code class="code">class</code> request is to control line-breaking
and hyphenation rules as defined by the <code class="code">cflags</code> request.  For
example, to inhibit line breaks before the characters belonging to the
<code class="code">prepunctx</code> class defined in the previous example, you can write
the following.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.cflags 2 \C'[prepunctx]'
</pre></div></div>

<p>See the <code class="code">cflags</code> request in <a class="ref" href="#Using-Symbols">Using Symbols</a>, for more details.
</p></dd></dl>


<hr>
</div>
<div class="subsection-level-extent" id="Special-Fonts">
<div class="nav-panel">
<p>
Next: <a href="#Artificial-Fonts" accesskey="n" rel="next">Artificial Fonts</a>, Previous: <a href="#Character-Classes" accesskey="p" rel="prev">Character Classes</a>, Up: <a href="#Using-Fonts" accesskey="u" rel="up">Using Fonts</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Special-Fonts-1">5.19.6 Special Fonts</h4>
<a class="index-entry-id" id="index-special-fonts-1"></a>
<a class="index-entry-id" id="index-fonts_002c-special"></a>

<p>Special fonts are those that <code class="code">gtroff</code> searches when it cannot find
the requested glyph in the current font.  The Symbol font is usually a
special font.
</p>
<p><code class="code">gtroff</code> provides the following two requests to add more special
fonts.  See <a class="xref" href="#Using-Symbols">Using Symbols</a>, for a detailed description of the glyph
searching mechanism in <code class="code">gtroff</code>.
</p>
<p>Usually, only non-TTY devices have special fonts.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002especial"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.special</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">s1</i></span> <span class="r"><i class="slanted">s2</i></span> &hellip;]</var><a class="copiable-link" href='#index-_002especial'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-special-2"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002efspecial"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.fspecial</code></strong> <var class="def-var-arguments">f [<span class="r"><i class="slanted">s1</i></span> <span class="r"><i class="slanted">s2</i></span> &hellip;]</var><a class="copiable-link" href='#index-_002efspecial'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-fspecial"></a>
<a class="index-entry-id" id="index-fonts-1"></a>
<a class="index-entry-id" id="index-DESC-4"></a>
<p>Use the <code class="code">special</code> request to define special fonts.  Initially, this
list is empty.
</p>
<p>Use the <code class="code">fspecial</code> request to designate special fonts only when
font&nbsp;<var class="var">f</var> is active.  Initially, this list is empty.
</p>
<p>Previous calls to <code class="code">special</code> or <code class="code">fspecial</code> are overwritten;
without arguments, the particular list of special fonts is set to empty.
Special fonts are searched in the order they appear as arguments.
</p>
<p>All fonts that appear in a call to <code class="code">special</code> or <code class="code">fspecial</code>
are loaded.
</p>
<p>See <a class="xref" href="#Using-Symbols">Using Symbols</a>, for the exact search order of glyphs.
</p></dd></dl>


<hr>
</div>
<div class="subsection-level-extent" id="Artificial-Fonts">
<div class="nav-panel">
<p>
Next: <a href="#Ligatures-and-Kerning" accesskey="n" rel="next">Ligatures and Kerning</a>, Previous: <a href="#Special-Fonts" accesskey="p" rel="prev">Special Fonts</a>, Up: <a href="#Using-Fonts" accesskey="u" rel="up">Using Fonts</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Artificial-Fonts-1">5.19.7 Artificial Fonts</h4>
<a class="index-entry-id" id="index-artificial-fonts"></a>
<a class="index-entry-id" id="index-fonts_002c-artificial"></a>

<p>There are a number of requests and escape sequences for artificially
creating fonts.  These are largely vestiges of the days when output
devices did not have a wide variety of fonts, and when <code class="code">nroff</code> and
<code class="code">troff</code> were separate programs.  Most of them are no longer
necessary in GNU <code class="code">troff</code>.  Nevertheless, they are supported.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cH_0027height_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\H<code class="code">'</code></code><span class="r"><i class="slanted">height</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cH_0027height_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cH"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cH_0027_002bheight_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\H<code class="code">'</code></code><span class="r"><i class="slanted"><code class="t">+</code>height</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cH_0027_002bheight_0027'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cH_0027_002dheight_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\H<code class="code">'</code></code><span class="r"><i class="slanted"><code class="t">-</code>height</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cH_0027_002dheight_0027'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002eheight_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.height]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002eheight_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002eheight"></a>
<a class="index-entry-id" id="index-changing-the-font-height-_0028_005cH_0029"></a>
<a class="index-entry-id" id="index-font-height_002c-changing-_0028_005cH_0029"></a>
<a class="index-entry-id" id="index-height_002c-font_002c-changing-_0028_005cH_0029"></a>
<p>Change (increment, decrement) the height of the current font, but not
the width.  If <var class="var">height</var> is zero, restore the original height.
Default scaling unit is &lsquo;<samp class="samp">z</samp>&rsquo;.
</p>
<p>The read-only register <code class="code">.height</code> contains the font height as set by
<code class="code">\H</code>.
</p>
<p>Currently, only the <samp class="option">-Tps</samp> and <samp class="option">-Tpdf</samp> devices support
this feature.
</p>
<p><code class="code">\H</code> doesn&rsquo;t produce an input token in GNU <code class="code">troff</code>.  As a
consequence, it can be used in requests like <code class="code">mc</code> (which expects
a single character as an argument) to change the font on the fly:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.mc \H'+5z'x\H'0'
</pre></div></div>

<p>In compatibility mode, <code class="code">gtroff</code> behaves differently: If an
increment or decrement is used, it is always taken relative to the
current type size and not relative to the previously selected font
height.  Thus,
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.cp 1
\H'+5'test \H'+5'test
</pre></div></div>

<p>prints the word &lsquo;<samp class="samp">test</samp>&rsquo; twice with the same font height (five points
larger than the current font size).
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cS_0027slant_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\S<code class="code">'</code></code><span class="r"><i class="slanted">slant</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cS_0027slant_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cS"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002eslant_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.slant]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002eslant_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002eslant"></a>
<a class="index-entry-id" id="index-changing-the-font-slant-_0028_005cS_0029"></a>
<a class="index-entry-id" id="index-font-slant_002c-changing-_0028_005cS_0029"></a>
<a class="index-entry-id" id="index-slant_002c-font_002c-changing-_0028_005cS_0029"></a>
<p>Slant the current font by <var class="var">slant</var> degrees.  Positive values slant to
the right.  Only integer values are possible.
</p>
<p>The read-only register <code class="code">.slant</code> contains the font slant as set by
<code class="code">\S</code>.
</p>
<p>Currently, only the <samp class="option">-Tps</samp> and <samp class="option">-Tpdf</samp> devices support
this feature.
</p>
<p><code class="code">\S</code> doesn&rsquo;t produce an input token in GNU <code class="code">troff</code>.  As a
consequence, it can be used in requests like <code class="code">mc</code> (which expects
a single character as an argument) to change the font on the fly:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.mc \S'20'x\S'0'
</pre></div></div>

<a class="index-entry-id" id="index-CSTR-_002354-errata-3"></a>
<a class="index-entry-id" id="index-CSTR-_002354-erratum_002c-_005cS-escape"></a>
<p>This escape is incorrectly documented in the <abbr class="acronym">AT&amp;T</abbr>
<code class="code">troff</code> manual; the slant is always set to an absolute value.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eul"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ul</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">lines</i></span>]</var><a class="copiable-link" href='#index-_002eul'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ul"></a>
<a class="index-entry-id" id="index-underlining-_0028ul_0029"></a>
<p>The <code class="code">ul</code> request normally underlines subsequent lines if a TTY
output device is used.  Otherwise, the lines are printed in italics
(only the term &lsquo;underlined&rsquo; is used in the following).  The single
argument is the quantity of input lines to be underlined; with no
argument, the next line is underlined.  If <var class="var">lines</var> is zero or
negative, stop the effects of <code class="code">ul</code> (if it was active).  Requests
and empty lines do not count for computing the number of underlined
input lines, even if they produce some output like <code class="code">tl</code>.  Lines
inserted by macros (e.g., invoked by a trap) do count.
</p>
<p>At the beginning of <code class="code">ul</code>, the current font is stored and the
underline font is activated.  Within the span of a <code class="code">ul</code> request, it
is possible to change fonts, but after the last line affected by
<code class="code">ul</code> the saved font is restored.
</p>
<p>This number of lines still to be underlined is associated with the
environment (see <a class="pxref" href="#Environments">Environments</a>).  The underline font can be changed
with the <code class="code">uf</code> request.
</p>


<p>The <code class="code">ul</code> request does not underline spaces.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ecu"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.cu</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">lines</i></span>]</var><a class="copiable-link" href='#index-_002ecu'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-cu"></a>
<a class="index-entry-id" id="index-continuous-underlining-_0028cu_0029"></a>
<a class="index-entry-id" id="index-underlining_002c-continuous-_0028cu_0029"></a>
<p>The <code class="code">cu</code> request is similar to <code class="code">ul</code> but underlines spaces as
well (if a TTY output device is used).
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002euf"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.uf</code></strong> <var class="def-var-arguments">font</var><a class="copiable-link" href='#index-_002euf'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-uf"></a>
<a class="index-entry-id" id="index-underline-font-_0028uf_0029"></a>
<a class="index-entry-id" id="index-font-for-underlining-_0028uf_0029"></a>
<p>Set the underline font (globally) used by <code class="code">ul</code> and <code class="code">cu</code>.  By
default, this is the font at position&nbsp;2.  <var class="var">font</var> can be either
a non-negative font position or the name of a font.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ebd"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.bd</code></strong> <var class="def-var-arguments">font [<span class="r"><i class="slanted">offset</i></span>]</var><a class="copiable-link" href='#index-_002ebd'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-bd"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002ebd-1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.bd</code></strong> <var class="def-var-arguments">font1 font2 [<span class="r"><i class="slanted">offset</i></span>]</var><a class="copiable-link" href='#index-_002ebd-1'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002eb_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.b]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002eb_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002eb"></a>
<a class="index-entry-id" id="index-imitating-boldface-_0028bd_0029"></a>
<a class="index-entry-id" id="index-boldface_002c-imitating-_0028bd_0029"></a>
<p>Embolden <var class="var">font</var> by overstriking its glyphs offset by <var class="var">offset</var>
units minus one.
</p>
<p>Two syntax forms are available.
</p>
<ul class="itemize mark-bullet">
<li>Imitate a bold font unconditionally.  The first argument specifies the
font to embolden, and the second is the number of basic units, minus
one, by which the two glyphs are offset.  If the second argument is
missing, emboldening is turned off.

<p><var class="var">font</var> can be either a non-negative font position or the name of a
font.
</p>
<p><var class="var">offset</var> is available in the <code class="code">.b</code> read-only register if a
special font is active; in the <code class="code">bd</code> request, its default unit is
&lsquo;<samp class="samp">u</samp>&rsquo;.
</p>
</li><li><a class="index-entry-id" id="index-fspecial-request_002c-and-imitating-bold"></a>
<a class="index-entry-id" id="index-special"></a>
<a class="index-entry-id" id="index-embolding-of-special-fonts"></a>
<a class="index-entry-id" id="index-special-fonts_002c-emboldening"></a>
Imitate a bold form conditionally.  Embolden <var class="var">font1</var> by <var class="var">offset</var>
only if font <var class="var">font2</var> is the current font.  This request can be
issued repeatedly to set up different emboldening values for different
current fonts.  If the second argument is missing, emboldening is turned
off for this particular current font.

<p>This affects special fonts only (either set up with the <code class="code">special</code>
command in font files or with the <code class="code">fspecial</code> request).
</p></li></ul>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ecs"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.cs</code></strong> <var class="def-var-arguments">font [<span class="r"><i class="slanted">width</i></span> [<span class="r"><i class="slanted">em-size</i></span>]]</var><a class="copiable-link" href='#index-_002ecs'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-cs"></a>
<a class="index-entry-id" id="index-constant-glyph-space-mode-_0028cs_0029"></a>
<a class="index-entry-id" id="index-mode-for-constant-glyph-space-_0028cs_0029"></a>
<a class="index-entry-id" id="index-glyph_002c-constant-space"></a>
<a class="index-entry-id" id="index-ps-request_002c-and-constant-glyph-space-mode"></a>
<p>Switch to and from <em class="dfn">constant glyph space mode</em>.  If activated, the
width of every glyph is <em class="math"><var class="var">width</var>/36</em> ems.  The em size is given
absolutely by <var class="var">em-size</var>; if this argument is missing, the em value
is taken from the current font size (as set with the <code class="code">ps</code> request)
when the font is effectively in use.  Without second and third argument,
constant glyph space mode is deactivated.
</p>
<p>Default scaling unit for <var class="var">em-size</var> is &lsquo;<samp class="samp">z</samp>&rsquo;; <var class="var">width</var> is an
integer.
</p></dd></dl>


<hr>
</div>
<div class="subsection-level-extent" id="Ligatures-and-Kerning">
<div class="nav-panel">
<p>
Next: <a href="#Dummy-Characters" accesskey="n" rel="next">Dummy Characters</a>, Previous: <a href="#Artificial-Fonts" accesskey="p" rel="prev">Artificial Fonts</a>, Up: <a href="#Using-Fonts" accesskey="u" rel="up">Using Fonts</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Ligatures-and-Kerning-1">5.19.8 Ligatures and Kerning</h4>
<a class="index-entry-id" id="index-ligatures-and-kerning"></a>
<a class="index-entry-id" id="index-kerning-and-ligatures"></a>

<p>Ligatures are groups of characters that are run together, i.e, producing
a single glyph.  For example, the letters &lsquo;f&rsquo; and &lsquo;i&rsquo; can form a
ligature &lsquo;fi&rsquo; as in the word &lsquo;file&rsquo;.  This produces a cleaner look
(albeit subtle) to the printed output.  Usually, ligatures are not
available in fonts for TTY output devices.
</p>
<p>Most PostScript fonts support the fi and fl ligatures.  The C/A/T
typesetter that was the target of <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> also
supported &lsquo;ff&rsquo;, &lsquo;ffi&rsquo;, and &lsquo;ffl&rsquo; ligatures.  Advanced typesetters or
&lsquo;expert&rsquo; fonts may include ligatures for &lsquo;ft&rsquo; and &lsquo;ct&rsquo;, although GNU
<code class="code">troff</code> does not support these (yet).
</p>
<p>Only the current font is checked for ligatures and kerns; neither
special fonts nor special charcters defined with the <code class="code">char</code> request
(and its siblings) are taken into account.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002elg"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.lg</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">flag</i></span>]</var><a class="copiable-link" href='#index-_002elg'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-lg"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002elg_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.lg]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002elg_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002elg-1"></a>
<a class="index-entry-id" id="index-activating-ligatures-_0028lg_0029"></a>
<a class="index-entry-id" id="index-ligatures_002c-activating-_0028lg_0029"></a>
<a class="index-entry-id" id="index-ligatures-enabled-register-_0028_002elg_0029"></a>
<p>Switch the ligature mechanism on or off; if the parameter is non-zero or
missing, ligatures are enabled, otherwise disabled.  Default is on.  The
current ligature mode can be found in the read-only register <code class="code">.lg</code>
(set to 1 or&nbsp;2 if ligatures are enabled, 0&nbsp;otherwise).
</p>
<p>Setting the ligature mode to&nbsp;2 enables the two-character ligatures
(fi, fl, and ff) and disables the three-character ligatures (ffi and
ffl).
</p></dd></dl>

<p><em class="dfn">Pairwise kerning</em> is another subtle typesetting mechanism that
modifies the distance between a glyph pair to improve readability.  In
most cases (but not always) the distance is decreased.
Typewriter-like fonts and fonts for terminals where all glyphs have the
same width don&rsquo;t use kerning.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002ekern"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.kern</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">flag</i></span>]</var><a class="copiable-link" href='#index-_002ekern'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-kern"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ekern_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.kern]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ekern_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ekern-1"></a>
<a class="index-entry-id" id="index-activating-kerning-_0028kern_0029"></a>
<a class="index-entry-id" id="index-kerning_002c-activating-_0028kern_0029"></a>
<a class="index-entry-id" id="index-kerning-enabled-register-_0028_002ekern_0029"></a>
<p>Switch kerning on or off.  If the parameter is non-zero or missing,
enable pairwise kerning, otherwise disable it.  The read-only register
<code class="code">.kern</code> is set to&nbsp;1 if pairwise kerning is enabled,
0&nbsp;otherwise.
</p>
<a class="index-entry-id" id="index-dummy-character-_0028_005c_0026_0029_002c-effect-on-kerning"></a>
<a class="index-entry-id" id="index-character_002c-dummy-_0028_005c_0026_0029_002c-effect-on-kerning"></a>
<p>If the font description file contains pairwise kerning information,
glyphs from that font are kerned.  Kerning between two glyphs can be
inhibited by placing <code class="code">\&amp;</code> between them: &lsquo;<samp class="samp">V\&amp;A</samp>&rsquo;.
</p>
<p>See <a class="xref" href="#Font-Description-File-Format">Font Description File Format</a>.
</p></dd></dl>

<a class="index-entry-id" id="index-track-kerning"></a>
<a class="index-entry-id" id="index-kerning_002c-track"></a>
<p><em class="dfn">Track kerning</em> expands or reduces the space between glyphs.  This
can be handy, for example, if you need to squeeze a long word onto a
single line or spread some text to fill a narrow column.  It must be
used with great care since it is usually considered bad typography if
the reader notices the effect.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002etkf"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.tkf</code></strong> <var class="def-var-arguments">f s1 n1 s2 n2</var><a class="copiable-link" href='#index-_002etkf'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-tkf"></a>
<a class="index-entry-id" id="index-activating-track-kerning-_0028tkf_0029"></a>
<a class="index-entry-id" id="index-track-kerning_002c-activating-_0028tkf_0029"></a>
<p>Enable track kerning for font&nbsp;<var class="var">f</var>.  If the current font
is&nbsp;<var class="var">f</var> the width of every glyph is increased by an amount
between <var class="var">n1</var> and <var class="var">n2</var> (<var class="var">n1</var>, <var class="var">n2</var> can be negative); if
the current type size is less than or equal to <var class="var">s1</var> the width is
increased by <var class="var">n1</var>; if it is greater than or equal to <var class="var">s2</var> the
width is increased by <var class="var">n2</var>; if the type size is greater than or
equal to <var class="var">s1</var> and less than or equal to <var class="var">s2</var> the increase in
width is a linear function of the type size.
</p>
<p>The default scaling unit is &lsquo;<samp class="samp">z</samp>&rsquo; for <var class="var">s1</var> and <var class="var">s2</var>, &lsquo;<samp class="samp">p</samp>&rsquo;
for <var class="var">n1</var> and <var class="var">n2</var>.
</p>
<p>The track kerning amount is added even to the rightmost glyph in a line;
for large values it is thus recommended to increase the line length by
the same amount to compensate.
</p></dd></dl>


<hr>
</div>
<div class="subsection-level-extent" id="Italic-Corrections">
<div class="nav-panel">
<p>
Next: <a href="#Dummy-Characters" accesskey="n" rel="next">Dummy Characters</a>, Previous: <a href="#Ligatures-and-Kerning" accesskey="p" rel="prev">Ligatures and Kerning</a>, Up: <a href="#Using-Fonts" accesskey="u" rel="up">Using Fonts</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Italic-Corrections-1">5.19.9 Italic Corrections</h4>

<p>When typesetting adjacent glyphs from typefaces of different slants, the
space between them may require adjustment.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002f-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\/</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_002f-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_002f"></a>
<a class="index-entry-id" id="index-italic-correction-_0028_005c_002f_0029"></a>
<a class="index-entry-id" id="index-correction_002c-italic-_0028_005c_002f_0029"></a>
<a class="index-entry-id" id="index-correction-between-oblique-and-upright-glyph-_0028_005c_002f_002c-_005c_002c_0029"></a>
<a class="index-entry-id" id="index-roman-glyph_002c-correction-after-italic-glyph-_0028_005c_002f_0029"></a>
<a class="index-entry-id" id="index-upright-glyph_002c-correction-after-oblique-glyph-_0028_005c_002f_0029"></a>
<p>Apply an <em class="dfn">italic correction</em>: modify the spacing of the preceding
glyph so that the distance between it and the following glyph is correct
if the latter is of upright shape.  For example, if an
italic&nbsp;&lsquo;<samp class="samp">f</samp>&rsquo; is followed immediately by a roman right
parenthesis, then in many fonts the top right portion of
the&nbsp;&lsquo;<samp class="samp">f</samp>&rsquo; overlaps the top left of the right parenthesis, which
is ugly.  Use this escape sequence whenever an oblique glyph is
immediately followed by an upright glyph without any intervening space.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002c-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\,</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_002c-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_002c"></a>
<a class="index-entry-id" id="index-left-italic-correction-_0028_005c_002c_0029"></a>
<a class="index-entry-id" id="index-correction_002c-left-italic-_0028_005c_002c_0029"></a>
<a class="index-entry-id" id="index-correction-between-upright-and-oblique-glyph-_0028_005c_002f_002c-_005c_002c_0029"></a>
<a class="index-entry-id" id="index-roman-glyph_002c-correction-before-italic-glyph-_0028_005c_002c_0029"></a>
<a class="index-entry-id" id="index-upright-glyph_002c-correction-before-oblique-glyph-_0028_005c_002c_0029"></a>
<p>Apply a <em class="dfn">left italic correction</em>: modify the spacing of the
following glyph so that the distance between it and the preceding
glyph is correct if the latter is of upright shape.  For example,
if a roman left parenthesis is immediately followed by an
italic&nbsp;&lsquo;<samp class="samp">f</samp>&rsquo;, then in many fonts the bottom left portion of
the&nbsp;&lsquo;<samp class="samp">f</samp>&rsquo; overlaps the bottom of the left parenthesis, which is
ugly.  Use this escape sequence whenever an upright glyph is followed
immediately by an oblique glyph without any intervening space.
</p></dd></dl>

<hr>
</div>
<div class="subsection-level-extent" id="Dummy-Characters">
<div class="nav-panel">
<p>
Previous: <a href="#Italic-Corrections" accesskey="p" rel="prev">Italic Corrections</a>, Up: <a href="#Using-Fonts" accesskey="u" rel="up">Using Fonts</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Dummy-Characters-1">5.19.10 Dummy Characters</h4>

<p>As discussed in <a class="ref" href="#Requests-and-Macros">Requests and Macros</a>, the first character on an
input line is treated specially.  Further, formatting a glyph has many
consequences on formatter state (see <a class="pxref" href="#Environments">Environments</a>).  Occasionally,
we want to escape this context or embrace some of those consequences
without actually rendering a glyph to the output.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_0026-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\&amp;</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_0026-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_0026"></a>
<a class="index-entry-id" id="index-dummy-character-_0028_005c_0026_0029"></a>
<a class="index-entry-id" id="index-character_002c-dummy-_0028_005c_0026_0029"></a>
<p>Interpolate a dummy character, which is constitutive of output but
invisible.<a class="footnote" id="DOCF81" href="#FOOT81"><sup>81</sup></a>  Its presence alters the interpretation context of a
subsequent input character, and enjoys several applications.
</p>
<ul class="itemize mark-bullet">
<li>Prevent insertion of extra space after an end-of-sentence character.

<div class="example">
<div class="group"><pre class="example-preformatted">Test.
Test.
    &rArr; Test.  Test.
Test.\&amp;
Test.
    &rArr; Test. Test.
</pre></div></div>

</li><li>Prevent recognition of a control character.

<div class="example">
<div class="group"><pre class="example-preformatted">.Test
    error&rarr; warning: macro 'Test' not defined
\&amp;.Test
    &rArr; .Test
</pre></div></div>

</li><li>Prevent kerning between two glyphs.


</li><li>Translate a character to &ldquo;nothing&rdquo;.

<div class="example">
<div class="group"><pre class="example-preformatted">.tr JIjiK\&amp;k\&amp;UVuv
Post universitum, alea jacta est, OK?
    &rArr; Post vniversitvm, alea iacta est, O?
</pre></div></div>
</li></ul>

<p>The dummy character escape sequence sees use in macro definitions as a
means of ensuring that arguments are treated as text even if they begin
with spaces or control characters.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de HD \&quot; typeset a simple bold heading
.  sp
.  ft B
\&amp;\\$1 \&quot; exercise: remove the \&amp;
.  ft
.  sp
..
.HD .\|.\|.\|surprised?
</pre></div></div>
</dd></dl>

<p>One way to think about the dummy character is to imagine placing the
symbol &lsquo;<samp class="samp">&amp;</samp>&rsquo; in the input at a certain location; if doing so has all
the side effects on formatting that you desire except for sticking an
ugly ampersand in the midst of your text, the dummy character is what
you want in its place.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_0029-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\)</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_0029-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_0029"></a>
<a class="index-entry-id" id="index-transparent-dummy-character-_0028_005c_0029_0029"></a>
<a class="index-entry-id" id="index-character_002c-transparent-dummy-_0028_005c_0029_0029"></a>
<a class="index-entry-id" id="index-dummy-character_002c-transparent-_0028_005c_0029_0029"></a>
<p>Interpolate a <i class="slanted">transparent</i> dummy character&mdash;one that is
transparent to end-of-sentence detection.  It behaves as <code class="code">\&amp;</code>,
except that <code class="code">\&amp;</code> is treated as letters and numerals normally are
after &lsquo;<samp class="samp">.</samp>&rsquo;, &lsquo;<samp class="samp">?</samp>&rsquo; and &lsquo;<samp class="samp">!</samp>&rsquo;; <code class="code">\&amp;</code> cancels end-of-sentence
detection, and <code class="code">\)</code> does not.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de Suffix-&amp;
.  nop \&amp;\\$1
..
.
.de Suffix-)
.  nop \)\\$1
..
.
Here's a sentence.\c
.Suffix-&amp; '
Another one.\c
.Suffix-) '
And a third.
    &rArr; Here's a sentence.' Another one.'  And a third.
</pre></div></div>
</dd></dl>




<hr>
</div>
</div>
<div class="section-level-extent" id="Manipulating-Type-Size-and-Vertical-Spacing">
<div class="nav-panel">
<p>
Next: <a href="#Colors" accesskey="n" rel="next">Colors</a>, Previous: <a href="#Using-Fonts" accesskey="p" rel="prev">Using Fonts</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Manipulating-Type-Size-and-Vertical-Spacing-1">5.20 Manipulating Type Size and Vertical Spacing</h3>
<a class="index-entry-id" id="index-manipulating-type-size-and-vertical-spacing"></a>

<a class="index-entry-id" id="index-text-baseline-1"></a>
<a class="index-entry-id" id="index-baseline_002c-text-1"></a>
<a class="index-entry-id" id="index-type-size"></a>
<a class="index-entry-id" id="index-size_002c-size"></a>
<a class="index-entry-id" id="index-vertical-spacing-1"></a>
<a class="index-entry-id" id="index-spacing_002c-vertical-1"></a>
<p>These concepts were introduced in <a class="ref" href="#Page-Geometry">Page Geometry</a>.  The height of a
font&rsquo;s tallest glyph is one em, which is equal to the type size in
points.<a class="footnote" id="DOCF82" href="#FOOT82"><sup>82</sup></a>  A vertical spacing of less than 120% of
the type size can make a document hard to read.  Larger proportions can
be useful to spread the text for annotations or proofreader&rsquo;s marks.  By
default, GNU <code class="code">troff</code> uses 10&nbsp;point type on 12&nbsp;point
spacing.
<a class="index-entry-id" id="index-leading"></a>
Typographers call the difference between type size and vertical spacing
<em class="dfn">leading</em>.<a class="footnote" id="DOCF83" href="#FOOT83"><sup>83</sup></a>
</p>


<ul class="mini-toc">
<li><a href="#Changing-the-Type-Size" accesskey="1">Changing the Type Size</a></li>
<li><a href="#Changing-the-Vertical-Spacing" accesskey="2">Changing the Vertical Spacing</a></li>
<li><a href="#Using-Fractional-Type-Sizes" accesskey="3">Using Fractional Type Sizes</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="Changing-the-Type-Size">
<div class="nav-panel">
<p>
Next: <a href="#Changing-the-Vertical-Spacing" accesskey="n" rel="next">Changing the Vertical Spacing</a>, Previous: <a href="#Manipulating-Type-Size-and-Vertical-Spacing" accesskey="p" rel="prev">Manipulating Type Size and Vertical Spacing</a>, Up: <a href="#Manipulating-Type-Size-and-Vertical-Spacing" accesskey="u" rel="up">Manipulating Type Size and Vertical Spacing</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Changing-the-Type-Size-1">5.20.1 Changing the Type Size</h4>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eps"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ps</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">size</i></span>]</var><a class="copiable-link" href='#index-_002eps'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ps"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002eps-1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ps</code></strong> <var class="def-var-arguments"><code class="t">+</code><span class="r"><i class="slanted">size</i></span></var><a class="copiable-link" href='#index-_002eps-1'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_002eps-2"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ps</code></strong> <var class="def-var-arguments"><code class="t">-</code><span class="r"><i class="slanted">size</i></span></var><a class="copiable-link" href='#index-_002eps-2'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cssize"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\s</code><span class="r"><i class="slanted">size</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cssize'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cs"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002es_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.s]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002es_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002es"></a>
<a class="index-entry-id" id="index-changing-type-sizes-_0028ps_002c-_005cs_0029"></a>
<a class="index-entry-id" id="index-type-sizes_002c-changing-_0028ps_002c-_005cs_0029"></a>
<a class="index-entry-id" id="index-point-sizes_002c-changing-_0028ps_002c-_005cs_0029"></a>
<p>Use the <code class="code">ps</code> request or the <code class="code">\s</code> escape sequence to change
(increase, decrease) the type size (in scaled points).  Specify
<var class="var">size</var> as either an absolute type size, or as a relative change from
the current size.  <code class="code">ps</code> with no argument restores the previous
size.  The <code class="code">ps</code> request&rsquo;s default scaling unit is &lsquo;<samp class="samp">z</samp>&rsquo;.  The
requested size is rounded to the nearest valid size (with ties rounding
down) within the limits supported by the device.  If the requested size
is non-positive, it is treated as 1<span class="dmn">u</span>.
</p>
<a class="index-entry-id" id="index-CSTR-_002354-errata-4"></a>
<a class="index-entry-id" id="index-CSTR-_002354-erratum_002c-ps-request"></a>
<a class="index-entry-id" id="index-CSTR-_002354-erratum_002c-_005cs-escape-sequence"></a>
<p>Type size alteration is incorrectly documented in the <abbr class="acronym">AT&amp;T</abbr>
<code class="code">troff</code> manual, which claims &ldquo;if [the requested size] is invalid,
the next larger valid size will result, with a maximum of
36&rdquo;.<a class="footnote" id="DOCF84" href="#FOOT84"><sup>84</sup></a>
</p>
<a class="index-entry-id" id="index-type-size-registers-_0028_002es_002c-_002eps_0029"></a>
<a class="index-entry-id" id="index-point-size-registers-_0028_002es_002c-_002eps_0029"></a>
<p>The read-only string-valued register <code class="code">.s</code> interpolates the type
size in points as a decimal fraction; it is associated with the
environment (see <a class="pxref" href="#Environments">Environments</a>).  To obtain the type size in scaled
points, interpolate the <code class="code">.ps</code> register instead (see <a class="pxref" href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a>).
</p>
<p>The <code class="code">\s</code> escape sequence supports a variety of syntax forms.
</p>
<dl class="table">
<dt><code class="code">\s<var class="var">n</var></code></dt>
<dd><p>Set the type size to <var class="var">n</var>&nbsp;points.  <var class="var">n</var>&nbsp;must be a single
digit.  If <var class="var">n</var>&nbsp;is 0, restore the previous size.
</p>
</dd>
<dt><code class="code">\s+<var class="var">n</var></code></dt>
<dt><code class="code">\s-<var class="var">n</var></code></dt>
<dd><p>Increase or decrease the type size by <var class="var">n</var>&nbsp;points.
<var class="var">n</var>&nbsp;must be exactly one digit.
</p>
</dd>
<dt><code class="code">\s(<var class="var">nn</var></code></dt>
<dd><p>Set the type size to <var class="var">nn</var>&nbsp;points.  <var class="var">nn</var> must be exactly two
digits.
</p>
</dd>
<dt><code class="code">\s+(<var class="var">nn</var></code></dt>
<dt><code class="code">\s-(<var class="var">nn</var></code></dt>
<dt><code class="code">\s(+<var class="var">nn</var></code></dt>
<dt><code class="code">\s(-<var class="var">nn</var></code></dt>
<dd><p>Alter the type size in points by the two-digit value <var class="var">nn</var>.
</p></dd>
</dl>

<p>See <a class="xref" href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a>, for further syntactical forms of the
<code class="code">\s</code> escape sequence that additionally accept decimal fractions.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">snap, snap,
.ps +2
grin, grin,
.ps +2
wink, wink, \s+2nudge, nudge,\s+8 say no more!
.ps 10
</pre></div></div>
</dd></dl>

<p>The <code class="code">\s</code> escape sequence affects the environment immediately and
doesn&rsquo;t produce an input token.  Consequently, it can be used in
requests like <code class="code">mc</code>, which expects a single character as an
argument, to change the type size on the fly.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.mc \s[20]x\s[0]
</pre></div></div>

<dl class="first-deffn">
<dt class="deffn" id="index-_002esizes"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.sizes</code></strong> <var class="def-var-arguments">s1 s2 &hellip; sn [<code class="t">0</code>]</var><a class="copiable-link" href='#index-_002esizes'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-sizes-1"></a>
<p>The <samp class="file">DESC</samp> file specifies which type sizes are allowed by the
output device; see <a class="ref" href="#DESC-File-Format"><samp class="file">DESC</samp> File Format</a>.  Use the <code class="code">sizes</code> request
to change this set of permissible sizes.  Arguments are in scaled
points; see <a class="ref" href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a>.  Each can be a single
type size (such as &lsquo;<samp class="samp">12000</samp>&rsquo;), or a range of sizes (such as
&lsquo;<samp class="samp">4000-72000</samp>&rsquo;).  You can optionally end the list with a &lsquo;<samp class="samp">0</samp>&rsquo;.
</p></dd></dl>

<hr>
</div>
<div class="subsection-level-extent" id="Changing-the-Vertical-Spacing">
<div class="nav-panel">
<p>
Next: <a href="#Using-Fractional-Type-Sizes" accesskey="n" rel="next">Using Fractional Type Sizes</a>, Previous: <a href="#Changing-the-Type-Size" accesskey="p" rel="prev">Changing the Type Size</a>, Up: <a href="#Manipulating-Type-Size-and-Vertical-Spacing" accesskey="u" rel="up">Manipulating Type Size and Vertical Spacing</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Changing-the-Vertical-Spacing-1">5.20.2 Changing the Vertical Spacing</h4>

<dl class="first-deffn">
<dt class="deffn" id="index-_002evs"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.vs</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">space</i></span>]</var><a class="copiable-link" href='#index-_002evs'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-vs"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002evs-1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.vs</code></strong> <var class="def-var-arguments"><code class="t">+</code><span class="r"><i class="slanted">space</i></span></var><a class="copiable-link" href='#index-_002evs-1'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_002evs-2"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.vs</code></strong> <var class="def-var-arguments"><code class="t">-</code><span class="r"><i class="slanted">space</i></span></var><a class="copiable-link" href='#index-_002evs-2'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ev_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.v]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ev_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ev"></a>
<a class="index-entry-id" id="index-changing-vertical-line-spacing-_0028vs_0029"></a>
<a class="index-entry-id" id="index-vertical-line-spacing_002c-changing-_0028vs_0029"></a>
<a class="index-entry-id" id="index-vertical-line-spacing-register-_0028_002ev_0029"></a>
<p>Set the vertical spacing to, or alter it by, <var class="var">space</var>.  The default
scaling unit is &lsquo;<samp class="samp">p</samp>&rsquo;.  If <code class="code">vs</code> is called without an argument,
the vertical spacing is reset to the previous value before the last call
to <code class="code">vs</code>.
<a class="index-entry-id" id="index-_002eV-register_002c-and-vs"></a>
GNU <code class="code">troff</code> emits a warning in category &lsquo;<samp class="samp">range</samp>&rsquo; if <var class="var">space</var>
is negative; the vertical spacing is then set to the smallest possible
positive value, the vertical motion quantum (as found in the <code class="code">.V</code>
register).
</p>
<p>&lsquo;<samp class="samp">.vs&nbsp;0</samp>&rsquo;<!-- /@w --> isn&rsquo;t saved in a diversion since it doesn&rsquo;t result in
a vertical motion.  You must explicitly issue this request before
interpolating the diversion.
</p>
<p>The read-only register <code class="code">.v</code> contains the vertical spacing; it is
associated with the environment (see <a class="pxref" href="#Environments">Environments</a>).
</p></dd></dl>

<a class="index-entry-id" id="index-vertical-line-spacing_002c-effective-value"></a>
<p>When a break occurs, GNU <code class="code">troff</code> performs the following procedure.
</p>
<ul class="itemize mark-bullet">
<li><a class="index-entry-id" id="index-extra-pre_002dvertical-line-space-_0028_005cx_0029"></a>
<a class="index-entry-id" id="index-line-space_002c-extra-pre_002dvertical-_0028_005cx_0029"></a>
Move the drawing position vertically by the <em class="dfn">extra pre-vertical line
space</em>, the minimum of all negative <code class="code">\x</code> escape sequence arguments
in the pending output line.

</li><li>Move the drawing position vertically by the vertical line spacing.

</li><li>Write out the pending output line.

</li><li><a class="index-entry-id" id="index-extra-post_002dvertical-line-space-_0028_005cx_0029"></a>
<a class="index-entry-id" id="index-line-space_002c-extra-post_002dvertical-_0028_005cx_0029"></a>
Move the drawing position vertically by the <em class="dfn">extra post-vertical line
space</em>, the maximum of all positive <code class="code">\x</code> escape sequence arguments
in the line that has just been output.

</li><li><a class="index-entry-id" id="index-post_002dvertical-line-spacing"></a>
<a class="index-entry-id" id="index-line-spacing_002c-post_002dvertical-_0028pvs_0029"></a>
Move the drawing position vertically by the <em class="dfn">post-vertical line
spacing</em> (see below).
</li></ul>

<a class="index-entry-id" id="index-double_002dspacing-_0028vs_002c-pvs_0029"></a>
<p>Prefer <code class="code">vs</code> or <code class="code">pvs</code> over <code class="code">ls</code> to produce double-spaced
documents.  <code class="code">vs</code> and <code class="code">pvs</code> have finer granularity than
<code class="code">ls</code>; moreover, some preprocessors assume single spacing.
See <a class="xref" href="#Manipulating-Spacing">Manipulating Spacing</a>, regarding the <code class="code">\x</code> escape sequence and
the <code class="code">ls</code> request.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002epvs"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.pvs</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">space</i></span>]</var><a class="copiable-link" href='#index-_002epvs'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-pvs"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002epvs-1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.pvs</code></strong> <var class="def-var-arguments"><code class="t">+</code><span class="r"><i class="slanted">space</i></span></var><a class="copiable-link" href='#index-_002epvs-1'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_002epvs-2"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.pvs</code></strong> <var class="def-var-arguments"><code class="t">-</code><span class="r"><i class="slanted">space</i></span></var><a class="copiable-link" href='#index-_002epvs-2'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002epvs_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.pvs]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002epvs_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002epvs-3"></a>
<a class="index-entry-id" id="index-ls-request_002c-alternative-to-_0028pvs_0029"></a>
<a class="index-entry-id" id="index-post_002dvertical-line-spacing_002c-changing-_0028pvs_0029"></a>
<a class="index-entry-id" id="index-post_002dvertical-line-spacing-register-_0028_002epvs_0029"></a>
<p>Set the post-vertical spacing to, or alter it by, <var class="var">space</var>.  The
default scaling unit is &lsquo;<samp class="samp">p</samp>&rsquo;.  If <code class="code">pvs</code> is called without an
argument, the post-vertical spacing is reset to the previous value
before the last call to <code class="code">pvs</code>.  GNU <code class="code">troff</code> emits a warning in
category &lsquo;<samp class="samp">range</samp>&rsquo; if <var class="var">space</var> is negative; the post-vertical
spacing is then set to zero.
</p>
<p>The read-only register <code class="code">.pvs</code> contains the post-vertical spacing;
it is associated with the environment (see <a class="pxref" href="#Environments">Environments</a>).
</p></dd></dl>


<hr>
</div>
<div class="subsection-level-extent" id="Using-Fractional-Type-Sizes">
<div class="nav-panel">
<p>
Previous: <a href="#Changing-the-Type-Size" accesskey="p" rel="prev">Changing the Type Size</a>, Up: <a href="#Manipulating-Type-Size-and-Vertical-Spacing" accesskey="u" rel="up">Manipulating Type Size and Vertical Spacing</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Using-Fractional-Type-Sizes-1">5.20.3 Using Fractional Type Sizes</h4>
<a class="index-entry-id" id="index-fractional-type-sizes"></a>
<a class="index-entry-id" id="index-fractional-point-sizes"></a>
<a class="index-entry-id" id="index-type-sizes_002c-fractional"></a>
<a class="index-entry-id" id="index-point-sizes_002c-fractional"></a>
<a class="index-entry-id" id="index-sizes_002c-fractional-type"></a>

<p>AT&amp;T <code class="code">troff</code> interpreted all type size measurements in points.
Combined with integer arithmetic, this design choice made it impossible
to support, for instance, ten and a half-point type.  In GNU
<code class="code">troff</code>, an output device can select a scaling factor that
subdivides a point into &ldquo;scaled points&rdquo;.  A type size expressed in
scaled points can thus represent a non-integral type size.
</p>
<a class="index-entry-id" id="index-s-scaling-unit"></a>
<a class="index-entry-id" id="index-unit_002c-scaling_002c-s"></a>
<a class="index-entry-id" id="index-scaling-unit-s"></a>
<a class="index-entry-id" id="index-z-scaling-unit"></a>
<a class="index-entry-id" id="index-unit_002c-scaling_002c-z"></a>
<a class="index-entry-id" id="index-scaling-unit-z"></a>
<a class="index-entry-id" id="index-ps-request_002c-with-fractional-type-sizes"></a>
<a class="index-entry-id" id="index-cs-request_002c-with-fractional-type-sizes"></a>
<a class="index-entry-id" id="index-tkf-request_002c-with-fractional-type-sizes"></a>
<a class="index-entry-id" id="index-_005cH_002c-with-fractional-type-sizes"></a>
<a class="index-entry-id" id="index-_005cs_002c-with-fractional-type-sizes"></a>
<p>A <em class="dfn">scaled point</em> is equal to <em class="math">1/<var class="var">sizescale</var></em> points, where
<var class="var">sizescale</var> is specified in the device description file <samp class="file">DESC</samp>,
and defaults to&nbsp;1.<a class="footnote" id="DOCF85" href="#FOOT85"><sup>85</sup></a>  Requests and escape sequences in GNU <code class="code">troff</code> interpret
arguments that represent a type size in scaled points, which the
formatter multiplies by <var class="var">sizescale</var> and converts to an integer.
Arguments treated in this way comprise those to the escape sequences
<code class="code">\H</code> and <code class="code">\s</code>, to the request <code class="code">ps</code>, the third argument to
the <code class="code">cs</code> request, and the second and fourth arguments to the
<code class="code">tkf</code> request.  Scaled points may be specified explicitly with the
<code class="code">z</code> scaling unit.
</p>
<p>For example, if <var class="var">sizescale</var> is&nbsp;1000, then a scaled point is one
thousandth of a point.  The request &lsquo;<samp class="samp">.ps 10.5</samp>&rsquo; is synonymous with
&lsquo;<samp class="samp">.ps 10.5z</samp>&rsquo; and sets the type size to 10,500&nbsp;scaled points, or
10.5&nbsp;points.  Consequently, in GNU <code class="code">troff</code>, the register
<code class="code">.s</code> can interpolate a non-integral type size.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005b_002eps_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.ps]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002eps_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002eps-3"></a>
<p>This read-only register interpolates the type size in scaled points; it
is associated with the environment (see <a class="pxref" href="#Environments">Environments</a>).
</p></dd></dl>

<p>It makes no sense to use the &lsquo;<samp class="samp">z</samp>&rsquo; scaling unit in a numeric
expression whose default scaling unit is neither &lsquo;<samp class="samp">u</samp>&rsquo; nor &lsquo;<samp class="samp">z</samp>&rsquo;,
so GNU <code class="code">troff</code> disallows this.  Similarly, it is nonsensical to use
a scaling unit other than &lsquo;<samp class="samp">z</samp>&rsquo; or &lsquo;<samp class="samp">u</samp>&rsquo; in a numeric expression
whose default scaling unit is &lsquo;<samp class="samp">z</samp>&rsquo;, and so GNU <code class="code">troff</code>
disallows this as well.
</p>
<p>Another GNU <code class="code">troff</code> scaling unit, &lsquo;<samp class="samp">s</samp>&rsquo;, multiplies by the
number of basic units in a scaled point.  Thus, &lsquo;<samp class="samp">\n[.ps]s</samp>&rsquo; is equal
to &lsquo;<samp class="samp">1m</samp>&rsquo; by definition.  Do not confuse the &lsquo;<samp class="samp">s</samp>&rsquo; and &lsquo;<samp class="samp">z</samp>&rsquo;
scaling units.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005b_002epsr_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.psr]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002epsr_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002epsr"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002esr_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.sr]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002esr_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002esr"></a>
<a class="index-entry-id" id="index-last_002drequested-type-size-registers-_0028_002epsr_002c-_002esr_0029"></a>
<a class="index-entry-id" id="index-type-size-registers_002c-last_002drequested-_0028_002epsr_002c-_002esr_0029"></a>
<a class="index-entry-id" id="index-last_002drequested-point-size-registers-_0028_002epsr_002c-_002esr_0029"></a>
<a class="index-entry-id" id="index-point-size-registers_002c-last_002drequested-_0028_002epsr_002c-_002esr_0029"></a>
<a class="index-entry-id" id="index-_002eps-register_002c-in-comparison-with-_002epsr"></a>
<a class="index-entry-id" id="index-_002es-register_002c-in-comparison-with-_002esr"></a>
<p>Output devices may be limited in the type sizes they can employ.  The
<code class="code">.s</code> and <code class="code">.ps</code> registers represent the type size selected by
the output driver as it understands a device&rsquo;s capability.  The last
<em class="emph">requested</em> type size is interpolated in scaled points by the
read-only register <code class="code">.psr</code> and in points as a decimal fraction by
the read-only string-valued register <code class="code">.sr</code>.  Both are associated
with the environment (see <a class="pxref" href="#Environments">Environments</a>).
</p>
<p>For example, if a type size of 10.95 points is requested, and the
nearest size permitted by a <code class="code">sizes</code> request (or by the <code class="code">sizes</code>
or <code class="code">sizescale</code> directives in the device&rsquo;s <samp class="file">DESC</samp> file) is 11
points, the output driver uses the latter value.
</p></dd></dl>

<p>The <code class="code">\s</code> escape sequence offers the following syntax forms that
work with fractional type sizes and accept scaling units.  You may of
course give them integral arguments.  The delimited forms need not use
the neutral apostrophe; see <a class="ref" href="#Delimiters">Delimiters</a>.
</p>
<dl class="table">
<dt><code class="code">\s[<var class="var">n</var>]</code></dt>
<dt><code class="code">\s'<var class="var">n</var>'</code></dt>
<dd><p>Set the type size to <var class="var">n</var>&nbsp;scaled points; <var class="var">n</var>&nbsp;is a
numeric expression with a default scaling unit of &lsquo;<samp class="samp">z</samp>&rsquo;.
</p>
</dd>
<dt><code class="code">\s[+<var class="var">n</var>]</code></dt>
<dt><code class="code">\s[-<var class="var">n</var>]</code></dt>
<dt><code class="code">\s+[<var class="var">n</var>]</code></dt>
<dt><code class="code">\s-[<var class="var">n</var>]</code></dt>
<dt><code class="code">\s'+<var class="var">n</var>'</code></dt>
<dt><code class="code">\s'-<var class="var">n</var>'</code></dt>
<dt><code class="code">\s+'<var class="var">n</var>'</code></dt>
<dt><code class="code">\s-'<var class="var">n</var>'</code></dt>
<dd><p>Increase or decrease the type size by <var class="var">n</var>&nbsp;scaled points;
<var class="var">n</var>&nbsp;is a numeric expression (which may start with a minus sign)
with a default scaling unit of &lsquo;<samp class="samp">z</samp>&rsquo;.
</p></dd>
</dl>



<hr>
</div>
</div>
<div class="section-level-extent" id="Colors">
<div class="nav-panel">
<p>
Next: <a href="#Strings" accesskey="n" rel="next">Strings</a>, Previous: <a href="#Manipulating-Type-Size-and-Vertical-Spacing" accesskey="p" rel="prev">Manipulating Type Size and Vertical Spacing</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Colors-1">5.21 Colors</h3>
<a class="index-entry-id" id="index-colors"></a>

<a class="index-entry-id" id="index-stroke-color"></a>
<a class="index-entry-id" id="index-color_002c-stroke"></a>
<a class="index-entry-id" id="index-fill-color"></a>
<a class="index-entry-id" id="index-color_002c-fill"></a>
<p>GNU <code class="code">troff</code> supports color output with a variety of color spaces
and up to 16 bits per channel.  Some devices, particularly terminals,
may be more limited.  When color support is enabled, two colors are
current at any given time: the <em class="dfn">stroke color</em>, with which glyphs,
rules (lines), and geometric objects like circles and polygons are
drawn, and the <em class="dfn">fill color</em>, which can be used to paint the interior
of a closed geometric figure.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002ecolor"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.color</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">n</i></span>]</var><a class="copiable-link" href='#index-_002ecolor'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-color"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ecolor_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.color]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ecolor_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ecolor-1"></a>
<p>If <var class="var">n</var> is missing or non-zero, enable the output of color-related
device-independent output commands (this is the default); otherwise,
disable them.  This request sets a global flag; it does not produce an
input token (see <a class="pxref" href="#Gtroff-Internals"><code class="code">gtroff</code> Internals</a>).
</p>
<p>The read-only register <code class="code">.color</code> is&nbsp;1 if colors are enabled,
0&nbsp;otherwise.
</p>
<p>Color can also be disabled with the <samp class="option">-c</samp> command-line option.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002edefcolor"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.defcolor</code></strong> <var class="def-var-arguments">ident scheme color-component &hellip;</var><a class="copiable-link" href='#index-_002edefcolor'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-defcolor"></a>
<p>Define a color named <var class="var">ident</var>.  <var class="var">scheme</var> selects a color space
and determines the quantity of required <var class="var">color-component</var>s; it must
be one of &lsquo;<samp class="samp">rgb</samp>&rsquo; (three components), &lsquo;<samp class="samp">cmy</samp>&rsquo; (three), &lsquo;<samp class="samp">cmyk</samp>&rsquo;
(four), or &lsquo;<samp class="samp">gray</samp>&rsquo; (one).  &lsquo;<samp class="samp">grey</samp>&rsquo; is accepted as a synonym of
&lsquo;<samp class="samp">gray</samp>&rsquo;.  The color components can be encoded as a single
hexadecimal value starting with &lsquo;<samp class="samp">#</samp>&rsquo; or &lsquo;<samp class="samp">##</samp>&rsquo;.  The former
indicates that each component is in the range 0&ndash;255 (0&ndash;FF), the latter
the range 0&ndash;65,535 (0&ndash;FFFF).
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.defcolor half gray #7f
.defcolor pink rgb #FFC0CB
.defcolor magenta rgb  ##ffff0000ffff
</pre></div></div>

<a class="index-entry-id" id="index-f-scaling-unit"></a>
<a class="index-entry-id" id="index-unit_002c-scaling_002c-f"></a>
<a class="index-entry-id" id="index-scaling-unit-f"></a>
<p>Alternatively, each color component can be specified as a decimal
fraction in the range 0&ndash;1, interpreted using a default scaling
unit of&nbsp;<code class="code">f</code>, which multiplies its value by 65,536 (but
clamps it at 65,535).
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.defcolor gray50 rgb 0.5 0.5 0.5
.defcolor darkgreen rgb 0.1f 0.5f 0.2f
</pre></div></div>
</dd></dl>

<a class="index-entry-id" id="index-default-color"></a>
<a class="index-entry-id" id="index-color_002c-default"></a>
<p>Each output device has a color named &lsquo;<samp class="samp">default</samp>&rsquo;, which cannot be
redefined.  A device&rsquo;s default stroke and fill colors are not
necessarily the same.  For the <code class="code">dvi</code>, <code class="code">html</code>, <code class="code">pdf</code>,
<code class="code">ps</code>, and <code class="code">xhtml</code> output devices, GNU <code class="code">troff</code>
automatically loads a macro file defining many color names at startup.
By the same mechanism, the devices supported by <code class="code">grotty</code> recognize
the eight standard ISO&nbsp;6429/EMCA-48 color names.<a class="footnote" id="DOCF86" href="#FOOT86"><sup>86</sup></a>
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002egcolor"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.gcolor</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">color</i></span>]</var><a class="copiable-link" href='#index-_002egcolor'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-gcolor"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cmc"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\m</code><span class="r"><i class="slanted">c</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cmc'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cm"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cm_0028co"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\m(</code><span class="r"><i class="slanted">co</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cm_0028co'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cm_005bcolor_005d"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\m[</code><span class="r"><i class="slanted">color</i></span><code class="t">]</code></strong><a class="copiable-link" href='#index-_005cm_005bcolor_005d'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002em_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.m]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002em_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002em"></a>
<p>Set the stroke color to <var class="var">color</var>.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.gcolor red
The next words
.gcolor
\m[red]are in red\m[]
and these words are in the previous color.
</pre></div></div>

<p>The escape sequence <code class="code">\m[]</code> restores the previous stroke color, as
does a <code class="code">gcolor</code> request without an argument.
</p>
<a class="index-entry-id" id="index-stroke-color-name-register-_0028_002em_0029"></a>
<a class="index-entry-id" id="index-name_002c-stroke-color_002c-register-_0028_002em_0029"></a>
<a class="index-entry-id" id="index-color-name_002c-stroke_002c-register-_0028_002em_0029"></a>
<p>The name of the current stroke color is available in the read-only
string-valued register &lsquo;<samp class="samp">.m</samp>&rsquo;; it is associated with the environment
(see <a class="pxref" href="#Environments">Environments</a>).  It interpolates nothing when the stroke color
is the default.
</p>
<p><code class="code">\m</code> doesn&rsquo;t produce an input token in GNU <code class="code">troff</code>
(see <a class="pxref" href="#Gtroff-Internals"><code class="code">gtroff</code> Internals</a>).  It therefore can be used in requests like
<code class="code">mc</code> (which expects a single character as an argument) to change
the color on the fly:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.mc \m[red]x\m[]
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002efcolor"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.fcolor</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">color</i></span>]</var><a class="copiable-link" href='#index-_002efcolor'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-fcolor"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cMc"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\M</code><span class="r"><i class="slanted">c</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cMc'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cM"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cM_0028co"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\M(</code><span class="r"><i class="slanted">co</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cM_0028co'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cM_005bcolor_005d"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\M[</code><span class="r"><i class="slanted">color</i></span><code class="t">]</code></strong><a class="copiable-link" href='#index-_005cM_005bcolor_005d'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002eM_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.M]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002eM_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002eM"></a>
<p>Set the fill color for objects drawn with <code class="code">\D'&hellip;'</code> escape
sequences.  The escape sequence <code class="code">\M[]</code> restores the previous fill
color, as does an <code class="code">fcolor</code> request without an argument.
</p>
<a class="index-entry-id" id="index-background-color-name-register-_0028_002eM_0029"></a>
<a class="index-entry-id" id="index-name_002c-background-color_002c-register-_0028_002eM_0029"></a>
<a class="index-entry-id" id="index-color-name_002c-background_002c-register-_0028_002eM_0029"></a>
<a class="index-entry-id" id="index-fill-color-name-register-_0028_002eM_0029"></a>
<a class="index-entry-id" id="index-name_002c-fill-color_002c-register-_0028_002eM_0029"></a>
<a class="index-entry-id" id="index-color-name_002c-fill_002c-register-_0028_002eM_0029"></a>
<p>The name of the current fill color is available in the read-only
string-valued register &lsquo;<samp class="samp">.M</samp>&rsquo;; it is associated with the environment
(see <a class="pxref" href="#Environments">Environments</a>).  It interpolates nothing when the fill color
is the default.  <code class="code">\M</code> doesn&rsquo;t produce an input token in GNU
<code class="code">troff</code>.
</p>
<p>Create an ellipse with a red interior as follows.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">\M[red]\h'0.5i'\D'E 2i 1i'\M[]
</pre></div></div>
</dd></dl>



<hr>
</div>
<div class="section-level-extent" id="Strings">
<div class="nav-panel">
<p>
Next: <a href="#Conditionals-and-Loops" accesskey="n" rel="next">Conditionals and Loops</a>, Previous: <a href="#Colors" accesskey="p" rel="prev">Colors</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Strings-1">5.22 Strings</h3>
<a class="index-entry-id" id="index-strings"></a>

<p>GNU <code class="code">troff</code> supports strings primarily for user convenience.
Conventionally, if one would define a macro only to interpolate a small
amount of text, without invoking requests or calling any other macros,
one defines a string instead.  Only one string is predefined by the
language.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002a_005b_002eT_005d"><span class="category-def">String: </span><span><strong class="def-name"><code class="t">\*[.T]</code></strong><a class="copiable-link" href='#index-_005c_002a_005b_002eT_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002eT"></a>
<a class="index-entry-id" id="index-_002eT-1"></a>
<a class="index-entry-id" id="index-output-device-name-string-_0028_002eT_0029-1"></a>
<p>Contains the name of the output device (for example, &lsquo;<samp class="samp">utf8</samp>&rsquo; or
&lsquo;<samp class="samp">pdf</samp>&rsquo;).
</p></dd></dl>

<p>The <code class="code">ds</code> request creates a string with a specified name and
contents and the <code class="code">\*</code> escape sequence dereferences its name,
interpolating its contents.  If the string named by the <code class="code">\*</code> escape
sequence does not exist, it is defined as empty, nothing is
interpolated, and a warning in category &lsquo;<samp class="samp">mac</samp>&rsquo; is emitted.
See <a class="xref" href="#Warnings">Warnings</a>, for information about the enablement and suppression of
warnings.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002eds-1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ds</code></strong> <var class="def-var-arguments">name [<span class="r"><i class="slanted">contents</i></span>]</var><a class="copiable-link" href='#index-_002eds-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ds-1"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002eds1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ds1</code></strong> <var class="def-var-arguments">name [<span class="r"><i class="slanted">contents</i></span>]</var><a class="copiable-link" href='#index-_002eds1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ds1"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002an"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\*</code><span class="r"><i class="slanted">n</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_002an'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_002a"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_002a_0028nm"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\*(</code><span class="r"><i class="slanted">nm</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_002a_0028nm'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005c_002a_005bname-_005barg1-arg2-_2026_005d_005d"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\*[</code><span class="r"><i class="slanted">name <span class="sansserif">[</span>arg1 arg2 &hellip;<span class="sansserif">]</span></i></span><code class="t">]</code></strong><a class="copiable-link" href='#index-_005c_002a_005bname-_005barg1-arg2-_2026_005d_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-string-interpolation-_0028_005c_002a_0029"></a>
<a class="index-entry-id" id="index-string-expansion-_0028_005c_002a_0029"></a>
<a class="index-entry-id" id="index-interpolation-of-strings-_0028_005c_002a_0029"></a>
<a class="index-entry-id" id="index-expansion-of-strings-_0028_005c_002a_0029"></a>
<a class="index-entry-id" id="index-string-arguments"></a>
<a class="index-entry-id" id="index-arguments_002c-to-strings"></a>
<p>Define a string called <var class="var">name</var> with contents <var class="var">contents</var>.  If
<var class="var">name</var> already exists as an alias, the target of the alias is
redefined; see <code class="code">als</code> and <code class="code">rm</code> below.  If <code class="code">ds</code> is called
with only one argument, <var class="var">name</var> is defined as an empty string.
Otherwise, GNU <code class="code">troff</code> stores <var class="var">contents</var> in copy
mode.<a class="footnote" id="DOCF87" href="#FOOT87"><sup>87</sup></a>
</p>
<p>The <code class="code">\*</code> escape sequence interpolates a previously defined string
variable <var class="var">name</var> (one-character name&nbsp;<var class="var">n</var>, two-character name
<var class="var">nm</var>).  The bracketed interpolation form accepts arguments that are
handled as macro arguments are; recall <a class="ref" href="#Calling-Macros">Calling Macros</a>.  In
contrast to macro calls, however, if a closing bracket &lsquo;<samp class="samp">]</samp>&rsquo; occurs
in a string argument, that argument must be enclosed in double quotes.
<code class="code">\*</code> is interpreted even in copy mode.  When defining strings,
argument interpolations must be escaped if they are to reference
parameters from the calling context; See <a class="xref" href="#Parameters">Parameters</a>.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds cite (\\$1, \\$2)
Gray codes are explored in \*[cite Morgan 1998].
    &rArr; Gray codes are explored in (Morgan, 1998).
</pre></div></div>


<a class="index-entry-id" id="index-trailing-spaces-in-string-definitions-and-appendments"></a>
<a class="index-entry-id" id="index-comments_002c-with-ds"></a>
<a class="index-entry-id" id="index-ds-request_002c-and-comments"></a>
<p><strong class="strong">Caution:</strong> Unlike other requests, the second argument to the
<code class="code">ds</code> request consumes the remainder of the input line, including
trailing spaces.  This means that comments on a line with such a request
can introduce unwanted space into a string when they are set off from
the material they annotate, as is conventional.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds H2O H\v'+.3m'\s'-2'2\v'-.3m'\s0O \&quot; water
</pre></div></div>

<p>Instead, place the comment on another line or put the comment escape
sequence immediately adjacent to the last character of the string.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds H2O H\v'+.3m'\s'-2'2\v'-.3m'\s0O\&quot; water
</pre></div></div>

<p>Ending string definitions (and appendments) with a comment, even an
empty one, prevents unwanted space from creeping into them during source
document maintenance.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds author Alice Pleasance Liddell\&quot;
.ds empty \&quot; might be appended to later with .as
</pre></div></div>

<a class="index-entry-id" id="index-trailing-double-quotes-in-strings"></a>
<a class="index-entry-id" id="index-double-quotes_002c-trailing_002c-in-strings"></a>
<a class="index-entry-id" id="index-ds-request_002c-and-double-quotes"></a>
<a class="index-entry-id" id="index-leading-spaces-with-ds"></a>
<a class="index-entry-id" id="index-spaces-with-ds"></a>
<a class="index-entry-id" id="index-ds-request_002c-and-leading-spaces"></a>
<p>An initial neutral double quote <code class="code">&quot;</code> in <var class="var">contents</var> is stripped
to allow embedding of leading spaces.  Any other <code class="code">&quot;</code> is interpreted
literally, but it is wise to use the special character escape sequence
<code class="code">\[dq]</code> instead if the string might be interpolated as part of a
macro argument; see <a class="ref" href="#Calling-Macros">Calling Macros</a>.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds salutation &quot;         Yours in a white wine sauce,\&quot;
.ds c-var-defn &quot;  char mydate[]=\[dq]2020-07-29\[dq];\&quot;
</pre></div></div>

<a class="index-entry-id" id="index-multi_002dline-strings"></a>
<a class="index-entry-id" id="index-strings_002c-multi_002dline"></a>
<a class="index-entry-id" id="index-newline-character_002c-in-strings_002c-escaping"></a>
<a class="index-entry-id" id="index-escaping-newline-characters_002c-in-strings"></a>
<p>Strings are not limited to a single input line of text.
<code class="code">\<kbd class="key">RET</kbd></code> works just as it does elsewhere.  The resulting string
is stored <em class="emph">without</em> the newlines.  Care is therefore required when
interpolating strings while filling is disabled.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds foo This string contains \
text on multiple lines \
of input.
</pre></div></div>

<p>It is not possible to embed a newline in a string that will be
interpreted as such when the string is interpolated.  To achieve that
effect, use <code class="code">\*</code> to interpolate a macro instead; see <a class="ref" href="#Punning-Names">Punning Names</a>.
</p>
<p>Because strings are similar to macros, they too can be defined so as to
suppress AT&amp;T <code class="code">troff</code> compatibility mode when used; see
<a class="ref" href="#Writing-Macros">Writing Macros</a> and <a class="ref" href="#Compatibility-Mode">Compatibility Mode</a>.  The <code class="code">ds1</code>
request defines a string such that compatibility mode is off when the
string is later interpolated.  To be more precise, a <em class="dfn">compatibility
save</em> input token is inserted at the beginning of the string, and a
<em class="dfn">compatibility restore</em> input token at the end.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr xxx 12345
.ds aa The value of xxx is \\n[xxx].
.ds1 bb The value of xxx is \\n[xxx].
.
.cp 1
.
\*(aa
    error&rarr; warning: register '[' not defined
    &rArr; The value of xxx is 0xxx].
\*(bb
    &rArr; The value of xxx is 12345.
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eas"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.as</code></strong> <var class="def-var-arguments">name [<span class="r"><i class="slanted">contents</i></span>]</var><a class="copiable-link" href='#index-_002eas'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-as"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002eas1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.as1</code></strong> <var class="def-var-arguments">name [<span class="r"><i class="slanted">contents</i></span>]</var><a class="copiable-link" href='#index-_002eas1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-as1"></a>
<a class="index-entry-id" id="index-appending-to-a-string-_0028as_0029"></a>
<a class="index-entry-id" id="index-string_002c-appending-_0028as_0029"></a>
<p>The <code class="code">as</code> request is similar to <code class="code">ds</code> but appends <var class="var">contents</var>
to the string stored as <var class="var">name</var> instead of redefining it.  If
<var class="var">name</var> doesn&rsquo;t exist yet, it is created.  If <code class="code">as</code> is called
with only one argument, no operation is performed (beyond dereferencing
the string).
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.as salutation &quot; with shallots, onions and garlic,\&quot;
</pre></div></div>

<p>The <code class="code">as1</code> request is similar to <code class="code">as</code>, but compatibility mode
is switched off when the appended portion of the string is later
interpolated.  To be more precise, a <em class="dfn">compatibility save</em> input
token is inserted at the beginning of the appended string, and a
<em class="dfn">compatibility restore</em> input token at the end.
</p></dd></dl>

<p>Several requests exist to perform rudimentary string operations.
Strings can be queried (<code class="code">length</code>) and modified (<code class="code">chop</code>,
<code class="code">substring</code>, <code class="code">stringup</code>, <code class="code">stringdown</code>), and their names
can be manipulated through renaming, removal, and aliasing (<code class="code">rn</code>,
<code class="code">rm</code>, <code class="code">als</code>).
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002elength"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.length</code></strong> <var class="def-var-arguments">reg anything</var><a class="copiable-link" href='#index-_002elength'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-length"></a>
<a class="index-entry-id" id="index-length-of-a-string-_0028length_0029"></a>
<a class="index-entry-id" id="index-string_002c-length-of-_0028length_0029"></a>
<a class="index-entry-id" id="index-length-request_002c-and-copy-mode"></a>
<a class="index-entry-id" id="index-copy-mode_002c-and-length-request"></a>
<a class="index-entry-id" id="index-mode_002c-copy_002c-and-length-request"></a>
<p>Compute the number of characters of <var class="var">anything</var> and store the count
in the register <var class="var">reg</var>.  If <var class="var">reg</var> doesn&rsquo;t exist, it is created.
<var class="var">anything</var> is read in copy mode.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds xxx abcd\h'3i'efgh
.length yyy \*[xxx]
\n[yyy]
    &rArr; 14
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002echop"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.chop</code></strong> <var class="def-var-arguments">object</var><a class="copiable-link" href='#index-_002echop'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-chop"></a>
<p>Remove the last character from the macro, string, or diversion named
<var class="var">object</var>.  This is useful for removing the newline from the end of a
diversion that is to be interpolated as a string.  This request can be
used repeatedly on the same <var class="var">object</var>; see <a class="ref" href="#Gtroff-Internals"><code class="code">gtroff</code> Internals</a>,
for details on nodes inserted additionally by GNU <code class="code">troff</code>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002esubstring"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.substring</code></strong> <var class="def-var-arguments">str start [<span class="r"><i class="slanted">end</i></span>]</var><a class="copiable-link" href='#index-_002esubstring'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-substring"></a>
<a class="index-entry-id" id="index-substring-_0028substring_0029"></a>
<p>Replace the string named <var class="var">str</var> with its substring bounded by the
indices <var class="var">start</var> and <var class="var">end</var>, inclusively.  The first character in
the string has index&nbsp;0.  If <var class="var">end</var> is omitted, it is implicitly
set to the largest valid value (the string length minus one).  Negative
indices count backward from the end of the string: the last character
has index&nbsp;&minus;1, the character before the last has
index&nbsp;&minus;2, and so on.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds xxx abcdefgh
.substring xxx 1 -4
\*[xxx]
    &rArr; bcde
.substring xxx 2
\*[xxx]
    &rArr; de
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002estringdown"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.stringdown</code></strong> <var class="def-var-arguments">str</var><a class="copiable-link" href='#index-_002estringdown'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-stringdown"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002estringup"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.stringup</code></strong> <var class="def-var-arguments">str</var><a class="copiable-link" href='#index-_002estringup'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-stringup"></a>
<a class="index-entry-id" id="index-case_002dtransforming-a-string-_0028stringdown_002c-stringup_0029"></a>
<a class="index-entry-id" id="index-uppercasing-a-string-_0028stringup_0029"></a>
<a class="index-entry-id" id="index-lowercasing-a-string-_0028stringdown_0029"></a>
<a class="index-entry-id" id="index-up_002dcasing-a-string-_0028stringup_0029"></a>
<a class="index-entry-id" id="index-down_002dcasing-a-string-_0028stringdown_0029"></a>
<p>Alter the string named <var class="var">str</var> by replacing each of its bytes with its
lowercase (<code class="code">stringdown</code>) or uppercase (<code class="code">stringup</code>) version (if
one exists).  Special characters in the string will often transform in
the expected way due to the regular naming convention for accented
characters.  When they do not, use substrings and/or catenation.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds resume R\['e]sum\['e]
\*[resume]
.stringdown resume
\*[resume]
.stringup resume
\*[resume]
    &rArr; Rsum rsum RSUM
</pre></div></div>
</dd></dl>

<p>(In practice, we would end the <code class="code">ds</code> request with a comment escape
<code class="code">\&quot;</code> to prevent space from creeping into the definition during
source document maintenance.)
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002ern"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.rn</code></strong> <var class="def-var-arguments">old new</var><a class="copiable-link" href='#index-_002ern'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-rn"></a>
<a class="index-entry-id" id="index-renaming-request-_0028rn_0029"></a>
<a class="index-entry-id" id="index-request_002c-renaming-_0028rn_0029"></a>
<a class="index-entry-id" id="index-renaming-macro-_0028rn_0029"></a>
<a class="index-entry-id" id="index-macro_002c-renaming-_0028rn_0029"></a>
<a class="index-entry-id" id="index-renaming-string-_0028rn_0029"></a>
<a class="index-entry-id" id="index-string_002c-renaming-_0028rn_0029"></a>
<a class="index-entry-id" id="index-renaming-diversion-_0028rn_0029"></a>
<a class="index-entry-id" id="index-diversion_002c-renaming-_0028rn_0029"></a>
<p>Rename the request, macro, diversion, or string <var class="var">old</var> to <var class="var">new</var>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002erm"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.rm</code></strong> <var class="def-var-arguments">name</var><a class="copiable-link" href='#index-_002erm'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-rm"></a>
<a class="index-entry-id" id="index-removing-request-_0028rm_0029"></a>
<a class="index-entry-id" id="index-request_002c-removing-_0028rm_0029"></a>
<a class="index-entry-id" id="index-removing-macro-_0028rm_0029"></a>
<a class="index-entry-id" id="index-macro_002c-removing-_0028rm_0029"></a>
<a class="index-entry-id" id="index-removing-string-_0028rm_0029"></a>
<a class="index-entry-id" id="index-string_002c-removing-_0028rm_0029"></a>
<a class="index-entry-id" id="index-removing-diversion-_0028rm_0029"></a>
<a class="index-entry-id" id="index-diversion_002c-removing-_0028rm_0029"></a>
<p>Remove the request, macro, diversion, or string <var class="var">name</var>.  GNU
<code class="code">troff</code> treats subsequent invocations as if the name had never
been defined.
</p></dd></dl>

<a class="anchor" id="als"></a><dl class="first-deffn">
<dt class="deffn" id="index-_002eals"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.als</code></strong> <var class="def-var-arguments">new old</var><a class="copiable-link" href='#index-_002eals'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-als"></a>
<a class="index-entry-id" id="index-alias_002c-string_002c-creating-_0028als_0029"></a>
<a class="index-entry-id" id="index-alias_002c-macro_002c-creating-_0028als_0029"></a>
<a class="index-entry-id" id="index-alias_002c-diversion_002c-creating-_0028als_0029"></a>
<a class="index-entry-id" id="index-creating-alias_002c-for-string-_0028als_0029"></a>
<a class="index-entry-id" id="index-creating-alias_002c-for-macro-_0028als_0029"></a>
<a class="index-entry-id" id="index-creating-alias_002c-for-diversion-_0028als_0029"></a>
<a class="index-entry-id" id="index-string_002c-creating-alias-for-_0028als_0029"></a>
<a class="index-entry-id" id="index-macro_002c-creating-alias-for-_0028als_0029"></a>
<a class="index-entry-id" id="index-diversion_002c-creating-alias-for-_0028als_0029"></a>
<p>Create an alias <var class="var">new</var> for the existing request, string, macro, or
diversion object named <var class="var">old</var>, causing the names to refer to the same
stored object.  If <var class="var">old</var> is undefined, a warning in category
&lsquo;<samp class="samp">mac</samp>&rsquo; is produced, and the request is ignored.  See <a class="xref" href="#Warnings">Warnings</a>,
for information about the enablement and suppression of warnings.
</p>
<p>To understand how the <code class="code">als</code> request works, consider two different
storage pools: one for objects (macros, strings, etc.), and another
for names.  As soon as an object is defined, GNU <code class="code">troff</code> adds it to
the object pool, adds its name to the name pool, and creates a link
between them.  When <code class="code">als</code> creates an alias, it adds a new name to
the name pool that gets linked to the same object as the old name.
</p>
<p>Now consider this example.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de foo
..
.
.als bar foo
.
.de bar
.  foo
..
.
.bar
    error&rarr; input stack limit exceeded (probable infinite
    error&rarr; loop)
</pre></div></div>

<p>In the above, <code class="code">bar</code> remains an <em class="emph">alias</em>&mdash;another name
for&mdash;the object referred to by <code class="code">foo</code>, which the second <code class="code">de</code>
request replaces.  Alternatively, imagine that the <code class="code">de</code> request
<em class="emph">dereferences</em> its argument before replacing it.  Either way, the
result of calling <code class="code">bar</code> is a recursive loop that finally leads to
an error.  See <a class="xref" href="#Writing-Macros">Writing Macros</a>.
</p>
<a class="index-entry-id" id="index-alias_002c-string_002c-removing-_0028rm_0029"></a>
<a class="index-entry-id" id="index-alias_002c-macro_002c-removing-_0028rm_0029"></a>
<a class="index-entry-id" id="index-alias_002c-diversion_002c-removing-_0028rm_0029"></a>
<a class="index-entry-id" id="index-removing-alias_002c-for-string-_0028rm_0029"></a>
<a class="index-entry-id" id="index-removing-alias_002c-for-macro-_0028rm_0029"></a>
<a class="index-entry-id" id="index-removing-alias_002c-for-diversion-_0028rm_0029"></a>
<a class="index-entry-id" id="index-string_002c-removing-alias-for-_0028rm_0029"></a>
<a class="index-entry-id" id="index-macro_002c-removing-alias-for-_0028rm_0029"></a>
<a class="index-entry-id" id="index-diversion_002c-removing-alias-for-_0028rm_0029"></a>
<p>To remove an alias, call <code class="code">rm</code> on its name.  The object itself is
not destroyed until it has no more names.
</p>
<p>When a request, macro, string, or diversion is aliased, redefinitions
and appendments &ldquo;write through&rdquo; alias names.  To replace an alias with
a separately defined object, you must use the <code class="code">rm</code> request on its
name first.
</p></dd></dl>



<hr>
</div>
<div class="section-level-extent" id="Conditionals-and-Loops">
<div class="nav-panel">
<p>
Next: <a href="#Writing-Macros" accesskey="n" rel="next">Writing Macros</a>, Previous: <a href="#Strings" accesskey="p" rel="prev">Strings</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Conditionals-and-Loops-1">5.23 Conditionals and Loops</h3>
<a class="index-entry-id" id="index-conditionals-and-loops"></a>
<a class="index-entry-id" id="index-loops-and-conditionals"></a>

<p><code class="code">groff</code> has <code class="code">if</code> and <code class="code">while</code> control structures like
other languages.  However, the syntax for grouping multiple input lines
in the branches or bodies of these structures is unusual.
</p>


<ul class="mini-toc">
<li><a href="#Operators-in-Conditionals" accesskey="1">Operators in Conditionals</a></li>
<li><a href="#if_002dthen" accesskey="2">if-then</a></li>
<li><a href="#if_002delse" accesskey="3">if-else</a></li>
<li><a href="#Conditional-Blocks" accesskey="4">Conditional Blocks</a></li>
<li><a href="#while" accesskey="5">while</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="Operators-in-Conditionals">
<div class="nav-panel">
<p>
Next: <a href="#if_002dthen" accesskey="n" rel="next">if-then</a>, Previous: <a href="#Conditionals-and-Loops" accesskey="p" rel="prev">Conditionals and Loops</a>, Up: <a href="#Conditionals-and-Loops" accesskey="u" rel="up">Conditionals and Loops</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Operators-in-Conditionals-1">5.23.1 Operators in Conditionals</h4>

<a class="index-entry-id" id="index-if-request_002c-operators-to-use-with"></a>
<a class="index-entry-id" id="index-ie-request_002c-operators-to-use-with"></a>
<a class="index-entry-id" id="index-while-request_002c-operators-to-use-with"></a>
<a class="index-entry-id" id="index-conditional-expressions"></a>
<a class="index-entry-id" id="index-expressions_002c-conditional"></a>
<p>In <code class="code">if</code>, <code class="code">ie</code>, and <code class="code">while</code> requests, in addition to the
numeric expressions described in <a class="ref" href="#Numeric-Expressions">Numeric Expressions</a>, several
Boolean operators are available; the members of this expanded class are
termed <em class="dfn">conditional expressions</em>.
</p>
<dl class="table">
<dt><code class="code">c <var class="var">glyph</var></code></dt>
<dd><p>True if <var class="var">glyph</var> is available, where <var class="var">glyph</var> is an ordinary
character, a special character &lsquo;<samp class="samp">\(<var class="var">xx</var></samp>&rsquo; or &lsquo;<samp class="samp">\[<var class="var">xxx</var>]</samp>&rsquo;,
&lsquo;<samp class="samp">\N'<var class="var">xxx</var>'</samp>&rsquo;, or has been defined by any of the <code class="code">char</code>,
<code class="code">fchar</code>, <code class="code">fschar</code>, or <code class="code">schar</code> requests.
</p>
</dd>
<dt><code class="code">d <var class="var">name</var></code></dt>
<dd><p>True if a string, macro, diversion, or request called <var class="var">name</var> exists.
</p>
</dd>
<dt><code class="code">e</code></dt>
<dd><p>True if the current page is even-numbered.
</p>
</dd>
<dt><code class="code">F <var class="var">font</var></code></dt>
<dd><p>True if <var class="var">font</var> exists.  <var class="var">font</var> is handled as if it were opened
with the <code class="code">ft</code> request (that is, font translation and styles are
applied), without actually mounting it.
</p>
</dd>
<dt><code class="code">m <var class="var">color</var></code></dt>
<dd><p>True if <var class="var">color</var> is defined.
</p>
</dd>
<dt id='index-conditional-output-for-terminal-_0028TTY_0029'><span><code class="code">n</code><a class="copiable-link" href='#index-conditional-output-for-terminal-_0028TTY_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-TTY_002c-conditional-output-for"></a>
<a class="index-entry-id" id="index-terminal_002c-conditional-output-for"></a>
<p>True if the document is being processed in <code class="code">nroff</code> mode.
See <a class="xref" href="#troff-and-nroff-Modes"><code class="code">troff</code> and <code class="code">nroff</code> Modes</a>.
</p>
</dd>
<dt><code class="code">o</code></dt>
<dd><p>True if the current page is odd-numbered.
</p>
</dd>
<dt><code class="code">r <var class="var">register</var></code></dt>
<dd><p>True if <var class="var">register</var> exists.
</p>
</dd>
<dt><code class="code">S <var class="var">style</var></code></dt>
<dd><p>True if <var class="var">style</var> is available for the current font family.  Font
translation is applied.
</p>
</dd>
<dt><code class="code">t</code></dt>
<dd><p>True if the document is being processed in <code class="code">troff</code> mode.
See <a class="xref" href="#troff-and-nroff-Modes"><code class="code">troff</code> and <code class="code">nroff</code> Modes</a>.
</p>
<a class="index-entry-id" id="index-vtroff"></a>
</dd>
<dt><code class="code">v</code></dt>
<dd><p>Always false.  This condition is recognized only for compatibility with
certain other <code class="code">troff</code> implementations.<a class="footnote" id="DOCF88" href="#FOOT88"><sup>88</sup></a>
</p></dd>
</dl>

<p>If the first argument to an <code class="code">if</code>, <code class="code">ie</code>, or <code class="code">while</code>
request begins with a non-alphanumeric character apart from <code class="code">!</code>
(see below); it performs an <i class="slanted">output comparison test</i>.
<a class="footnote" id="DOCF89" href="#FOOT89"><sup>89</sup></a>
</p>
<a class="index-entry-id" id="index-output-comparison-operator"></a>
<dl class="table">
<dt><code class="code"><code class="code">'</code><var class="var">xxx</var><code class="code">'</code><var class="var">yyy</var><code class="code">'</code></code></dt>
<dd><p>True if formatting the comparands <var class="var">xxx</var> and <var class="var">yyy</var> produces the
same output commands.  The delimiter need not be a neutral apostrophe:
the output comparison operator accepts the same delimiters as most
escape sequences; see <a class="ref" href="#Delimiters">Delimiters</a>.  This <em class="dfn">output comparison
operator</em> formats <var class="var">xxx</var> and <var class="var">yyy</var> in separate environments;
after the comparison, the resulting data are discarded.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ie &quot;|&quot;\fR|\fP&quot; true
.el false
    &rArr; true
</pre></div></div>

<p>The resulting glyph properties, including font family, style, size, and
slant, must match, but not necessarily the requests and/or escape
sequences used to obtain them.  In the previous example, &lsquo;<samp class="samp">|</samp>&rsquo; and
&lsquo;<samp class="samp">\fR|\fP</samp>&rsquo; result in &lsquo;<samp class="samp">|</samp>&rsquo; glyphs in the same typefaces at the
same positions, so the comparands are equal.  If &lsquo;<samp class="samp">.ft&nbsp;I</samp>&rsquo; had
been added before the &lsquo;<samp class="samp">.ie</samp>&rsquo;, they would differ: the first &lsquo;<samp class="samp">|</samp>&rsquo;
would produce an italic &lsquo;<samp class="samp">|</samp>&rsquo;, not a roman one.  Motions must match
in orientation and magnitude to within the applicable horizontal and
vertical motion quanta of the device, after rounding.  &lsquo;<samp class="samp">.if
&quot;\u\d&quot;\v'0'&quot;</samp>&rsquo; is false even though both comparands result in zero net
motion, because motions are not interpreted or optimized but sent as-is
to the output.<a class="footnote" id="DOCF90" href="#FOOT90"><sup>90</sup></a>  On the other hand, &lsquo;<samp class="samp">.if &quot;\d&quot;\v'0.5m'&quot;</samp>&rsquo; is true, because
<code class="code">\d</code> is defined as a downward motion of one-half em.<a class="footnote" id="DOCF91" href="#FOOT91"><sup>91</sup></a>
</p>
<a class="index-entry-id" id="index-string-comparison"></a>
<a class="index-entry-id" id="index-comparison-of-strings"></a>
<p>Surround the comparands with <code class="code">\?</code> to avoid formatting them; this
causes them to be compared character by character, as with string
comparisons in other programming languages.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ie &quot;\?|\?&quot;\?\fR|\fP\?&quot; true
.el false
    &rArr; false
</pre></div></div>

<a class="index-entry-id" id="index-_005c_003f_002c-and-copy-mode"></a>
<a class="index-entry-id" id="index-copy-mode_002c-and-_005c_003f"></a>
<a class="index-entry-id" id="index-mode_002c-copy_002c-and-_005c_003f"></a>
<p>Since comparands protected with <code class="code">\?</code> are read in copy mode
(see <a class="pxref" href="#Copy-Mode">Copy Mode</a>), they need not even be valid <code class="code">groff</code> syntax.
The escape character is still lexically recognized, however, and
consumes the next character.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds a \[
.ds b \[
.if '\?\*a\?'\?\*b\?' a and b equivalent
.if '\?\\?'\?\\?' backslashes equivalent
    &rArr; a and b equivalent
</pre></div></div>
</dd>
</dl>

<p>The above operators can&rsquo;t be combined with most others, but a leading
&lsquo;<samp class="samp">!</samp>&rsquo;, not followed immediately by spaces or tabs, complements an
expression.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr x 1
.ie !r x register x is not defined
.el      register x is defined
    &rArr; register x is defined
</pre></div></div>

<p>Spaces and tabs are optional immediately after the &lsquo;<samp class="samp">c</samp>&rsquo;, &lsquo;<samp class="samp">d</samp>&rsquo;,
&lsquo;<samp class="samp">F</samp>&rsquo;, &lsquo;<samp class="samp">m</samp>&rsquo;, &lsquo;<samp class="samp">r</samp>&rsquo;, and &lsquo;<samp class="samp">S</samp>&rsquo; operators, but right after
&lsquo;<samp class="samp">!</samp>&rsquo;, they end the predicate and the conditional evaluates
true.<a class="footnote" id="DOCF92" href="#FOOT92"><sup>92</sup></a>
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr x 1
.ie ! r x register x is not defined
.el       register x is defined
    &rArr; r x register x is not defined
</pre></div></div>

<p>The unexpected &lsquo;<samp class="samp">r x</samp>&rsquo; in the output is a clue that our conditional
was not interpreted as we planned, but matters may not always be so
obvious.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="if_002dthen">
<div class="nav-panel">
<p>
Next: <a href="#if_002delse" accesskey="n" rel="next">if-else</a>, Previous: <a href="#Operators-in-Conditionals" accesskey="p" rel="prev">Operators in Conditionals</a>, Up: <a href="#Conditionals-and-Loops" accesskey="u" rel="up">Conditionals and Loops</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="if_002dthen-1">5.23.2 if-then</h4>
<a class="index-entry-id" id="index-if_002dthen"></a>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eif"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.if</code></strong> <var class="def-var-arguments">cond-expr anything</var><a class="copiable-link" href='#index-_002eif'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-if"></a>
<p>Evaluate the conditional expression <var class="var">cond-expr</var>, and if it evaluates
true (or to a positive value), interpret the remainder of the line
<var class="var">anything</var> as if it were an input line.  Recall from <a class="ref" href="#Invoking-Requests">Invoking Requests</a> that any quantity of spaces between arguments to requests
serves only to separate them; leading spaces in <var class="var">anything</var> are thus
not seen.  <var class="var">anything</var> effectively <em class="emph">cannot</em> be omitted; if
<var class="var">cond-expr</var> is true and <var class="var">anything</var> is empty, the newline at the
end of the control line is interpreted as a blank input line (and
therefore a blank text line).
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">super\c
tanker
.nr force-word-break 1
super\c
.if ((\n[force-word-break] = 1) &amp; \n[.int])
tanker
    &rArr; supertanker super tanker
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002enop"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.nop</code></strong> <var class="def-var-arguments">anything</var><a class="copiable-link" href='#index-_002enop'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-nop"></a>
<p>Interpret <var class="var">anything</var> as if it were an input line.  This is similar
to &lsquo;<samp class="samp">.if&nbsp;1</samp>&rsquo;.  <code class="code">nop</code> is not really &ldquo;no operation&rdquo;; its
argument <em class="emph">is</em> processed&mdash;unconditionally.  It can be used to cause
text lines to share indentation with surrounding control lines.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.als real-MAC MAC
.de wrapped-MAC
.  tm MAC: called with arguments \\$@
.  nop \\*[real-MAC]\\
..
.als MAC wrapped-MAC
\# Later...
.als MAC real-MAC
</pre></div></div>

<p>In the above, we&rsquo;ve used aliasing, <code class="code">nop</code>, and the interpolation of
a macro as a string to interpose a wrapper around the macro &lsquo;<samp class="samp">MAC</samp>&rsquo;
(perhaps to debug it).
</p></dd></dl>


<hr>
</div>
<div class="subsection-level-extent" id="if_002delse">
<div class="nav-panel">
<p>
Next: <a href="#while" accesskey="n" rel="next">while</a>, Previous: <a href="#Operators-in-Conditionals" accesskey="p" rel="prev">Operators in Conditionals</a>, Up: <a href="#Conditionals-and-Loops" accesskey="u" rel="up">Conditionals and Loops</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="if_002delse-1">5.23.3 if-else</h4>
<a class="index-entry-id" id="index-if_002delse"></a>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eie"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ie</code></strong> <var class="def-var-arguments">cond-expr anything</var><a class="copiable-link" href='#index-_002eie'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ie"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002eel"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.el</code></strong> <var class="def-var-arguments">anything</var><a class="copiable-link" href='#index-_002eel'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-el"></a>
<p>Use the <code class="code">ie</code> and <code class="code">el</code> requests to write an if-then-else.  The
first request is the &ldquo;if&rdquo; part and the latter is the &ldquo;else&rdquo; part.
Unusually among programming languages, any number of non-conditional
requests may be interposed between the <code class="code">ie</code> branch and the
<code class="code">el</code> branch.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr a 0
.ie \na a is non-zero.
.nr a +1
.el a was not positive but is now \na.
    &rArr; a was not positive but is now 1.
</pre></div></div>

<p>Another way in which <code class="code">el</code> is an ordinary request is that it does
not lexically &ldquo;bind&rdquo; more tightly to its <code class="code">ie</code> counterpart than it
does to any other request.  This fact can surprise C programmers.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr a 1
.nr z 0
.ie \nz \
.  ie \na a is true
.  el     a is false
.el z is false
    error&rarr; warning: unbalanced 'el' request
    &rArr; a is false
</pre></div></div>

<p>To conveniently nest conditionals, keep reading.
</p>
</dd></dl>


<hr>
</div>
<div class="subsection-level-extent" id="Conditional-Blocks">
<div class="nav-panel">
<p>
Next: <a href="#while" accesskey="n" rel="next">while</a>, Previous: <a href="#Operators-in-Conditionals" accesskey="p" rel="prev">Operators in Conditionals</a>, Up: <a href="#Conditionals-and-Loops" accesskey="u" rel="up">Conditionals and Loops</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Conditional-Blocks-1">5.23.4 Conditional Blocks</h4>
<a class="index-entry-id" id="index-conditional-blocks"></a>
<a class="index-entry-id" id="index-blocks_002c-conditional"></a>

<p>It is frequently desirable for a control structure to govern more than
one request, macro call, text line, or a combination of the foregoing.
The opening and closing brace escape sequences <code class="code">\{</code> and <code class="code">\}</code>
define such groups.  These <em class="dfn">conditional blocks</em> can furthermore be
nested.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_007b-2"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\{</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_007b-2'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_007b"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_007d-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\}</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_007d-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_007b-1"></a>
<a class="index-entry-id" id="index-_005c_007d"></a>
<a class="index-entry-id" id="index-beginning-of-conditional-block-_0028_005c_007b_0029"></a>
<a class="index-entry-id" id="index-end-of-conditional-block-_0028_005c_007d_0029"></a>
<a class="index-entry-id" id="index-conditional-block_002c-beginning-_0028_005c_007b_0029"></a>
<a class="index-entry-id" id="index-conditional-block_002c-end-_0028_005c_007d_0029"></a>
<a class="index-entry-id" id="index-block_002c-conditional_002c-beginning-_0028_005c_007b_0029"></a>
<a class="index-entry-id" id="index-block_002c-conditional_002c-end-_0028_005c_007d_0029"></a>
<a class="index-entry-id" id="index-brace-escape-sequences-_0028_005c_007b_002c-_005c_007d_0029"></a>
<a class="index-entry-id" id="index-escape-sequences_002c-brace-_0028_005c_007b_002c-_005c_007d_0029"></a>
<a class="index-entry-id" id="index-opening-brace-escape-sequence-_0028_005c_007d_0029"></a>
<a class="index-entry-id" id="index-closing-brace-escape-sequence-_0028_005c_007d_0029"></a>
<a class="index-entry-id" id="index-brace-escape-sequence_002c-opening-_0028_005c_007d_0029"></a>
<a class="index-entry-id" id="index-brace-escape-sequence_002c-closing-_0028_005c_007d_0029"></a>
<p><code class="code">\{</code> begins a conditional block; it must appear (after optional
spaces and tabs) immediately subsequent to the conditional expression of
an <code class="code">if</code>, <code class="code">ie</code>, or <code class="code">while</code>
request,<a class="footnote" id="DOCF93" href="#FOOT93"><sup>93</sup></a> or as the argument to an <code class="code">el</code>
request.
</p>
<p><code class="code">\}</code> ends a condition block and should appear on a line with other
occurrences of itself as necessary to match <code class="code">\{</code> sequences.  It
can be preceded by a control character, spaces, and tabs.  Input after
any quantity of <code class="code">\}</code> sequences on the same line is processed only
if all of the preceding conditions to which they correspond are true.
Furthermore, a <code class="code">\}</code> closing the body of a <code class="code">while</code> request
must be the last such escape sequence on an input line.
</p>
<p>Brace escape sequences outside of control structures have no meaning and
produce no output.
</p>
<p><strong class="strong">Caution:</strong> Input lines using <code class="code">\{</code> often end with
<code class="code">\RET</code>, especially in macros that consist primarily of control
lines.  Forgetting to use <code class="code">\RET</code> on an input line after <code class="code">\{</code>
is a common source of error.
</p></dd></dl>

<p>We might write the following in a page header macro.  If we delete
<code class="code">\RET</code>, the header will carry an unwanted extra empty line (except
on page&nbsp;1).
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.if (\\n[%] != 1) \{\
.  ie ((\\n[%] % 2) = 0) .tl \\*[even-numbered-page-title]
.  el                    .tl \\*[odd-numbered-page-title]
.\}
</pre></div></div>

<p>Let us take a closer look at how conditional blocks nest.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">A
.if 0 \{ B
C
D
\}E
F
    &rArr; A F
</pre></div></div>

<div class="example">
<div class="group"><pre class="example-preformatted">N
.if 1 \{ O
.  if 0 \{ P
Q
R\} S\} T
U
    &rArr; N O U
</pre></div></div>

<p>The above behavior may challenge the intuition; it was implemented to
retain compatibility with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>.  For clarity, it
is idiomatic to end input lines with <code class="code">\{</code> (followed by
<code class="code">\<kbd class="key">RET</kbd></code> if appropriate), and to precede <code class="code">\}</code> on an input
line with nothing more than a control character, spaces, tabs, and other
instances of itself.
</p>
<p>We can use <code class="code">ie</code>, <code class="code">el</code>, and conditional blocks to simulate the
multi-way &ldquo;switch&rdquo; or &ldquo;case&rdquo; control structures of other languages.
The following example is adapted from the <code class="code">groff</code> <samp class="file">man</samp>
package.  Indentation is used to clarify the logic.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.\&quot; Simulate switch/case in roff.
.      ie '\\$2'1' .ds title General Commands\&quot;
.el \{.ie '\\$2'2' .ds title System Calls\&quot;
.el \{.ie '\\$2'3' .ds title Library Functions\&quot;
.el \{.ie '\\$2'4' .ds title Kernel Interfaces\&quot;
.el \{.ie '\\$2'5' .ds title File Formats\&quot;
.el \{.ie '\\$2'6' .ds title Games\&quot;
.el \{.ie '\\$2'7' .ds title Miscellaneous Information\&quot;
.el \{.ie '\\$2'8' .ds title System Management\&quot;
.el \{.ie '\\$2'9' .ds title Kernel Development\&quot;
.el                .ds title \&quot; empty
.\}\}\}\}\}\}\}\}
</pre></div></div>


<hr>
</div>
<div class="subsection-level-extent" id="while">
<div class="nav-panel">
<p>
Previous: <a href="#if_002delse" accesskey="p" rel="prev">if-else</a>, Up: <a href="#Conditionals-and-Loops" accesskey="u" rel="up">Conditionals and Loops</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="while-1">5.23.5 while</h4>
<a class="index-entry-id" id="index-while"></a>

<p><code class="code">groff</code> provides a looping construct: the <code class="code">while</code> request.
Its syntax matches the <code class="code">if</code> request.
</p>
<a class="index-entry-id" id="index-body_002c-of-a-while-request"></a>
<dl class="first-deffn">
<dt class="deffn" id="index-_002ewhile"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.while</code></strong> <var class="def-var-arguments">cond-expr anything</var><a class="copiable-link" href='#index-_002ewhile'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-while-1"></a>
<p>Evaluate the conditional expression <var class="var">cond-expr</var>, and repeatedly
execute <var class="var">anything</var> unless and until <var class="var">cond-expr</var> evaluates false.
<var class="var">anything</var>, which is often a conditional block, is referred to as
the <code class="code">while</code> request&rsquo;s <em class="dfn">body</em>.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr a 0 1
.while (\na &lt; 9) \{\
\n+a,
.\}
\n+a
    &rArr; 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
</pre></div></div>

<a class="index-entry-id" id="index-de-request_002c-and-while"></a>
<p>GNU <code class="code">troff</code> treats the body of a <code class="code">while</code> request similarly to
that of a <code class="code">de</code> request (albeit one not read in copy
mode<a class="footnote" id="DOCF94" href="#FOOT94"><sup>94</sup></a>), but stores it under an internal name
and deletes it when the loop finishes.  The operation of a macro
containing a <code class="code">while</code> request can slow significantly if the
<code class="code">while</code> body is large.  Each time the macro is executed, the
<code class="code">while</code> body is parsed and stored again.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de xxx
.  nr num 10
.  while (\\n[num] &gt; 0) \{\
.    \&quot; many lines of code
.    nr num -1
.  \}
..
</pre></div></div>

<a class="index-entry-id" id="index-recursive-macros"></a>
<a class="index-entry-id" id="index-macros_002c-recursive"></a>
<p>An often better solution&mdash;and one that is more portable, since
<abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> lacked the <code class="code">while</code> request&mdash;is to
instead write a recursive macro.  It will be parsed only
once.<a class="footnote" id="DOCF95" href="#FOOT95"><sup>95</sup></a>
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de yyy
.  if (\\n[num] &gt; 0) \{\
.    \&quot; many lines of code
.    nr num -1
.    yyy
.  \}
..
.
.de xxx
.  nr num 10
.  yyy
..
</pre></div></div>

<p>To prevent infinite loops, the default number of available recursion
levels is 1,000 or somewhat less.<a class="footnote" id="DOCF96" href="#FOOT96"><sup>96</sup></a>  You can
disable this protective measure, or raise the limit, by setting the
<code class="code">slimit</code> register.  See <a class="xref" href="#Debugging">Debugging</a>.
</p>
<p>As noted above, if a <code class="code">while</code> body begins with a conditional block,
its closing brace must end an input line.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.if 1 \{\
.  nr a 0 1
.  while (\n[a] &lt; 10) \{\
.    nop \n+[a]
.\}\}
    error&rarr; unbalanced brace escape sequences
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ebreak"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.break</code></strong><a class="copiable-link" href='#index-_002ebreak'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-break-2"></a>
<a class="index-entry-id" id="index-while-request_002c-confusing-with-br"></a>
<a class="index-entry-id" id="index-break-request_002c-in-a-while-loop"></a>
<a class="index-entry-id" id="index-continue-request_002c-in-a-while-loop"></a>
<p>Exit a <code class="code">while</code> loop.  Do not confuse this request with a
typographical break or the <code class="code">br</code> request.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002econtinue"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.continue</code></strong><a class="copiable-link" href='#index-_002econtinue'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-continue"></a>
<p>Skip the remainder of a <code class="code">while</code> loop&rsquo;s body, immediately starting
the next iteration.
</p></dd></dl>



<hr>
</div>
</div>
<div class="section-level-extent" id="Writing-Macros">
<div class="nav-panel">
<p>
Next: <a href="#Page-Motions" accesskey="n" rel="next">Page Motions</a>, Previous: <a href="#Conditionals-and-Loops" accesskey="p" rel="prev">Conditionals and Loops</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Writing-Macros-1">5.24 Writing Macros</h3>
<a class="index-entry-id" id="index-writing-macros"></a>
<a class="index-entry-id" id="index-macros_002c-writing"></a>

<p>A <em class="dfn">macro</em> is a stored collection of text and control lines that can
be interpolated multiple times.  Use macros to define common operations.
Macros are called in the same way that requests are invoked.  While
requests exist for the purpose of creating macros, simply calling an
undefined macro, or interpolating it as a string, will cause it to be
defined as empty.  See <a class="xref" href="#Identifiers">Identifiers</a>.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002ede"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.de</code></strong> <var class="def-var-arguments">name [<span class="r"><i class="slanted">end</i></span>]</var><a class="copiable-link" href='#index-_002ede'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-de"></a>
<p>Define a macro <var class="var">name</var>, replacing the definition of any existing
request, macro, string, or diversion called <var class="var">name</var>.  If
<var class="var">name</var> already exists as an alias, the target of the alias is
redefined; recall <a class="ref" href="#Strings">Strings</a>.  GNU <code class="code">troff</code> enters copy
mode,<a class="footnote" id="DOCF97" href="#FOOT97"><sup>97</sup></a> storing subsequent input lines as the
macro definition.  If the optional second argument is not specified, the
definition ends with the control line &lsquo;<samp class="samp">..</samp>&rsquo; (two dots).
Alternatively, <var class="var">end</var> identifies a macro whose call syntax at the
start of a control line ends the definition of <var class="var">name</var>; <var class="var">end</var> is
then called normally.  A macro definition must end in the same
conditional block (if any) in which it began (see <a class="pxref" href="#Conditional-Blocks">Conditional Blocks</a>).  Spaces or tabs are permitted after the control character in
the line containing this ending token (either &lsquo;<samp class="samp">.</samp>&rsquo; or
&lsquo;<samp class="samp"><var class="var">end</var></samp>&rsquo;), but a tab immediately after the token prevents its
recognition as the end of a macro definition.  The macro <var class="var">end</var> can
be called with arguments.<a class="footnote" id="DOCF98" href="#FOOT98"><sup>98</sup></a>
</p>
<p>Here is a small example macro called &lsquo;<samp class="samp">P</samp>&rsquo; that causes a break and
inserts some vertical space.  It could be used to separate paragraphs.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de P
.  br
.  sp .8v
..
</pre></div></div>

<p>We can define one macro within another.  Attempting to nest &lsquo;<samp class="samp">..</samp>&rsquo;
navely will end the outer definition because the inner definition
isn&rsquo;t interpreted as such until the outer macro is later interpolated.
We can use an end macro instead.  Each level of nesting should use a
unique end macro.
</p>
<p>An end macro need not be defined until it is called.  This fact enables
a nested macro definition to begin inside one macro and end inside
another.  Consider the following example.<a class="footnote" id="DOCF99" href="#FOOT99"><sup>99</sup></a>
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de m1
.  de m2 m3
you
..
.de m3
Hello,
Joe.
..
.de m4
do
..
.m1
know?
.  m3
What
.m4
.m2
    &rArr; Hello, Joe.  What do you know?
</pre></div></div>

<p>A nested macro definition <em class="emph">can</em> be terminated with &lsquo;<samp class="samp">..</samp>&rsquo; and
nested macros <em class="emph">can</em> reuse end macros, but these control lines must
be escaped multiple times for each level of nesting.  The necessity of
this escaping and the utility of nested macro definitions will become
clearer when we employ macro parameters and consider the behavior of
copy mode in detail.
</p></dd></dl>

<p><code class="code">de</code> defines a macro that inherits the compatibility mode
enablement status of its context (see <a class="pxref" href="#Implementation-Differences">Implementation Differences</a>).
Often it is desirable to make a macro that uses <code class="code">groff</code> features
callable from contexts where compatibility mode is on; for instance,
when writing extensions to a historical macro package.  To achieve this,
compatibility mode needs to be switched off while such a macro is
interpreted&mdash;without disturbing that state when it is finished.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002ede1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.de1</code></strong> <var class="def-var-arguments">name [<span class="r"><i class="slanted">end</i></span>]</var><a class="copiable-link" href='#index-_002ede1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-de1"></a>
<p>The <code class="code">de1</code> request defines a macro to be interpreted with
compatibility mode disabled.  When <var class="var">name</var> is called, compatibility
mode enablement status is saved; it is restored when the call completes.
Observe the extra backlash before the interpolation of register
&lsquo;<samp class="samp">xxx</samp>&rsquo;; we&rsquo;ll explore this subject in <a class="ref" href="#Copy-Mode">Copy Mode</a>.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr xxx 12345
.de aa
The value of xxx is \\n[xxx].
.  br
..
.de1 bb
The value of xxx is \\n[xxx].
..
.cp 1
.aa
    error&rarr; warning: register '[' not defined
    &rArr; The value of xxx is 0xxx].
.bb
    &rArr; The value of xxx is 12345.
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002edei"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.dei</code></strong> <var class="def-var-arguments">name [<span class="r"><i class="slanted">end</i></span>]</var><a class="copiable-link" href='#index-_002edei'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-dei"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002edei1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.dei1</code></strong> <var class="def-var-arguments">name [<span class="r"><i class="slanted">end</i></span>]</var><a class="copiable-link" href='#index-_002edei1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-dei1"></a>
<p>The <code class="code">dei</code> request defines a macro with its name and end
macro indirected through strings.  That is, it interpolates strings
named <var class="var">name</var> and <var class="var">end</var> before performing the definition.
</p>
<p>The following examples are equivalent.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds xx aa
.ds yy bb
.dei xx yy
</pre></div></div>

<div class="example">
<div class="group"><pre class="example-preformatted">.de aa bb
</pre></div></div>

<p>The <code class="code">dei1</code> request bears the same relationship to <code class="code">dei</code> as
<code class="code">de1</code> does to <code class="code">de</code>; it temporarily turns compatibility mode
off when <var class="var">name</var> is called.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eam"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.am</code></strong> <var class="def-var-arguments">name [<span class="r"><i class="slanted">end</i></span>]</var><a class="copiable-link" href='#index-_002eam'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-am"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002eam1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.am1</code></strong> <var class="def-var-arguments">name [<span class="r"><i class="slanted">end</i></span>]</var><a class="copiable-link" href='#index-_002eam1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-am1"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002eami"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ami</code></strong> <var class="def-var-arguments">name [<span class="r"><i class="slanted">end</i></span>]</var><a class="copiable-link" href='#index-_002eami'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ami"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002eami1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ami1</code></strong> <var class="def-var-arguments">name [<span class="r"><i class="slanted">end</i></span>]</var><a class="copiable-link" href='#index-_002eami1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ami1"></a>
<a class="index-entry-id" id="index-appending-to-a-macro-_0028am_0029"></a>
<a class="index-entry-id" id="index-macro_002c-appending-to-_0028am_0029"></a>
<p><code class="code">am</code> appends subsequent input lines to macro <var class="var">name</var>, extending
its definition, and otherwise working as <code class="code">de</code> does.
</p>
<p>To make the previously defined &lsquo;<samp class="samp">P</samp>&rsquo; macro set indented instead of
block paragraphs, add the necessary code to the existing macro.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.am P
.ti +5n
..
</pre></div></div>

<p>The other requests are analogous to their &lsquo;<samp class="samp">de</samp>&rsquo; counterparts.  The
<code class="code">am1</code> request turns off compatibility mode during interpretation of
the appendment.  The <code class="code">ami</code> request appends indirectly, meaning that
strings <var class="var">name</var> and <var class="var">end</var> are interpolated with the resulting
names used before appending.  The <code class="code">ami1</code> request is similar to
<code class="code">ami</code>, disabling compatibility mode during interpretation of the
appended lines.
</p></dd></dl>

<a class="index-entry-id" id="index-trace_002etmac"></a>
<p>Using <samp class="file">trace.tmac</samp>, you can trace calls to <code class="code">de</code>,
<code class="code">de1</code>, <code class="code">am</code>, and <code class="code">am1</code>.  You can also use the
<code class="code">backtrace</code> request at any point desired to troubleshoot tricky
spots (see <a class="pxref" href="#Debugging">Debugging</a>).
</p>
<p>See <a class="xref" href="#Strings">Strings</a>, for the <code class="code">als</code>, <code class="code">rm</code>, and <code class="code">rn</code> requests to
create an alias of, remove, and rename a macro, respectively.
</p>
<a class="index-entry-id" id="index-object-creation"></a>
<p>Macro identifiers share their name space with requests, strings, and
diversions; see <a class="ref" href="#Identifiers">Identifiers</a>.  The <code class="code">am</code>, <code class="code">as</code>, <code class="code">da</code>,
<code class="code">de</code>, <code class="code">di</code>, and <code class="code">ds</code> requests (together with their
variants) create a new object only if the name of the macro, diversion,
or string is currently undefined or if it is defined as a request;
normally, they modify the value of an existing object.  See <a class="xref" href="#als">the
description of the <code class="code">als</code> request</a>, for pitfalls when redefining a
macro that is aliased.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002ereturn"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.return</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">anything</i></span>]</var><a class="copiable-link" href='#index-_002ereturn'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-return"></a>
<p>Exit a macro, immediately returning to the caller.  If called with an
argument <var class="var">anything</var>, exit twice&mdash;the current macro and the macro
one level higher.  This is used to define a wrapper macro for
<code class="code">return</code> in <samp class="file">trace.tmac</samp>.
</p></dd></dl>



<ul class="mini-toc">
<li><a href="#Parameters" accesskey="1">Parameters</a></li>
<li><a href="#Copy-Mode" accesskey="2">Copy Mode</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="Parameters">
<div class="nav-panel">
<p>
Next: <a href="#Copy-Mode" accesskey="n" rel="next">Copy Mode</a>, Previous: <a href="#Writing-Macros" accesskey="p" rel="prev">Writing Macros</a>, Up: <a href="#Writing-Macros" accesskey="u" rel="up">Writing Macros</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Parameters-1">5.24.1 Parameters</h4>
<a class="index-entry-id" id="index-parameters"></a>

<p>Macro calls and string interpolations optionally accept a list of
arguments; recall <a class="ref" href="#Calling-Macros">Calling Macros</a>.  At the time such an
interpolation takes place, these <em class="dfn">parameters</em> can be examined using
a register and a variety of escape sequences starting with &lsquo;<samp class="samp">\$</samp>&rsquo;.
All such escape sequences are interpreted even in copy mode, a fact we
shall motivate and explain below (see <a class="pxref" href="#Copy-Mode">Copy Mode</a>).
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005b_002e_0024_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.$]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002e_0024_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002e_0024"></a>
<a class="index-entry-id" id="index-parameter-count-register-_0028_002e_0024_0029"></a>
<p>The count of parameters available to a macro or string is kept in this
read-only register.  The <code class="code">shift</code> request can change its value.
</p></dd></dl>

<p>Any individual parameter can be accessed by its position in the list of
arguments to the macro call, numbered from left to right starting at 1,
with one of the following escape sequences.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_0024n"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\$</code><span class="r"><i class="slanted">n</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_0024n'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_0024"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_0024_0028nn"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\$(</code><span class="r"><i class="slanted">nn</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_0024_0028nn'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005c_0024_005bnnn_005d"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\$[</code><span class="r"><i class="slanted">nnn</i></span><code class="t">]</code></strong><a class="copiable-link" href='#index-_005c_0024_005bnnn_005d'> &para;</a></span></dt>
<dd><p>Interpolate the <var class="var">n</var>th, <var class="var">nn</var>th, or <var class="var">nnn</var>th parameter.  The
first form expects only a single digit (1&le;<var class="var">n</var>&le;9)), the
second two digits (01&le;<var class="var">nn</var>&le;99)), and the third any
positive integer <var class="var">nnn</var>.  Macros and strings accept an unlimited
number of parameters.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eshift"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.shift</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">n</i></span>]</var><a class="copiable-link" href='#index-_002eshift'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-shift"></a>
<p>Shift the parameters <var class="var">n</var> places (1&nbsp;by default).  This is a
&ldquo;left shift&rdquo;: what was parameter&nbsp;<var class="var">i</var> becomes parameter
<em class="math"><var class="var">i</var>-<var class="var">n</var></em>.  The parameters formerly in positions 1
to&nbsp;<var class="var">n</var> are no longer available.  Shifting by a non-positive
amount performs no operation.  The register <code class="code">.$</code> is adjusted
accordingly.
</p></dd></dl>

<a class="index-entry-id" id="index-copy-mode_002c-and-macro-parameters"></a>
<a class="index-entry-id" id="index-mode_002c-copy_002c-and-macro-parameters"></a>
<a class="index-entry-id" id="index-macro_002c-parameters-_0028_005c_0024_0029"></a>
<a class="index-entry-id" id="index-parameters_002c-macro-_0028_005c_0024_0029"></a>
<p>In practice, parameter interpolations are usually seen prefixed with an
extra escape character.  This is because the <code class="code">\$</code> family of escape
sequences is interpreted even in copy mode.<a class="footnote" id="DOCF100" href="#FOOT100"><sup>100</sup></a>
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_0024_002a-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\$*</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_0024_002a-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_0024_002a"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_0024_0040-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\$@</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_0024_0040-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_0024_0040"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_0024_005e-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\$^</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_0024_005e-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_0024_005e"></a>
<p>In some cases it is convenient to interpolate all of the parameters at
once (to pass them to a request, for instance).  The <code class="code">\$*</code> escape
concatenates the parameters, separating them with spaces.  <code class="code">\$@</code>
is similar, concatenating the parameters, surrounding each with double
quotes and separating them with spaces.  If not in compatibility mode,
the interpolation depth of double quotes is preserved (see <a class="pxref" href="#Calling-Macros">Calling Macros</a>).  <code class="code">\$^</code> interpolates all parameters as if they were
arguments to the <code class="code">ds</code> request.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de foo
. tm $1='\\$1'
. tm $2='\\$2'
. tm $*='\\$*'
. tm $@='\\$@'
. tm $^='\\$^'
..
.foo &quot; This is a &quot;test&quot;
    error&rarr; $1=' This is a '
    error&rarr; $2='test&quot;'
    error&rarr; $*=' This is a  test&quot;'
    error&rarr; $@='&quot; This is a &quot; &quot;test&quot;&quot;'
    error&rarr; $^='&quot; This is a &quot;test&quot;'
</pre></div></div>

<p><code class="code">\$*</code> is useful when writing a macro that doesn&rsquo;t need to
distinguish its arguments, or even to not interpret them; examples
include macros that produce diagnostic messages by wrapping the
<code class="code">tm</code> or <code class="code">ab</code> requests.  Use <code class="code">\$@</code> when writing a macro
that may need to shift its parameters and/or wrap a macro or request
that finds the count significant.  If in doubt, prefer <code class="code">\$@</code> to
<code class="code">\$*</code>.  An application of <code class="code">\$^</code> is seen in <samp class="file">trace.tmac</samp>,
which redefines some requests and macros for debugging purposes.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_00240-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\$0</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_00240-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_00240"></a>
<a class="index-entry-id" id="index-macro-name-register-_0028_005c_00240_0029"></a>
<a class="index-entry-id" id="index-als-request_002c-and-_005c_00240"></a>
<p>Interpolate the name by which the macro being interpreted was called.
The <code class="code">als</code> request can cause a macro to have more than one name.
Applying string interpolation to a macro does not change this name.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de foo
.  tm \\$0
..
.als bar foo
.
.de aaa
.  foo
..
.de bbb
.  bar
..
.de ccc
\\*[foo]\\
..
.de ddd
\\*[bar]\\
..
.
.aaa
    error&rarr; foo
.bbb
    error&rarr; bar
.ccc
    error&rarr; ccc
.ddd
    error&rarr; ddd
</pre></div></div>
</dd></dl>


<hr>
</div>
<div class="subsection-level-extent" id="Copy-Mode">
<div class="nav-panel">
<p>
Previous: <a href="#Parameters" accesskey="p" rel="prev">Parameters</a>, Up: <a href="#Writing-Macros" accesskey="u" rel="up">Writing Macros</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Copy-Mode-1">5.24.2 Copy Mode</h4>
<a class="index-entry-id" id="index-copy-mode"></a>
<a class="index-entry-id" id="index-copy-mode-1"></a>
<a class="index-entry-id" id="index-mode_002c-copy"></a>
<a class="index-entry-id" id="index-mode_002c-copy-1"></a>

<a class="index-entry-id" id="index-_005cn_002c-when-reading-text-for-a-macro"></a>
<a class="index-entry-id" id="index-_005c_0024_002c-when-reading-text-for-a-macro"></a>
<a class="index-entry-id" id="index-_005c_002a_002c-when-reading-text-for-a-macro"></a>
<a class="index-entry-id" id="index-_005cRET_002c-when-reading-text-for-a-macro"></a>
<p>When GNU <code class="code">troff</code> processes certain requests, most importantly those
which define or append to a macro or string, it does so in <em class="dfn">copy
mode</em>: it copies the characters of the definition into a dedicated
storage region, interpolating the escape sequences <code class="code">\n</code>, <code class="code">\g</code>,
<code class="code">\$</code>, <code class="code">\*</code>, <code class="code">\V</code>, and <code class="code">\?</code> normally; interpreting
<code class="code">\<kbd class="key">RET</kbd></code> immediately; discarding comments <code class="code">\&quot;</code> and
<code class="code">\#</code>; interpolating the current leader, escape, or tab character
with <code class="code">\a</code>, <code class="code">\e</code>, and <code class="code">\t</code>, respectively; and storing all
other escape sequences in an encoded form.
</p>
<a class="index-entry-id" id="index-interpretation-mode"></a>
<a class="index-entry-id" id="index-mode_002c-interpretation"></a>
<p>The complement of copy mode&mdash;a <code class="code">roff</code> formatter&rsquo;s behavior when
not defining or appending to a macro, string, or diversion&mdash;where all
macros are interpolated, requests invoked, and valid escape sequences
processed immediately upon recognition, can be termed
<em class="dfn">interpretation mode</em>.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_005c-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\\</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_005c-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_005c"></a>
<p>The escape character, <code class="code">\</code> by default, can escape itself.  This
enables you to control whether a given <code class="code">\n</code>, <code class="code">\g</code>, <code class="code">\$</code>,
<code class="code">\*</code>, <code class="code">\V</code>, or <code class="code">\?</code> escape sequence is interpreted at the
time the macro containing it is defined, or later when the macro is
called.<a class="footnote" id="DOCF101" href="#FOOT101"><sup>101</sup></a>
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr x 20
.de y
.nr x 10
\&amp;\nx
\&amp;\\nx
..
.y
    &rArr; 20 10
</pre></div></div>

<p>You can think of <code class="code">\\</code> as a &ldquo;delayed&rdquo; backslash; it is the escape
character followed by a backslash from which the escape character has
removed its special meaning.  Consequently, &lsquo;<samp class="samp">\\</samp>&rsquo; is not an escape
sequence in the usual sense.  In any escape sequence &lsquo;<samp class="samp">\<var class="var">X</var></samp>&rsquo;
that GNU <code class="code">troff</code> does not recognize, the escape character is
ignored and <var class="var">X</var> is output.  An unrecognized escape sequence causes
a warning in category &lsquo;<samp class="samp">escape</samp>&rsquo;, with two exceptions&mdash;&lsquo;<samp class="samp">\\</samp>&rsquo; is
the first.
</p></dd></dl>

<a class="index-entry-id" id="index-_005c_005c_002c-when-reading-text-for-a-macro"></a>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_002e-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\.</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_002e-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_002e"></a>
<p><code class="code">\.</code> escapes the control character.  It is similar to <code class="code">\\</code> in
that it isn&rsquo;t a true escape sequence.  It is used to permit nested macro
definitions to end without a named macro call to conclude them.  Without
a syntax for escaping the control character, this would not be possible.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de m1
foo
.
.  de m2
bar
\\..
.
..
.m1
.m2
    &rArr; foo bar
</pre></div></div>

<p>The first backslash is consumed while the macro is read, and the second
is interpreted when macro <code class="code">m1</code> is called.
</p></dd></dl>

<p><code class="code">roff</code> documents should not use the <code class="code">\\</code> or <code class="code">\.</code>
character sequences outside of copy mode; they serve only to obfuscate
the input.  Use <code class="code">\e</code> to represent the escape character,
<code class="code">\[rs]</code> to obtain a backslash glyph, and <code class="code">\&amp;</code> before &lsquo;<samp class="samp">.</samp>&rsquo;
and &lsquo;<samp class="samp">'</samp>&rsquo; where GNU <code class="code">troff</code> expects them as control characters
if you mean to use them literally (recall <a class="ref" href="#Requests-and-Macros">Requests and Macros</a>).
</p>
<p>Macro definitions can be nested to arbitrary depth.  The mechanics of
parsing the escape character have significant consequences for this
practice.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de M1
\\$1
.  de M2
\\\\$1
.    de M3
\\\\\\\\$1
\\\\..
.    M3 hand.
\\..
.  M2 of
..
This understeer is getting
.M1 out
    &rArr; This understeer is getting out of hand.
</pre></div></div>

<p>Each escape character is interpreted twice&mdash;once in copy mode, when the
macro is defined, and once in interpretation mode, when the macro is
called.  As seen above, this fact leads to exponential growth in the
quantity of escape characters required to delay interpolation of
<code class="code">\n</code>, <code class="code">\g</code>, <code class="code">\$</code>, <code class="code">\*</code>, <code class="code">\V</code>, and <code class="code">\?</code> at
each nesting level, which can be daunting.  GNU <code class="code">troff</code> offers a
solution.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cE-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\E</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cE-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cE"></a>
<p><code class="code">\E</code> represents an escape character that is not interpreted in copy
mode.  You can use it to ease the writing of nested macro definitions.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de M1
.  nop \E$1
.  de M2
.    nop \E$1
.    de M3
.      nop \E$1
\\\\..
.    M3 better.
\\..
.  M2 bit
..
This vehicle handles
.M1 a
    &rArr; This vehicle handles a bit better.
</pre></div></div>

<p>Observe that because <code class="code">\.</code> is not a true escape sequence, we can&rsquo;t
use <code class="code">\E</code> to keep &lsquo;<samp class="samp">..</samp>&rsquo; from ending a macro definition
prematurely.  If the multiplicity of backslashes complicates
maintenance, use end macros.
</p>
<p><code class="code">\E</code> is also convenient to define strings containing escape
sequences that need to work when used in copy mode (for example, as
macro arguments), or which will be interpolated at varying macro nesting
depths.  We might define strings to begin and end superscripting
as follows.<a class="footnote" id="DOCF102" href="#FOOT102"><sup>102</sup></a>
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds { \v'-.9m\s'\En[.s]*7u/10u'+.7m'
.ds } \v'-.7m\s0+.9m'
</pre></div></div>

<p>When the <code class="code">ec</code> request is used to redefine the escape character,
<code class="code">\E</code> also makes it easier to distinguish the semantics of an escape
character from the other meaning(s) its character might have.  Consider
the use of an unusual escape character, &lsquo;<samp class="samp">-</samp>&rsquo;.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr a 1
.ec -
.de xx
--na
..
.xx
    &rArr; -na
</pre></div></div>

<p>This result may surprise you; some people expect &lsquo;<samp class="samp">1</samp>&rsquo; to be output
since register &lsquo;<samp class="samp">a</samp>&rsquo; has clearly been defined with that value.  What
has happened?  The robotic replacement of &lsquo;<samp class="samp">\</samp>&rsquo; with &lsquo;<samp class="samp">-</samp>&rsquo; has led
us astray.  You might recognize the sequence &lsquo;<samp class="samp">--</samp>&rsquo; more readily with
the default escape character as &lsquo;<samp class="samp">\-</samp>&rsquo;, the special character escape
sequence for the minus sign glyph.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr a 1
.ec -
.de xx
-Ena
..
.xx
    &rArr; 1
</pre></div></div>
</dd></dl>



<hr>
</div>
</div>
<div class="section-level-extent" id="Page-Motions">
<div class="nav-panel">
<p>
Next: <a href="#Drawing-Geometric-Objects" accesskey="n" rel="next">Drawing Geometric Objects</a>, Previous: <a href="#Writing-Macros" accesskey="p" rel="prev">Writing Macros</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Page-Motions-1">5.25 Page Motions</h3>
<a class="index-entry-id" id="index-page-motions"></a>
<a class="index-entry-id" id="index-motions_002c-page"></a>

<p>See <a class="xref" href="#Manipulating-Spacing">Manipulating Spacing</a>, for a discussion of the most commonly used
request for vertical motion, <code class="code">sp</code>, which spaces downward by one
vee.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002emk"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.mk</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">reg</i></span>]</var><a class="copiable-link" href='#index-_002emk'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-mk"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002ert"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.rt</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">dist</i></span>]</var><a class="copiable-link" href='#index-_002ert'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-rt"></a>
<a class="index-entry-id" id="index-marking-vertical-page-location-_0028mk_0029"></a>
<a class="index-entry-id" id="index-page-location_002c-vertical_002c-marking-_0028mk_0029"></a>
<a class="index-entry-id" id="index-location_002c-vertical_002c-page_002c-marking-_0028mk_0029"></a>
<a class="index-entry-id" id="index-vertical-page-location_002c-marking-_0028mk_0029"></a>
<a class="index-entry-id" id="index-returning-to-marked-vertical-page-location-_0028rt_0029"></a>
<a class="index-entry-id" id="index-page-location_002c-vertical_002c-returning-to-marked-_0028rt_0029"></a>
<a class="index-entry-id" id="index-location_002c-vertical_002c-page_002c-returning-to-marked-_0028rt_0029"></a>
<a class="index-entry-id" id="index-vertical-page-location_002c-returning-to-marked-_0028rt_0029"></a>
<p>You can <em class="dfn">mark</em> a location on a page for subsequent <em class="dfn">return</em>.
<code class="code">mk</code> takes an argument, a register name in which to store the
current page location.  If given no argument, it stores the location in
an internal register.  This location can be used later by the <code class="code">rt</code>
or the <code class="code">sp</code> requests (or the <code class="code">\v</code> escape).
</p>
<p>The <code class="code">rt</code> request returns <em class="emph">upward</em> to the location marked with
the last <code class="code">mk</code> request.  If used with an argument, it returns to a
vertical position&nbsp;<var class="var">dist</var> from the top of the page (no previous
call to <code class="code">mk</code> is necessary in this case).  The default scaling
unit is &lsquo;<samp class="samp">v</samp>&rsquo;.
</p>
<p>If a page break occurs between a <code class="code">mk</code> request and its matching
<code class="code">rt</code> request, the <code class="code">rt</code> request is silently ignored.
</p>
<p>A simple implementation of a macro to set text in two columns follows.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr column-length 1.5i
.nr column-gap 4m
.nr bottom-margin 1m
.
.de 2c
.  br
.  mk
.  ll \\n[column-length]u
.  wh -\\n[bottom-margin]u 2c-trap
.  nr right-side 0
..
.
.de 2c-trap
.  ie \\n[right-side] \{\
.    nr right-side 0
.    po -(\\n[column-length]u + \\n[column-gap]u)
.    \&quot; remove trap
.    wh -\\n[bottom-margin]u
.  \}
.  el \{\
.    \&quot; switch to right side
.    nr right-side 1
.    po +(\\n[column-length]u + \\n[column-gap]u)
.    rt
.  \}
..
</pre></div></div>

<p>Now let us apply our two-column macro.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.pl 1.5i
.ll 4i
This is a small test that shows how the
rt request works in combination with mk.

.2c
Starting here, text is typeset in two columns.
Note that this implementation isn't robust
and thus not suited for a real two-column
macro.
    &rArr; This is a small test that shows how the
    &rArr; rt request works in combination with mk.
    &rArr;
    &rArr; Starting  here,    isn't    robust
    &rArr; text is typeset    and   thus  not
    &rArr; in two columns.    suited  for   a
    &rArr; Note that  this    real two-column
    &rArr; implementation     macro.
</pre></div></div>
</dd></dl>

<p>Several escape sequences enable fine control of movement about the page.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cv_0027expr_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\v<code class="code">'</code></code><span class="r"><i class="slanted">expr</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cv_0027expr_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cv"></a>
<a class="index-entry-id" id="index-vertical-motion-_0028_005cv_0029"></a>
<a class="index-entry-id" id="index-motion_002c-vertical-_0028_005cv_0029"></a>
<p>Vertically move the drawing position.  <var class="var">expr</var> indicates the
magnitude of motion: positive is downward and and negative upward.  The
default scaling unit is &lsquo;<samp class="samp">v</samp>&rsquo;.  The motion is relative to the current
drawing position unless <var class="var">expr</var> begins with the boundary-relative
motion operator &lsquo;<samp class="samp">|</samp>&rsquo;.  See <a class="xref" href="#Numeric-Expressions">Numeric Expressions</a>.
</p>
<p>Text processing continues at the new drawing position; usually, vertical
motions should be in balanced pairs to avoid a confusing page layout.
</p>
<p><code class="code">\v</code> will not spring a vertical position trap.  This can be useful;
for example, consider a page bottom trap macro that prints a marker in
the margin to indicate continuation of a footnote.  See <a class="xref" href="#Traps">Traps</a>.
</p></dd></dl>

<p>A few escape sequences that produce vertical motion are unusual.  They
are thought to originate early in AT&amp;T <code class="code">nroff</code> history to achieve
super- and subscripting by half-line motions on line printers and
teletypewriters before the phototypesetter made more precise positioning
available.  They are reckoned in ems&mdash;not vees&mdash;to maintain continuity
with their original purpose of moving relative to the size of the type
rather than the distance between text baselines (vees).<a class="footnote" id="DOCF103" href="#FOOT103"><sup>103</sup></a>
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cr-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\r</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cr-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cr"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cu-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\u</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cu-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cu"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cd-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\d</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cd-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cd"></a>
<p>Move upward&nbsp;1<span class="dmn">m</span>, upward&nbsp;.5<span class="dmn">m</span>, and
downward&nbsp;.5<span class="dmn">m</span>, respectively.
</p></dd></dl>

<p>Let us see these escape sequences in use.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">Obtain 100 cm\u3\d of \ka\d\092\h'|\nau'\r233\dU.
</pre></div></div>

<p>In the foregoing we have paired <code class="code">\u</code> and <code class="code">\d</code> to typeset a
superscript, and later a full em negative (&ldquo;reverse&rdquo;) motion to place
a superscript above a subscript.  A numeral-width horizontal motion
escape sequence aligns the proton and nucleon numbers, while <code class="code">\k</code>
marks a horizontal position to which <code class="code">\h</code> returns so that we could
stack them.  (We shall discuss these horizontal motion escape sequences
presently.)  In serious applications, we often want to alter the type
size of the -scripts and to fine-tune the vertical motions, as the
<code class="code">groff</code> <samp class="file">ms</samp> package does with its super- and subscripting
string definitions.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005ch_0027expr_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\h<code class="code">'</code></code><span class="r"><i class="slanted">expr</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005ch_0027expr_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005ch"></a>
<a class="index-entry-id" id="index-inserting-horizontal-space-_0028_005ch_0029"></a>
<a class="index-entry-id" id="index-horizontal-space-_0028_005ch_0029"></a>
<a class="index-entry-id" id="index-space_002c-horizontal-_0028_005ch_0029"></a>
<a class="index-entry-id" id="index-horizontal-motion-_0028_005ch_0029"></a>
<a class="index-entry-id" id="index-motion_002c-horizontal-_0028_005ch_0029"></a>
<p>Horizontally move the drawing position.  <var class="var">expr</var> indicates the
magnitude of motion: positive is rightward and negative leftward.  The
default scaling unit is &lsquo;<samp class="samp">m</samp>&rsquo;.  The motion is relative to the current
drawing position unless <var class="var">expr</var> begins with the boundary-relative
motion operator &lsquo;<samp class="samp">|</samp>&rsquo;.  See <a class="xref" href="#Numeric-Expressions">Numeric Expressions</a>.
</p></dd></dl>

<p>The following string definition sets the TeX
logo.<a class="footnote" id="DOCF104" href="#FOOT104"><sup>104</sup></a>
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds TeX T\h'-.1667m'\v'.224m'E\v'-.224m'\h'-.125m'X\&quot;
</pre></div></div>

<p>There are a number of special-case escape sequences for horizontal
motion.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cSP-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\<kbd class="key">SP</kbd></code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cSP-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cSP"></a>
<a class="index-entry-id" id="index-space_002c-unbreakable-and-unadjustable-_0028_005cSP_0029"></a>
<a class="index-entry-id" id="index-unbreakable-and-unadjustable-space-_0028_005cSP_0029"></a>
<a class="index-entry-id" id="index-unadjustable-and-unbreakable-space-_0028_005cSP_0029"></a>
<a class="index-entry-id" id="index-_005cspace"></a>
<p>Move right one word space.  (The input is a backslash followed by a
space.)  This escape sequence can be thought of as a non-adjustable,
unbreakable space.  Usually you want <code class="code">\~</code> instead; see
<a class="ref" href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a>.
</p></dd></dl>

<a class="index-entry-id" id="index-thin-space-_0028_005c_007c_0029"></a>
<a class="index-entry-id" id="index-space_002c-thin-_0028_005c_007c_0029"></a>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_007c-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\|</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_007c-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_007c"></a>
<p>Move one-sixth <span class="dmn">em</span> to the right on typesetting output devices.  If
a glyph named &lsquo;<samp class="samp">\|</samp>&rsquo; is defined in the current font, its width is
used instead, even on terminal output devices.
</p></dd></dl>

<a class="index-entry-id" id="index-hair-space-_0028_005c_005e_0029"></a>
<a class="index-entry-id" id="index-space_002c-hair-_0028_005c_005e_0029"></a>
<dl class="first-deffn">
<dt class="deffn" id="index-_005c_005e-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\^</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_005e-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_005e"></a>
<p>Move one-twelfth <span class="dmn">em</span> to the right on typesetting output devices.
If a glyph named &lsquo;<samp class="samp">\^</samp>&rsquo; is defined in the current font, its width is
used instead, even on terminal output devices.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c0-1"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\0</code><span class="r"><i class="slanted"></i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c0-1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c0"></a>
<a class="index-entry-id" id="index-space_002c-width-of-a-digit-_0028numeral_0029-_0028_005c0_0029"></a>
<a class="index-entry-id" id="index-digit_002dwidth-space-_0028_005c0_0029"></a>
<a class="index-entry-id" id="index-figure-space-_0028_005c0_0029"></a>
<a class="index-entry-id" id="index-numeral_002dwidth-space-_0028_005c0_0029"></a>
<p>Move right by the width of a numeral in the current font.
</p></dd></dl>

<p>Horizontal motions are not discarded at the end of an output line as
word spaces are.  See <a class="xref" href="#Breaking">Breaking</a>.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cw_0027anything_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\w<code class="code">'</code></code><span class="r"><i class="slanted">anything</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cw_0027anything_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cw"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005bst_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[st]</code></strong><a class="copiable-link" href='#index-_005cn_005bst_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-st"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005bsb_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[sb]</code></strong><a class="copiable-link" href='#index-_005cn_005bsb_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-sb"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005brst_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[rst]</code></strong><a class="copiable-link" href='#index-_005cn_005brst_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-rst"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005brsb_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[rsb]</code></strong><a class="copiable-link" href='#index-_005cn_005brsb_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-rsb"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005bct_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[ct]</code></strong><a class="copiable-link" href='#index-_005cn_005bct_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ct"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005bssc_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[ssc]</code></strong><a class="copiable-link" href='#index-_005cn_005bssc_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ssc"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005bskw_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[skw]</code></strong><a class="copiable-link" href='#index-_005cn_005bskw_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-skw"></a>
<a class="index-entry-id" id="index-width-escape-_0028_005cw_0029"></a>
<p>Interpolate the width of <var class="var">anything</var> in basic units.  This escape
sequence allows several properties of formatted output to be measured
without writing it out.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">The length of the string 'abc' is \w'abc'u.
    &rArr; The length of the string 'abc' is 72u.
</pre></div></div>

<a class="index-entry-id" id="index-dummy-environment_002c-used-by-_005cw-escape-sequence"></a>
<a class="index-entry-id" id="index-environment_002c-dummy_002c-used-by-_005cw-escape-sequence"></a>
<p><var class="var">anything</var> is processed in a dummy environment: this means that
font and type size changes, for example, may occur within it without
affecting subsequent output.
</p>
<p>After each use, <code class="code">\w</code> sets several registers.
</p>
<a class="index-entry-id" id="index-CSTR-_002354-errata-5"></a>
<a class="index-entry-id" id="index-CSTR-_002354-erratum_002c-sb-register"></a>
<a class="index-entry-id" id="index-CSTR-_002354-erratum_002c-st-register"></a>
<dl class="table">
<dt><code class="code">st</code></dt>
<dt><code class="code">sb</code></dt>
<dd><p>The maximum vertical displacements of the text baseline above and below,
respectively.  The sign convention is opposite that of relative vertical
motions; that is, depth below the (original) baseline is negative.
These registers are incorrectly documented in the <abbr class="acronym">AT&amp;T</abbr>
<code class="code">troff</code> manual as &ldquo;the highest and lowest extent of [the argument
to <code class="code">\w</code>] relative to the baseline&rdquo;.
</p>
</dd>
<dt><code class="code">rst</code></dt>
<dt><code class="code">rsb</code></dt>
<dd><p>Like <code class="code">st</code> and <code class="code">sb</code>, but taking account of the heights and
depths of glyphs.  In other words, these registers store the highest and
lowest vertical positions attained by <var class="var">anything</var>, doing what
<abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> documented <code class="code">st</code> and <code class="code">sb</code> as doing.
</p>
</dd>
<dt><code class="code">ct</code></dt>
<dd><p>Characterizes the geometry of glyphs occurring in <var class="var">anything</var>.
</p>
<dl class="table">
<dt>0</dt>
<dd><p>only short glyphs, no descenders or tall glyphs
</p>
</dd>
<dt>1</dt>
<dd><p>at least one descender
</p>
</dd>
<dt>2</dt>
<dd><p>at least one tall glyph
</p>
</dd>
<dt>3</dt>
<dd><p>at least one each of a descender and a tall glyph
</p></dd>
</dl>

</dd>
<dt><code class="code">ssc</code></dt>
<dd><p>The amount of horizontal space (possibly negative) that should be added
to the last glyph before a subscript.
</p>
</dd>
<dt><code class="code">skw</code></dt>
<dd><p>How far to right of the center of the last glyph in the <code class="code">\w</code>
argument, the center of an accent from a roman font should be placed
over that glyph.
</p></dd>
</dl>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005ckp"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\k</code><span class="r"><i class="slanted">p</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005ckp'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005ck"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005ck_0028ps"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\k(</code><span class="r"><i class="slanted">ps</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005ck_0028ps'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005ck_005bposition_005d"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\k[</code><span class="r"><i class="slanted">position</i></span><code class="t">]</code></strong><a class="copiable-link" href='#index-_005ck_005bposition_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-saving-horizontal-input-line-position-_0028_005ck_0029"></a>
<a class="index-entry-id" id="index-horizontal-input-line-position_002c-saving-_0028_005ck_0029"></a>
<a class="index-entry-id" id="index-input-line-position_002c-horizontal_002c-saving-_0028_005ck_0029"></a>
<a class="index-entry-id" id="index-position_002c-horizontal-input-line_002c-saving-_0028_005ck_0029"></a>
<a class="index-entry-id" id="index-line_002c-input_002c-horizontal-position_002c-saving-_0028_005ck_0029"></a>
<p>Store the current horizontal position in the <em class="emph">input</em> line in a
register with the name <var class="var">position</var> (one-character name&nbsp;<var class="var">p</var>,
two-character name <var class="var">ps</var>).  Use this, for example, to return to the
beginning of a string for highlighting or other decoration.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bhp_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[hp]</code></strong><a class="copiable-link" href='#index-_005cn_005bhp_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-hp"></a>
<a class="index-entry-id" id="index-horizontal-input-line-position-register-_0028hp_0029"></a>
<a class="index-entry-id" id="index-input-line_002c-horizontal-position_002c-register-_0028hp_0029"></a>
<a class="index-entry-id" id="index-position_002c-horizontal_002c-in-input-line_002c-register-_0028hp_0029"></a>
<a class="index-entry-id" id="index-line_002c-input_002c-horizontal-position_002c-register-_0028hp_0029"></a>
<p>The current horizontal position at the input line.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005b_002ek_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.k]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ek_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ek"></a>
<a class="index-entry-id" id="index-horizontal-output-line-position-register-_0028_002ek_0029"></a>
<a class="index-entry-id" id="index-output-line_002c-horizontal-position_002c-register-_0028_002ek_0029"></a>
<a class="index-entry-id" id="index-position_002c-horizontal_002c-in-output-line_002c-register-_0028_002ek_0029"></a>
<a class="index-entry-id" id="index-line_002c-output_002c-horizontal-position_002c-register-_0028_002ek_0029"></a>
<p>A read-only register containing the current horizontal output position
(relative to the current indentation).
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005co_0027abc_2026_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\o<code class="code">'</code></code><span class="r"><i class="slanted">abc&hellip;</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005co_0027abc_2026_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005co"></a>
<a class="index-entry-id" id="index-overstriking-glyphs-_0028_005co_0029"></a>
<a class="index-entry-id" id="index-glyphs_002c-overstriking-_0028_005co_0029"></a>
<p>Overstrike the glyphs of characters <var class="var">a</var>, <var class="var">b</var>, <var class="var">c</var>, &hellip;;
the glyphs are centered, written, and the drawing position advanced by
the widest of the glyphs.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005czc"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\z</code><span class="r"><i class="slanted">c</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005czc'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cz"></a>
<a class="index-entry-id" id="index-zero_002dwidth-printing-_0028_005cz_002c-_005cZ_0029"></a>
<a class="index-entry-id" id="index-printing_002c-zero_002dwidth-_0028_005cz_002c-_005cZ_0029"></a>
<p>Format the character <var class="var">c</var> with zero width; that is, without advancing
the drawing position.  Use <code class="code">\z</code> to overstrike glyphs aligned to
their left edges, in contrast to <code class="code">\o</code>&rsquo;s centering.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cZ_0027anything_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\Z<code class="code">'</code></code><span class="r"><i class="slanted">anything</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cZ_0027anything_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cZ"></a>
<a class="index-entry-id" id="index-zero_002dwidth-printing-_0028_005cz_002c-_005cZ_0029-1"></a>
<a class="index-entry-id" id="index-printing_002c-zero_002dwidth-_0028_005cz_002c-_005cZ_0029-1"></a>
<p>Save the drawing position, format <var class="var">anything</var>, then restore it.  Tabs
and leaders in the argument are ignored with an error diagnostic.
</p>
<p>We might implement a strike-through macro thus.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de ST
.nr width \w'\\$1'
\Z@\v'-.25m'\l'\\n[width]u'@\\$1
..
.
This is
.ST &quot;a test&quot;
an actual emergency!
</pre></div></div>
</dd></dl>



<hr>
</div>
<div class="section-level-extent" id="Drawing-Geometric-Objects">
<div class="nav-panel">
<p>
Next: <a href="#Traps" accesskey="n" rel="next">Traps</a>, Previous: <a href="#Page-Motions" accesskey="p" rel="prev">Page Motions</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Drawing-Geometric-Objects-1">5.26 Drawing Geometric Objects</h3>
<a class="index-entry-id" id="index-drawing-requests"></a>
<a class="index-entry-id" id="index-requests-for-drawing"></a>

<p>A few of the formatter&rsquo;s escape sequences draw lines and other geometric
objects.  Combined with each other and with page motion commands
(see <a class="pxref" href="#Page-Motions">Page Motions</a>), a wide variety of figures is possible.  For
complex drawings, these operations can be cumbersome; the preprocessors
<code class="code">gpic</code> or <code class="code">ggrn</code> are typically used instead.
</p>
<p>The <code class="code">\l</code> and <code class="code">\L</code> escape sequences draw horizontal and
vertical sequences of glyphs, respectively.  Even the simplest of
output devices supports them.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cl_0027l_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\l<code class="code">'</code></code><span class="r"><i class="slanted">l</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cl_0027l_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cl"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cl_0027lc_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\l<code class="code">'</code></code><span class="r"><i class="slanted">lc</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cl_0027lc_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-drawing-horizontal-lines-_0028_005cl_0029"></a>
<a class="index-entry-id" id="index-horizontal-line_002c-drawing-_0028_005cl_0029"></a>
<a class="index-entry-id" id="index-line_002c-horizontal_002c-drawing-_0028_005cl_0029"></a>
<p>Draw a horizontal line of length <var class="var">l</var> from the drawing position.
Rightward motion is positive.  Afterward, the drawing position is at the
right end of the line.  The default scaling unit is &lsquo;<samp class="samp">m</samp>&rsquo;.
</p>
<a class="index-entry-id" id="index-baseline-rule-special-character_0028_005c_005bru_005d_0029"></a>
<a class="index-entry-id" id="index-glyph_002c-underscore-_0028_005c_005bru_005d_0029"></a>
<a class="index-entry-id" id="index-line-drawing-glyph"></a>
<a class="index-entry-id" id="index-glyph_002c-for-line-drawing"></a>
<p>The optional second parameter&nbsp;<var class="var">c</var> is a character with which to
draw the line.  The default is the baseline rule special character,
<code class="code">\[ru]</code>.
</p>
<a class="index-entry-id" id="index-dummy-character-_0028_005c_0026_0029_002c-effect-on-_005cl-escape-sequence"></a>
<a class="index-entry-id" id="index-character_002c-dummy-_0028_005c_0026_0029_002c-effect-on-_005cl-escape-sequence"></a>
<p>If <var class="var">c</var> is a valid scaling unit, put <code class="code">\&amp;</code> after <var class="var">l</var> to
disambiguate the input.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de textbox
\[br]\\$*\[br]\l'|0\[rn]'\l'|0\[ul]'
..
</pre></div></div>

<p>The foregoing outputs a box rule (a vertical line), the text
argument(s), and another box rule.  We employ the boundary-relative
motion operator &lsquo;<samp class="samp">|</samp>&rsquo;.  Finally, the line-drawing escape sequences
draw a radical extender (a form of overline) and an underline from the
drawing position to the position coresponding to beginning of the
<em class="emph">input</em> line.  The drawing position returns to just after the
right-hand box rule because the lengths of the drawn lines are negative,
as noted above.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cL_0027l_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\L<code class="code">'</code></code><span class="r"><i class="slanted">l</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cL_0027l_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cL"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cL_0027lc_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\L<code class="code">'</code></code><span class="r"><i class="slanted">lc</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cL_0027lc_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-drawing-vertical-lines-_0028_005cL_0029"></a>
<a class="index-entry-id" id="index-vertical-line-drawing-_0028_005cL_0029"></a>
<a class="index-entry-id" id="index-line_002c-vertical_002c-drawing-_0028_005cL_0029"></a>
<a class="index-entry-id" id="index-line-drawing-glyph-1"></a>
<a class="index-entry-id" id="index-glyph-for-line-drawing"></a>
<a class="index-entry-id" id="index-box-rule-glyph-_0028_005c_005bbr_005d_0029"></a>
<a class="index-entry-id" id="index-glyph_002c-box-rule-_0028_005c_005bbr_005d_0029"></a>
<p>Draw a vertical line of length <var class="var">l</var> from the drawing position.
Downward motion is positive.  The default scaling unit is &lsquo;<samp class="samp">v</samp>&rsquo;.  The
default character is the box rule, <code class="code">\[br]</code>.  As with vertical
motion escape sequences, text processing continues where the line ends.
<code class="code">\L</code> is otherwise similar to <code class="code">\l</code>.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">$ nroff &lt;&lt;EOF
This is a \L'3v'test.
EOF
    &rArr; This is a
    &rArr;           |
    &rArr;           |
    &rArr;           |test.
</pre></div></div>

<p>When writing text, the drawing position is at the text baseline; recall
<a class="ref" href="#Page-Geometry">Page Geometry</a>.
</p></dd></dl>

<p>The <code class="code">\D</code> escape sequence provides <em class="dfn">drawing commands</em> that
direct the output device to render geometrical objects rather than
glyphs.  Specific devices may support only a subset, or may feature
additional ones; consult the man page for the output driver in use.
Terminal devices in particular implement almost none.  See <a class="xref" href="#Graphics-Commands">Graphics Commands</a>.
</p>
<p>Rendering starts at the drawing position; when finished, the drawing
position is left at the rightmost point of the object, even for closed
figures, except where noted.  GNU <code class="code">troff</code> draws stroked (outlined)
objects with the stroke color, and shades filled ones with the fill
color.  See <a class="xref" href="#Colors">Colors</a>.  Coordinates <var class="var">h</var> and <var class="var">v</var> are horizontal
and vertical motions relative to the drawing position or previous point
in the command.  The default scaling unit for horizontal measurements
(and diameters of circles) is &lsquo;<samp class="samp">m</samp>&rsquo;; for vertical ones, &lsquo;<samp class="samp">v</samp>&rsquo;.
</p>
<p>Circles, ellipses, and polygons can be drawn filled or stroked.  These
are independent properties; if you want a filled, stroked figure, you
must draw the same figure twice using each drawing command.  A filled
figure is always smaller than an outlined one because the former is
drawn only within its defined area, whereas strokes have a line
thickness (set with &lsquo;<samp class="samp">\D't'</samp>&rsquo;).
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">\h'1i'\v'1i'\
\# increase line thickness
\Z'\D't 5p''\
\# draw stroked (unfilled) polygon
\Z'\D'p 3 3 -6 0''\
\# draw filled (solid) polygon
\Z'\D'P 3 3 -6 0''
</pre></div></div>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cD_0027command-argument-_2026_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\D<code class="code">'</code></code><span class="r"><i class="slanted">command argument &hellip;</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cD_0027command-argument-_2026_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cD"></a>
<p>Drawing command escape sequence parameters begin with an ordinary
character, <var class="var">command</var>, selecting the type of object to be drawn,
followed by <var class="var">argument</var>s whose meaning is determined by
<var class="var">command</var>.
</p>
<dl class="table">
<dt id='index-drawing-a-spline-_0028_005cD_0027_007e-_2026_0027_0029'><span><code class="code">\D'~ <var class="var">h1</var> <var class="var">v1</var> &hellip; <var class="var">hn</var> <var class="var">vn</var>'</code><a class="copiable-link" href='#index-drawing-a-spline-_0028_005cD_0027_007e-_2026_0027_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-spline_002c-drawing-_0028_005cD_0027_007e-_2026_0027_0029"></a>
<p>Draw a B-spline to each point in sequence, leaving the drawing position
at (<var class="var">hn</var>, <var class="var">vn</var>).
</p>
</dd>
<dt id='index-arc_002c-drawing-_0028_005cD_0027a-_2026_0027_0029'><span><code class="code">\D'a <var class="var">hc</var> <var class="var">vc</var> <var class="var">h</var> <var class="var">v</var>'</code><a class="copiable-link" href='#index-arc_002c-drawing-_0028_005cD_0027a-_2026_0027_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-drawing-an-arc-_0028_005cD_0027a-_2026_0027_0029"></a>
<p>Draw a circular arc centered at (<var class="var">hc</var>, <var class="var">vc</var>) counterclockwise
from the drawing position to a point (<var class="var">h</var>, <var class="var">v</var>) relative to the
center.  <a class="footnote" id="DOCF105" href="#FOOT105"><sup>105</sup></a>
</p>
</dd>
<dt id='index-circle_002c-stroked_002c-drawing-_0028_005cD_0027c-_2026_0027_0029'><span><code class="code">\D'c <var class="var">d</var>'</code><a class="copiable-link" href='#index-circle_002c-stroked_002c-drawing-_0028_005cD_0027c-_2026_0027_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-drawing-a-stroked-circle-_0028_005cD_0027c-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-stroked-circle_002c-drawing-_0028_005cD_0027c-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-circle_002c-outlined_002c-drawing-_0028_005cD_0027c-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-drawing-an-outlined-circle-_0028_005cD_0027c-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-outlined-circle_002c-drawing-_0028_005cD_0027c-_2026_0027_0029"></a>
<p>Draw a circle of diameter <var class="var">d</var> with its leftmost point at the drawing
position.
</p>
</dd>
<dt id='index-circle_002c-filled_002c-drawing-_0028_005cD_0027C-_2026_0027_0029'><span><code class="code">\D'C <var class="var">d</var>'</code><a class="copiable-link" href='#index-circle_002c-filled_002c-drawing-_0028_005cD_0027C-_2026_0027_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-drawing-a-filled-circle-_0028_005cD_0027C-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-filled-circle_002c-drawing-_0028_005cD_0027C-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-circle_002c-solid_002c-drawing-_0028_005cD_0027C-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-drawing-a-solid-circle-_0028_005cD_0027C-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-solid-circle_002c-drawing-_0028_005cD_0027C-_2026_0027_0029"></a>
<p>As &lsquo;<samp class="samp">\D'C <span class="r">&hellip;</span>'</samp>&rsquo;, but the circle is filled.
</p>
</dd>
<dt id='index-ellipse_002c-stroked_002c-drawing-_0028_005cD_0027e-_2026_0027_0029'><span><code class="code">\D'e <var class="var">h</var> <var class="var">v</var>'</code><a class="copiable-link" href='#index-ellipse_002c-stroked_002c-drawing-_0028_005cD_0027e-_2026_0027_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-drawing-a-stroked-ellipse-_0028_005cD_0027e-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-stroked-ellipse_002c-drawing-_0028_005cD_0027e-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-ellipse_002c-outlined_002c-drawing-_0028_005cD_0027e-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-drawing-an-outlined-ellipse-_0028_005cD_0027e-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-outlined-ellipse_002c-drawing-_0028_005cD_0027e-_2026_0027_0029"></a>
<p>Draw an ellipse of width <var class="var">h</var> and height <var class="var">v</var> with its leftmost
point at the drawing position.
</p>
</dd>
<dt id='index-ellipse_002c-filled_002c-drawing-_0028_005cD_0027E-_2026_0027_0029'><span><code class="code">\D'E <var class="var">x</var> <var class="var">y</var>'</code><a class="copiable-link" href='#index-ellipse_002c-filled_002c-drawing-_0028_005cD_0027E-_2026_0027_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-drawing-a-filled-ellipse-_0028_005cD_0027E-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-filled-ellipse_002c-drawing-_0028_005cD_0027E-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-ellipse_002c-solid_002c-drawing-_0028_005cD_0027E-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-drawing-a-solid-ellipse-_0028_005cD_0027E-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-solid-ellipse_002c-drawing-_0028_005cD_0027E-_2026_0027_0029"></a>
<p>As &lsquo;<samp class="samp">\D'e <span class="r">&hellip;</span>'</samp>&rsquo;, but the ellipse is filled.
</p>
</dd>
<dt id='index-line_002c-drawing-_0028_005cD_0027l-_2026_0027_0029'><span><code class="code">\D'l <var class="var">dx</var> <var class="var">dy</var>'</code><a class="copiable-link" href='#index-line_002c-drawing-_0028_005cD_0027l-_2026_0027_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-drawing-a-line-_0028_005cD_0027l-_2026_0027_0029"></a>
<p>Draw line from the drawing position to (<var class="var">h</var>, <var class="var">v</var>).
</p>
<p>The following is a macro for drawing a box around a text argument; for
simplicity, the box margin is a fixed at 0.2<span class="dmn">m</span>.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de TEXTBOX
.  nr @wd \w'\\$1'
\h'.2m'\
\h'-.2m'\v'(.2m - \\n[rsb]u)'\
\D'l 0 -(\\n[rst]u - \\n[rsb]u + .4m)'\
\D'l (\\n[@wd]u + .4m) 0'\
\D'l 0 (\\n[rst]u - \\n[rsb]u + .4m)'\
\D'l -(\\n[@wd]u + .4m) 0'\
\h'.2m'\v'-(.2m - \\n[rsb]u)'\
\\$1\
\h'.2m'
..
</pre></div></div>

<p>The argument is measured with the <code class="code">\w</code> escape sequence.  Its width
is stored in register <code class="code">@wd</code>.  <code class="code">\w</code> also sets the registers
<code class="code">rst</code> and <code class="code">rsb</code>; these contain its maximum vertical extents of
the argument.  Then, four lines are drawn to form a box, offset by the
box margin.
</p>
</dd>
<dt id='index-polygon_002c-stroked_002c-drawing-_0028_005cD_0027p-_2026_0027_0029'><span><code class="code">\D'p <var class="var">h1</var> <var class="var">v1</var> &hellip; <var class="var">hn</var> <var class="var">vn</var>'</code><a class="copiable-link" href='#index-polygon_002c-stroked_002c-drawing-_0028_005cD_0027p-_2026_0027_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-drawing-a-stroked-polygon-_0028_005cD_0027p-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-stroked-polygon_002c-drawing-_0028_005cD_0027p-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-polygon_002c-outlined_002c-drawing-_0028_005cD_0027p-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-drawing-an-outlined-polygon-_0028_005cD_0027p-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-outlined-polygon_002c-drawing-_0028_005cD_0027p-_2026_0027_0029"></a>
<p>Draw polygon with vertices at drawing position and each point in
sequence.  GNU <code class="code">troff</code> closes the polygon by drawing a line from
(<var class="var">hn</var>, <var class="var">vn</var>) back to the initial drawing position.
Afterward, the drawing position is left at (<var class="var">hn</var>, <var class="var">vn</var>).
</p>
</dd>
<dt id='index-polygon_002c-filled_002c-drawing-_0028_005cD_0027P-_2026_0027_0029'><span><code class="code">\D'P <var class="var">dx1</var> <var class="var">dy1</var> <var class="var">dx2</var> <var class="var">dy2</var> &hellip;'</code><a class="copiable-link" href='#index-polygon_002c-filled_002c-drawing-_0028_005cD_0027P-_2026_0027_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-drawing-a-filled-polygon-_0028_005cD_0027P-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-filled-polygon_002c-drawing-_0028_005cD_0027P-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-polygon_002c-solid_002c-drawing-_0028_005cD_0027P-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-drawing-a-solid-polygon-_0028_005cD_0027P-_2026_0027_0029"></a>
<a class="index-entry-id" id="index-solid-polygon_002c-drawing-_0028_005cD_0027P-_2026_0027_0029"></a>
<p>As &lsquo;<samp class="samp">\D'P <span class="r">&hellip;</span>'</samp>&rsquo;, but the polygon is filled.
</p>
<p>The following macro is like the &lsquo;<samp class="samp">\D'l'</samp>&rsquo; example, but shades the
box.  We draw the box before writing the text because colors in GNU
<code class="code">troff</code> have no transparency; in othe opposite order, the filled
polygon would occlude the text.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de TEXTBOX
.  nr @wd \w'\\$1'
\h'.2m'\
\h'-.2m'\v'(.2m - \\n[rsb]u)'\
\M[lightcyan]\
\D'P 0 -(\\n[rst]u - \\n[rsb]u + .4m) \
     (\\n[@wd]u + .4m) 0 \
     0 (\\n[rst]u - \\n[rsb]u + .4m) \
     -(\\n[@wd]u + .4m) 0'\
\h'.2m'\v'-(.2m - \\n[rsb]u)'\
\M[]\
\\$1\
\h'.2m'
..
</pre></div></div>

</dd>
<dt id='index-line-thickness-_0028_005cD_0027t-_2026_0027_0029'><span><code class="code">\D't <var class="var">n</var>'</code><a class="copiable-link" href='#index-line-thickness-_0028_005cD_0027t-_2026_0027_0029'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-thickness-of-lines-_0028_005cD_0027t-_2026_0027_0029"></a>
<p>Set the stroke thickness of geometric objects to <var class="var">n</var> basic units.  A
zero <var class="var">n</var> selects the minimal supported thickness.  A negative
<var class="var">n</var> selects a thickness proportional to the type size; this is the
default.
</p></dd>
</dl>
</dd></dl>

<p>In a hazy penumbra between text rendering and drawing commands we locate
the bracket-building escape sequence, <code class="code">\b</code>.  It can assemble
apparently large glyphs by vertically stacking ordinary ones.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cb_0027contents_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\b<code class="code">'</code></code><span class="r"><i class="slanted">contents</i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cb_0027contents_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cb"></a>
<a class="index-entry-id" id="index-pile_002c-glyph-_0028_005cb_0029"></a>
<a class="index-entry-id" id="index-glyph-pile-_0028_005cb_0029"></a>
<a class="index-entry-id" id="index-stacking-glyphs-_0028_005cb_0029"></a>
<p>Pile and center a sequence of glyphs vertically on the output line.
<em class="dfn">Piling</em> stacks glyphs corresponding to each character in
<var class="var">contents</var>, read from left to right, and placed from top to bottom.
GNU <code class="code">troff</code> separates the glyphs vertically by 1<span class="dmn">m</span>, and the
pile itself is centered 0.5<span class="dmn">m</span> above the text baseline.  The
horizontal drawing position is then advanced by the width of the widest
glyph in the pile.
</p>
<a class="index-entry-id" id="index-_005cb_002c-limitations-of"></a>
<a class="index-entry-id" id="index-limitations-of-_005cb-escape-sequence"></a>
<p>This rather inflexible positioning algorithm doesn&rsquo;t work with the
<code class="code">dvi</code> output device since its bracket pieces vary in height.
Instead, use the <code class="code">geqn</code> preprocessor.
</p>
<p><a class="ref" href="#Manipulating-Spacing">Manipulating Spacing</a> describes how to adjust the vertical spacing
of the output line with the <code class="code">\x</code> escape sequence.
</p>
<p>The application of <code class="code">\b</code> that lends its name is construction of
brackets, braces, and parentheses when typesetting mathematics.  We
might construct a large opening (left) brace as follows.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">\b'\[lt]\[bv]\[lk]\[bv]\[lb]'
</pre></div></div>

<p>See <cite class="cite">groff_char<span class="r">(7)</span></cite> for a list of special character
identifiers.
</p></dd></dl>



<hr>
</div>
<div class="section-level-extent" id="Deferring-Output">
<div class="nav-panel">
<p>
Next: <a href="#Traps" accesskey="n" rel="next">Traps</a>, Previous: <a href="#Drawing-Geometric-Objects" accesskey="p" rel="prev">Drawing Geometric Objects</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Deferring-Output-1">5.27 Deferring Output</h3>
<a class="index-entry-id" id="index-deferred-output"></a>

<a class="index-entry-id" id="index-environment"></a>
<a class="index-entry-id" id="index-diversion"></a>
<a class="index-entry-id" id="index-trap"></a>
<p>A few <code class="code">roff</code> language elements are generally not used in simple
documents, but arise as page layouts become more sophisticated and
demanding.  <em class="dfn">Environments</em> collect formatting parameters like line
length and typeface.  A <em class="dfn">diversion</em> stores formatted output for
later use.  A <em class="dfn">trap</em> is a condition on the input or output, tested
automatically by the formatter, that is associated with a macro, causing
it to be called when that condition is fulfilled.
</p>
<p>Footnote support often exercises all three of the foregoing features.  A
simple implementation might work as follows.  A pair of macros is
defined: one starts a footnote and the other ends it.  The author calls
the first macro where a footnote marker is desired.  The macro
establishes a diversion so that the footnote text is collected at the
place in the body text where its corresponding marker appears.  An
environment is created for the footnote so that it is set at a smaller
typeface.  The footnote text is formatted in the diversion using that
environment, but it does not yet appear in the output.  The document
author calls the footnote end macro, which returns to the previous
environment and ends the diversion.  Later, after much more body text in
the document, a trap, set a small distance above the page bottom, is
sprung.  The macro called by the trap draws a line across the page and
emits the stored diversion.  Thus, the footnote is rendered.
</p>
<p>Diversions and traps make the text formatting process non-linear.  Let
us imagine a set of text lines or paragraphs labelled &lsquo;<samp class="samp">A</samp>&rsquo;,
&lsquo;<samp class="samp">B</samp>&rsquo;, and so on.  If we set up a trap that produces text &lsquo;<samp class="samp">T</samp>&rsquo;
(as a page footer, say), and we also use a diversion to store the
formatted text &lsquo;<samp class="samp">D</samp>&rsquo;, then a document with input text in the order
&lsquo;<samp class="samp">A B C D E F</samp>&rsquo; might render as &lsquo;<samp class="samp">A B C E T F</samp>&rsquo;.  The diversion
&lsquo;<samp class="samp">D</samp>&rsquo; will never be output if we do not call for it.
</p>
<p>Environments of themselves are not a source of non-linearity in document
formatting: environment switches have immediate effect.  One could
always write a macro to change as many formatting parameters as desired
with a single convenient call.  But because diversions can be nested and
macros called by traps that are sprung by other trap-called macros, they
may be called upon in varying contexts.  For example, consider a page
header that is always to be set in Helvetica.  A document that uses
Times for most of its body text, but Courier for displayed code
examples, poses a challenge if a page break occurs in the middle of a
code display; if the header trap assumes that the &ldquo;previous font&rdquo; is
always Times, the rest of the example will be formatted in the wrong
typeface.  One could carefully save all formatting parameters upon
entering the trap and restore them upon leaving it, but this is verbose,
error-prone, and not future-proof as the <code class="code">groff</code> language develops.
Environments save us considerable effort.
</p>

<hr>
</div>
<div class="section-level-extent" id="Traps">
<div class="nav-panel">
<p>
Next: <a href="#Diversions" accesskey="n" rel="next">Diversions</a>, Previous: <a href="#Deferring-Output" accesskey="p" rel="prev">Deferring Output</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Traps-1">5.28 Traps</h3>
<a class="index-entry-id" id="index-traps"></a>

<p><em class="dfn">Traps</em> are locations in the output or conditions on the input that,
when reached or fulfilled, call a specified macro.  These traps can
occur at a given location on the page, at a given location in the
current diversion (together, these are known as <i class="slanted">vertical
position traps</i>), at a blank line, at a line with leading space
characters, after a quantity of input lines, or at the end of input.
Macros called by traps are passed no arguments.
<a class="index-entry-id" id="index-planting-a-trap"></a>
<a class="index-entry-id" id="index-trap_002c-planting"></a>
Setting a trap is also called <em class="dfn">planting</em> one.
<a class="index-entry-id" id="index-trap_002c-springing"></a>
<a class="index-entry-id" id="index-springing-a-trap"></a>
It is said that a trap is <em class="dfn">sprung</em> if its condition is fulfilled.
</p>


<ul class="mini-toc">
<li><a href="#Vertical-Position-Traps" accesskey="1">Vertical Position Traps</a></li>
<li><a href="#Input-Line-Traps" accesskey="2">Input Line Traps</a></li>
<li><a href="#Blank-Line-Traps" accesskey="3">Blank Line Traps</a></li>
<li><a href="#Leading-Space-Traps" accesskey="4">Leading Space Traps</a></li>
<li><a href="#End_002dof_002dinput-Traps" accesskey="5">End-of-input Traps</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="Vertical-Position-Traps">
<div class="nav-panel">
<p>
Next: <a href="#Page-Location-Traps" accesskey="n" rel="next">Page Location Traps</a>, Previous: <a href="#Traps" accesskey="p" rel="prev">Traps</a>, Up: <a href="#Traps" accesskey="u" rel="up">Traps</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Vertical-Position-Traps-1">5.28.1 Vertical Position Traps</h4>
<a class="index-entry-id" id="index-vertical-position-traps"></a>
<a class="index-entry-id" id="index-traps_002c-vertical-position"></a>

<p>A <em class="dfn">vertical position trap</em> calls a macro when the formatter&rsquo;s
vertical drawing position reaches or passes, in the downward direction,
a certain location on the output page or in a diversion.  Its
applications include setting page headers and footers, body text in
multiple columns, and footnotes.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002evpt"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.vpt</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">flag</i></span>]</var><a class="copiable-link" href='#index-_002evpt'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-vpt"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002evpt_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.vpt]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002evpt_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002evpt-1"></a>
<a class="index-entry-id" id="index-enabling-vertical-position-traps-_0028vpt_0029"></a>
<a class="index-entry-id" id="index-vertical-position-traps_002c-enabling-_0028vpt_0029"></a>
<a class="index-entry-id" id="index-vertical-position-trap-enable-register-_0028_002evpt_0029"></a>
<p>Enable vertical position traps if <var class="var">flag</var> is non-zero or absent;
disable them otherwise.  Vertical position traps are those set by the
<code class="code">wh</code> request or by <code class="code">dt</code> within a diversion.  The parameter
that controls whether vertical position traps are enabled is global.
Initially, vertical position traps are enabled.  The current value is
stored in the <code class="code">.vpt</code> read-only register.
</p>
<a class="index-entry-id" id="index-page-break_002c-prevented-by-vpt"></a>
<a class="index-entry-id" id="index-break_002c-page_002c-prevented-by-vpt"></a>
<a class="index-entry-id" id="index-page-ejection_002c-prevented-by-vpt"></a>
<a class="index-entry-id" id="index-ejection_002c-page_002c-prevented-by-vpt"></a>
<p>A page can&rsquo;t be ejected if <code class="code">vpt</code> is set to zero; see <a class="ref" href="#The-Implicit-Page-Trap">The Implicit Page Trap</a>.
</p></dd></dl>



<ul class="mini-toc">
<li><a href="#Page-Location-Traps" accesskey="1">Page Location Traps</a></li>
<li><a href="#The-Implicit-Page-Trap" accesskey="2">The Implicit Page Trap</a></li>
<li><a href="#Diversion-Traps" accesskey="3">Diversion Traps</a></li>
</ul>
<hr>
<div class="subsubsection-level-extent" id="Page-Location-Traps">
<div class="nav-panel">
<p>
Next: <a href="#The-Implicit-Page-Trap" accesskey="n" rel="next">The Implicit Page Trap</a>, Previous: <a href="#Vertical-Position-Traps" accesskey="p" rel="prev">Vertical Position Traps</a>, Up: <a href="#Vertical-Position-Traps" accesskey="u" rel="up">Vertical Position Traps</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Page-Location-Traps-1">5.28.1.1 Page Location Traps</h4>
<a class="index-entry-id" id="index-page-location-traps"></a>
<a class="index-entry-id" id="index-traps_002c-page-location"></a>

<p>A <em class="dfn">page location trap</em> is a vertical position trap that applies to
the page; that is, to undiverted output.  Many can be present; manage
them with the <code class="code">wh</code> and <code class="code">ch</code> requests.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002ewh"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.wh</code></strong> <var class="def-var-arguments">dist [<span class="r"><i class="slanted">name</i></span>]</var><a class="copiable-link" href='#index-_002ewh'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-wh"></a>
<p>Plant macro <var class="var">name</var> as page location trap at <var class="var">dist</var>.  The default
scaling unit is &lsquo;<samp class="samp">v</samp>&rsquo;.  Non-negative values for <var class="var">dist</var> set the
trap relative to the top of the page; negative values set the trap
relative to the bottom of the page.  It is not possible to plant a trap
less than one basic unit from the page bottom: a <var class="var">dist</var> of <code class="code">-0</code>
is interpreted as <code class="code">0</code>, the top of the page.<a class="footnote" id="DOCF106" href="#FOOT106"><sup>106</sup></a>  An existing <em class="emph">visible</em> trap (see below) at
<var class="var">dist</var> is removed; this is <code class="code">wh</code>&rsquo;s sole function if <var class="var">name</var>
is missing.
</p>
<p>A trap is sprung only if it is <em class="dfn">visible</em>, meaning that its location
is reachable on the page<a class="footnote" id="DOCF107" href="#FOOT107"><sup>107</sup></a> and it
is not hidden by another trap at the same location already planted
there.
</p>
<a class="index-entry-id" id="index-page-headers"></a>
<a class="index-entry-id" id="index-page-footers"></a>
<a class="index-entry-id" id="index-headers-1"></a>
<a class="index-entry-id" id="index-footers-1"></a>
<a class="index-entry-id" id="index-top-margin"></a>
<a class="index-entry-id" id="index-margin_002c-top"></a>
<a class="index-entry-id" id="index-bottom-margin"></a>
<a class="index-entry-id" id="index-margin_002c-bottom"></a>
<p>A macro package might set headers and footers as follows; this example
configures vertical margins of one inch to the body text, and one
half-inch to the titles.  Observe the use of the no-break control
character with <code class="code">sp</code> request to position our text baselines,
and the page number character &lsquo;<samp class="samp">%</samp>&rsquo; used with the <code class="code">tl</code> request.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.\&quot; hdfo.roff
.de hd                  \&quot; page header
'  sp .5i
'  tl '\\*(Ti''\\*(Da'  \&quot; title and date strings
'  sp .5i
..
.de fo                  \&quot; page footer
'  sp .5i
.  tl ''%''
.  bp
..
.wh 0   hd             \&quot; trap at top of the page
.wh -1i fo             \&quot; trap 1 inch from bottom
</pre></div></div>

<p>To use these traps, copy the above (or load it from a file with the
<code class="code">so</code> or <code class="code">mso</code> requests), then set up the strings it uses.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.so hdfo.roff
.ds Ti Final Report\&quot;
.ds Da 21 May 2023\&quot;
.ti
On 5 August of last year,
this committee tasked me with the investigation of the
CFIT (controlled flight into terrain) incident of
.\&quot; <i class="i">...and so on...</i>
</pre></div></div>

<p>A trap above the top or at or below the bottom of the page can be made
visible by either moving it into the page area or increasing the page
length so that the trap is on the page.  Negative trap values always use
the <em class="emph">current</em> page length; they are not converted to an absolute
vertical position.
<a class="index-entry-id" id="index-page-location-traps_002c-debugging"></a>
<a class="index-entry-id" id="index-debugging-page-location-traps"></a>
We can use the <code class="code">ptr</code> request to dump our page location traps to the
standard error stream (see <a class="pxref" href="#Debugging">Debugging</a>).  Their positions are reported
in basic units; an <code class="code">nroff</code> device example follows.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.pl 5i
.wh -1i xx
.ptr
    error&rarr; xx      -240
.pl 100i
.ptr
    error&rarr; xx      -240
</pre></div></div>

<p>It is possible to have more than one trap at the same location (although
only one at a time can be visible); to achieve this, the traps must be
defined at different locations, then moved to the same place with the
<code class="code">ch</code> request.  In the following example, the many empty lines
caused by the <code class="code">bp</code> request are not shown in the output.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de a
.  nop a
..
.de b
.  nop b
..
.de c
.  nop c
..
.
.wh 1i a
.wh 2i b
.wh 3i c
.bp
    &rArr; a b c
</pre></div></div>
<div class="example">
<div class="group"><pre class="example-preformatted">.ch b 1i
.ch c 1i
.bp
    &rArr; a
</pre></div></div>
<div class="example">
<div class="group"><pre class="example-preformatted">.ch a 0.5i
.bp
    &rArr; a b
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005b_002et_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.t]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002et_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002et"></a>
<a class="index-entry-id" id="index-distance-to-next-vertical-position-trap-register-_0028_002et_0029"></a>
<a class="index-entry-id" id="index-trap_002c-distance-to-next-vertical-position_002c-register-_0028_002et_0029"></a>
<p>The read-only register <code class="code">.t</code> holds the distance to the next vertical
position trap.  If there are no traps between the current position and
the bottom of the page, it contains the distance to the page bottom.
Within a diversion, in the absence of a diversion trap, this distance is
the largest representable integer in basic units&mdash;effectively infinite.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ech"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ch</code></strong> <var class="def-var-arguments">name [<span class="r"><i class="slanted">dist</i></span>]</var><a class="copiable-link" href='#index-_002ech'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ch"></a>
<a class="index-entry-id" id="index-changing-trap-location-_0028ch_0029"></a>
<a class="index-entry-id" id="index-trap_002c-changing-location-_0028ch_0029"></a>
<p>Change the location of a trap by moving macro <var class="var">name</var> to new location
<var class="var">dist</var>, or by unplanting it altogether if <var class="var">dist</var> is absent.  The
default scaling unit is &lsquo;<samp class="samp">v</samp>&rsquo;.  Parameters to <code class="code">ch</code> are specified
in the opposite order from <code class="code">wh</code>.  If <var class="var">name</var> is the earliest
planted macro of multiple traps at the same location, (re)moving it from
that location exposes the macro next least recently planted at the same
place.<a class="footnote" id="DOCF108" href="#FOOT108"><sup>108</sup></a>
</p>
<p>Changing a trap&rsquo;s location is useful for building up footnotes in a
diversion to allow more space at the bottom of the page for them.
</p>

</dd></dl>

<p>The same macro can be installed simultaneously at multiple locations;
however, only the earliest-planted instance&mdash;that has not yet been
deleted with <code class="code">wh</code>&mdash;will be moved by <code class="code">ch</code>.  The following
example (using an <code class="code">nroff</code> device) illustrates this behavior.  Blank
lines have been elided from the output.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de T
Trap sprung at \\n(nlu.
.br
..
.wh 1i T
.wh 2i T
foo
.sp 11i
.bp
.ch T 4i
bar
.sp 11i
.bp
.ch T 5i
baz
.sp 11i
.bp
.wh 5i
.ch T 6i
qux
.sp 11i
</pre></div></div>
<div class="example">
<div class="group"><pre class="example-preformatted">    &rArr; foo
    &rArr; Trap sprung at 240u.
    &rArr; Trap sprung at 480u.
    &rArr; bar
    &rArr; Trap sprung at 480u.
    &rArr; Trap sprung at 960u.
    &rArr; baz
    &rArr; Trap sprung at 480u.
    &rArr; Trap sprung at 1200u.
    &rArr; qux
    &rArr; Trap sprung at 1440u.
</pre></div></div>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005b_002ene_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.ne]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ene_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ene-1"></a>
<p>The read-only register <code class="code">.ne</code> contains the amount of space that was
needed in the last <code class="code">ne</code> request that caused a trap to be sprung;
it is useful in conjunction with the <code class="code">.trunc</code> register.  See <a class="xref" href="#Page-Control">Page Control</a>.  Since the <code class="code">.ne</code> register is set only by traps, it
doesn&rsquo;t make sense to interpolate it outside of macros called by traps.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005b_002etrunc_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.trunc]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002etrunc_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002etrunc"></a>
<a class="index-entry-id" id="index-ne-request_002c-and-the-_002etrunc-register"></a>
<a class="index-entry-id" id="index-truncated-vertical-space-register-_0028_002etrunc_0029"></a>
<p>A read-only register containing the amount of vertical space truncated
from an <code class="code">sp</code> request by the most recently sprung vertical
position trap, or, if the trap was sprung by an <code class="code">ne</code> request,
minus the amount of vertical motion produced by the <code class="code">ne</code>
request.  In other words, at the point a trap is sprung, it
represents the difference of what the vertical position would have
been but for the trap, and what the vertical position actually is.
Since the <code class="code">.trunc</code> register is set only by traps, it doesn&rsquo;t make
sense to interpolate it outside of macros called by traps.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005b_002epe_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.pe]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002epe_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002epe"></a>
<a class="index-entry-id" id="index-bp-request_002c-and-traps-_0028_002epe_0029"></a>
<a class="index-entry-id" id="index-traps_002c-sprung-by-bp-request-_0028_002epe_0029"></a>
<a class="index-entry-id" id="index-page-ejection-status-register-_0028_002epe_0029"></a>
<p>This Boolean-valued, read-only register interpolates&nbsp;1 while a page
is being ejected, and 0&nbsp;otherwise.
</p>
<p>In the following example, we plant the same trap at the top and the
bottom of the page.  We also make the trap report its name and the
vertical drawing position.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de T
.tm \\$0: page \\n%, nl=\\n[nl] .pe=\\n[.pe]
..
.ll 46n
.wh 0 T
.wh -1v T
Those who can make you believe absurdities can make you
commit atrocities. \[em] Voltaire
    error&rarr; T: page 1, nl=0 .pe=0
    error&rarr; T: page 1, nl=2600 .pe=1
    &rArr; Those who can make you believe absurdities can
    &rArr; make you commit atrocities. -- Voltaire
</pre></div></div>
</dd></dl>

<a class="index-entry-id" id="index-diversions_002c-and-traps"></a>
<a class="index-entry-id" id="index-traps_002c-and-diversions"></a>
<p>When designing macros, keep in mind that diversions and traps do
normally interact.  For example, if a trap calls a header macro (while
outputting a diversion) that tries to change the font on the current
page, the effect is not visible before the diversion has completely been
printed (except for input protected with <code class="code">\!</code> or <code class="code">\?</code>) since
the data in the diversion is already formatted.  In most cases, this is
not the expected behaviour.
</p>

<hr>
</div>
<div class="subsubsection-level-extent" id="The-Implicit-Page-Trap">
<div class="nav-panel">
<p>
Next: <a href="#Diversion-Traps" accesskey="n" rel="next">Diversion Traps</a>, Previous: <a href="#Page-Location-Traps" accesskey="p" rel="prev">Page Location Traps</a>, Up: <a href="#Vertical-Position-Traps" accesskey="u" rel="up">Vertical Position Traps</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="The-Implicit-Page-Trap-1">5.28.1.2 The Implicit Page Trap</h4>
<a class="index-entry-id" id="index-implicit-trap"></a>
<a class="index-entry-id" id="index-trap_002c-implicit"></a>

<a class="index-entry-id" id="index-page-break-2"></a>
<a class="index-entry-id" id="index-break_002c-page-2"></a>
<a class="index-entry-id" id="index-page-ejection-2"></a>
<a class="index-entry-id" id="index-ejection_002c-page-2"></a>
<p>If, after starting GNU <code class="code">troff</code> without loading a macro package, you
use the <code class="code">ptr</code> request to dump a list of the active traps to the
standard error stream,<a class="footnote" id="DOCF109" href="#FOOT109"><sup>109</sup></a>  nothing is reported.
Yet the <code class="code">.t</code> register will report a steadily decreasing value with
every output line your document produces, and once the value of
<code class="code">.t</code> gets to within <code class="code">.V</code> of zero, you will notice that
something trap-like happens&mdash;the page is ejected, a new one begins, and
the value of <code class="code">.t</code> becomes large once more.
</p>
<p>This <em class="dfn">implicit page trap</em> always exists in the top-level
diversion;<a class="footnote" id="DOCF110" href="#FOOT110"><sup>110</sup></a> it works like a trap in some
ways but not others.  Its purpose is to eject the current page and start
the next one.  It has no name, so it cannot be moved or deleted with
<code class="code">wh</code> or <code class="code">ch</code> requests.  You cannot hide it by placing another
trap at its location, and can move it only by redefining the page length
with <code class="code">pl</code>.  Its operation is suppressed when vertical page traps
are disabled with GNU <code class="code">troff</code>&rsquo;s <code class="code">vpt</code> request.
</p>

<hr>
</div>
<div class="subsubsection-level-extent" id="Diversion-Traps">
<div class="nav-panel">
<p>
Next: <a href="#Input-Line-Traps" accesskey="n" rel="next">Input Line Traps</a>, Previous: <a href="#The-Implicit-Page-Trap" accesskey="p" rel="prev">The Implicit Page Trap</a>, Up: <a href="#Vertical-Position-Traps" accesskey="u" rel="up">Vertical Position Traps</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Diversion-Traps-1">5.28.1.3 Diversion Traps</h4>
<a class="index-entry-id" id="index-diversion-traps"></a>
<a class="index-entry-id" id="index-traps_002c-diversion"></a>

<p>A diversion is not formatted in the context of a page, so it lacks page
location traps; instead it can have a <em class="dfn">diversion trap</em>.  There can
exist at most one such vertical position trap per diversion.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002edt"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.dt</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">dist</i></span> <span class="r"><i class="slanted">name</i></span>]</var><a class="copiable-link" href='#index-_002edt'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-dt"></a>
<a class="index-entry-id" id="index-_002et-register_002c-and-diversions"></a>
<a class="index-entry-id" id="index-setting-diversion-trap-_0028dt_0029"></a>
<a class="index-entry-id" id="index-diversion-trap_002c-setting-_0028dt_0029"></a>
<a class="index-entry-id" id="index-trap_002c-diversion_002c-setting-_0028dt_0029"></a>
<p>Set a trap <em class="emph">within</em> a diversion at location <var class="var">dist</var>, which is
interpreted relative to diversion rather than page boundaries.  If invoked with
fewer than two arguments, any diversion trap in the current diversion is
removed.  The register <code class="code">.t</code> works within diversions.  It is an
error to invoke <code class="code">dt</code> in the top-level diversion.
See <a class="xref" href="#Diversions">Diversions</a>.
</p></dd></dl>


<hr>
</div>
</div>
<div class="subsection-level-extent" id="Input-Line-Traps">
<div class="nav-panel">
<p>
Next: <a href="#Blank-Line-Traps" accesskey="n" rel="next">Blank Line Traps</a>, Previous: <a href="#Diversion-Traps" accesskey="p" rel="prev">Diversion Traps</a>, Up: <a href="#Traps" accesskey="u" rel="up">Traps</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Input-Line-Traps-1">5.28.2 Input Line Traps</h4>
<a class="index-entry-id" id="index-input-line-traps"></a>
<a class="index-entry-id" id="index-traps_002c-input-line"></a>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eit"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.it</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">n</i></span> <span class="r"><i class="slanted">name</i></span>]</var><a class="copiable-link" href='#index-_002eit'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-it"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002eitc"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.itc</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">n</i></span> <span class="r"><i class="slanted">name</i></span>]</var><a class="copiable-link" href='#index-_002eitc'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-itc"></a>
<a class="index-entry-id" id="index-setting-input-line-trap-_0028it_002c-itc_0029"></a>
<a class="index-entry-id" id="index-input-line-trap_002c-setting-_0028it_002c-itc_0029"></a>
<a class="index-entry-id" id="index-trap_002c-input-line_002c-setting-_0028it_002c-itc_0029"></a>
<a class="index-entry-id" id="index-clearing-input-line-trap-_0028it_002c-itc_0029"></a>
<a class="index-entry-id" id="index-input-line-trap_002c-clearing-_0028it_002c-itc_0029"></a>
<a class="index-entry-id" id="index-trap_002c-input-line_002c-clearing-_0028it_002c-itc_0029"></a>
<p>Set an input line trap, calling macro <var class="var">name</var> after processing the
next <var class="var">n</var>&nbsp;productive input lines (recall <a class="ref" href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a>).  Any existing input line trap in the
environment is replaced.  Without arguments, <code class="code">it</code> and <code class="code">itc</code>
clear any input line trap that has not yet sprung.
</p>
<p>Consider a macro &lsquo;<samp class="samp">.ST <var class="var">s n</var></samp>&rsquo; which sets the next
<var class="var">n</var>&nbsp;input lines in the font style&nbsp;<var class="var">s</var>.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de ST \&quot; Use style $1 for next $2 text lines.
.  it \\$2 ES
.  ft \\$1
..
.de ES \&quot; end ST
.  ft R
..
.ST I 1
oblique
face
.ST I 1
oblique\c
face
    &rArr; <i class="i">oblique</i> face <i class="i">oblique</i>face &nbsp;<span class="r">(second &ldquo;face&rdquo; upright)</span>
</pre></div></div>

<a class="index-entry-id" id="index-input-line-traps-and-interrupted-lines-_0028itc_0029"></a>
<a class="index-entry-id" id="index-interrupted-lines-and-input-line-traps-_0028itc_0029"></a>
<a class="index-entry-id" id="index-traps_002c-input-line_002c-and-interrupted-lines-_0028itc_0029"></a>
<a class="index-entry-id" id="index-lines_002c-interrupted_002c-and-input-line-traps-_0028itc_0029"></a>
<p>Unlike the <code class="code">ce</code> and <code class="code">rj</code> requests, <code class="code">it</code> counts lines
interrupted with the <code class="code">\c</code> escape sequence separately (see <a class="pxref" href="#Line-Continuation">Line Continuation</a>); <code class="code">itc</code> does not.  To see the difference, let&rsquo;s
change the previous example to use <code class="code">itc</code> instead.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted"><span class="r">&hellip;</span>
.  itc \\$2 ES
<span class="r">&hellip;</span>
    &rArr; <i class="i">oblique</i> face <i class="i">obliqueface</i> &nbsp;<span class="r">(second &ldquo;face&rdquo; oblique)</span>
</pre></div></div>

<p>You can think of the <code class="code">ce</code> and <code class="code">rj</code> requests as implicitly
creating an input line trap with <code class="code">itc</code> that schedules a break when
the trap is sprung.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de BR
.  br
.  <i class="slanted">internal: disable centering-without-filling</i>
..
.
.de ce
.  if \\n[.br] .br
.  itc \\$1 BR
.  <i class="slanted">internal: enable centering-without-filling</i>
..
</pre></div></div>

<p>Let us consider in more detail the sorts of input lines that are or are
not &ldquo;productive&rdquo;.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de Trap
TRAP SPRUNG
..
.de Mac
.if r a \l'5n'
..
.it 2 Trap
.
foo
.Mac
bar
baz
.it 1 Trap
.sp \&quot; moves, but does not write or draw
qux
.itc 1 Trap
\h'5n'\c \&quot; moves, but does not write or draw
jat
</pre></div></div>

<p>When &lsquo;<samp class="samp">Trap</samp>&rsquo; gets called depends on whether the &lsquo;<samp class="samp">a</samp>&rsquo; register is
defined; the control line with the <code class="code">if</code> request may or may not
produce written output.  We also see that the spacing request <code class="code">sp</code>,
while certainly affecting the output, does not spring the input line
trap.  Similarly, the horizontal motion escape sequence <code class="code">\h</code> also
affected the output, but was not &ldquo;written&rdquo;.  Observe that we had to
follow it with <code class="code">\c</code> and use <code class="code">itc</code> to prevent the newline at
the end of the text line from causing a word break, which, like an
ordinary space character, counts as written output.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">$ groff -Tascii input-trap-example.groff
    &rArr; foo bar TRAP SPRUNG baz
    &rArr;
    &rArr; qux TRAP SPRUNG      jat TRAP SPRUNG
$ groff -Tascii -ra1 input-trap-example.groff
    &rArr; foo _____ TRAP SPRUNG bar baz
    &rArr;
    &rArr; qux TRAP SPRUNG      jat TRAP SPRUNG
</pre></div></div>
</dd></dl>

<p>Input line traps are associated with the environment
(see <a class="pxref" href="#Environments">Environments</a>); switching to another environment suspends the
current input line trap, and going back resumes it, restoring the count
of qualifying lines enumerated in that environment.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Blank-Line-Traps">
<div class="nav-panel">
<p>
Next: <a href="#Leading-Space-Traps" accesskey="n" rel="next">Leading Space Traps</a>, Previous: <a href="#Input-Line-Traps" accesskey="p" rel="prev">Input Line Traps</a>, Up: <a href="#Traps" accesskey="u" rel="up">Traps</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Blank-Line-Traps-1">5.28.3 Blank Line Traps</h4>
<a class="index-entry-id" id="index-blank-line-traps"></a>
<a class="index-entry-id" id="index-traps_002c-blank-line"></a>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eblm"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.blm</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">name</i></span>]</var><a class="copiable-link" href='#index-_002eblm'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-blm"></a>
<a class="index-entry-id" id="index-blank-line-macro-_0028blm_0029-2"></a>
<p>Set a blank line trap, calling the macro <var class="var">name</var> when GNU
<code class="code">troff</code> encounters a blank line in an input file, instead of the
usual behavior (see <a class="pxref" href="#Breaking">Breaking</a>).  A line consisting only of spaces is
also treated as blank and subject to this trap.  If no argument is
supplied, the default blank line behavior is (re-)established.
</p></dd></dl>


<hr>
</div>
<div class="subsection-level-extent" id="Leading-Space-Traps">
<div class="nav-panel">
<p>
Next: <a href="#End_002dof_002dinput-Traps" accesskey="n" rel="next">End-of-input Traps</a>, Previous: <a href="#Blank-Line-Traps" accesskey="p" rel="prev">Blank Line Traps</a>, Up: <a href="#Traps" accesskey="u" rel="up">Traps</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Leading-Space-Traps-1">5.28.4 Leading Space Traps</h4>
<a class="index-entry-id" id="index-leading-space-traps"></a>
<a class="index-entry-id" id="index-traps_002c-leading-space"></a>

<dl class="first-deffn">
<dt class="deffn" id="index-_002elsm"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.lsm</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">name</i></span>]</var><a class="copiable-link" href='#index-_002elsm'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-lsm"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005blsn_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[lsn]</code></strong><a class="copiable-link" href='#index-_005cn_005blsn_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-lsn"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005blss_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[lss]</code></strong><a class="copiable-link" href='#index-_005cn_005blss_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-lss"></a>
<a class="index-entry-id" id="index-leading-spaces-macro-_0028lsm_0029"></a>
<p>Set a leading space trap, calling the macro <var class="var">name</var> when GNU
<code class="code">troff</code> encounters leading spaces in an input line; the implicit
line break that normally happens in this case is suppressed.  If no
argument is supplied, the default leading space behavior is
(re-)established (see <a class="pxref" href="#Breaking">Breaking</a>).
</p>
<p>The count of leading spaces on an input line is stored in register
<code class="code">lsn</code>, and the amount of corresponding horizontal motion in
register <code class="code">lss</code>, irrespective of whether a leading space trap is
set.  When it is, the leading spaces are removed from the input line,
and no motion is produced before calling <var class="var">name</var>.
</p>
</dd></dl>


<hr>
</div>
<div class="subsection-level-extent" id="End_002dof_002dinput-Traps">
<div class="nav-panel">
<p>
Previous: <a href="#Leading-Space-Traps" accesskey="p" rel="prev">Leading Space Traps</a>, Up: <a href="#Traps" accesskey="u" rel="up">Traps</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="End_002dof_002dinput-Traps-1">5.28.5 End-of-input Traps</h4>
<a class="index-entry-id" id="index-end_002dof_002dinput-traps"></a>
<a class="index-entry-id" id="index-traps_002c-end_002dof_002dinput"></a>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eem"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.em</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">name</i></span>]</var><a class="copiable-link" href='#index-_002eem'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-em"></a>
<a class="index-entry-id" id="index-setting-end_002dof_002dinput-trap-_0028em_0029"></a>
<a class="index-entry-id" id="index-end_002dof_002dinput-trap_002c-setting-_0028em_0029"></a>
<a class="index-entry-id" id="index-trap_002c-end_002dof_002dinput_002c-setting-_0028em_0029"></a>
<a class="index-entry-id" id="index-end_002dof_002dinput-macro-_0028em_0029"></a>
<a class="index-entry-id" id="index-macro_002c-end_002dof_002dinput-_0028em_0029"></a>
<p>Set a trap at the end of input, calling macro <var class="var">name</var> after the last
line of the last input file has been processed.  If no argument is
given, any existing end-of-input trap is removed.
</p>
<p>For example, if the document had to have a section at the bottom of the
last page for someone to approve it, the <code class="code">em</code> request could be
used.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de approval
\c
.  ne 3v
.  sp (\\n[.t]u - 3v)
.  in +4i
.  lc _
.  br
Approved:\t\a
.  sp
Date:\t\t\a
..
.
.em approval
</pre></div></div>

<p>The <code class="code">\c</code> in the above example needs explanation.  For historical
reasons (compatibility with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>), the
end-of-input macro exits as soon as it causes a page break if no
partially collected line remains.<a class="footnote" id="DOCF111" href="#FOOT111"><sup>111</sup></a>
</p>
<a class="index-entry-id" id="index-page-break_002c-final"></a>
<a class="index-entry-id" id="index-break_002c-page_002c-final"></a>
<a class="index-entry-id" id="index-page-ejection_002c-of-final-page"></a>
<a class="index-entry-id" id="index-ejection_002c-page_002c-of-final-page"></a>
<p>Let us assume that there is no <code class="code">\c</code> in the above <code class="code">approval</code>
macro, that the page is full, and last output line has been broken with,
say, a <code class="code">br</code> request.  Because there is no more room, a <code class="code">ne</code>
request at this point causes a page ejection, which in turn makes
<code class="code">troff</code> exit immediately as just described.  In most situations,
this is not desired; people generally want to format the input after
<code class="code">ne</code>.
</p>
<p>To force processing of the whole end-of-input macro independently of
this behavior, it is thus advisable to (invisibly) ensure the existence
of a partially collected line (<code class="code">\c</code>) whenever there is a chance
that a page break can happen.  In the above example, invoking the
<code class="code">ne</code> request ensures that there is room for the subsequent
formatted output on the same page, so we need insert <code class="code">\c</code> only
once.
</p>
<p>The next example shows how to append three lines, then start a new page
unconditionally.  Since &lsquo;<samp class="samp">.ne&nbsp;1</samp>&rsquo;<!-- /@w --> doesn&rsquo;t give the desired
effect&mdash;there is always one line available or we are already at the
beginning of the next page&mdash;we temporarily increase the page length by
one line so that we can use &lsquo;<samp class="samp">.ne&nbsp;2</samp>&rsquo;<!-- /@w -->.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de EM
.pl +1v
\c
.ne 2
line one
.br
\c
.ne 2
line two
.br
\c
.ne 2
line three
.br
.pl -1v
\c
'bp
..
.em EM
</pre></div></div>

<p>This specific feature affects only the first potential page break caused
by the end-of-input macro; further page breaks emitted by the macro are
handled normally.
</p>
<p>Another possible use of the <code class="code">em</code> request is to make GNU
<code class="code">troff</code> emit a single large page instead of multiple pages.  For
example, one may want to produce a long plain text file for reading
in a terminal or emulator without page footers and headers interrupting
the body of the document.  One approach is to set the page length at the
beginning of the document to a very large value to hold all the
text,<a class="footnote" id="DOCF112" href="#FOOT112"><sup>112</sup></a> and
automatically adjust it to the exact height of the document after the
text has been output.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de adjust-page-length
.  br
.  pl \\n[nl]u \&quot; \n[nl]: current vertical position
..
.
.de single-page-mode
.  pl 99999
.  em adjust-page-length
..
.
.\&quot; Activate the above code if configured.
.if \n[do-continuous-rendering] \
.  single-page-mode
</pre></div></div>

<p>Since only one end-of-input trap exists and another macro package may
already use it, care must be taken not to break the mechanism.  A simple
solution would be to append the above macro to the macro package&rsquo;s
end-of-input macro using the <code class="code">am</code> request.
</p></dd></dl>



<hr>
</div>
</div>
<div class="section-level-extent" id="Diversions">
<div class="nav-panel">
<p>
Next: <a href="#Punning-Names" accesskey="n" rel="next">Punning Names</a>, Previous: <a href="#Traps" accesskey="p" rel="prev">Traps</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Diversions-1">5.29 Diversions</h3>
<a class="index-entry-id" id="index-diversions"></a>

<p>In <code class="code">roff</code> systems it is possible to format text as if for output,
but instead of writing it immediately, one can <em class="dfn">divert</em> the
formatted text into a named storage area.  It is retrieved later by
specifying its name after a control character.   The same name space is
used for such <i class="slanted">diversions</i> as for strings and macros; see
<a class="ref" href="#Identifiers">Identifiers</a>.  Such text is sometimes said to be &ldquo;stored in a
macro&rdquo;, but this coinage obscures the important distinction between
macros and strings on one hand and diversions on the other; the former
store <em class="emph">unformatted</em> input text, and the latter capture
<em class="emph">formatted</em> output.  Diversions also do not interpret arguments.
Applications of diversions include &ldquo;keeps&rdquo; (preventing a page break
from occurring at an inconvenient place by forcing a set of output lines
to be set as a group), footnotes, tables of contents, and indices.
<a class="index-entry-id" id="index-top_002dlevel-diversion"></a>
<a class="index-entry-id" id="index-diversion_002c-top_002dlevel"></a>
For orthogonality it is said that GNU <code class="code">troff</code> is in the
<em class="dfn">top-level diversion</em> if no diversion is active (that is, formatted
output is being &ldquo;diverted&rdquo; immediately to the output device).
</p>
<p>Dereferencing an undefined diversion will create an empty one of that
name and cause a warning in category &lsquo;<samp class="samp">mac</samp>&rsquo; to be emitted.
See <a class="xref" href="#Warnings">Warnings</a>, for information about the enablement and suppression of
warnings.  A diversion does not exist for the purpose of testing with
the <code class="code">d</code> conditional operator until its initial definition ends
(see <a class="pxref" href="#Operators-in-Conditionals">Operators in Conditionals</a>).  The following requests are used to
create and alter diversions.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002edi"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.di</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">name</i></span>]</var><a class="copiable-link" href='#index-_002edi'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-di"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002eda"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.da</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">name</i></span>]</var><a class="copiable-link" href='#index-_002eda'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-da"></a>
<a class="index-entry-id" id="index-beginning-diversion-_0028di_002c-box_0029"></a>
<a class="index-entry-id" id="index-diversion_002c-beginning-_0028di_002c-box_0029"></a>
<a class="index-entry-id" id="index-ending-diversion-_0028di_002c-box_0029"></a>
<a class="index-entry-id" id="index-diversion_002c-ending-_0028di_002c-box_0029"></a>
<a class="index-entry-id" id="index-appending-to-a-diversion-_0028da_002c-boxa_0029"></a>
<a class="index-entry-id" id="index-diversion_002c-appending-to-_0028da_002c-boxa_0029"></a>
<p>Start collecting formatted output in a diversion called <var class="var">name</var>.  The
<code class="code">da</code> request appends to a diversion called <var class="var">name</var>, creating it
if necessary.  If <var class="var">name</var> already exists as an alias, the target of
the alias is replaced or appended to; recall <a class="ref" href="#Strings">Strings</a>.  The pending
output line is diverted as well.  Switching to another environment (with
the <code class="code">ev</code> request) before invoking <code class="code">di</code> or <code class="code">da</code> avoids
including any pending output line in the diversion; see
<a class="ref" href="#Environments">Environments</a>.
</p>
<p>Invoking <code class="code">di</code> or <code class="code">da</code> without an argument stops diverting
output to the diversion named by the most recent corresponding request.
If <code class="code">di</code> or <code class="code">da</code> is called without an argument when there is no
current diversion, a warning in category &lsquo;<samp class="samp">di</samp>&rsquo; is produced.
See <a class="xref" href="#Warnings">Warnings</a>, for information about the enablement and suppression
of warnings.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">Before the diversion.
.di yyy
In the diversion.
.br
.di
After the diversion.
.br
    &rArr; After the diversion.
.yyy
    &rArr; Before the diversion.  In the diversion.
</pre></div></div>
</dd></dl>

<a class="index-entry-id" id="index-box-_0028diversion-operation_0029"></a>
<p>GNU <code class="code">troff</code> supports <em class="dfn">box</em> requests to exclude a partially
collected line from a diversion, as this is often desirable.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002ebox"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.box</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">name</i></span>]</var><a class="copiable-link" href='#index-_002ebox'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-box"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002eboxa"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.boxa</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">name</i></span>]</var><a class="copiable-link" href='#index-_002eboxa'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-boxa"></a>
<p>Divert (or append) output to <var class="var">name</var>, similarly to the <code class="code">di</code> and
<code class="code">da</code> requests, respectively.  Any pending output line is <em class="emph">not</em>
included in the diversion.  Without an argument, stop diverting output;
any pending output line inside the diversion is discarded.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">Before the box.
.box xxx
In the box.
.br
Hidden treasure.
.box
After the box.
.br
    &rArr; Before the box.  After the box.
.xxx
    &rArr; In the box.
</pre></div></div>
</dd></dl>

<p>Apart from pending output line inclusion and the request names that
populate them, boxes are handled exactly as diversions are.  All of the
following <code class="code">groff</code> language elements can be used with them
interchangeably.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005b_002ez_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.z]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ez_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ez"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ed_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.d]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ed_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ed"></a>
<a class="index-entry-id" id="index-nl-register_002c-and-_002ed"></a>
<a class="index-entry-id" id="index-nested-diversions"></a>
<a class="index-entry-id" id="index-diversion_002c-nested"></a>
<a class="index-entry-id" id="index-diversion-name-register-_0028_002ez_0029"></a>
<a class="index-entry-id" id="index-vertical-position-in-diversion-register-_0028_002ed_0029"></a>
<a class="index-entry-id" id="index-position_002c-vertical_002c-in-diversion_002c-register-_0028_002ed_0029"></a>
<a class="index-entry-id" id="index-diversion_002c-vertical-position-in_002c-register-_0028_002ed_0029"></a>
<p>Diversions may be nested.  The read-only string-valued register
<code class="code">.z</code> contains the name of the current diversion.  The read-only
register <code class="code">.d</code> contains the current vertical place in the diversion.
If the input text is not being diverted, <code class="code">.d</code> reports the same
location as the register <code class="code">nl</code>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005b_002eh_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.h]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002eh_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002eh"></a>
<a class="index-entry-id" id="index-high_002dwater-mark-register-_0028_002eh_0029"></a>
<a class="index-entry-id" id="index-mark_002c-high_002dwater_002c-register-_0028_002eh_0029"></a>
<a class="index-entry-id" id="index-position-of-lowest-text-line-_0028_002eh_0029"></a>
<a class="index-entry-id" id="index-text-line_002c-position-of-lowest-_0028_002eh_0029"></a>
<p>The read-only register <code class="code">.h</code> stores the <em class="dfn">high-water mark</em> on the
current page or in the current diversion.  It corresponds to the text
baseline of the lowest line on the page.<a class="footnote" id="DOCF113" href="#FOOT113"><sup>113</sup></a>
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.tm .h==\n[.h], nl==\n[nl]
    &rArr; .h==0, nl==-1
This is a test.
.br
.sp 2
.tm .h==\n[.h], nl==\n[nl]
    &rArr; .h==40, nl==120
</pre></div></div>

<a class="index-entry-id" id="index-_002eh-register_002c-difference-from-nl"></a>
<a class="index-entry-id" id="index-nl-register_002c-difference-from-_002eh"></a>
<p>As implied by the example, vertical motion does not produce text
baselines and thus does not increase the value interpolated by
&lsquo;<samp class="samp">\n[.h]</samp>&rsquo;.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bdn_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[dn]</code></strong><a class="copiable-link" href='#index-_005cn_005bdn_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-dn"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005bdl_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[dl]</code></strong><a class="copiable-link" href='#index-_005cn_005bdl_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-dl"></a>
<a class="index-entry-id" id="index-dn-register_002c-and-da-_0028boxa_0029"></a>
<a class="index-entry-id" id="index-dl-register_002c-and-da-_0028boxa_0029"></a>
<a class="index-entry-id" id="index-da-request_002c-and-dn-_0028dl_0029"></a>
<a class="index-entry-id" id="index-boxa-request_002c-and-dn-_0028dl_0029"></a>
<p>After completing a diversion, the writable registers <code class="code">dn</code> and
<code class="code">dl</code> contain its vertical and horizontal sizes.  Only the lines
just processed are counted: for the computation of <code class="code">dn</code> and
<code class="code">dl</code>, the requests <code class="code">da</code> and <code class="code">boxa</code> are handled as if
<code class="code">di</code> and <code class="code">box</code> had been used, respectively&mdash;lines that have
been already stored in the diversion (box) are not taken into account.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.\&quot; Center text both horizontally and vertically.
.\&quot; Macro .(c starts centering mode; .)c terminates it.
.
.\&quot; Disable the escape character with .eo so that we
.\&quot; don't have to double backslashes on the &quot;\n&quot;s.
.eo
.de (c
.  br
.  ev (c
.  evc 0
.  in 0
.  nf
.  di @c
..
</pre></div></div>
<div class="example">
<div class="group"><pre class="example-preformatted">.de )c
.  br
.  ev
.  di
.  nr @s (((\n[.t]u - \n[dn]u) / 2u) - 1v)
.  sp \n[@s]u
.  ce 1000
.  @c
.  ce 0
.  sp \n[@s]u
.  br
.  fi
.  rr @s
.  rm @c
..
.ec
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005c_0021anything"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\!</code><span class="r"><i class="slanted">anything</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005c_0021anything'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_0021"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005c_003fanything_005c_003f"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\?</code><span class="r"><i class="slanted">anything</i></span><code class="t">\?</code></strong><a class="copiable-link" href='#index-_005c_003fanything_005c_003f'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005c_003f"></a>
<a class="index-entry-id" id="index-transparent-output-_0028_005c_0021_002c-_005c_003f_0029"></a>
<a class="index-entry-id" id="index-output_002c-transparent-_0028_005c_0021_002c-_005c_003f_0029"></a>
<p><em class="dfn">Transparently</em> embed <var class="var">anything</var> into the current diversion,
preventing requests, macro calls, and escape sequences from being
interpreted when read into a diversion.  This is useful for preventing
them from taking effect until the diverted text is actually output.  The
<code class="code">\!</code> escape sequence transparently embeds input up to and including
the end of the line.  The <code class="code">\?</code> escape sequence transparently embeds
input until its own next occurrence.
</p>
<a class="index-entry-id" id="index-_005c_003f_002c-and-copy-mode-1"></a>
<a class="index-entry-id" id="index-copy-mode_002c-and-_005c_003f-1"></a>
<a class="index-entry-id" id="index-mode_002c-copy_002c-and-_005c_003f-1"></a>
<a class="index-entry-id" id="index-_005c_0021_002c-and-copy-mode"></a>
<a class="index-entry-id" id="index-copy-mode_002c-and-_005c_0021"></a>
<a class="index-entry-id" id="index-mode_002c-copy_002c-and-_005c_0021"></a>
<p><var class="var">anything</var> may not contain newlines; use <code class="code">\!</code> by itself to
embed newlines in a diversion.  The escape sequence <code class="code">\?</code> is also
recognized in copy mode and turned into a single internal code; it is
this code that terminates <var class="var">anything</var>.  Thus the following example
prints&nbsp;4.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.nr x 1
.nf
.di d
\?\\?\\\\?\\\\\\\\nx\\\\?\\?\?
.di
.nr x 2
.di e
.d
.di
.nr x 3
.di f
.e
.di
.nr x 4
.f
</pre></div></div>

<p>Both escape sequences read the data in copy mode.
</p>
<a class="index-entry-id" id="index-_005c_0021_002c-in-top_002dlevel-diversion"></a>
<a class="index-entry-id" id="index-top_002dlevel-diversion_002c-and-_005c_0021"></a>
<a class="index-entry-id" id="index-diversion_002c-top_002dlevel_002c-and-_005c_0021"></a>
<p>If <code class="code">\!</code> is used in the top-level diversion, its argument is
directly embedded into GNU <code class="code">troff</code>&rsquo;s intermediate output.  This can
be used, for example, to control a postprocessor that processes the data
before it is sent to an output driver.
</p>
<a class="index-entry-id" id="index-_005c_003f_002c-in-top_002dlevel-diversion"></a>
<a class="index-entry-id" id="index-top_002dlevel-diversion_002c-and-_005c_003f"></a>
<a class="index-entry-id" id="index-diversion_002c-top_002dlevel_002c-and-_005c_003f"></a>
<p>The <code class="code">\?</code> escape used in the top-level diversion produces no output
at all; its argument is simply ignored.
</p></dd></dl>

<a class="index-entry-id" id="index-_005c_0021_002c-and-output-request"></a>
<a class="index-entry-id" id="index-output-request_002c-and-_005c_0021"></a>
<a class="index-entry-id" id="index-output-request_002c-and-copy-mode"></a>
<a class="index-entry-id" id="index-copy-mode_002c-and-output-request"></a>
<a class="index-entry-id" id="index-mode_002c-copy_002c-and-output-request"></a>
<dl class="first-deffn">
<dt class="deffn" id="index-_002eoutput"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.output</code></strong> <var class="def-var-arguments">contents</var><a class="copiable-link" href='#index-_002eoutput'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-output"></a>
<p>Emit <var class="var">contents</var> directly to GNU <code class="code">troff</code>&rsquo;s intermediate output
(subject to copy mode interpretation); this is similar to <code class="code">\!</code> used
at the top level.  An initial neutral double quote in <var class="var">contents</var> is
stripped to allow embedding of leading spaces.
</p>
<p>This request can&rsquo;t be used before the first page has started&mdash;if you
get an error, simply insert <code class="code">.br</code> before the <code class="code">output</code> request.
</p>
<p>Use with caution!  It is normally only needed for mark-up used by a
postprocessor that does something with the output before sending it to
the output device, filtering out <var class="var">contents</var> again.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002easciify"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.asciify</code></strong> <var class="def-var-arguments">div</var><a class="copiable-link" href='#index-_002easciify'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-asciify"></a>
<a class="index-entry-id" id="index-unformatting-diversions-_0028asciify_0029"></a>
<a class="index-entry-id" id="index-diversion_002c-unformatting-_0028asciify_0029"></a>
<a class="index-entry-id" id="index-trin-request_002c-and-asciify"></a>
<p><em class="dfn">Unformat</em> the diversion <var class="var">div</var> in a way such that Unicode basic
Latin (<abbr class="acronym">ASCII</abbr>) characters, characters translated with the
<code class="code">trin</code> request, space characters, and some escape sequences, that
were formatted and diverted into <var class="var">div</var> are treated like ordinary
input characters when <var class="var">div</var> is reread.  Doing so can be useful in
conjunction with the <code class="code">writem</code> request.  <code class="code">asciify</code> can be also
used for gross hacks; for example, the following sets
register&nbsp;<code class="code">n</code> to&nbsp;1.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.tr @.
.di x
@nr n 1
.br
.di
.tr @@
.asciify x
.x
</pre></div></div>

<p><code class="code">asciify</code> cannot return all items in a diversion to their source
equivalent: nodes such as those produced by the <code class="code">\N</code> escape
sequence will remain nodes, so the result cannot be guaranteed to be a
pure string.  See <a class="xref" href="#Copy-Mode">Copy Mode</a>.  Glyph parameters such as the type face
and size are not preserved; use <code class="code">unformat</code> to achieve that.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eunformat"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.unformat</code></strong> <var class="def-var-arguments">div</var><a class="copiable-link" href='#index-_002eunformat'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-unformat"></a>
<p>Like <code class="code">asciify</code>, unformat the diversion <var class="var">div</var>.  However,
<code class="code">unformat</code> handles only tabs and spaces between words, the latter
usually arising from spaces or newlines in the input.  Tabs are treated
as input tokens, and spaces become adjustable again.  The vertical sizes
of lines are not preserved, but glyph information (font, type size,
space width, and so on) is retained.
</p></dd></dl>



<hr>
</div>
<div class="section-level-extent" id="Punning-Names">
<div class="nav-panel">
<p>
Next: <a href="#Environments" accesskey="n" rel="next">Environments</a>, Previous: <a href="#Diversions" accesskey="p" rel="prev">Diversions</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Punning-Names-1">5.30 Punning Names</h3>
<a class="index-entry-id" id="index-diversions-1"></a>

<p>Macros, strings, and diversions share a name space; recall
<a class="ref" href="#Identifiers">Identifiers</a>.  Internally, the same mechanism is used to store
them.  You can thus call a macro with string interpolation syntax and
vice versa.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de subject
Typesetting
..
.de predicate
rewards attention to detail
..
\*[subject] \*[predicate].
Truly.
    &rArr; Typesetting
    &rArr;  rewards attention to detail Truly.
</pre></div></div>

<p>What went wrong?  Strings don&rsquo;t contain newlines, but macros do.  String
interpolation placed a newline at the end of &lsquo;<samp class="samp">\*[subject]</samp>&rsquo;, and the
next thing on the input was a space.  Then when &lsquo;<samp class="samp">\*[predicate]</samp>&rsquo; was
interpolated, it was followed by the empty request &lsquo;<samp class="samp">.</samp>&rsquo; on a line by
itself.  If we want to use macros as strings, we must take interpolation
behavior into account.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de subject
Typesetting\\
..
.de predicate
rewards attention to detail\\
..
\*[subject] \*[predicate].
Truly.
    &rArr; Typesetting rewards attention to detail.  Truly.
</pre></div></div>

<p>By ending each text line of the macros with an escaped
<code class="code">\<kbd class="key">RET</kbd></code>, we get the desired effect (see <a class="pxref" href="#Line-Continuation">Line Continuation</a>).<a class="footnote" id="DOCF114" href="#FOOT114"><sup>114</sup></a>
What would have happened if we had used only one backslash at a time
instead?
</p>
<p>Interpolating a string does not hide existing macro arguments.  We can
also place the escaped newline outside the string interpolation instead
of within the string definition.  Thus, in a macro, a more efficient way
of doing
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.xx \\$@
</pre></div></div>

<p>is
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">\\*[xx]\\
</pre></div></div>

<p>The latter calling syntax doesn&rsquo;t change the value of <code class="code">\$0</code>, which
is then inherited from the calling macro (see <a class="pxref" href="#Parameters">Parameters</a>).
</p>
<p>Diversions can be also called with string syntax.  It is sometimes
convenient to copy one-line diversions to a string.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.di xx
the
.ft I
interpolation system
.ft
.br
.di
.ds yy This is a test of \*(xx\c
\*(yy.
    &rArr; This is a test of the <i class="i">interpolation system</i>.
</pre></div></div>

<p>As the previous example shows, it is possible to store formatted output
in strings.  The <code class="code">\c</code> escape sequence prevents the subsequent
newline from being interpreted as a break (again,
see <a class="pxref" href="#Line-Continuation">Line Continuation</a>).
</p>
<p>Copying multi-output line diversions produces unexpected results.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.di xxx
a funny
.br
test
.br
.di
.ds yyy This is \*[xxx]\c
\*[yyy].
    &rArr; test This is a funny.
</pre></div></div>

<p>Usually, it is not predictable whether a diversion contains one or more
output lines, so this mechanism should be avoided.  With <abbr class="acronym">AT&amp;T</abbr>
<code class="code">troff</code>, this was the only solution to strip off a final newline
from a diversion.  Another disadvantage is that the spaces in the copied
string are already formatted, preventing their adjustment.  This can
cause ugly results.
</p>
<a class="index-entry-id" id="index-stripping-final-newline-in-diversions"></a>
<a class="index-entry-id" id="index-diversion_002c-stripping-final-newline"></a>
<a class="index-entry-id" id="index-final-newline_002c-stripping-in-diversions"></a>
<a class="index-entry-id" id="index-newline_002c-final_002c-stripping-in-diversions"></a>
<a class="index-entry-id" id="index-horizontal-space_002c-unformatting"></a>
<a class="index-entry-id" id="index-space_002c-horizontal_002c-unformatting"></a>
<a class="index-entry-id" id="index-unformatting-horizontal-space"></a>
<p>A clean solution to this problem is available in GNU <code class="code">troff</code>, using
the requests <code class="code">chop</code> to remove the final newline of a diversion, and
<code class="code">unformat</code> to make the horizontal spaces adjustable again.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.box xxx
a funny
.br
test
.br
.box
.chop xxx
.unformat xxx
This is \*[xxx].
    &rArr; This is a funny test.
</pre></div></div>

<p>See <a class="xref" href="#Gtroff-Internals"><code class="code">gtroff</code> Internals</a>.
</p>

<hr>
</div>
<div class="section-level-extent" id="Environments">
<div class="nav-panel">
<p>
Next: <a href="#Suppressing-Output" accesskey="n" rel="next">Suppressing Output</a>, Previous: <a href="#Diversions" accesskey="p" rel="prev">Diversions</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Environments-1">5.31 Environments</h3>
<a class="index-entry-id" id="index-environments"></a>

<p>As discussed in <a class="ref" href="#Deferring-Output">Deferring Output</a>, environments store most of the
parameters that determine the appearance of text.  A default environment
named &lsquo;<samp class="samp">0</samp>&rsquo; exists when GNU <code class="code">troff</code> starts up; it is modified by
formatting-related requests and escape sequences.
</p>
<a class="index-entry-id" id="index-stack"></a>
<p>You can create new environments and switch among them.  Only one is
current at any given time.  Active environments are managed using a
<em class="dfn">stack</em>, a data structure supporting &ldquo;push&rdquo; and &ldquo;pop&rdquo;
operations.  The current environment is at the top of the stack.
The same environment name can be pushed onto the stack multiple times,
possibly interleaved with others.  Popping the environment stack does
not destroy the current environment; it remains accessible by name and
can be made current again by pushing it at any time.  Environments
cannot be renamed or deleted, and can only be modified when current.  To
inspect the environment stack, use the <code class="code">pev</code> request; see
<a class="ref" href="#Debugging">Debugging</a>.
</p>
<p>Environments store the following information.
</p>
<ul class="itemize mark-bullet">
<li>a partially collected line, if any

</li><li>data about the most recently output glyph and line (registers
<code class="code">.cdp</code>, <code class="code">.cht</code>, <code class="code">.csk</code>, <code class="code">.n</code>, <code class="code">.w</code>)

</li><li>typeface parameters (size, family, style, height and slant, inter-word
and inter-sentence space sizes)

</li><li>page parameters (line length, title length, vertical spacing, line
spacing, indentation, line numbering, centering, right-alignment,
underlining, hyphenation parameters)

</li><li>filling enablement; adjustment enablement and mode

</li><li>tab stops; tab, leader, escape, control, no-break control, hyphenation,
and margin characters

</li><li>input line traps

</li><li>stroke and fill colors
</li></ul>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eev"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ev</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">ident</i></span>]</var><a class="copiable-link" href='#index-_002eev'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ev"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002eev_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.ev]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002eev_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002eev-1"></a>
<a class="index-entry-id" id="index-switching-environments-_0028ev_0029"></a>
<a class="index-entry-id" id="index-environment_002c-switching-_0028ev_0029"></a>
<a class="index-entry-id" id="index-environment-number_002fname-register-_0028_002eev_0029"></a>
<p>Enter the environment <var class="var">ident</var>, which is created if it does not
already exist, using the same parameters as for the default environment
used at startup.  With no argument, GNU <code class="code">troff</code> switches to the
previous environment.
</p>
<p>Invoking <code class="code">ev</code> with an argument puts environment <var class="var">ident</var> onto
the top of the environment stack.  (If it isn&rsquo;t already present in the
stack, this is a proper push.)  Without an argument, <code class="code">ev</code> pops the
environment stack, making the previous environment current.  It is an
error to pop the environment stack with no previous environment
available.  The read-only string-valued register <code class="code">.ev</code> contains the
name of the current environment&mdash;the one at the top of the stack.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ev footnote-env
.fam N
.ps 6
.vs 8
.ll -.5i
.ev

<span class="r">&hellip;</span>

.ev footnote-env
\[dg] Observe the smaller text and vertical spacing.
.ev
</pre></div></div>

<p>We can familiarize ourselves with stack behavior by wrapping the
<code class="code">ev</code> request with a macro that reports the contents of the
<code class="code">.ev</code> register to the standard error stream.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de EV
.  ev \\$1
.  tm environment is now \\n[.ev]
..
.
.EV foo
.EV bar
.EV
.EV baz
.EV
.EV
.EV
</pre></div></div>

<div class="example">
<div class="group"><pre class="example-preformatted">    error&rarr; environment is now foo
    error&rarr; environment is now bar
    error&rarr; environment is now foo
    error&rarr; environment is now baz
    error&rarr; environment is now foo
    error&rarr; environment is now 0
    error&rarr; error: environment stack underflow
    error&rarr; environment is now 0
</pre></div></div>

</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eevc"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.evc</code></strong> <var class="def-var-arguments">environment</var><a class="copiable-link" href='#index-_002eevc'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-evc"></a>
<a class="index-entry-id" id="index-copying-environment-_0028evc_0029"></a>
<a class="index-entry-id" id="index-environment_002c-copying-_0028evc_0029"></a>
<p>Copy the contents of <var class="var">environment</var> to the current environment.
</p>
<p>The following environment data are not copied.
</p>
<ul class="itemize mark-bullet">
<li>a partially collected line, if present;

</li><li>the interruption status of the previous input line (due to use of the
<code class="code">\c</code> escape sequence);

</li><li>the count of remaining lines to center, to right-justify, or to
underline (with or without underlined spaces)&mdash;these are set to zero;

</li><li>the activation status of temporary indentation;

</li><li>input line traps and their associated data;

</li><li>the activation status of line numbering (which can be reactivated with
&lsquo;<samp class="samp">.nm&nbsp;+0</samp>&rsquo;<!-- /@w -->); and

</li><li>the count of consecutive hyphenated lines (set to zero).
</li></ul>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005b_002ew_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.w]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ew_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ew"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002echt_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.cht]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002echt_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002echt"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ecdp_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.cdp]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ecdp_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ecdp"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ecsk_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.csk]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ecsk_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ecsk"></a>
<a class="index-entry-id" id="index-environment_002c-dimensions-of-last-glyph-_0028_002ew_002c-_002echt_002c-_002ecdp_002c-_002ecsk_0029"></a>
<a class="index-entry-id" id="index-width_002c-of-last-glyph-_0028_002ew_0029"></a>
<a class="index-entry-id" id="index-height_002c-of-last-glyph-_0028_002echt_0029"></a>
<a class="index-entry-id" id="index-depth_002c-of-last-glyph-_0028_002ecdp_0029"></a>
<a class="index-entry-id" id="index-skew_002c-of-last-glyph-_0028_002ecsk_0029"></a>
<a class="index-entry-id" id="index-last-glyph_002c-dimensions-_0028_002ew_002c-_002echt_002c-_002ecdp_002c-_002ecsk_0029"></a>
<a class="index-entry-id" id="index-glyph_002c-last_002c-dimensions-_0028_002ew_002c-_002echt_002c-_002ecdp_002c-_002ecsk_0029"></a>
<p>The <code class="code">\n[.w]</code> register contains the width of the last glyph
formatted in the environment.
</p>
<p>The <code class="code">\n[.cht]</code> register contains the height of the last glyph
formatted in the environment.
</p>
<p>The <code class="code">\n[.cdp]</code> register contains the depth of the last glyph
formatted in the environment.  It is positive for glyphs extending below
the baseline.
</p>
<p>The <code class="code">\n[.csk]</code> register contains the <em class="dfn">skew</em> (how far to the
right of the glyph&rsquo;s center that GNU <code class="code">troff</code> should place an
accent) of the last glyph formatted in the environment.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005b_002en_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.n]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002en_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002en"></a>
<a class="index-entry-id" id="index-environment_002c-previous-line-length-_0028_002en_0029"></a>
<a class="index-entry-id" id="index-line-length_002c-previous-_0028_002en_0029"></a>
<a class="index-entry-id" id="index-length-of-previous-line-_0028_002en_0029"></a>
<a class="index-entry-id" id="index-previous-line-length-_0028_002en_0029"></a>
<p>The <code class="code">\n[.n]</code> register contains the length of the previous output
line emitted in the environment.
</p></dd></dl>




<hr>
</div>
<div class="section-level-extent" id="Suppressing-Output">
<div class="nav-panel">
<p>
Next: <a href="#Colors" accesskey="n" rel="next">Colors</a>, Previous: <a href="#Environments" accesskey="p" rel="prev">Environments</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Suppressing-Output-1">5.32 Suppressing Output</h3>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cO_005bnum_005d"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\O[</code><span class="r"><i class="slanted">num</i></span><code class="t">]</code></strong><a class="copiable-link" href='#index-_005cO_005bnum_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cO"></a>
<a class="index-entry-id" id="index-suppressing-output-_0028_005cO_0029"></a>
<a class="index-entry-id" id="index-output_002c-suppressing-_0028_005cO_0029"></a>
<p>Suppress GNU <code class="code">troff</code> output of glyphs and geometric objects.  The
sequences <code class="code">\O2</code>, <code class="code">\O3</code>, <code class="code">\O4</code>, and <code class="code">\O5</code> are
intended for internal use by <code class="code">grohtml</code>.
</p>
<dl class="table">
<dt>&lsquo;<samp class="samp">\O0</samp>&rsquo;</dt>
<dd><p>Disable the emission of glyphs and geometric objects to the output
driver, provided that this sequence occurs at the outermost suppression
level (see <code class="code">\O3</code> and <code class="code">\04</code> below).  Horizontal motions
corresponding to non-overstruck glyph widths still occur.
</p>
</dd>
<dt>&lsquo;<samp class="samp">\O1</samp>&rsquo;</dt>
<dd><p>Enable the emission of glyphs and geometric objects to the output
driver, provided that this sequence occurs at the outermost suppression
level.
</p></dd>
</dl>

<a class="index-entry-id" id="index-opminx"></a>
<a class="index-entry-id" id="index-opminy"></a>
<a class="index-entry-id" id="index-opmaxx"></a>
<a class="index-entry-id" id="index-opmaxy"></a>
<p><code class="code">\O0</code> and <code class="code">\O1</code> also reset the four registers <code class="code">opminx</code>,
<code class="code">opminy</code>, <code class="code">opmaxx</code>, and <code class="code">opmaxy</code> to &minus;1.  These
four registers mark the top left and bottom right hand corners of a box
encompassing all written or drawn output.
</p>
<dl class="table">
<dt>&lsquo;<samp class="samp">\O2</samp>&rsquo;</dt>
<dd><p>At the outermost suppression level, enable emission of glyphs and
geometric objects, and write to the standard error stream the page
number and values of the four aforementioned registers encompassing
glyphs written since the last interpolation of a <code class="code">\O</code> sequence, as
well as the page offset, line length, image file name (if any),
horizontal and vertical device motion quanta, and input file name.
Numeric values are in basic units.
</p>
</dd>
<dt>&lsquo;<samp class="samp">\O3</samp>&rsquo;</dt>
<dd><p>Begin a nested suppression level.  <code class="command">grohtml</code> uses this mechanism
to create images of output preprocessed with <code class="command">gpic</code>,
<code class="command">geqn</code>, and <code class="command">gtbl</code>.  At startup, GNU <code class="code">troff</code> is at
the outermost suppression level.  <code class="command">pre-grohtml</code> generates these
sequences when processing the document, using GNU <code class="command">troff</code> with
the <code class="code">ps</code> output device, Ghostscript, and the PNM tools to produce
images in PNG format.  They start a new page if the device is not
<code class="code">html</code> or <code class="code">xhtml</code>, to reduce the number of images crossing a
page boundary.
</p>
</dd>
<dt>&lsquo;<samp class="samp">\O4</samp>&rsquo;</dt>
<dd><p>End a nested suppression level.
</p></dd>
</dl>

<dl class="table">
<dt>&lsquo;<samp class="samp">\O[5<var class="var">P</var><var class="var">file</var>]</samp>&rsquo;</dt>
<dd><p>At the outermost suppression level, write the name <code class="code">file</code> to the
standard error stream at position <var class="var">P</var>, which must be one of
<code class="code">l</code>, <code class="code">r</code>, <code class="code">c</code>, or&nbsp;<code class="code">i</code>, corresponding to left,
right, centered, and inline alignments within the document,
respectively.  <var class="var">file</var> is a name associated with the production of
the next image.
</p></dd>
</dl>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005b_002eO_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.O]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002eO_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002eO"></a>
<a class="index-entry-id" id="index-suppression-nesting-level-register"></a>
<a class="index-entry-id" id="index-nesting-level_002c-suppression_002c-register"></a>
<a class="index-entry-id" id="index-level_002c-suppression-nesting_002c-register"></a>
<p>Output suppression nesting level applied by <code class="code">\O3</code> and <code class="code">\O4</code>
escape sequences.
</p></dd></dl>



<hr>
</div>
<div class="section-level-extent" id="I_002fO">
<div class="nav-panel">
<p>
Next: <a href="#Postprocessor-Access" accesskey="n" rel="next">Postprocessor Access</a>, Previous: <a href="#Suppressing-Output" accesskey="p" rel="prev">Suppressing Output</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="I_002fO-1">5.33 I/O</h3>
<a class="index-entry-id" id="index-i_002fo"></a>
<a class="index-entry-id" id="index-input-and-output-requests"></a>
<a class="index-entry-id" id="index-requests-for-input-and-output"></a>
<a class="index-entry-id" id="index-output-and-input-requests"></a>

<p><code class="code">gtroff</code> has several requests for including files:
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002eso"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.so</code></strong> <var class="def-var-arguments">file</var><a class="copiable-link" href='#index-_002eso'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-so"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002esoquiet"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.soquiet</code></strong> <var class="def-var-arguments">file</var><a class="copiable-link" href='#index-_002esoquiet'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-soquiet"></a>
<a class="index-entry-id" id="index-including-a-file-_0028so_0029"></a>
<a class="index-entry-id" id="index-file_002c-inclusion-_0028so_0029"></a>
<p>Replace the <code class="code">so</code> request&rsquo;s control line with the contents of the
file named by the argument, &ldquo;sourcing&rdquo; it.  <var class="var">file</var> is sought in
the directories specified by <samp class="option">-I</samp> command-line option.  If
<var class="var">file</var> does not exist, a warning in category &lsquo;<samp class="samp">file</samp>&rsquo; is produced
and the request has no further effect.  See <a class="xref" href="#Warnings">Warnings</a>, for
information about the enablement and suppression of warnings.
</p>
<p><code class="code">so</code> can be useful for large documents; e.g., allowing each chapter
of a book to be kept in a separate file.  However, files interpolated
with <code class="code">so</code> are not preprocessed; to overcome this limitation, see
the <cite class="cite">gsoelim<span class="r">(1)</span></cite> man page.
</p>
<p>Since GNU <code class="code">troff</code> replaces the entire control line with the
contents of a file, it matters whether <code class="code">file</code> is terminated with a
newline or not.  Assume that file <samp class="file">xxx</samp> contains only the word
&lsquo;<samp class="samp">foo</samp>&rsquo; without a trailing newline.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">$ printf 'foo' &gt; xxx

The situation is
.so xxx
bar.
    &rArr; The situation is foobar.
</pre></div></div>

<p><code class="code">soquiet</code> works the same way, except that no warning diagnostic is
issued if <var class="var">file</var> does not exist.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002epso"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.pso</code></strong> <var class="def-var-arguments">command</var><a class="copiable-link" href='#index-_002epso'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-pso"></a>
<p>Read the standard output from the specified <var class="var">command</var> and include
it in place of the <code class="code">pso</code> request.
</p>
<a class="index-entry-id" id="index-safer-mode-3"></a>
<a class="index-entry-id" id="index-mode_002c-safer-3"></a>
<a class="index-entry-id" id="index-unsafe-mode-3"></a>
<a class="index-entry-id" id="index-mode_002c-unsafe-3"></a>
<p>It is an error to use this request in safer mode, which is the
default.  Invoke GNU <code class="code">troff</code> or a front end with the <samp class="option">-U</samp>
option to enable unsafe mode.
</p>
<p>The comment regarding a final newline for the <code class="code">so</code> request is valid
for <code class="code">pso</code> also.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002emso"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.mso</code></strong> <var class="def-var-arguments">file</var><a class="copiable-link" href='#index-_002emso'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-mso"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002emsoquiet"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.msoquiet</code></strong> <var class="def-var-arguments">file</var><a class="copiable-link" href='#index-_002emsoquiet'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-msoquiet"></a>
<p>Identical to the <code class="code">so</code> and <code class="code">soquiet</code> requests, respectively,
except that <code class="code">gtroff</code> searches for the specified <var class="var">file</var> in the
same directories as macro files for the <samp class="option">-m</samp> command-line option.
If the file name to be included has the form <samp class="file"><var class="var">name</var>.tmac</samp> and
it isn&rsquo;t found, these requests try to include <samp class="file">tmac.<var class="var">name</var></samp> and
vice versa.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002etrf"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.trf</code></strong> <var class="def-var-arguments">file</var><a class="copiable-link" href='#index-_002etrf'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-trf"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002ecf"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.cf</code></strong> <var class="def-var-arguments">file</var><a class="copiable-link" href='#index-_002ecf'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-cf"></a>
<a class="index-entry-id" id="index-transparent-output-_0028cf_002c-trf_0029"></a>
<a class="index-entry-id" id="index-output_002c-transparent-_0028cf_002c-trf_0029"></a>
<a class="index-entry-id" id="index-cf-request_002c-and-copy-mode"></a>
<a class="index-entry-id" id="index-copy-mode_002c-and-cf-request"></a>
<a class="index-entry-id" id="index-mode_002c-copy_002c-and-cf-request"></a>
<a class="index-entry-id" id="index-trf-request_002c-and-copy-mode"></a>
<a class="index-entry-id" id="index-copy-mode_002c-and-trf-request"></a>
<a class="index-entry-id" id="index-mode_002c-copy_002c-and-trf-request"></a>
<p>Transparently output the contents of <var class="var">file</var>.  Each line is output as
if it were preceded by <code class="code">\!</code>; however, the lines are <em class="emph">not</em>
subject to copy mode interpretation.  If the file does not end with a
newline, <code class="code">trf</code> adds one.  Both requests cause a break.
</p>
<p>When used in a diversion, these requests embed a node (see <a class="pxref" href="#Gtroff-Internals"><code class="code">gtroff</code> Internals</a>) in it that, when reread, causes the contents of <var class="var">file</var>
to be transparently copied to the output.  In <abbr class="acronym">AT&amp;T</abbr>
<code class="code">troff</code>, the contents of <var class="var">file</var> are immediately copied to the
output regardless of whether there is a current diversion; this
behaviour is so anomalous that it must be considered a bug.
</p>
<a class="index-entry-id" id="index-trf-request_002c-and-invalid-characters"></a>
<a class="index-entry-id" id="index-characters_002c-invalid-for-trf-request"></a>
<a class="index-entry-id" id="index-invalid-characters-for-trf-request"></a>
<p>While <code class="code">cf</code> copies the contents of <var class="var">file</var> completely
unprocessed, <code class="code">trf</code> disallows characters such as NUL that are not
valid <code class="code">gtroff</code> input characters (see <a class="pxref" href="#Identifiers">Identifiers</a>).
</p>
<p>For <code class="code">cf</code>, within a diversion, &ldquo;completely unprocessed&rdquo; means that
each line of a file to be inserted is handled as if it were preceded by
<code class="code">\!\\!</code>.
</p>
<p>To define a macro&nbsp;<code class="code">x</code> containing the contents of
file&nbsp;<samp class="file">f</samp>, use
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ev 1
.di x
.trf f
.di
.ev
</pre></div></div>

<p>The calls to <code class="code">ev</code> prevent the partially collected output line
from becoming part of the diversion (see <a class="pxref" href="#Diversions">Diversions</a>).
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002enx"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.nx</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">file</i></span>]</var><a class="copiable-link" href='#index-_002enx'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-nx"></a>
<a class="index-entry-id" id="index-processing-next-file-_0028nx_0029"></a>
<a class="index-entry-id" id="index-file_002c-processing-next-_0028nx_0029"></a>
<a class="index-entry-id" id="index-next-file_002c-processing-_0028nx_0029"></a>
<p>Force <code class="code">gtroff</code> to continue processing of the file specified as an
argument.  If no argument is given, immediately jump to the end of file.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002erd"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.rd</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">prompt</i></span> [<span class="r"><i class="slanted">arg1</i></span> <span class="r"><i class="slanted">arg2</i></span> &hellip;]]</var><a class="copiable-link" href='#index-_002erd'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-rd"></a>
<a class="index-entry-id" id="index-reading-from-standard-input-_0028rd_0029"></a>
<a class="index-entry-id" id="index-standard-input_002c-reading-from-_0028rd_0029"></a>
<a class="index-entry-id" id="index-input_002c-standard_002c-reading-from-_0028rd_0029"></a>
<p>Read from standard input, and include what is read as though it were
part of the input file.  Text is read until a blank line is encountered.
</p>
<p>If standard input is a TTY input device (keyboard), write <var class="var">prompt</var>
to standard error, followed by a colon (or send BEL for a beep if no
argument is given).
</p>
<p>Arguments after <var class="var">prompt</var> are available for the input.  For example,
the line
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.rd data foo bar
</pre></div></div>

<p>with the input &lsquo;<samp class="samp">This&nbsp;is&nbsp;\$2.</samp>&rsquo;<!-- /@w --> prints
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">This is bar.
</pre></div></div>
</dd></dl>

<a class="index-entry-id" id="index-form-letters"></a>
<a class="index-entry-id" id="index-letters_002c-form"></a>
<p>Using the <code class="code">nx</code> and <code class="code">rd</code> requests, it is easy to set up form
letters.  The form letter template is constructed like this, putting the
following lines into a file called <samp class="file">repeat.let</samp>:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ce
\*(td
.sp 2
.nf
.rd
.sp
.rd
.fi
Body of letter.
.bp
.nx repeat.let
</pre></div></div>

<a class="index-entry-id" id="index-ex-request_002c-used-with-nx-and-rd"></a>
<p>When this is run, a file containing the following lines should be
redirected in.  Requests included in this file are executed as though
they were part of the form letter.  The last block of input is the
<code class="code">ex</code> request, which tells GNU <code class="code">troff</code> to stop processing.  If
this were not there, <code class="code">troff</code> would not know when to stop.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">Trent A. Fisher
708 NW 19th Av., #202
Portland, OR  97209

Dear Trent,

Len Adollar
4315 Sierra Vista
San Diego, CA  92103

Dear Mr. Adollar,

.ex
</pre></div></div>

<dl class="first-deffn">
<dt class="deffn" id="index-_002epi"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.pi</code></strong> <var class="def-var-arguments">pipe</var><a class="copiable-link" href='#index-_002epi'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-pi"></a>
<p>Pipe the output of <code class="code">gtroff</code> to the shell command(s) specified by
<var class="var">pipe</var>.  This request must occur before <code class="code">gtroff</code> has a chance
to print anything.
</p>
<a class="index-entry-id" id="index-safer-mode-4"></a>
<a class="index-entry-id" id="index-mode_002c-safer-4"></a>
<a class="index-entry-id" id="index-unsafe-mode-4"></a>
<a class="index-entry-id" id="index-mode_002c-unsafe-4"></a>
<p>It is an error to use this request in safer mode, which is the
default.  Invoke GNU <code class="code">troff</code> or a front end with the <samp class="option">-U</samp>
option to enable unsafe mode.
</p>
<p>Multiple calls to <code class="code">pi</code> are allowed, acting as a chain.  For
example,
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.pi foo
.pi bar
...
</pre></div></div>

<p>is the same as &lsquo;<samp class="samp">.pi&nbsp;foo&nbsp;|&nbsp;bar</samp>&rsquo;<!-- /@w -->.
</p>
<a class="index-entry-id" id="index-groff_002c-and-pi-request"></a>
<a class="index-entry-id" id="index-pi-request_002c-and-groff"></a>
<p>The intermediate output format of GNU <code class="code">troff</code> is piped to the
specified commands.  Consequently, calling <code class="code">groff</code> without the
<samp class="option">-Z</samp> option normally causes a fatal error.
</p></dd></dl>

<a class="index-entry-id" id="index-system-commands_002c-running"></a>
<a class="index-entry-id" id="index-running-system-commands"></a>
<dl class="first-deffn">
<dt class="deffn" id="index-_002esy"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.sy</code></strong> <var class="def-var-arguments">cmds</var><a class="copiable-link" href='#index-_002esy'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-sy"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005bsystat_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[systat]</code></strong><a class="copiable-link" href='#index-_005cn_005bsystat_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-systat"></a>
<p>Execute the shell command(s) specified by <var class="var">cmds</var>.  The output is not
saved anywhere, so it is up to the user to do so.
</p>
<a class="index-entry-id" id="index-safer-mode-5"></a>
<a class="index-entry-id" id="index-mode_002c-safer-5"></a>
<a class="index-entry-id" id="index-unsafe-mode-5"></a>
<a class="index-entry-id" id="index-mode_002c-unsafe-5"></a>
<p>It is an error to use this request in safer mode; this is the default.
Give GNU <code class="code">troff</code> or a front end program the <samp class="option">-U</samp> option to
enable unsafe mode.
</p>
<p>The following code fragment introduces the current time into a document.
</p>
<a class="index-entry-id" id="index-perl"></a>
<div class="example">
<div class="group"><pre class="example-preformatted">.sy perl -e 'printf &quot;.nr H %d\\n.nr M %d\\n.nr S %d\\n&quot;,\
             (localtime(time))[2,1,0]' &gt; /tmp/x\n[$$]
.so /tmp/x\n[$$]
.sy rm /tmp/x\n[$$]
\nH:\nM:\nS
</pre></div></div>

<p>This works by having the Perl script (run by <code class="code">sy</code>) write
<code class="code">nr</code> requests that set the registers <code class="code">H</code>, <code class="code">M</code>, and
<code class="code">S</code> to a temporary file.  The <code class="code">roff</code> document then reads the
temporary file using the <code class="code">so</code> request.
</p>
<a class="index-entry-id" id="index-time_002c-formatting"></a>
<a class="index-entry-id" id="index-formatting-the-time"></a>
<p>The registers <code class="code">seconds</code>, <code class="code">minutes</code>, and <code class="code">hours</code>,
initialized at startup of GNU <code class="code">troff</code>, should satisfy most
requirements.  Use the <code class="code">af</code> request to format their values for
output.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.af hours 00
.af minutes 00
.af seconds 00
\n[hours]:\n[minutes]:\n[seconds]
    &rArr; 02:17:54
</pre></div></div>

<a class="index-entry-id" id="index-system_0028_0029-return-value-register-_0028systat_0029"></a>
<p>The writable register <code class="code">systat</code> contains the return value of the
<code class="code">system()</code> function executed by the last <code class="code">sy</code> request.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eopen"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.open</code></strong> <var class="def-var-arguments">stream file</var><a class="copiable-link" href='#index-_002eopen'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-open"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002eopena"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.opena</code></strong> <var class="def-var-arguments">stream file</var><a class="copiable-link" href='#index-_002eopena'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-opena"></a>
<a class="index-entry-id" id="index-opening-file-_0028open_0029"></a>
<a class="index-entry-id" id="index-file_002c-opening-_0028open_0029"></a>
<a class="index-entry-id" id="index-appending-to-a-file-_0028opena_0029"></a>
<a class="index-entry-id" id="index-file_002c-appending-to-_0028opena_0029"></a>
<p>Open the specified <var class="var">file</var> for writing and associates the specified
<var class="var">stream</var> with it.
</p>
<p>The <code class="code">opena</code> request is like <code class="code">open</code>, but if the file exists,
append to it instead of truncating it.
</p>
<a class="index-entry-id" id="index-safer-mode-6"></a>
<a class="index-entry-id" id="index-mode_002c-safer-6"></a>
<a class="index-entry-id" id="index-unsafe-mode-6"></a>
<a class="index-entry-id" id="index-mode_002c-unsafe-6"></a>
<p>It is an error to use these requests in safer mode; this is the default.
Give GNU <code class="code">troff</code> or a front end program the <samp class="option">-U</samp> option to
enable unsafe mode.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ewrite"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.write</code></strong> <var class="def-var-arguments">stream data</var><a class="copiable-link" href='#index-_002ewrite'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-write"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002ewritec"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.writec</code></strong> <var class="def-var-arguments">stream data</var><a class="copiable-link" href='#index-_002ewritec'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-writec"></a>
<a class="index-entry-id" id="index-copy-mode_002c-and-write-request"></a>
<a class="index-entry-id" id="index-write-request_002c-and-copy-mode"></a>
<a class="index-entry-id" id="index-mode_002c-copy_002c-and-write-request"></a>
<a class="index-entry-id" id="index-copy-mode_002c-and-writec-request"></a>
<a class="index-entry-id" id="index-writec-request_002c-and-copy-mode"></a>
<a class="index-entry-id" id="index-mode_002c-copy_002c-and-writec-request"></a>
<a class="index-entry-id" id="index-writing-to-file-_0028write_002c-writec_0029"></a>
<a class="index-entry-id" id="index-file_002c-writing-to-_0028write_002c-writec_0029"></a>
<p>Write to the file associated with the specified <var class="var">stream</var>.  The
stream must previously have been the subject of an open request.  The
remainder of the line is interpreted as the <code class="code">ds</code> request reads its
second argument: an initial neutral double quote in <var class="var">contents</var> is
stripped to allow embedding of leading spaces, and it is read in copy
mode.
</p>
<p>The <code class="code">writec</code> request is like <code class="code">write</code>, but only <code class="code">write</code>
appends a newline to the data.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ewritem"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.writem</code></strong> <var class="def-var-arguments">stream xx</var><a class="copiable-link" href='#index-_002ewritem'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-writem"></a>
<a class="index-entry-id" id="index-asciify-request_002c-and-writem"></a>
<p>Write the contents of the macro or string <var class="var">xx</var> to the file
associated with the specified <var class="var">stream</var>.
</p>
<a class="index-entry-id" id="index-writem-request_002c-and-copy-mode"></a>
<a class="index-entry-id" id="index-copy-mode_002c-and-writem-request"></a>
<a class="index-entry-id" id="index-mode_002c-copy_002c-and-writem-request"></a>
<p><var class="var">xx</var> is read in copy mode, i.e., already formatted elements are
ignored.  Consequently, diversions must be unformatted with the
<code class="code">asciify</code> request before calling <code class="code">writem</code>.  Usually, this
means a loss of information.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eclose"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.close</code></strong> <var class="def-var-arguments">stream</var><a class="copiable-link" href='#index-_002eclose'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-close"></a>
<a class="index-entry-id" id="index-closing-file-_0028close_0029"></a>
<a class="index-entry-id" id="index-file_002c-closing-_0028close_0029"></a>
<p>Close the specified <var class="var">stream</var>; the stream is no longer an acceptable
argument to the <code class="code">write</code> request.
</p>
<p>Here a simple macro to write an index entry.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.open idx test.idx
.
.de IX
.  write idx \\n[%] \\$*
..
.
.IX test entry
.
.close idx
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cVe"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\V</code><span class="r"><i class="slanted">e</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cVe'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cV"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cV_0028ev"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\V(</code><span class="r"><i class="slanted">ev</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cV_0028ev'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cV_005benv_005d"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\V[</code><span class="r"><i class="slanted">env</i></span><code class="t">]</code></strong><a class="copiable-link" href='#index-_005cV_005benv_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cV_002c-and-copy-mode"></a>
<a class="index-entry-id" id="index-copy-mode_002c-and-_005cV"></a>
<a class="index-entry-id" id="index-mode_002c-copy_002c-and-_005cV"></a>
<p>Interpolate the contents of the specified environment variable <var class="var">env</var>
(one-character name&nbsp;<var class="var">e</var>, two-character name <var class="var">ev</var>) as
returned by the function <cite class="cite">getenv<span class="r">(3)</span></cite>.  <code class="code">\V</code> is interpreted
even in copy mode (see <a class="pxref" href="#Copy-Mode">Copy Mode</a>).
</p></dd></dl>



<hr>
</div>
<div class="section-level-extent" id="Postprocessor-Access">
<div class="nav-panel">
<p>
Next: <a href="#Miscellaneous" accesskey="n" rel="next">Miscellaneous</a>, Previous: <a href="#I_002fO" accesskey="p" rel="prev">I/O</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Postprocessor-Access-1">5.34 Postprocessor Access</h3>
<a class="index-entry-id" id="index-postprocessor-access"></a>
<a class="index-entry-id" id="index-access-to-postprocessor"></a>

<p>Two escape sequences and two requests enable documents to pass
information directly to a postprocessor.  These are useful for
exercising device-specific capabilities that the <code class="code">groff</code> language
does not abstract or generalize; examples include the embedding of
hyperlinks and image files.  Device-specific functions are documented in
each output driver&rsquo;s man page, such as <cite class="cite">gropdf<span class="r">(1)</span></cite>,
<cite class="cite">grops<span class="r">(1)</span></cite>, or <cite class="cite">grotty<span class="r">(1)</span></cite>.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002edevice"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.device</code></strong> <var class="def-var-arguments">xxx <span class="r">&hellip;</span></var><a class="copiable-link" href='#index-_002edevice'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-device"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cX_0027xxx-_2026_0027"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\X<code class="code">'</code></code><span class="r"><i class="slanted">xxx <span class="r">&hellip;</span></i></span><code class="t"><code class="code">'</code></code></strong><a class="copiable-link" href='#index-_005cX_0027xxx-_2026_0027'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cX"></a>
<p>Embed all <var class="var">xxx</var> arguments into GNU <code class="code">troff</code> output as parameters
to a device control command &lsquo;<samp class="samp">x&nbsp;X</samp>&rsquo;<!-- /@w -->.  The meaning and
interpretation of such parameters is determined by the output driver or
other postprocessor.
</p>
<a class="index-entry-id" id="index-device-request_002c-and-copy-mode"></a>
<a class="index-entry-id" id="index-copy-mode_002c-and-device-request"></a>
<a class="index-entry-id" id="index-mode_002c-copy_002c-and-device-request"></a>
<p>The <code class="code">device</code> request processes its arguments in copy mode
(see <a class="pxref" href="#Copy-Mode">Copy Mode</a>).  An initial neutral double quote in <var class="var">contents</var>
is stripped to allow embedding of leading spaces.
<a class="index-entry-id" id="index-_005c_0026_002c-in-_005cX"></a>
<a class="index-entry-id" id="index-_005c_0029_002c-in-_005cX"></a>
<a class="index-entry-id" id="index-_005c_0025_002c-in-_005cX"></a>
<a class="index-entry-id" id="index-_005c_003a_002c-in-_005cX"></a>
By contrast, within <code class="code">\X</code> arguments, the escape sequences <code class="code">\&amp;</code>,
<code class="code">\)</code>, <code class="code">\%</code>, and <code class="code">\:</code> are ignored; <code class="code">\<kbd class="key">SP</kbd></code> and
<code class="code">\~</code> are converted to single space characters; and <code class="code">\\</code> has
its escape character stripped.  So that the basic Latin subset of the
Unicode character set<a class="footnote" id="DOCF115" href="#FOOT115"><sup>115</sup></a> can be reliably encoded in device control
commands, seven special character escape sequences (&lsquo;<samp class="samp">\-</samp>&rsquo;,
&lsquo;<samp class="samp">\[aq]</samp>&rsquo;, &lsquo;<samp class="samp">\[dq]</samp>&rsquo;, &lsquo;<samp class="samp">\[ga]</samp>&rsquo;, &lsquo;<samp class="samp">\[ha]</samp>&rsquo;, &lsquo;<samp class="samp">\[rs]</samp>&rsquo;,
and &lsquo;<samp class="samp">\[ti]</samp>&rsquo;,) are mapped to basic Latin characters; see the
<cite class="cite">groff_char<span class="r">(7)</span></cite> man page.  For this transformation, character
translations and special character definitions are
ignored.<a class="footnote" id="DOCF116" href="#FOOT116"><sup>116</sup></a> The use of any
other escape sequence in <code class="code">\X</code> parameters is normally an error.
</p>
<a class="index-entry-id" id="index-use_005fcharnames_005fin_005fspecial"></a>
<a class="index-entry-id" id="index-DESC-file_002c-and-use_005fcharnames_005fin_005fspecial-keyword"></a>
<a class="index-entry-id" id="index-_005cX_002c-and-special-characters"></a>
<p>If the <code class="code">use_charnames_in_special</code> directive appears in the output
device&rsquo;s <samp class="file">DESC</samp> file, the use of special character escape sequences
is <em class="emph">not</em> an error; they are simply output verbatim (with the
exception of the seven mapped to Unicode basic Latin characters,
discussed above).  <code class="code">use_charnames_in_special</code> is currently employed
only by <code class="code">grohtml</code>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002edevicem"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.devicem</code></strong> <var class="def-var-arguments">name</var><a class="copiable-link" href='#index-_002edevicem'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-devicem"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cYn"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\Y</code><span class="r"><i class="slanted">n</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cYn'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_005cY"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cY_0028nm"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\Y(</code><span class="r"><i class="slanted">nm</i></span><code class="t"></code></strong><a class="copiable-link" href='#index-_005cY_0028nm'> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-_005cY_005bname_005d"><span class="category-def">Escape&nbsp;sequence: </span><span><strong class="def-name"><code class="t">\Y[</code><span class="r"><i class="slanted">name</i></span><code class="t">]</code></strong><a class="copiable-link" href='#index-_005cY_005bname_005d'> &para;</a></span></dt>
<dd><p>This is approximately equivalent to &lsquo;<samp class="samp">\X'\*[<var class="var">name</var>]'</samp>&rsquo;
(one-character name&nbsp;<var class="var">n</var>, two-character name <var class="var">nm</var>).
However, the contents of the string or macro <var class="var">name</var> are not
interpreted; also it is permitted for <var class="var">name</var> to have been defined as
a macro and thus contain newlines (it is not permitted for the argument
to <code class="code">\X</code> to contain newlines).  The inclusion of newlines requires
an extension to the <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> output format, and
confuses drivers that do not know about this extension (see <a class="pxref" href="#Device-Control-Commands">Device Control Commands</a>).
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002etag"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.tag</code></strong> <var class="def-var-arguments">name</var><a class="copiable-link" href='#index-_002etag'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-tag"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002etaga"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.taga</code></strong> <var class="def-var-arguments">name</var><a class="copiable-link" href='#index-_002etaga'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-taga"></a>
<p>Reserved for internal use.
</p></dd></dl>



<hr>
</div>
<div class="section-level-extent" id="Miscellaneous">
<div class="nav-panel">
<p>
Next: <a href="#Gtroff-Internals" accesskey="n" rel="next"><code class="code">gtroff</code> Internals</a>, Previous: <a href="#Postprocessor-Access" accesskey="p" rel="prev">Postprocessor Access</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Miscellaneous-1">5.35 Miscellaneous</h3>

<p>We document here GNU <code class="code">troff</code> features that fit poorly elsewhere.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002enm"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.nm</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">start</i></span> [<span class="r"><i class="slanted">increment</i></span> [<span class="r"><i class="slanted">space</i></span> [<span class="r"><i class="slanted">indentation</i></span>]]]]</var><a class="copiable-link" href='#index-_002enm'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-nm"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005bln_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[ln]</code></strong><a class="copiable-link" href='#index-_005cn_005bln_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ln"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002enm_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.nm]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002enm_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002enm-1"></a>
<a class="index-entry-id" id="index-printing-line-numbers-_0028nm_0029"></a>
<a class="index-entry-id" id="index-line-numbers_002c-printing-_0028nm_0029"></a>
<a class="index-entry-id" id="index-numbers_002c-line_002c-printing-_0028nm_0029"></a>
<p>Begin (or, with no arguments, cease) numbering output lines.
<var class="var">start</var> assigns the number of the <em class="emph">next</em> output line.  Only
line numbers divisible by <var class="var">increment</var> are marked (default:
&lsquo;<samp class="samp">1</samp>&rsquo;).  <var class="var">space</var> configures the horizontal spacing between the
number and the text (default: &lsquo;<samp class="samp">1</samp>&rsquo;).  Any given <var class="var">indentation</var> is
applied to the numbers (default: &lsquo;<samp class="samp">0</samp>&rsquo;).  The third and fourth
arguments are reckoned in numeral widths (<code class="code">\0</code>).  <var class="var">start</var> must
be non-negative and <var class="var">increment</var> positive.
</p>
<p>The formatter aligns the number to the right in a width of three numeral
spaces plus <var class="var">indentation</var>, then catenates <var class="var">space</var> and the output
line.  The line length is <em class="emph">not</em> reduced.  Depending on the value of
the page offset,<a class="footnote" id="DOCF117" href="#FOOT117"><sup>117</sup></a> numbers wider than
the allocated space protrude into the left margin, or shift the output
line to the right.
</p>
<p>Line numbering parameters corresponding to missing arguments are not
altered.  After numbering is disabled, &lsquo;<samp class="samp">.nm +0</samp>&rsquo; resumes it using
the previously active parameters.
</p>
<p>The parameters of <code class="code">nm</code> are associated with the environment
(see <a class="pxref" href="#Environments">Environments</a>).
</p>
<a class="index-entry-id" id="index-output-line-number-register-_0028ln_0029"></a>
<a class="index-entry-id" id="index-line-number_002c-output_002c-register-_0028ln_0029"></a>
<p>While numbering is enabled, the output line number register <code class="code">ln</code> is
updated as each line is output, even if no line number is formatted with
it because it is being skipped (it is not a multiple of <var class="var">increment</var>)
or because numbering is suppressed (see the <code class="code">nn</code> request below).
</p>
<p>The <code class="code">.nm</code> register tracks the enablement status of numbering.
Temporary suspension of numbering with the <code class="code">nn</code> request does
<em class="emph">not</em> alter its value.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.po 5n
.ll 44n
Programming,
when stripped of all its circumstantial irrelevancies,
.nm 999 1 1 -4
boils down to no more and no less than
.nm +0 3
very effective thinking so as to avoid unmastered
.nn 2
complexity,
to very vigorous separation of your many
different concerns.
.br
\(em Edsger Dijkstra
.sp
.nm 1 1 1
This guy's arrogance takes your breath away.
.br
\(em John Backus
    &rArr;      Programming,  when  stripped of all its cir-
    &rArr;  999 cumstantial irrelevancies, boils down to  no
    &rArr;      more  and no less than very effective think-
    &rArr;      ing so as to avoid unmastered complexity, to
    &rArr;      very vigorous separation of your  many  dif-
    &rArr;      ferent concerns.
    &rArr; 1002 -- Edsger Dijkstra
    &rArr;
    &rArr;    1 This guy&rsquo;s arrogance takes your breath away.
    &rArr;    2 -- John Backus
</pre></div></div>
</dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002enn"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.nn</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">skip</i></span>]</var><a class="copiable-link" href='#index-_002enn'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-nn"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002enn_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.nn]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002enn_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002enn-1"></a>
<p>Suppress numbering of the next <var class="var">skip</var> output lines that would
otherwise be numbered.  The default is&nbsp;1.  <code class="code">nn</code> can be invoked
when line numbering is not active; suppression of numbering will take
effect for <var class="var">skip</var> lines once <code class="code">nm</code> enables it.
</p>
<p>The <code class="code">.nn</code> register stores the count of output lines still to have
their numbering suppressed.
</p>
<p>This count is associated with the environment (see <a class="pxref" href="#Environments">Environments</a>).
</p></dd></dl>

<p>To test whether the current output line will be numbered, you must check
both the <code class="code">.nm</code> and <code class="code">.nn</code> registers.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">  .de is-numbered
  .  nop This line
  .  ie (\\n[.nm] &amp; (1-\\n[.nn])) IS
  .  el                           ISN'T
  .  nop numbered.
  .  br
  ..
  Test line numbering.
  .is-numbered
  .nm 1
  .nn 1
  .is-numbered
  .is-numbered
  .nm
  .is-numbered
    &rArr; Test line numbering.  This line ISN&rsquo;T numbered.
    &rArr; This line ISN&rsquo;T numbered.
    &rArr;   1 This line IS numbered.
    &rArr; This line ISN&rsquo;T numbered.
</pre></div></div>

<dl class="first-deffn">
<dt class="deffn" id="index-_002emc"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.mc</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">margin-character</i></span> [<span class="r"><i class="slanted">distance</i></span>]</var><a class="copiable-link" href='#index-_002emc'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-mc"></a>
<a class="index-entry-id" id="index-margin-glyph-_0028mc_0029"></a>
<a class="index-entry-id" id="index-glyph_002c-for-margins-_0028mc_0029"></a>
<p>Begin (or, with no arguments, cease) writing a <em class="dfn">margin-character</em> to
the right of each output line.  The <var class="var">distance</var> argument separates
<var class="var">margin-character</var> from the right margin.  If absent, the most
recent value is used; the default is 10&nbsp;points.  If an output line
exceeds the line length, the margin character is appended to it.
<a class="index-entry-id" id="index-tl-request_002c-and-mc"></a>
No margin character is written on lines produced by the <code class="code">tl</code>
request.
</p>
<p>The margin character is a property of the output line; the margin
character last configured when the line is output controls.  If the
margin character is disabled before an output line breaks, none is
output (but see below).
</p>
<p>The margin character is associated with the environment
(see <a class="pxref" href="#Environments">Environments</a>).
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ll 5i
.nf
.mc \[br]
This paragraph is marked with a margin character.
.sp
As seen above, vertical space isn't thus marked.
\&amp;
An output line that is present, but empty, is.
    &rArr; This paragraph is marked with a margin character.  |
    &rArr;
    &rArr; As seen above, vertical space isn&rsquo;t thus marked.   |
    &rArr;                                                    |
    &rArr; An output line that is present, but empty, is.     |
</pre></div></div>
</dd></dl>

<p>For compatibility with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>, a call to <code class="code">mc</code>
to set the margin character can&rsquo;t be undone immediately; at least one
line gets a margin character.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ll 10n
.nf
.mc |
.mc *
.mc
foo
bar
    &rArr; foo        *
    &rArr; bar
</pre></div></div>

<a class="index-entry-id" id="index-gdiffmk"></a>
<a class="index-entry-id" id="index-nrchbar"></a>
<a class="index-entry-id" id="index-changebar"></a>
<a class="index-entry-id" id="index-diffmk"></a>
<p>The margin character mechanism is commonly used to annotate changes in
documents.  The <code class="code">groff</code> distribution ships a program,
<code class="command">gdiffmk</code>, to assist with this task.<a class="footnote" id="DOCF118" href="#FOOT118"><sup>118</sup></a>
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002epsbb"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.psbb</code></strong> <var class="def-var-arguments">file</var><a class="copiable-link" href='#index-_002epsbb'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-psbb"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005bllx_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[llx]</code></strong><a class="copiable-link" href='#index-_005cn_005bllx_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-llx"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005blly_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[lly]</code></strong><a class="copiable-link" href='#index-_005cn_005blly_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-lly"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005burx_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[urx]</code></strong><a class="copiable-link" href='#index-_005cn_005burx_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-urx"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005bury_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[ury]</code></strong><a class="copiable-link" href='#index-_005cn_005bury_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ury"></a>
<a class="index-entry-id" id="index-PostScript_002c-bounding-box"></a>
<a class="index-entry-id" id="index-bounding-box"></a>
<p>Retrieve the bounding box of the PostScript image found in <var class="var">file</var>,
which must conform to Adobe&rsquo;s <em class="dfn">Document Structuring Conventions</em>
(DSC), locate a <code class="code">%%BoundingBox</code> comment, and store the (upper-,
lower-, <span class="w-nolinebreak-text">-left</span><!-- /@w -->, <span class="w-nolinebreak-text">-right</span><!-- /@w -->) values into the registers <code class="code">llx</code>,
<code class="code">lly</code>, <code class="code">urx</code>, and <code class="code">ury</code>.  If an error occurs (for
example, if no <code class="code">%%BoundingBox</code> comment is present), the formatter
sets these registers to&nbsp;0.
</p>
<p>The search path for <var class="var">file</var> can be controlled with the <samp class="option">-I</samp>
command-line option.
</p></dd></dl>




<hr>
</div>
<div class="section-level-extent" id="Gtroff-Internals">
<div class="nav-panel">
<p>
Next: <a href="#Debugging" accesskey="n" rel="next">Debugging</a>, Previous: <a href="#Miscellaneous" accesskey="p" rel="prev">Miscellaneous</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="gtroff-Internals">5.36 <code class="code">gtroff</code> Internals</h3>

<a class="index-entry-id" id="index-input-token"></a>
<a class="index-entry-id" id="index-token_002c-input"></a>
<a class="index-entry-id" id="index-output-node"></a>
<a class="index-entry-id" id="index-node_002c-output"></a>
<p><code class="code">gtroff</code> processes input in three steps.  One or more input
characters are converted to an <em class="dfn">input token</em>.<a class="footnote" id="DOCF119" href="#FOOT119"><sup>119</sup></a>  Then, one or more input tokens are converted to
an <em class="dfn">output node</em>.  Finally, output nodes are converted to the
intermediate output language understood by all output devices.
</p>
<p>Actually, before step one happens, <code class="code">gtroff</code> converts certain escape
sequences into reserved input characters (not accessible by the user);
such reserved characters are used for other internal processing also &ndash;
this is the very reason why not all characters are valid input.
See <a class="xref" href="#Identifiers">Identifiers</a>, for more on this topic.
</p>
<p>For example, the input string &lsquo;<samp class="samp">fi\[:u]</samp>&rsquo; is converted into a
character token &lsquo;<samp class="samp">f</samp>&rsquo;, a character token &lsquo;<samp class="samp">i</samp>&rsquo;, and a special
token &lsquo;<samp class="samp">:u</samp>&rsquo; (representing u&nbsp;umlaut).  Later on, the character
tokens &lsquo;<samp class="samp">f</samp>&rsquo; and &lsquo;<samp class="samp">i</samp>&rsquo; are merged to a single output node
representing the ligature glyph &lsquo;<samp class="samp">fi</samp>&rsquo; (provided the current font has
a glyph for this ligature); the same happens with &lsquo;<samp class="samp">:u</samp>&rsquo;.  All output
glyph nodes are &lsquo;processed&rsquo;, which means that they are invariably
associated with a given font, font size, advance width, etc.  During the
formatting process, <code class="code">gtroff</code> itself adds various nodes to control
the data flow.
</p>
<p>Macros, diversions, and strings collect elements in two chained lists: a
list of input tokens that have been passed unprocessed, and a list of
output nodes.  Consider the following diversion.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.di xxx
a
\!b
c
.br
.di
</pre></div></div>

<p>It contains these elements.
</p>
<table class="multitable">
<tbody><tr><td>node list</td><td>token list</td><td>element number</td></tr>
<tr><td><i class="i">line start node</i></td><td>&mdash;</td><td>1</td></tr>
<tr><td><i class="i">glyph node <code class="code">a</code></i></td><td>&mdash;</td><td>2</td></tr>
<tr><td><i class="i">word space node</i></td><td>&mdash;</td><td>3</td></tr>
<tr><td>&mdash;</td><td><code class="code">b</code></td><td>4</td></tr>
<tr><td>&mdash;</td><td><code class="code">\n</code></td><td>5</td></tr>
<tr><td><i class="i">glyph node <code class="code">c</code></i></td><td>&mdash;</td><td>6</td></tr>
<tr><td><i class="i">vertical size node</i></td><td>&mdash;</td><td>7</td></tr>
<tr><td><i class="i">vertical size node</i></td><td>&mdash;</td><td>8</td></tr>
<tr><td>&mdash;</td><td><code class="code">\n</code></td><td>9</td></tr>
</tbody>
</table>

<a class="index-entry-id" id="index-_005cv_002c-internal-representation"></a>
<p>Elements 1, 7, and&nbsp;8 are inserted by <code class="code">gtroff</code>; the latter two
(which are always present) specify the vertical extent of the last line,
possibly modified by <code class="code">\x</code>.  The <code class="code">br</code> request finishes the
pending output line, inserting a newline input token, which is
subsequently converted to a space when the diversion is reread.  Note
that the word space node has a fixed width that isn&rsquo;t adjustable
anymore.  To convert horizontal space nodes back to input tokens, use
the <code class="code">unformat</code> request.
</p>
<p>Macros only contain elements in the token list (and the node list is
empty); diversions and strings can contain elements in both lists.
</p>
<p>The <code class="code">chop</code> request simply reduces the number of elements in a
macro, string, or diversion by one.  Exceptions are <em class="dfn">compatibility
save</em> and <em class="dfn">compatibility ignore</em> input tokens, which are ignored.
The <code class="code">substring</code> request also ignores those input tokens.
</p>
<p>Some requests like <code class="code">tr</code> or <code class="code">cflags</code> work on glyph identifiers
only; this means that the associated glyph can be changed without
destroying this association.  This can be very helpful for substituting
glyphs.  In the following example, we assume that glyph &lsquo;<samp class="samp">foo</samp>&rsquo; isn&rsquo;t
available by default, so we provide a substitution using the
<code class="code">fchar</code> request and map it to input character &lsquo;<samp class="samp">x</samp>&rsquo;.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.fchar \[foo] foo
.tr x \[foo]
</pre></div></div>

<p>Now let us assume that we install an additional special font &lsquo;<samp class="samp">bar</samp>&rsquo;
that has glyph &lsquo;<samp class="samp">foo</samp>&rsquo;.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.special bar
.rchar \[foo]
</pre></div></div>

<p>Since glyphs defined with <code class="code">fchar</code> are searched before glyphs in
special fonts, we must call <code class="code">rchar</code> to remove the definition of the
fallback glyph.  Anyway, the translation is still active; &lsquo;<samp class="samp">x</samp>&rsquo; now
maps to the real glyph &lsquo;<samp class="samp">foo</samp>&rsquo;.
</p>
<a class="index-entry-id" id="index-compatibility-mode_002c-and-parameters"></a>
<a class="index-entry-id" id="index-mode_002c-compatibility_002c-and-parameters"></a>
<a class="index-entry-id" id="index-arguments_002c-and-compatibility-mode"></a>
<a class="index-entry-id" id="index-parameters_002c-and-compatibility-mode"></a>
<a class="index-entry-id" id="index-macro-arguments_002c-and-compatibility-mode"></a>
<a class="index-entry-id" id="index-request-arguments_002c-and-compatibility-mode"></a>
<p>Macro and request arguments preserve compatibility mode enablement.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.cp 1     \&quot; switch to compatibility mode
.de xx
\\$1
..
.cp 0     \&quot; switch compatibility mode off
.xx caf\['e]
    &rArr; caf
</pre></div></div>

<p>Since compatibility mode is enabled while <code class="code">de</code> is invoked, the
macro <code class="code">xx</code> enables compatibility mode when it is called.  Argument
<code class="code">$1</code> can still be handled properly because it inherits the
compatibility mode enablement status that was active at the point where
<code class="code">xx</code> was called.
</p>
<p>After interpolation of the parameters, the compatibility save and
restore tokens are removed.
</p>



<hr>
</div>
<div class="section-level-extent" id="Debugging">
<div class="nav-panel">
<p>
Next: <a href="#Implementation-Differences" accesskey="n" rel="next">Implementation Differences</a>, Previous: <a href="#Gtroff-Internals" accesskey="p" rel="prev"><code class="code">gtroff</code> Internals</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Debugging-1">5.37 Debugging</h3>
<a class="index-entry-id" id="index-debugging"></a>

<div class="flushright"><p class="flushright-paragraph"><i class="slanted">Standard troff voodoo, just put a power of two backslashes in
front of it until it works and if you still have problems add a \c.</i>
&mdash; Ron Natalie
</p></div>
<p>GNU <code class="code">troff</code> is not the easiest language to debug, in part thanks to
its design features of recursive interpolation and the use of
multi-stage pipeline processing in the surrounding system.  Nevertheless
there exist several features useful for troubleshooting.
</p>
<p>Preprocessors use the <code class="code">lf</code> request to preserve the identity of the
line numbers and names of input files.  GNU <code class="code">troff</code> emits a variety
of error diagnostics and supports several categories of warning; the
output of these can be selectively suppressed.  A trace of the
formatter&rsquo;s input processing stack can be emitted when errors or
warnings occur by means of GNU <code class="code">troff</code>&rsquo;s <samp class="option">-b</samp> option, or
produced on demand with the <code class="code">backtrace</code> request.  The <code class="code">tm</code>
and related requests can be used to emit customized diagnostic messages
or for instrumentation while troubleshooting.  The <code class="code">ex</code> and
<code class="code">ab</code> requests cause early termination with successful and error
exit codes respectively, to halt further processing when continuing
would be fruitless.  Examine the state of the formatter with requests
that write lists of defined names (macros, strings, and diversions),
environments, registers, and page location traps to the standard error
stream.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002elf"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.lf</code></strong> <var class="def-var-arguments">line [<span class="r"><i class="slanted">file</i></span>]</var><a class="copiable-link" href='#index-_002elf'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-lf"></a>
<a class="index-entry-id" id="index-soelim"></a>
<a class="index-entry-id" id="index-multi_002dfile-documents"></a>
<a class="index-entry-id" id="index-documents_002c-multi_002dfile"></a>
<a class="index-entry-id" id="index-setting-input-line-number-_0028lf_0029"></a>
<a class="index-entry-id" id="index-input-line-number_002c-setting-_0028lf_0029"></a>
<a class="index-entry-id" id="index-number_002c-input-line_002c-setting-_0028lf_0029"></a>
<p>Set the input line number (and, optionally, the file name) GNU
<code class="code">troff</code> shall use for error and warning messages.  <var class="var">line</var> is
the input line number of the <em class="emph">next</em> line.  Without an argument, the
request is ignored.
</p>
<p><code class="code">lf</code>&rsquo;s primary purpose is to aid the debugging of documents that
undergo preprocessing.  Programs like <code class="command">tbl</code> that transform input
in their own languages into <code class="code">roff</code> requests use it so that any
diagnostic messages emitted by <code class="code">troff</code> correspond to the source
document.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002etm"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.tm</code></strong> <var class="def-var-arguments">message</var><a class="copiable-link" href='#index-_002etm'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-tm"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002etm1"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.tm1</code></strong> <var class="def-var-arguments">message</var><a class="copiable-link" href='#index-_002etm1'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-tm1"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_002etmc"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.tmc</code></strong> <var class="def-var-arguments">message</var><a class="copiable-link" href='#index-_002etmc'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-tmc"></a>
<a class="index-entry-id" id="index-printing-to-stderr-_0028tm_002c-tm1_002c-tmc_0029"></a>
<a class="index-entry-id" id="index-stderr_002c-printing-to-_0028tm_002c-tm1_002c-tmc_0029"></a>
<p>Send <var class="var">message</var>, which consumes the remainder of the input line and
cannot contain special characters, to the standard error stream,
followed by a newline.  Leading spaces in <var class="var">message</var> are ignored.
</p>
<p><code class="code">tm1</code> is similar, but recognizes and strips a leading neutral
double quote from <var class="var">message</var> to allow the embedding of leading
spaces.
</p>
<p><code class="code">tmc</code> works as <code class="code">tm1</code>, but does not append a newline.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eab"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ab</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">message</i></span>]</var><a class="copiable-link" href='#index-_002eab'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ab"></a>
<a class="index-entry-id" id="index-aborting-_0028ab_0029"></a>
<p>Write any <var class="var">message</var> to the standard error stream (like <code class="code">tm</code>)
and then abort GNU <code class="code">troff</code>; that is, stop processing and terminate
with a failure status.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eex"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ex</code></strong><a class="copiable-link" href='#index-_002eex'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ex"></a>
<a class="index-entry-id" id="index-ex-request_002c-use-in-debugging"></a>
<a class="index-entry-id" id="index-exiting-_0028ex_0029"></a>
<p>Exit GNU <code class="code">troff</code>; that is, stop processing and terminate with a
successful status.  To stop processing only the current file, use the
<code class="code">nx</code> request; see <a class="ref" href="#I_002fO">I/O</a>.
</p></dd></dl>

<p>When doing something involved, it is useful to leave the debugging
statements in the code and have them turned on by a command-line flag.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.if \n[DB] .tm debugging output
</pre></div></div>

<p>To activate such statements, use the <samp class="option">-r</samp> option to set the
register.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">groff -rDB=1 <i class="slanted">file</i>
</pre></div></div>

<p>If it is known in advance that there are many errors and no useful
output, GNU <code class="code">troff</code> can be forced to suppress formatted output with
the <samp class="option">-z</samp> option.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002epev"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.pev</code></strong><a class="copiable-link" href='#index-_002epev'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-pev"></a>
<a class="index-entry-id" id="index-dumping-environments-_0028pev_0029"></a>
<a class="index-entry-id" id="index-environments_002c-dumping-_0028pev_0029"></a>
<p>Report the state of the current environment followed by that of all
other environments to the standard error stream.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002epm"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.pm</code></strong><a class="copiable-link" href='#index-_002epm'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-pm"></a>
<a class="index-entry-id" id="index-dumping-symbol-table-_0028pm_0029"></a>
<a class="index-entry-id" id="index-symbol-table_002c-dumping-_0028pm_0029"></a>
<p>Report, to the standard error stream, the names of all defined macros,
strings, and diversions with their sizes in bytes.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002epnr"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.pnr</code></strong><a class="copiable-link" href='#index-_002epnr'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-pnr"></a>
<a class="index-entry-id" id="index-dumping-registers-_0028pnr_0029"></a>
<a class="index-entry-id" id="index-registers_002c-dumping-_0028pnr_0029"></a>
<p>Report the names and contents of all currently defined registers to the
standard error stream.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002eptr"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.ptr</code></strong><a class="copiable-link" href='#index-_002eptr'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-ptr"></a>
<a class="index-entry-id" id="index-dumping-page-location-traps-_0028ptr_0029"></a>
<a class="index-entry-id" id="index-listing-page-location-traps-_0028ptr_0029"></a>
<a class="index-entry-id" id="index-traps_002c-page-location_002c-dumping-_0028ptr_0029"></a>
<a class="index-entry-id" id="index-traps_002c-page-location_002c-listing-_0028ptr_0029"></a>
<p>Report the names and positions of all page location traps to the
standard error stream.  Empty slots in the list, where a trap has been
planted but subsequently (re)moved, are printed as well.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002efl"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.fl</code></strong><a class="copiable-link" href='#index-_002efl'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-fl"></a>
<a class="index-entry-id" id="index-flush-output-_0028fl_0029"></a>
<a class="index-entry-id" id="index-output_002c-flush-_0028fl_0029"></a>
<a class="index-entry-id" id="index-interactive-use-of-gtroff"></a>
<a class="index-entry-id" id="index-gtroff_002c-interactive-use"></a>
<p>Instruct <code class="code">gtroff</code> to flush its output immediately.  The intent is
for interactive use, but this behaviour is currently not implemented in
<code class="code">gtroff</code>.  Contrary to Unix <code class="code">troff</code>, TTY output is sent to a
device driver also (<code class="code">grotty</code>), making it non-trivial to communicate
interactively.
</p>
<p>This request causes a line break.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ebacktrace"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.backtrace</code></strong><a class="copiable-link" href='#index-_002ebacktrace'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-backtrace"></a>
<a class="index-entry-id" id="index-backtrace-of-input-stack-_0028backtrace_0029"></a>
<a class="index-entry-id" id="index-input-stack_002c-backtrace-_0028backtrace_0029"></a>
<p>Write the state of the input stack to the standard error stream.
</p>
<p>Consider the following in a file <samp class="file">test</samp>.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de xxx
.  backtrace
..
.de yyy
.  xxx
..
.
.yyy
    error&rarr; troff: backtrace: 'test':2: macro 'xxx'
    error&rarr; troff: backtrace: 'test':5: macro 'yyy'
    error&rarr; troff: backtrace: file 'test':8
</pre></div></div>

<p>The <samp class="option">-b</samp> option of GNU <code class="code">troff</code> causes a backtrace to be
generated on each error or warning.  Some warnings have to be enabled;
See <a class="xref" href="#Warnings">Warnings</a>.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_005cn_005bslimit_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[slimit]</code></strong><a class="copiable-link" href='#index-_005cn_005bslimit_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-slimit"></a>
<a class="index-entry-id" id="index-input-stack_002c-setting-limit"></a>
<p>If greater than&nbsp;0, sets the maximum quantity of objects on GNU
<code class="code">troff</code>&rsquo;s internal input stack.  If less than or equal to&nbsp;0,
there is no limit: recursion can continue until program memory is
exhausted.  The default is 1,000.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002ewarnscale"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.warnscale</code></strong> <var class="def-var-arguments">su</var><a class="copiable-link" href='#index-_002ewarnscale'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-warnscale"></a>
<p>Set the scaling unit used in certain warnings to <var class="var">su</var>, which can take the values &lsquo;<samp class="samp">u</samp>&rsquo;, &lsquo;<samp class="samp">i</samp>&rsquo;, &lsquo;<samp class="samp">c</samp>&rsquo;,
&lsquo;<samp class="samp">p</samp>&rsquo;, and &lsquo;<samp class="samp">P</samp>&rsquo;.  The default is &lsquo;<samp class="samp">i</samp>&rsquo;.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002espreadwarn"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.spreadwarn</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">limit</i></span>]</var><a class="copiable-link" href='#index-_002espreadwarn'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-spreadwarn"></a>
<p>Emit a <code class="code">break</code> warning if the additional space inserted for each
space between words in an output line adjusted to both margins with
&lsquo;<samp class="samp">.ad&nbsp;b</samp>&rsquo;<!-- /@w --> is larger than or equal to <var class="var">limit</var>.  A negative
value is treated as zero; an absent argument toggles the warning on and
off without changing <var class="var">limit</var>.  The default scaling unit is &lsquo;<samp class="samp">m</samp>&rsquo;.
At startup, <code class="code">spreadwarn</code> is inactive and <var class="var">limit</var> is 3<span class="dmn">m</span>.
</p>
<p>For example,
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.spreadwarn 0.2m
</pre></div></div>

<p>causes a warning if <code class="code">break</code> warnings are not suppressed and
<code class="code">gtroff</code> must add 0.2<span class="dmn">m</span> or more for each inter-word space in a
line.  See <a class="xref" href="#Warnings">Warnings</a>.
</p></dd></dl>

<a class="index-entry-id" id="index-warnings"></a>
<p>GNU <code class="code">troff</code> has command-line options for reporting warnings
(<samp class="option">-w</samp>) and backtraces (<samp class="option">-b</samp>) when a warning or an error
occurs.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002ewarn"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.warn</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">n</i></span>]</var><a class="copiable-link" href='#index-_002ewarn'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-warn"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ewarn_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.warn]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ewarn_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ewarn-1"></a>
<a class="index-entry-id" id="index-warning-level-_0028warn_0029"></a>
<p>Select the categories, or &ldquo;types&rdquo;, of reported warnings.
<var class="var">n</var>&nbsp;is the sum of the numeric codes associated with each
warning category that is to be enabled; all other categories are
disabled.  The categories and their associated codes are listed in
<a class="ref" href="#Warnings">Warnings</a>.  For example, &lsquo;<samp class="samp">.warn 0</samp>&rsquo; disables all warnings, and
&lsquo;<samp class="samp">.warn 1</samp>&rsquo; disables all warnings except those about missing glyphs.
If no argument is given, all warning categories are enabled.
</p>
<p>The read-only register <code class="code">.warn</code> contains the sum of the numeric
codes of enabled warning categories.
</p></dd></dl>



<ul class="mini-toc">
<li><a href="#Warnings" accesskey="1">Warnings</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="Warnings">
<div class="nav-panel">
<p>
Previous: <a href="#Debugging" accesskey="p" rel="prev">Debugging</a>, Up: <a href="#Debugging" accesskey="u" rel="up">Debugging</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Warnings-1">5.37.1 Warnings</h4>
<a class="index-entry-id" id="index-warnings-1"></a>

<p>Warning diagnostics emitted by GNU <code class="code">troff</code> are divided into named,
numbered categories.  The name associated with each warning category is
used by the <samp class="option">-w</samp> and <samp class="option">-W</samp> options.  Each category is also
assigned a power of two; the sum of enabled category values is used by
the <code class="code">warn</code> request and the <code class="code">.warn</code> register.
</p>
<p>Warnings of each category are produced under the following
circumstances.
</p>
<a class="index-entry-id" id="index-categories_002c-warning"></a>
<a class="index-entry-id" id="index-warning-categories"></a>
<dl class="table">
<dt>&lsquo;<samp class="samp">char</samp>&rsquo;</dt>
<dt>&lsquo;<samp class="samp">1</samp>&rsquo;</dt>
<dd><p>No mounted font defines a glyph for the requested character.  This
category is enabled by default.
</p>
</dd>
<dt>&lsquo;<samp class="samp">number</samp>&rsquo;</dt>
<dt>&lsquo;<samp class="samp">2</samp>&rsquo;</dt>
<dd><p>An invalid numeric expression was encountered.  This category is enabled
by default.
See <a class="xref" href="#Numeric-Expressions">Numeric Expressions</a>.
</p>
</dd>
<dt id='index-filling_002c-and-break-warnings'><span>&lsquo;<samp class="samp">break</samp>&rsquo;<a class="copiable-link" href='#index-filling_002c-and-break-warnings'> &para;</a></span></dt>
<dt>&lsquo;<samp class="samp">4</samp>&rsquo;</dt>
<dd><a class="index-entry-id" id="index-mode_002c-fill_002c-and-break-warnings"></a>
<p>A filled output line could not be broken such that its length was less
than the output line length &lsquo;<samp class="samp">\n[.l]</samp>&rsquo;.  This category is enabled by
default.
</p>
</dd>
<dt>&lsquo;<samp class="samp">delim</samp>&rsquo;</dt>
<dt>&lsquo;<samp class="samp">8</samp>&rsquo;</dt>
<dd><p>The closing delimiter in an escape sequence was missing or mismatched.
</p>
</dd>
<dt id='index-ie-request_002c-and-warnings'><span>&lsquo;<samp class="samp">el</samp>&rsquo;<a class="copiable-link" href='#index-ie-request_002c-and-warnings'> &para;</a></span></dt>
<dt>&lsquo;<samp class="samp">16</samp>&rsquo;</dt>
<dd><a class="index-entry-id" id="index-el-request_002c-and-warnings"></a>
<p>The <code class="code">el</code> request was encountered with no prior corresponding
<code class="code">ie</code> request.  See <a class="xref" href="#if_002delse">if-else</a>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">scale</samp>&rsquo;</dt>
<dt>&lsquo;<samp class="samp">32</samp>&rsquo;</dt>
<dd><p>A scaling unit inappropriate to its context was used in a numeric
expression.
</p>
</dd>
<dt>&lsquo;<samp class="samp">range</samp>&rsquo;</dt>
<dt>&lsquo;<samp class="samp">64</samp>&rsquo;</dt>
<dd><p>A numeric expression was out of range for its context.
</p>
</dd>
<dt>&lsquo;<samp class="samp">syntax</samp>&rsquo;</dt>
<dt>&lsquo;<samp class="samp">128</samp>&rsquo;</dt>
<dd><p>A self-contradictory hyphenation mode was requested; an empty or
incomplete numeric expression was encountered; an operand to a numeric
operator was missing; an attempt was made to define a recursive, empty,
or nonsensical character class; or a <code class="code">groff</code> extension conditional
expression operator was used while in compatibility mode.
</p>
</dd>
<dt id='index-di-request_002c-and-warnings'><span>&lsquo;<samp class="samp">di</samp>&rsquo;<a class="copiable-link" href='#index-di-request_002c-and-warnings'> &para;</a></span></dt>
<dt>&lsquo;<samp class="samp">256</samp>&rsquo;</dt>
<dd><a class="index-entry-id" id="index-da-request_002c-and-warnings"></a>
<a class="index-entry-id" id="index-box-request_002c-and-warnings"></a>
<a class="index-entry-id" id="index-boxa-request_002c-and-warnings"></a>
<p>A <code class="code">di</code>, <code class="code">da</code>, <code class="code">box</code>, or <code class="code">boxa</code> request was invoked
without an argument when there was no current diversion.
</p>
</dd>
<dt id='index-de_002c-de1_002c-dei-requests_002c-and-warnings'><span>&lsquo;<samp class="samp">mac</samp>&rsquo;<a class="copiable-link" href='#index-de_002c-de1_002c-dei-requests_002c-and-warnings'> &para;</a></span></dt>
<dt>&lsquo;<samp class="samp">512</samp>&rsquo;</dt>
<dd><a class="index-entry-id" id="index-am_002c-am1_002c-ami-requests_002c-and-warnings"></a>
<a class="index-entry-id" id="index-ds_002c-ds1-requests_002c-and-warnings"></a>
<a class="index-entry-id" id="index-as_002c-as1-requests_002c-and-warnings"></a>
<a class="index-entry-id" id="index-di-request_002c-and-warnings-1"></a>
<a class="index-entry-id" id="index-da-request_002c-and-warnings-1"></a>
<a class="index-entry-id" id="index-box_002c-boxa-requests_002c-and-warnings"></a>
<a class="index-entry-id" id="index-_005c_002a_002c-and-warnings"></a>
<p>An undefined string, macro, or diversion was used.  When such an object
is dereferenced, an empty one of that name is automatically created.
So, unless it is later deleted, at most one warning is given for each.
</p>
<p>This warning is also emitted upon an attempt to move an unplanted trap
macro (see <a class="pxref" href="#Page-Location-Traps">Page Location Traps</a>).  In such cases, the unplanted macro
is <em class="emph">not</em> dereferenced, so it is not created if it does not exist.
</p>
</dd>
<dt id='index-nr-request_002c-and-warnings'><span>&lsquo;<samp class="samp">reg</samp>&rsquo;<a class="copiable-link" href='#index-nr-request_002c-and-warnings'> &para;</a></span></dt>
<dt>&lsquo;<samp class="samp">1024</samp>&rsquo;</dt>
<dd><a class="index-entry-id" id="index-_005cR_002c-and-warnings"></a>
<a class="index-entry-id" id="index-_005cn_002c-and-warnings"></a>
<p>An undefined register was used.  When an undefined register is
dereferenced, it is automatically defined with a value of&nbsp;0.  So,
unless it is later deleted, at most one warning is given for each.
</p>
</dd>
<dt id='index-_005ct_002c-and-warnings'><span>&lsquo;<samp class="samp">tab</samp>&rsquo;<a class="copiable-link" href='#index-_005ct_002c-and-warnings'> &para;</a></span></dt>
<dt>&lsquo;<samp class="samp">2048</samp>&rsquo;</dt>
<dd><p>A tab character was encountered where a number was expected, or appeared
in an unquoted macro argument.
</p>
</dd>
<dt id='index-_005c_007d_002c-and-warnings'><span>&lsquo;<samp class="samp">right-brace</samp>&rsquo;<a class="copiable-link" href='#index-_005c_007d_002c-and-warnings'> &para;</a></span></dt>
<dt>&lsquo;<samp class="samp">4096</samp>&rsquo;</dt>
<dd><p>A right brace escape sequence <code class="code">\}</code> was encountered where a number
was expected.
</p>
</dd>
<dt>&lsquo;<samp class="samp">missing</samp>&rsquo;</dt>
<dt>&lsquo;<samp class="samp">8192</samp>&rsquo;</dt>
<dd><p>A request was invoked with a mandatory argument absent.
</p>
</dd>
<dt>&lsquo;<samp class="samp">input</samp>&rsquo;</dt>
<dt>&lsquo;<samp class="samp">16384</samp>&rsquo;</dt>
<dd><p>An invalid character occurred on the input stream.
</p>
</dd>
<dt>&lsquo;<samp class="samp">escape</samp>&rsquo;</dt>
<dt>&lsquo;<samp class="samp">32768</samp>&rsquo;</dt>
<dd><p>An unsupported escape sequence was encountered.
</p>
</dd>
<dt id='index-compatibility-mode'><span>&lsquo;<samp class="samp">space</samp>&rsquo;<a class="copiable-link" href='#index-compatibility-mode'> &para;</a></span></dt>
<dt>&lsquo;<samp class="samp">65536</samp>&rsquo;</dt>
<dd><p>A space was missing between a request or macro and its argument.  This
warning is produced when an undefined name longer than two characters is
encountered and the first two characters of the name constitute a
defined name.  No request is invoked, no macro called, and an empty
macro is not defined.  This category is enabled by default.  It never
occurs in compatibility mode.
</p>
</dd>
<dt>&lsquo;<samp class="samp">font</samp>&rsquo;</dt>
<dt>&lsquo;<samp class="samp">131072</samp>&rsquo;</dt>
<dd><p>A non-existent font was selected, or the selection was ignored because a
font selection escape sequence was used after the output line
continuation escape sequence on an input line.  This category is enabled
by default.
</p>
</dd>
<dt>&lsquo;<samp class="samp">ig</samp>&rsquo;</dt>
<dt>&lsquo;<samp class="samp">262144</samp>&rsquo;</dt>
<dd><p>An invalid escape sequence occurred in input ignored using the <code class="code">ig</code>
request.  This warning category diagnoses a condition that is an error
when it occurs in non-ignored input.
</p>
</dd>
<dt>&lsquo;<samp class="samp">color</samp>&rsquo;</dt>
<dt>&lsquo;<samp class="samp">524288</samp>&rsquo;</dt>
<dd><p>An undefined color was selected, an attempt was made to define a color
using an unrecognized color space, an invalid component in a color
definition was encountered, or an attempt was made to redefine a default
color.
</p>
</dd>
<dt>&lsquo;<samp class="samp">file</samp>&rsquo;</dt>
<dt>&lsquo;<samp class="samp">1048576</samp>&rsquo;</dt>
<dd><p>An attempt was made to load a file that does not exist.  This category
is enabled by default.
</p></dd>
</dl>

<p>Two warning names group other warning categories for convenience.
</p>
<dl class="table">
<dt>&lsquo;<samp class="samp">all</samp>&rsquo;</dt>
<dd><p>All warning categories except &lsquo;<samp class="samp">di</samp>&rsquo;, &lsquo;<samp class="samp">mac</samp>&rsquo; and &lsquo;<samp class="samp">reg</samp>&rsquo;.
This shorthand is intended to produce all warnings that are useful with
macro packages written for <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> and its
descendants, which have less fastidious diagnostics than GNU
<code class="code">troff</code>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">w</samp>&rsquo;</dt>
<dd><p>All warning categories.  Authors of documents and macro packages
targeting <code class="code">groff</code> are encouraged to use this setting.
</p></dd>
</dl>


<hr>
</div>
</div>
<div class="section-level-extent" id="Implementation-Differences">
<div class="nav-panel">
<p>
Next: <a href="#Safer-Mode" accesskey="n" rel="next">Safer Mode</a>, Previous: <a href="#Debugging" accesskey="p" rel="prev">Debugging</a>, Up: <a href="#GNU-troff-Reference" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Implementation-Differences-1">5.38 Implementation Differences</h3>
<a class="index-entry-id" id="index-implementation-differences"></a>
<a class="index-entry-id" id="index-differences-in-implementation"></a>
<a class="index-entry-id" id="index-incompatibilities-with-AT_0026T-troff"></a>

<p>GNU <code class="code">troff</code> has a number of features that cause incompatibilities
with documents written for other versions of <code class="code">troff</code>.  Some GNU
extensions to <code class="code">troff</code> have become supported by other
implementations.
</p>


<ul class="mini-toc">
<li><a href="#Safer-Mode" accesskey="1">Safer Mode</a></li>
<li><a href="#Compatibility-Mode" accesskey="2">Compatibility Mode</a></li>
<li><a href="#Other-Differences" accesskey="3">Other Differences</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="Safer-Mode">
<div class="nav-panel">
<p>
Next: <a href="#Compatibility-Mode" accesskey="n" rel="next">Compatibility Mode</a>, Previous: <a href="#Implementation-Differences" accesskey="p" rel="prev">Implementation Differences</a>, Up: <a href="#Implementation-Differences" accesskey="u" rel="up">Implementation Differences</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Safer-Mode-1">5.38.1 Safer Mode</h4>
<a class="index-entry-id" id="index-safer-mode-7"></a>
<a class="index-entry-id" id="index-mode_002c-safer-7"></a>

<a class="index-entry-id" id="index-pi-request_002c-disabled-by-default"></a>
<a class="index-entry-id" id="index-sy-request_002c-disabled-by-default"></a>
<p>The formatter operates in &ldquo;safer&rdquo; mode by default; to mitigate risks
from untrusted input documents, the <code class="code">pi</code> and <code class="code">sy</code> requests are
disabled.  GNU <code class="code">troff</code>&rsquo;s <samp class="option">-U</samp> option enables &ldquo;unsafe
mode&rdquo;, restoring their function and enabling additional <code class="code">groff</code>
extension requests, <code class="code">open</code>, <code class="code">opena</code>, and <code class="code">pso</code>.
See <a class="xref" href="#I_002fO">I/O</a>.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Compatibility-Mode">
<div class="nav-panel">
<p>
Next: <a href="#Safer-Mode" accesskey="n" rel="next">Safer Mode</a>, Previous: <a href="#Other-Differences" accesskey="p" rel="prev">Other Differences</a>, Up: <a href="#Implementation-Differences" accesskey="u" rel="up">Implementation Differences</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Compatibility-Mode-1">5.38.2 Compatibility Mode</h4>
<a class="index-entry-id" id="index-compatibility-mode-1"></a>
<a class="index-entry-id" id="index-mode_002c-compatibility"></a>

<a class="index-entry-id" id="index-long-names"></a>
<a class="index-entry-id" id="index-names_002c-long"></a>
<a class="index-entry-id" id="index-_005c_002a_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-_005cn_002c-incompatibilities-with-AT_0026T-troff"></a>
<p>Long identifier names may be GNU <code class="code">troff</code>&rsquo;s most obvious innovation.
<abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> interprets &lsquo;<samp class="samp">.dsabcd</samp>&rsquo; as defining a
string &lsquo;<samp class="samp">ab</samp>&rsquo; with contents &lsquo;<samp class="samp">cd</samp>&rsquo;.  Normally, GNU <code class="code">troff</code>
interprets this as a call of a macro named <code class="code">dsabcd</code>.
<abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> also interprets &lsquo;<samp class="samp">\*[</samp>&rsquo; and &lsquo;<samp class="samp">\n[</samp>&rsquo; as
an interpolation of a string or register, respectively, named &lsquo;<samp class="samp">[</samp>&rsquo;.
In GNU <code class="code">troff</code>, however, the &lsquo;<samp class="samp">[</samp>&rsquo; is normally interpreted as
delimiting a long name.  In compatibility mode, GNU <code class="code">troff</code>
interprets names in the traditional way; they thus can be two characters
long at most.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_002ecp"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.cp</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">n</i></span>]</var><a class="copiable-link" href='#index-_002ecp'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-cp"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002eC_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.C]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002eC_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002eC"></a>
<p>If <var class="var">n</var> is missing or non-zero, turn on compatibility mode;
otherwise, turn it off.
</p>
<p>The read-only register <code class="code">.C</code> is&nbsp;1 if compatibility mode is on,
0&nbsp;otherwise.
</p>
<p>Compatibility mode can be also turned on with the <samp class="option">-C</samp>
command-line option.
</p></dd></dl>

<dl class="first-deffn">
<dt class="deffn" id="index-_002edo"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.do</code></strong> <var class="def-var-arguments">name</var><a class="copiable-link" href='#index-_002edo'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-do"></a>
</dd><dt class="deffnx def-cmd-deffn" id="index-_005cn_005b_002ecp_005d"><span class="category-def">Register: </span><span><strong class="def-name"><code class="t">\n[.cp]</code></strong><a class="copiable-link" href='#index-_005cn_005b_002ecp_005d'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-_002ecp-1"></a>
<p>The <code class="code">do</code> request interprets the string, request, diversion, or
macro <var class="var">name</var> (along with any further arguments) with compatibility
mode disabled.  Compatibility mode is restored (only if it was active)
when the <em class="emph">expansion</em> of <var class="var">name</var> is interpreted; that is, the
restored compatibility state applies to the contents of the macro,
string, or diversion <var class="var">name</var> as well as data read from files or pipes
if <var class="var">name</var> is any of the <code class="code">so</code>, <code class="code">soquiet</code>, <code class="code">mso</code>,
<code class="code">msoquiet</code>, or <code class="code">pso</code> requests.
</p>
<p>The following example illustrates several aspects of <code class="code">do</code> behavior.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de mac1
FOO
..
.de1 mac2
groff
.mac1
..
.de mac3
compatibility
.mac1
..
.de ma
\\$1
..
.cp 1
.do mac1
.do mac2 \&quot; mac2, defined with .de1, calls &quot;mac1&quot;
.do mac3 \&quot; mac3 calls &quot;ma&quot; with argument &quot;c1&quot;
.do mac3 \[ti] \&quot; groff syntax accepted in .do arguments
    &rArr; FOO groff FOO compatibility c1 ~
</pre></div></div>

<p>The read-only register <code class="code">.cp</code>, meaningful only when dereferenced
from a <code class="code">do</code> request, is&nbsp;1 if compatibility mode was on when
the <code class="code">do</code> request was encountered, and 0&nbsp;if it was not.  This
register is specialized and may require a statement of rationale.
</p>
<p>When writing macro packages or documents that use GNU <code class="code">troff</code>
features and which may be mixed with other packages or documents that do
not&mdash;common scenarios include serial processing of man pages or use of
the <code class="code">so</code> or <code class="code">mso</code> requests&mdash;you may desire correct operation
regardless of compatibility mode enablement in the surrounding context.
It may occur to you to save the existing value of &lsquo;<samp class="samp">\n(.C</samp>&rsquo; into a
register, say, &lsquo;<samp class="samp">_C</samp>&rsquo;, at the beginning of your file, turn
compatibility mode off with &lsquo;<samp class="samp">.cp 0</samp>&rsquo;, then restore it from that
register at the end with &lsquo;<samp class="samp">.cp \n(_C</samp>&rsquo;.  At the same time, a modular
design of a document or macro package may lead you to multiple layers of
inclusion.  You cannot use the same register name everywhere lest you
&ldquo;clobber&rdquo; the value from a preceding or enclosing context.  The
two-character register name space of <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> is
confining and mnemonically challenging; you may wish to use the more
capacious name space of GNU <code class="code">troff</code>.  However, attempting &lsquo;<samp class="samp">.nr
_my_saved_C \n(.C</samp>&rsquo; will not work in compatibility mode; the register
name is too long.  &ldquo;This is exactly what <code class="code">do</code> is for,&rdquo; you think,
&lsquo;<samp class="samp">.do nr _my_saved_C \n(.C</samp>&rsquo;.  The foregoing will always save zero to
your register, because <code class="code">do</code> turns compatibility mode <em class="emph">off</em>
while it interprets its argument list.
</p>
<p>To robustly save compatibility mode before switching it off, use
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.do nr _my_saved_C \n[.cp]
.cp 0
</pre></div></div>

<p>at the beginning of your file, followed by
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.cp \n[_my_saved_C]
.do rr _my_saved_C
</pre></div></div>

<p>at the end.  As in the C language, we all have to share one big
name space, so choose a register name that is unlikely to collide with
other uses.
</p></dd></dl>

<a class="index-entry-id" id="index-input-level-in-delimited-arguments"></a>
<a class="index-entry-id" id="index-interpolation-depth-in-delimited-arguments"></a>
<a class="index-entry-id" id="index-delimited-arguments_002c-incompatibilities-with-AT_0026T-troff"></a>
<p>Normally, GNU <code class="code">troff</code> preserves the interpolation depth in
delimited arguments, but not in compatibility mode.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.ds xx '
\w'abc\*(xxdef'
    &rArr; 168 <span class="r">(normal mode on a terminal device)</span>
    &rArr; 72def' <span class="r">(compatibility mode on a terminal device)</span>
</pre></div></div>

<a class="index-entry-id" id="index-_005cf_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-_005cH_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-_005cs_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-_005cS_002c-incompatibilities-with-AT_0026T-troff"></a>
<p>Furthermore, the escape sequences <code class="code">\f</code>, <code class="code">\H</code>, <code class="code">\m</code>,
<code class="code">\M</code>, <code class="code">\R</code>, <code class="code">\s</code>, and <code class="code">\S</code> are transparent for the
purpose of recognizing a control character at the beginning of a line
only in compatibility mode.  For example, this code produces bold output
in both cases, but the text differs.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.de xx
Hello!
..
\fB.xx\fP
    &rArr; .xx <span class="r">(normal mode)</span>
    &rArr; Hello! <span class="r">(compatibility mode)</span>
</pre></div></div>

<a class="index-entry-id" id="index-_005cs_002c-incompatibilities-with-AT_0026T-troff-1"></a>
<p>Normally, the syntax form <code class="code">\s</code><var class="var">n</var> accepts only a single
character (a digit) for <var class="var">n</var>, consistently with other forms that
originated in <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>, like <code class="code">\*</code>, <code class="code">\$</code>,
<code class="code">\f</code>, <code class="code">\g</code>, <code class="code">\k</code>, <code class="code">\n</code>, and <code class="code">\z</code>.  In
compatibility mode only, a non-zero&nbsp;<var class="var">n</var> must be in the range
4&ndash;39.  Legacy documents relying upon this quirk of parsing<a class="footnote" id="DOCF120" href="#FOOT120"><sup>120</sup></a> should be migrated to another
<code class="code">\s</code> form.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Other-Differences">
<div class="nav-panel">
<p>
Previous: <a href="#Compatibility-Mode" accesskey="p" rel="prev">Compatibility Mode</a>, Up: <a href="#Implementation-Differences" accesskey="u" rel="up">Implementation Differences</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Other-Differences-1">5.38.3 Other Differences</h4>

<p><code class="code">groff</code> request names unrecognized by other <code class="code">troff</code>
implementations will likely be ignored by them; escape sequences that
are <code class="code">groff</code> extensions are liable to be interpreted as if the
escape character were not present.
<a class="index-entry-id" id="index-_005c_007e_002c-incompatibilities-with-AT_0026T-troff"></a>
For example, the adjustable, non-breaking escape sequence <code class="code">\~</code>
is also supported by Heirloom Doctools <code class="code">troff</code> 050915 (September
2005), <code class="code">mandoc</code> 1.9.5 (2009-09-21), <code class="code">neatroff</code> (commit
1c6ab0f6e, 2016-09-13), and Plan&nbsp;9 from User Space <code class="code">troff</code>
(commit 93f8143600, 2022-08-12), but not by Solaris or Documenter&rsquo;s
Workbench <code class="code">troff</code>s.
See <a class="xref" href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a>.
</p>
<a class="index-entry-id" id="index-_005cA_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-_005c_007c_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-_005c_005e_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-_005c_0026_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-_005c_007b_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-_005c_007d_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-_005cSP_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-_005c_0027_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-_005c_0060_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-_005c_002d_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-_005c_005f_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-_005c_0021_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-_005c_0025_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-_005cc_002c-incompatibilities-with-AT_0026T-troff"></a>
<p>GNU <code class="code">troff</code> does not allow the use of the escape sequences
<code class="code">\|</code>, <code class="code">\^</code>, <code class="code">\&amp;</code>, <code class="code">\{</code>, <code class="code">\}</code>,
<code class="code">\<kbd class="key">SP</kbd></code>, <code class="code">\'</code>, <code class="code">\`</code>, <code class="code">\-</code>, <code class="code">\_</code>, <code class="code">\!</code>,
<code class="code">\%</code>, and <code class="code">\c</code> in identifiers; <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>
does.  The <code class="code">\A</code> escape sequence (see <a class="pxref" href="#Identifiers">Identifiers</a>) may be
helpful in avoiding use of these escape sequences in names.
</p>
<a class="index-entry-id" id="index-adjustment-to-both-margins_002c-difference-from-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-rivers"></a>
<p>When adjusting to both margins, <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> at first
adjusts spaces starting from the right; GNU <code class="code">troff</code> begins from
the left.  Both implementations adjust spaces from opposite ends on
alternating output lines in this adjustment mode to prevent &ldquo;rivers&rdquo;
in the text.
</p>
<a class="index-entry-id" id="index-hyphenation_002c-incompatibilities-with-AT_0026T-troff"></a>
<p>GNU <code class="code">troff</code> does not always hyphenate words as <abbr class="acronym">AT&amp;T</abbr>
<code class="code">troff</code> does.  The <abbr class="acronym">AT&amp;T</abbr> implementation uses a set of
hard-coded rules specific to English, while GNU <code class="code">troff</code> uses
language-specific hyphenation pattern files derived from TeX.
Furthermore, in old versions of <code class="code">troff</code> there was a limited amount
of space to store hyphenation exceptions (arguments to the <code class="code">hw</code>
request); GNU <code class="code">troff</code> has no such restriction.
</p>
<a class="index-entry-id" id="index-output-device-name-string-_0028_002eT_0029_002c-in-other-implementations"></a>
<p>GNU <code class="code">troff</code> predefines a string <code class="code">.T</code> containing the argument
given to the <samp class="option">-T</samp> command-line option, namely the current output
device (for example, &lsquo;<samp class="samp">pdf</samp>&rsquo; or &lsquo;<samp class="samp">utf8</samp>&rsquo;).  The existence of this
string is a common feature of post-CSTR&nbsp;#54
<code class="code">troff</code>s<a class="footnote" id="DOCF121" href="#FOOT121"><sup>121</sup></a> but valid values are specific
to each implementation.
</p>
<a class="index-entry-id" id="index-removal-of-read_002donly-registers_002c-incompatibility-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-register_002c-read_002donly_002c-removal_002c-incompatibility-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-read_002donly-register-removal_002c-incompatibility-with-AT_0026T-troff"></a>
<p><abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> ignored attempts to remove read-only
registers; GNU <code class="code">troff</code> honors such requests.  See <a class="xref" href="#Built_002din-Registers">Built-in Registers</a>.
</p>
<a class="index-entry-id" id="index-output-device-usage-register-_0028_002eT_0029_002c-incompatibility-with-AT_0026T-troff"></a>
<p>The (read-only) register <code class="code">.T</code> interpolates&nbsp;1 if GNU
<code class="code">troff</code> is called with the <samp class="option">-T</samp> command-line option, and
0&nbsp;otherwise.  This behavior differs from AT&amp;T <code class="code">troff</code>, which
interpolated&nbsp;1 only if <code class="code">nroff</code> was the formatter and was
called with <samp class="option">-T</samp>.
</p>
<a class="index-entry-id" id="index-lf-request_002c-incompatibilities-with-AT_0026T-troff"></a>
<p><abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> and other implementations handle the
<code class="code">lf</code> request differently.  For them, its <var class="var">line</var> argument
changes the line number of the <em class="emph">current</em> line.
</p>
<a class="index-entry-id" id="index-environment-availability-and-naming_002c-incompatibilities-with"></a>
<p><abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> had only environments named &lsquo;<samp class="samp">0</samp>&rsquo;,
&lsquo;<samp class="samp">1</samp>&rsquo;, and &lsquo;<samp class="samp">2</samp>&rsquo;.  In GNU <code class="code">troff</code>, any number of environments
may exist, using any valid identifiers for their names
(see <a class="pxref" href="#Identifiers">Identifiers</a>.)
</p>
<a class="index-entry-id" id="index-fractional-point-sizes-1"></a>
<a class="index-entry-id" id="index-fractional-type-sizes-1"></a>
<a class="index-entry-id" id="index-point-sizes_002c-fractional-1"></a>
<a class="index-entry-id" id="index-type-sizes_002c-fractional-1"></a>
<a class="index-entry-id" id="index-sizes_002c-fractional"></a>
<a class="index-entry-id" id="index-ps-request_002c-incompatibilities-with-AT_0026T-troff"></a>
<p>Fractional type sizes cause one noteworthy incompatibility.  In
<abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> the <code class="code">ps</code> request ignores scaling units
and thus &lsquo;<samp class="samp">.ps 10u</samp>&rsquo; sets the type size to 10&nbsp;points, whereas in
GNU <code class="code">troff</code> it sets the type size to 10&nbsp;<em class="emph">scaled</em> points.
See <a class="xref" href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a>.
</p>
<a class="index-entry-id" id="index-ab-request_002c-incompatibilities-with-AT_0026T-troff"></a>
<p>The <code class="code">ab</code> request differs from <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>:
GNU <code class="code">troff</code> writes no message to the standard error stream if no
arguments are given, and it exits with a failure status instead of a
successful one.
</p>
<a class="index-entry-id" id="index-bp-request_002c-incompatibilities-with-AT_0026T-troff"></a>
<p>The <code class="code">bp</code> request differs from <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>:
GNU <code class="code">troff</code> does not accept a scaling unit on the argument, a page
number; the former (somewhat uselessly) does.
</p>
<a class="index-entry-id" id="index-pm-request_002c-incompatibilities-with-AT_0026T-troff"></a>
<p>The <code class="code">pm</code> request differs from <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>:
GNU <code class="code">troff</code> reports the sizes of macros, strings, and diversions in
bytes and ignores an argument to report only the sum of the sizes.
</p>
<a class="index-entry-id" id="index-ss-request_002c-incompatibilities-with-AT_0026T-troff"></a>
<p>Unlike <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>, GNU <code class="code">troff</code> does not ignore the
<code class="code">ss</code> request if the output is a terminal device; instead, the
values of minimal inter-word and additional inter-sentence space are
each rounded down to the nearest multiple of&nbsp;12.
</p>
<a class="index-entry-id" id="index-bd-request_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-cs-request_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-tr-request_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-fp-request_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-input-characters-and-output-glyphs_002c-compatibility-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-output-glyphs_002c-and-input-characters_002c-compatibility-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-characters_002c-input_002c-and-output-glyphs_002c-compatibility-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-glyphs_002c-output_002c-and-input-characters_002c-compatibility-with-AT_0026T-troff"></a>
<p>In GNU <code class="code">troff</code> there is a fundamental difference between
(unformatted) characters and (formatted) glyphs.  Everything that
affects how a glyph is output is stored with the glyph node; once a
glyph node has been constructed, it is unaffected by any subsequent
requests that are executed, including <code class="code">bd</code>, <code class="code">cs</code>, <code class="code">tkf</code>,
<code class="code">tr</code>, or <code class="code">fp</code> requests.  Normally, glyphs are constructed from
characters immediately before the glyph is added to an output line.
Macros, diversions, and strings are all, in fact, the same type of
object; they contain a sequence of intermixed character and glyph nodes.
Special characters transform from one to the other: before being added
to the output, they behave as characters; afterward, they are glyphs.  A
glyph node does not behave like a character node when it is processed by
a macro: it does not inherit any of the special properties that the
character from which it was constructed might have had.  For example,
the input
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.di x
\\\\
.br
.di
.x
</pre></div></div>

<p>produces &lsquo;<samp class="samp">\\</samp>&rsquo; in GNU <code class="code">troff</code>.  Each pair of backslashes
becomes one backslash <em class="emph">glyph</em>; the resulting backslashes are thus
not interpreted as escape <em class="emph">characters</em> when they are reread as the
diversion is output.  <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> <em class="emph">would</em> interpret
them as escape characters when rereading them and end up printing one
&lsquo;<samp class="samp">\</samp>&rsquo;.
</p>
<a class="index-entry-id" id="index-printing-backslash-_0028_005c_005c_002c-_005ce_002c-_005cE_002c-_005c_005brs_005d_0029"></a>
<a class="index-entry-id" id="index-backslash_002c-printing-_0028_005c_005c_002c-_005ce_002c-_005cE_002c-_005c_005brs_005d_0029"></a>
<a class="index-entry-id" id="index-_005ce_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-_005c_0021_002c-incompatibilities-with-AT_0026T-troff-1"></a>
<a class="index-entry-id" id="index-_005c_003f_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-transparent-output_002c-incompatibilities-with-AT_0026T-troff"></a>
<a class="index-entry-id" id="index-output_002c-transparent_002c-incompatibilities-with-AT_0026T-troff"></a>
<p>One correct way to obtain a printable backslash in most documents is to
use the <code class="code">\e</code> escape sequence; this always prints a single instance
of the current escape character,<a class="footnote" id="DOCF122" href="#FOOT122"><sup>122</sup></a> regardless of whether or not it is used in a diversion; it
also works in both GNU <code class="code">troff</code> and <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>.
</p>
<p>The other correct way, appropriate in contexts independent of the
backslash&rsquo;s common use as a <code class="code">troff</code> escape character&mdash;perhaps in
discussion of character sets or other programming languages&mdash;is
the character escape <code class="code">\(rs</code> or <code class="code">\[rs]</code>, for &ldquo;reverse
solidus&rdquo;, from its name in the <abbr class="acronym">ECMA-6</abbr> (<abbr class="acronym">ISO/IEC</abbr> 646)
standard.<a class="footnote" id="DOCF123" href="#FOOT123"><sup>123</sup></a>
</p>
<p>To store an escape sequence in a diversion that is interpreted when the
diversion is reread, either use the traditional <code class="code">\!</code> transparent
output facility, or, if this is unsuitable, the new <code class="code">\?</code> escape
sequence.  See <a class="xref" href="#Diversions">Diversions</a> and <a class="ref" href="#Gtroff-Internals"><code class="code">gtroff</code> Internals</a>.
</p>
<p>In the somewhat pathological case where a diversion exists containing a
partially collected line and a partially collected line at the top-level
diversion has never existed, <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> will output the
partially collected line at the end of input; GNU <code class="code">troff</code> will not.
</p>




<hr>
</div>
</div>
</div>
<div class="chapter-level-extent" id="File-Formats">
<div class="nav-panel">
<p>
Next: <a href="#Copying-This-Manual" accesskey="n" rel="next">Copying This Manual</a>, Previous: <a href="#GNU-troff-Reference" accesskey="p" rel="prev">GNU <code class="code">troff</code> Reference</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU <code class="code">troff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="chapter" id="File-Formats-1">6 File Formats</h2>
<a class="index-entry-id" id="index-file-formats"></a>
<a class="index-entry-id" id="index-formats_002c-file"></a>

<p>All files read and written by <code class="code">gtroff</code> are text files.  The
following two sections describe their format.
</p>




<ul class="mini-toc">
<li><a href="#gtroff-Output" accesskey="1"><code class="code">gtroff</code> Output</a></li>
<li><a href="#Device-and-Font-Description-Files" accesskey="2">Device and Font Description Files</a></li>
</ul>
<hr>
<div class="section-level-extent" id="gtroff-Output">
<div class="nav-panel">
<p>
Next: <a href="#Device-and-Font-Description-Files" accesskey="n" rel="next">Device and Font Description Files</a>, Previous: <a href="#File-Formats" accesskey="p" rel="prev">File Formats</a>, Up: <a href="#File-Formats" accesskey="u" rel="up">File Formats</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="gtroff-Output-1">6.1 <code class="code">gtroff</code> Output</h3>
<a class="index-entry-id" id="index-gtroff_002c-output"></a>
<a class="index-entry-id" id="index-output_002c-gtroff"></a>

<p>This section describes the <code class="code">groff</code> intermediate output format
produced by GNU <code class="code">troff</code>.
</p>
<p>As <code class="code">groff</code> is a wrapper program around GNU <code class="code">troff</code> and
automatically calls an output driver (or &ldquo;postprocessor&rdquo;), this output
does not show up normally.  This is why it is called
<em class="emph">intermediate</em>.  <code class="code">groff</code> provides the option <samp class="option">-Z</samp> to
inhibit postprocessing such that the produced intermediate output is
sent to standard output just as it is when calling GNU <code class="code">troff</code>
directly.
</p>
<a class="index-entry-id" id="index-troff-output"></a>
<a class="index-entry-id" id="index-output_002c-troff"></a>
<a class="index-entry-id" id="index-intermediate-output"></a>
<a class="index-entry-id" id="index-output_002c-intermediate"></a>
<p>Here, the term <em class="dfn">troff output</em> describes what is output by
GNU <code class="code">troff</code>, while <em class="dfn">intermediate output</em> refers to the language
that is accepted by the parser that prepares this output for the output
drivers.  This parser handles whitespace more flexibly than
<abbr class="acronym">AT&amp;T</abbr>&rsquo;s implementation and implements obsolete elements for
compatibility; otherwise, both formats are the same.<a class="footnote" id="DOCF124" href="#FOOT124"><sup>124</sup></a>
</p>
<p>The main purpose of the intermediate output concept is to facilitate the
development of postprocessors by providing a common programming
interface for all devices.  It has a language of its own that is
completely different from the <code class="code">gtroff</code> language.  While the
<code class="code">gtroff</code> language is a high-level programming language for text
processing, the intermediate output language is a kind of low-level
assembler language by specifying all positions on the page for writing
and drawing.
</p>
<p>The intermediate output produced by <code class="code">gtroff</code> is fairly readable,
while output from <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> is rather hard to
understand because of strange habits that are still supported, but not
used any longer by <code class="code">gtroff</code>.
</p>


<ul class="mini-toc">
<li><a href="#Language-Concepts" accesskey="1">Language Concepts</a></li>
<li><a href="#Command-Reference" accesskey="2">Command Reference</a></li>
<li><a href="#Intermediate-Output-Examples" accesskey="3">Intermediate Output Examples</a></li>
<li><a href="#Output-Language-Compatibility" accesskey="4">Output Language Compatibility</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="Language-Concepts">
<div class="nav-panel">
<p>
Next: <a href="#Command-Reference" accesskey="n" rel="next">Command Reference</a>, Previous: <a href="#gtroff-Output" accesskey="p" rel="prev"><code class="code">gtroff</code> Output</a>, Up: <a href="#gtroff-Output" accesskey="u" rel="up"><code class="code">gtroff</code> Output</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Language-Concepts-1">6.1.1 Language Concepts</h4>

<p>The fundamental operation of the GNU <code class="code">troff</code> formatter is the
translation of the <code class="code">groff</code> input language into a device-independent
form primarily concerned with what has to be written or drawn at
specific positions on the output device.  This language is simple and
imperative.  In the following discussion, the term <em class="dfn">command</em> always
refers to this intermediate output language, and never to the
<code class="code">groff</code> language intended for direct use by document authors.
Intermediate output commands comprise several categories: glyph output;
font, color, and text size selection; motion of the printing position;
page advancement; drawing of geometric objects; and device control
commands, a catch-all for operations not easily classified as any of the
foregoing, such as directives to start and stop output, identify the
intended output device, or place URL hyperlinks in supported output
formats.
</p>

<ul class="mini-toc">
<li><a href="#Separation" accesskey="1">Separation</a></li>
<li><a href="#Argument-Units" accesskey="2">Argument Units</a></li>
<li><a href="#Document-Parts" accesskey="3">Document Parts</a></li>
</ul>
<hr>
<div class="subsubsection-level-extent" id="Separation">
<div class="nav-panel">
<p>
Next: <a href="#Argument-Units" accesskey="n" rel="next">Argument Units</a>, Previous: <a href="#Language-Concepts" accesskey="p" rel="prev">Language Concepts</a>, Up: <a href="#Language-Concepts" accesskey="u" rel="up">Language Concepts</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Separation-1">6.1.1.1 Separation</h4>

<p><abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> output has strange requirements regarding
whitespace.  The <code class="code">gtroff</code> output parser, however, is more tolerant,
making whitespace maximally optional.  Such characters, i.e., the tab,
space, and newline, always have a syntactical meaning.  They are never
printable because spacing within the output is always done by
positioning commands.
</p>
<p>Any sequence of space or tab characters is treated as a single
<em class="dfn">syntactical space</em>.  It separates commands and arguments, but is
only required when there would occur a clashing between the command code
and the arguments without the space.  Most often, this happens when
variable-length command names, arguments, argument lists, or command
clusters meet.  Commands and arguments with a known, fixed length need
not be separated by syntactical space.
</p>
<p>A line break is a syntactical element, too.  Every command argument can
be followed by whitespace, a comment, or a newline character.  Thus a
<em class="dfn">syntactical line break</em> is defined to consist of optional
syntactical space that is optionally followed by a comment, and a
newline character.
</p>
<p>The normal commands, those for positioning and text, consist of a single
letter taking a fixed number of arguments.  For historical reasons, the
parser allows stacking of such commands on the same line, but
fortunately, in <code class="code">gtroff</code>&rsquo;s intermediate output, every command with
at least one argument is followed by a line break, thus providing
excellent readability.
</p>
<p>The other commands&mdash;those for drawing and device controlling&mdash;have a
more complicated structure; some recognize long command names, and some
take a variable number of arguments.  So all &lsquo;<samp class="samp">D</samp>&rsquo; and &lsquo;<samp class="samp">x</samp>&rsquo;
commands were designed to request a syntactical line break after their
last argument.  Only one command, &lsquo;<samp class="samp">x&nbsp;X</samp>&rsquo;<!-- /@w -->, has an argument that
can span several input lines; all other commands must have all of
their arguments on the same line as the command, i.e., the arguments may
not be split by a line break.
</p>
<p>Empty lines (these are lines containing only space and/or a comment),
can occur everywhere.  They are just ignored.
</p>
<hr>
</div>
<div class="subsubsection-level-extent" id="Argument-Units">
<div class="nav-panel">
<p>
Next: <a href="#Document-Parts" accesskey="n" rel="next">Document Parts</a>, Previous: <a href="#Separation" accesskey="p" rel="prev">Separation</a>, Up: <a href="#Language-Concepts" accesskey="u" rel="up">Language Concepts</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Argument-Units-1">6.1.1.2 Argument Units</h4>

<p>Some commands take integer arguments that are assumed to represent
values in a measurement unit, but the letter for the corresponding
scaling unit is not written with the output command arguments.  Most
commands assume the scaling unit &lsquo;<samp class="samp">u</samp>&rsquo;, the basic unit of the device,
some use &lsquo;<samp class="samp">z</samp>&rsquo;, the scaled point unit of the device, while others,
such as the color commands, expect plain integers.
</p>
<p>Single characters can have the eighth bit set, as can the names of
fonts and special characters.  The names of characters and fonts can be
of arbitrary length.  A character that is to be printed is always in
the current font.
</p>
<p>A string argument is always terminated by the next whitespace character
(space, tab, or newline); an embedded &lsquo;<samp class="samp">#</samp>&rsquo; character is regarded as
part of the argument, not as the beginning of a comment command.  An
integer argument is already terminated by the next non-digit character,
which then is regarded as the first character of the next argument or
command.
</p>
<hr>
</div>
<div class="subsubsection-level-extent" id="Document-Parts">
<div class="nav-panel">
<p>
Previous: <a href="#Argument-Units" accesskey="p" rel="prev">Argument Units</a>, Up: <a href="#Language-Concepts" accesskey="u" rel="up">Language Concepts</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Document-Parts-1">6.1.1.3 Document Parts</h4>

<p>A correct intermediate output document consists of two parts, the
<em class="dfn">prologue</em> and the <em class="dfn">body</em>.
</p>
<p>The task of the prologue is to set the general device parameters using
three exactly specified commands.  <code class="code">gtroff</code>&rsquo;s prologue is
guaranteed to consist of the following three lines (in that order):
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">x T <var class="var">device</var>
x res <var class="var">n</var> <var class="var">h</var> <var class="var">v</var>
x init
</pre></div></div>

<p>with the arguments set as outlined in <a class="ref" href="#Device-Control-Commands">Device Control Commands</a>.
The parser for the intermediate output format is able to interpret
additional whitespace and comments as well even in the prologue.
</p>
<p>The body is the main section for processing the document data.
Syntactically, it is a sequence of any commands different from the ones
used in the prologue.  Processing is terminated as soon as the first
&lsquo;<samp class="samp">x&nbsp;stop</samp>&rsquo;<!-- /@w --> command is encountered; the last line of any
<code class="code">gtroff</code> intermediate output always contains such a command.
</p>
<p>Semantically, the body is page oriented.  A new page is started by a
&lsquo;<samp class="samp">p</samp>&rsquo; command.  Positioning, writing, and drawing commands are always
done within the current page, so they cannot occur before the first
&lsquo;<samp class="samp">p</samp>&rsquo; command.  Absolute positioning (by the &lsquo;<samp class="samp">H</samp>&rsquo; and &lsquo;<samp class="samp">V</samp>&rsquo;
commands) is done relative to the current page; all other positioning is
done relative to the current location within this page.
</p>

<hr>
</div>
</div>
<div class="subsection-level-extent" id="Command-Reference">
<div class="nav-panel">
<p>
Next: <a href="#Intermediate-Output-Examples" accesskey="n" rel="next">Intermediate Output Examples</a>, Previous: <a href="#Language-Concepts" accesskey="p" rel="prev">Language Concepts</a>, Up: <a href="#gtroff-Output" accesskey="u" rel="up"><code class="code">gtroff</code> Output</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Command-Reference-1">6.1.2 Command Reference</h4>

<p>This section describes all intermediate output commands, both from
<abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> as well as the <code class="code">gtroff</code> extensions.
</p>

<ul class="mini-toc">
<li><a href="#Comment-Command" accesskey="1">Comment Command</a></li>
<li><a href="#Simple-Commands" accesskey="2">Simple Commands</a></li>
<li><a href="#Graphics-Commands" accesskey="3">Graphics Commands</a></li>
<li><a href="#Device-Control-Commands" accesskey="4">Device Control Commands</a></li>
<li><a href="#Obsolete-Command" accesskey="5">Obsolete Command</a></li>
</ul>
<hr>
<div class="subsubsection-level-extent" id="Comment-Command">
<div class="nav-panel">
<p>
Next: <a href="#Simple-Commands" accesskey="n" rel="next">Simple Commands</a>, Previous: <a href="#Command-Reference" accesskey="p" rel="prev">Command Reference</a>, Up: <a href="#Command-Reference" accesskey="u" rel="up">Command Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Comment-Command-1">6.1.2.1 Comment Command</h4>

<dl class="table">
<dt><code class="code">#<var class="var">anything</var>&lsaquo;<span class="r">end of line</span>&rsaquo;</code></dt>
<dd><p>A comment.  Ignore any characters from the &lsquo;<samp class="samp">#</samp>&rsquo; character up to the
next newline character.
</p>
<p>This command is the only possibility for commenting in the intermediate
output.  Each comment can be preceded by arbitrary syntactical space;
every command can be terminated by a comment.
</p></dd>
</dl>

<hr>
</div>
<div class="subsubsection-level-extent" id="Simple-Commands">
<div class="nav-panel">
<p>
Next: <a href="#Graphics-Commands" accesskey="n" rel="next">Graphics Commands</a>, Previous: <a href="#Comment-Command" accesskey="p" rel="prev">Comment Command</a>, Up: <a href="#Command-Reference" accesskey="u" rel="up">Command Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Simple-Commands-1">6.1.2.2 Simple Commands</h4>

<p>The commands in this subsection have a command code consisting of a
single character, taking a fixed number of arguments.  Most of them are
commands for positioning and text writing.  These commands are tolerant
of whitespace.  Optionally, syntactical space can be inserted before,
after, and between the command letter and its arguments.  All of these
commands are stackable; i.e., they can be preceded by other simple
commands or followed by arbitrary other commands on the same line.  A
separating syntactical space is necessary only when two integer
arguments would clash or if the preceding argument ends with a string
argument.
</p>
<dl class="table">
<dt><code class="code">C <var class="var">id</var>&lsaquo;<span class="r">whitespace</span>&rsaquo;</code></dt>
<dd><p>Typeset the glyph of the special character <var class="var">id</var>.  Trailing
syntactical space is necessary to allow special character names of
arbitrary length.  The drawing position is not advanced.
</p>
</dd>
<dt><code class="code">c <var class="var">g</var></code></dt>
<dd><p>Typeset the glyph of the ordinary character&nbsp;<var class="var">c</var>.  The drawing
position is not advanced.
</p>
</dd>
<dt><code class="code">f <var class="var">n</var></code></dt>
<dd><p>Select the font mounted at position&nbsp;<var class="var">n</var>.  <var class="var">n</var>&nbsp;cannot
be negative.
</p>
</dd>
<dt><code class="code">H <var class="var">n</var></code></dt>
<dd><p>Horizontally move the drawing position to <var class="var">n</var>&nbsp;basic units from
the left edge of the page.  <var class="var">n</var>&nbsp;cannot be negative.
</p>
</dd>
<dt><code class="code">h <var class="var">n</var></code></dt>
<dd><p>Move the drawing position right <var class="var">n</var> basic units.  <abbr class="acronym">AT&amp;T</abbr>
<code class="code">troff</code> allowed negative <var class="var">n</var>; GNU <code class="code">troff</code> does not produce
such values, but <code class="code">groff</code>&rsquo;s output driver library handles them.
</p>
</dd>
<dt><code class="code">m <var class="var">color-scheme</var> <span class="r">[</span><var class="var">component</var> &hellip;<span class="r">]</span></code></dt>
<dd><p>Select the stroke color using the <var class="var">component</var>s in the color space
<var class="var">scheme</var>.  Each <var class="var">component</var> is an integer between 0 and 65535.
The quantity of components and their meanings vary with each
<var class="var">scheme</var>.  This command is a <code class="code">groff</code> extension.
</p>
<dl class="table">
<dt><code class="code">mc <var class="var">cyan</var> <var class="var">magenta</var> <var class="var">yellow</var></code></dt>
<dd><p>Use the CMY color scheme with components cyan, magenta, and yellow.
</p>
</dd>
<dt><code class="code">md</code></dt>
<dd><p>Use the default color (no components; black in most cases).
</p>
</dd>
<dt><code class="code">mg <var class="var">gray</var></code></dt>
<dd><p>Use a grayscale color scheme with a component ranging between 0 (black)
and 65535 (white).
</p>
</dd>
<dt><code class="code">mk <var class="var">cyan</var> <var class="var">magenta</var> <var class="var">yellow</var> <var class="var">black</var></code></dt>
<dd><p>Use the CMYK color scheme with components cyan, magenta, yellow, and
black.
</p>
</dd>
<dt><code class="code">mr <var class="var">red</var> <var class="var">green</var> <var class="var">blue</var></code></dt>
<dd><p>Use the RGB color scheme with components red, green, and blue.
</p></dd>
</dl>

</dd>
<dt><code class="code">N <var class="var">n</var></code></dt>
<dd><p>Typeset the glyph with index&nbsp;<var class="var">n</var> in the current font.
<var class="var">n</var>&nbsp;is normally a non-negative integer.  The drawing position
is not advanced.  The <code class="code">html</code> and <code class="code">xhtml</code> devices use this
command with negative&nbsp;<var class="var">n</var> to produce unbreakable space; the
absolute value of <var class="var">n</var> is taken and interpreted in basic units.
</p>
</dd>
<dt><code class="code">n <var class="var">b</var> <var class="var">a</var></code></dt>
<dd><p>Indicate a break.  No action is performed; the command is present to
make the output more easily parsed.  The integers <var class="var">b</var>
and&nbsp;<var class="var">a</var> describe the vertical space amounts before and after
the break, respectively.  GNU <code class="code">troff</code> issues this command but
<code class="code">groff</code>&rsquo;s output driver library ignores it.  See <code class="code">v</code> and
<code class="code">V</code> below.
</p>
</dd>
<dt><code class="code">p <var class="var">n</var></code></dt>
<dd><p>Begin a new page, setting its number to&nbsp;<var class="var">n</var>.  Each page is
independent, even from those using the same number.  The vertical
drawing position is set to&nbsp;0.  All positioning, writing, and
drawing commands are interpreted in the context of a page, so a
<code class="code">p</code>&nbsp;command must precede them.
</p>
</dd>
<dt><code class="code">s <var class="var">n</var></code></dt>
<dd><p>Set type size to <var class="var">n</var> scaled points (unit&nbsp;<code class="code">z</code> in GNU
<code class="code">troff</code>.
<abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> used unscaled points <code class="code">p</code> instead;
see <a class="ref" href="#Output-Language-Compatibility">Output Language Compatibility</a>.
</p>
</dd>
<dt><code class="code">t <var class="var">xyz</var>&lsaquo;<span class="r">whitespace</span>&rsaquo;</code></dt>
<dt><code class="code">t <var class="var">xyz</var> <var class="var">dummy-arg</var>&lsaquo;<span class="r">whitespace</span>&rsaquo;</code></dt>
<dd><p>Typeset a word <var class="var">xyz</var>; that is, set a sequence of ordinary glyphs
named <var class="var">x</var>, <var class="var">y</var>, <var class="var">z</var>, &hellip;, terminated by a space
character or a line break; an optional second integer argument is
ignored (this allows the formatter to generate an even number of
arguments). Each glyph is set at the current drawing position, and the position is
then advanced horizontally by the glyph&rsquo;s width.  A glyph&rsquo;s width is
read from its metrics in the font description file, scaled to the
current type size, and rounded to a multiple of the horizontal motion
quantum.  Use the <code class="code">C</code> command to emplace glyphs of special
characters.  The <code class="code">t</code>&nbsp;command is a <code class="code">groff</code> extension and
is output only for devices whose <samp class="file">DESC</samp> file contains the
<code class="code">tcommand</code> directive; see <a class="ref" href="#DESC-File-Format"><samp class="file">DESC</samp> File Format</a>.
</p>
</dd>
<dt><code class="code">u <var class="var">n</var> <var class="var">xyz</var>&lsaquo;<span class="r">whitespace</span>&rsaquo;</code></dt>
<dd><p>Typeset word <var class="var">xyz</var> with track kerning.  As <code class="code">t</code>, but after
placing each glyph, the drawing position is further advanced
horizontally by&nbsp;<var class="var">n</var> basic units (<code class="code">u</code>).  The
<code class="code">u</code>&nbsp;command is a <code class="code">groff</code> extension and is output only for
devices whose <samp class="file">DESC</samp> file contains the <code class="code">tcommand</code> directive;
see <a class="ref" href="#DESC-File-Format"><samp class="file">DESC</samp> File Format</a>.
</p>
</dd>
<dt><code class="code">V <var class="var">n</var></code></dt>
<dd><p>Vertically move the drawing position to <var class="var">n</var>&nbsp;basic units from
the top edge of the page.  <var class="var">n</var>&nbsp;cannot be negative.
</p>
</dd>
<dt><code class="code">v <var class="var">n</var></code></dt>
<dd><p>Move the drawing position down <var class="var">n</var> basic units.  <abbr class="acronym">AT&amp;T</abbr>
<code class="code">troff</code> allowed negative <var class="var">n</var>; GNU <code class="code">troff</code> does not produce
such values, but <code class="code">groff</code>&rsquo;s output driver library handles them.
</p>
</dd>
<dt><code class="code">w</code></dt>
<dd><p>Indicate an inter-word space.  No action is performed; the command is
present to make the output more easily parsed.  Only adjustable,
breakable inter-word spaces are thus described; those resulting from
<code class="code">\~</code> or horizontal motion escape sequences are not.  GNU
<code class="code">troff</code> issues this command but <code class="code">groff</code>&rsquo;s output driver
library ignores it.  See <code class="code">h</code> and <code class="code">H</code> above.
</p></dd>
</dl>

<hr>
</div>
<div class="subsubsection-level-extent" id="Graphics-Commands">
<div class="nav-panel">
<p>
Next: <a href="#Device-Control-Commands" accesskey="n" rel="next">Device Control Commands</a>, Previous: <a href="#Simple-Commands" accesskey="p" rel="prev">Simple Commands</a>, Up: <a href="#Command-Reference" accesskey="u" rel="up">Command Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Graphics-Commands-1">6.1.2.3 Graphics Commands</h4>

<p>Each graphics or drawing command in the intermediate output starts with
the letter &lsquo;<samp class="samp">D</samp>&rsquo;, followed by one or two characters that specify a
subcommand; this is followed by a fixed or variable number of integer
arguments that are separated by a single space character.  A &lsquo;<samp class="samp">D</samp>&rsquo;
command may not be followed by another command on the same line (apart
from a comment), so each &lsquo;<samp class="samp">D</samp>&rsquo; command is terminated by a syntactical
line break.
</p>
<p><code class="code">gtroff</code> output follows the classical spacing rules (no space
between command and subcommand, all arguments are preceded by a single
space character), but the parser allows optional space between the
command letters and makes the space before the first argument optional.
As usual, each space can be any sequence of tab and space characters.
</p>
<p>Some graphics commands can take a variable number of arguments.  In this
case, they are integers representing a size measured in basic units
&lsquo;<samp class="samp">u</samp>&rsquo;.  The arguments called <var class="var">h1</var>, <var class="var">h2</var>, &hellip;, <var class="var">hn</var>
stand for horizontal distances where positive means right, negative
left.  The arguments called <var class="var">v1</var>, <var class="var">v2</var>, &hellip;, <var class="var">vn</var> stand
for vertical distances where positive means down, negative up.  All
these distances are offsets relative to the current location.
</p>
<p>Each graphics command directly corresponds to a similar <code class="code">gtroff</code>
<code class="code">\D</code> escape sequence.  See <a class="xref" href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a>.
</p>
<p>Unknown &lsquo;<samp class="samp">D</samp>&rsquo; commands are assumed to be device-specific.  Its
arguments are parsed as strings; the whole information is then sent to
the postprocessor.
</p>
<p>In the following command reference, the syntax element &lsaquo;<span class="r">line
break</span>&rsaquo; means a syntactical line break as defined above.
</p>
<dl class="table">
<dt><code class="code">D~ <var class="var">h1</var> <var class="var">v1</var> <var class="var">h2</var> <var class="var">v2</var> &hellip; <var class="var">hn</var> <var class="var">vn</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>Draw B-spline from current position to offset (<var class="var">h1</var>,<var class="var">v1</var>), then
to offset (<var class="var">h2</var>,<var class="var">v2</var>), if given, etc., up to
(<var class="var">hn</var>,<var class="var">vn</var>).  This command takes a variable number of argument
pairs; the current position is moved to the terminal point of the drawn
curve.
</p>
</dd>
<dt><code class="code">Da <var class="var">h1</var> <var class="var">v1</var> <var class="var">h2</var> <var class="var">v2</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>Draw arc from current position to
(<var class="var">h1</var>,<var class="var">v1</var>)<em class="math">+</em>(<var class="var">h2</var>,<var class="var">v2</var>) with center at
(<var class="var">h1</var>,<var class="var">v1</var>); then move the current position to the final point
of the arc.
</p>
</dd>
<dt><code class="code">DC <var class="var">d</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dt><code class="code">DC <var class="var">d</var> <var class="var">dummy-arg</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>Draw a solid circle using the current fill color with
diameter&nbsp;<var class="var">d</var> (integer in basic units &lsquo;<samp class="samp">u</samp>&rsquo;) with leftmost
point at the current position; then move the current position to the
rightmost point of the circle.  An optional second integer argument is
ignored (this allows the formatter to generate an even number of
arguments).  This command is a <code class="code">gtroff</code> extension.
</p>
</dd>
<dt><code class="code">Dc <var class="var">d</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>Draw circle line with diameter&nbsp;<var class="var">d</var> (integer in basic units
&lsquo;<samp class="samp">u</samp>&rsquo;) with leftmost point at the current position; then move the
current position to the rightmost point of the circle.
</p>
</dd>
<dt><code class="code">DE <var class="var">h</var> <var class="var">v</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>Draw a solid ellipse in the current fill color with a horizontal
diameter of&nbsp;<var class="var">h</var> and a vertical diameter of&nbsp;<var class="var">v</var> (both
integers in basic units &lsquo;<samp class="samp">u</samp>&rsquo;) with the leftmost point at the current
position; then move to the rightmost point of the ellipse.  This command
is a <code class="code">gtroff</code> extension.
</p>
</dd>
<dt><code class="code">De <var class="var">h</var> <var class="var">v</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>Draw an outlined ellipse with a horizontal diameter of&nbsp;<var class="var">h</var> and
a vertical diameter of&nbsp;<var class="var">v</var> (both integers in basic units
&lsquo;<samp class="samp">u</samp>&rsquo;) with the leftmost point at current position; then move to the
rightmost point of the ellipse.
</p>
</dd>
<dt><code class="code">DF <var class="var">color-scheme</var> <span class="r">[</span><var class="var">component</var> &hellip;<span class="r">]</span>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>Set fill color for solid drawing objects using different color schemes;
the analogous command for setting the color of text, line graphics, and
the outline of graphic objects is &lsquo;<samp class="samp">m</samp>&rsquo;.  The color components are
specified as integer arguments between 0 and 65535.  The number of color
components and their meaning vary for the different color schemes.
These commands are generated by <code class="code">gtroff</code>&rsquo;s escape sequences
&lsquo;<samp class="samp">\D'F &hellip;'</samp>&rsquo; and <code class="code">\M</code> (with no other corresponding
graphics commands).  No position changing.  This command is a
<code class="code">gtroff</code> extension.
</p>
<dl class="table">
<dt><code class="code">DFc <var class="var">cyan</var> <var class="var">magenta</var> <var class="var">yellow</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>Set fill color for solid drawing objects using the CMY color scheme,
having the 3&nbsp;color components <var class="var">cyan</var>, <var class="var">magenta</var>, and
<var class="var">yellow</var>.
</p>
</dd>
<dt><code class="code">DFd&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>Set fill color for solid drawing objects to the default fill color value
(black in most cases).  No component arguments.
</p>
</dd>
<dt><code class="code">DFg <var class="var">gray</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>Set fill color for solid drawing objects to the shade of gray given by
the argument, an integer between 0 (black) and 65535 (white).
</p>
</dd>
<dt><code class="code">DFk <var class="var">cyan</var> <var class="var">magenta</var> <var class="var">yellow</var> <var class="var">black</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>Set fill color for solid drawing objects using the CMYK color scheme,
having the 4&nbsp;color components <var class="var">cyan</var>, <var class="var">magenta</var>,
<var class="var">yellow</var>, and <var class="var">black</var>.
</p>
</dd>
<dt><code class="code">DFr <var class="var">red</var> <var class="var">green</var> <var class="var">blue</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>Set fill color for solid drawing objects using the RGB color scheme,
having the 3&nbsp;color components <var class="var">red</var>, <var class="var">green</var>, and
<var class="var">blue</var>.
</p></dd>
</dl>

</dd>
<dt><code class="code">Df <var class="var">n</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>The argument&nbsp;<var class="var">n</var> must be an integer in the range <em class="math">-32767</em>
to 32767.
</p>
<dl class="table">
<dt><em class="math">0 &le; <var class="var">n</var> &le; 1000</em></dt>
<dd><p>Set the color for filling solid drawing objects to a shade of gray,
where 0 corresponds to solid white, 1000 (the default) to solid black,
and values in between to intermediate shades of gray; this is obsoleted
by command &lsquo;<samp class="samp">DFg</samp>&rsquo;.
</p>
</dd>
<dt><em class="math"><var class="var">n</var> &lt; 0</em> or <em class="math"><var class="var">n</var> &gt; 1000</em></dt>
<dd><p>Set the filling color to the color that is currently being used for the
text and the outline, see command &lsquo;<samp class="samp">m</samp>&rsquo;.  For example, the command
sequence
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">mg 0 0 65535
Df -1
</pre></div></div>

<p>sets all colors to blue.
</p></dd>
</dl>

<p>No position changing.  This command is a <code class="code">gtroff</code> extension.
</p>
</dd>
<dt><code class="code">Dl <var class="var">h</var> <var class="var">v</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>Draw line from current position to offset (<var class="var">h</var>,<var class="var">v</var>) (integers in
basic units &lsquo;<samp class="samp">u</samp>&rsquo;); then set current position to the end of the drawn
line.
</p>
</dd>
<dt><code class="code">Dp <var class="var">h1</var> <var class="var">v1</var> <var class="var">h2</var> <var class="var">v2</var> &hellip; <var class="var">hn</var> <var class="var">vn</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>Draw a polygon line from current position to offset (<var class="var">h1</var>,<var class="var">v1</var>),
from there to offset (<var class="var">h2</var>,<var class="var">v2</var>), etc., up to offset
(<var class="var">hn</var>,<var class="var">vn</var>), and from there back to the starting position.  For
historical reasons, the position is changed by adding the sum of all
arguments with odd index to the actual horizontal position and the even
ones to the vertical position.  Although this doesn&rsquo;t make sense it is
kept for compatibility.
This command is a <code class="code">gtroff</code> extension.
</p>
</dd>
<dt><code class="code">DP <var class="var">h1</var> <var class="var">v1</var> <var class="var">h2</var> <var class="var">v2</var> &hellip; <var class="var">hn</var> <var class="var">vn</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>Draw a solid polygon in the current fill color rather than an outlined
polygon, using the same arguments and positioning as the corresponding
&lsquo;<samp class="samp">Dp</samp>&rsquo; command.
This command is a <code class="code">gtroff</code> extension.
</p>
</dd>
<dt><code class="code">Dt <var class="var">n</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>Set the current line thickness to&nbsp;<var class="var">n</var> (an integer in basic
units &lsquo;<samp class="samp">u</samp>&rsquo;) if <em class="math"><var class="var">n</var>&gt;0</em>; if <em class="math"><var class="var">n</var>=0</em> select the
smallest available line thickness; if <em class="math"><var class="var">n</var>&lt;0</em> set the line
thickness proportional to the type size (this is the default before the
first &lsquo;<samp class="samp">Dt</samp>&rsquo; command was specified).  For historical reasons, the
horizontal position is changed by adding the argument to the actual
horizontal position, while the vertical position is not changed.
Although this doesn&rsquo;t make sense it is kept for compatibility.
This command is a <code class="code">gtroff</code> extension.
</p></dd>
</dl>

<hr>
</div>
<div class="subsubsection-level-extent" id="Device-Control-Commands">
<div class="nav-panel">
<p>
Next: <a href="#Obsolete-Command" accesskey="n" rel="next">Obsolete Command</a>, Previous: <a href="#Graphics-Commands" accesskey="p" rel="prev">Graphics Commands</a>, Up: <a href="#Command-Reference" accesskey="u" rel="up">Command Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Device-Control-Commands-1">6.1.2.4 Device Control Commands</h4>

<p>Each device control command starts with the letter &lsquo;<samp class="samp">x</samp>&rsquo;, followed by
a space character (optional or arbitrary space or tab in <code class="code">gtroff</code>)
and a subcommand letter or word; each argument (if any) must be preceded
by a syntactical space.  All &lsquo;<samp class="samp">x</samp>&rsquo; commands are terminated by a
syntactical line break; no device control command can be followed by
another command on the same line (except a comment).
</p>
<p>The subcommand is basically a single letter, but to increase
readability, it can be written as a word, i.e., an arbitrary sequence of
characters terminated by the next tab, space, or newline character.  All
characters of the subcommand word but the first are simply ignored.  For
example, <code class="code">gtroff</code> outputs the initialization command &lsquo;<samp class="samp">x&nbsp;i</samp>&rsquo;<!-- /@w -->
as &lsquo;<samp class="samp">x&nbsp;init</samp>&rsquo;<!-- /@w --> and the resolution command &lsquo;<samp class="samp">x&nbsp;r</samp>&rsquo;<!-- /@w --> as
&lsquo;<samp class="samp">x&nbsp;res</samp>&rsquo;<!-- /@w -->.
</p>
<p>In the following, the syntax element &lsaquo;<span class="r">line break</span>&rsaquo; means a
syntactical line break (see <a class="pxref" href="#Separation">Separation</a>).
</p>
<dl class="table">
<dt><code class="code">xF <var class="var">name</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>The &lsquo;<samp class="samp">F</samp>&rsquo; stands for <var class="var">Filename</var>.
</p>
<p>Use <var class="var">name</var> as the intended name for the current file in error
reports.  This is useful for remembering the original file name when
<code class="code">gtroff</code> uses an internal piping mechanism.  The input file is not
changed by this command.  This command is a <code class="code">gtroff</code> extension.
</p>
</dd>
<dt><code class="code">xf <var class="var">n</var> <var class="var">s</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>The &lsquo;<samp class="samp">f</samp>&rsquo; stands for <var class="var">font</var>.
</p>
<p>Mount font position&nbsp;<var class="var">n</var> (a non-negative integer) with font
named&nbsp;<var class="var">s</var> (a text word).  See <a class="xref" href="#Font-Positions">Font Positions</a>.
</p>
</dd>
<dt><code class="code">xH <var class="var">n</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>The &lsquo;<samp class="samp">H</samp>&rsquo; stands for <var class="var">Height</var>.
</p>
<p>Set glyph height to&nbsp;<var class="var">n</var> (a positive integer in scaled points
&lsquo;<samp class="samp">z</samp>&rsquo;).  <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> uses the unit points (&lsquo;<samp class="samp">p</samp>&rsquo;)
instead.  See <a class="xref" href="#Output-Language-Compatibility">Output Language Compatibility</a>.
</p>
</dd>
<dt><code class="code">xi&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>The &lsquo;<samp class="samp">i</samp>&rsquo; stands for <var class="var">init</var>.
</p>
<p>Initialize device.  This is the third command of the prologue.
</p>
</dd>
<dt><code class="code">xp&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>The &lsquo;<samp class="samp">p</samp>&rsquo; stands for <var class="var">pause</var>.
</p>
<p>Parsed but ignored.  The <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> manual documents
this command as
</p>
<div class="display">
<pre class="display-preformatted">pause device, can be restarted
</pre></div>

<p>but GNU <code class="code">troff</code> output drivers do nothing with this command.
</p>
</dd>
<dt><code class="code">xr <var class="var">n</var> <var class="var">h</var> <var class="var">v</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>The &lsquo;<samp class="samp">r</samp>&rsquo; stands for <var class="var">resolution</var>.
</p>
<p>Resolution is&nbsp;<var class="var">n</var>, while <var class="var">h</var> is the minimal horizontal
motion, and <var class="var">v</var> the minimal vertical motion possible with this
device; all arguments are positive integers in basic units &lsquo;<samp class="samp">u</samp>&rsquo; per
inch.  This is the second command of the prologue.
</p>
</dd>
<dt><code class="code">xS <var class="var">n</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>The &lsquo;<samp class="samp">S</samp>&rsquo; stands for <var class="var">Slant</var>.
</p>
<p>Set slant to&nbsp;<var class="var">n</var> (an integer in basic units &lsquo;<samp class="samp">u</samp>&rsquo;).
</p>
</dd>
<dt><code class="code">xs&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>The &lsquo;<samp class="samp">s</samp>&rsquo; stands for <var class="var">stop</var>.
</p>
<p>Terminates the processing of the current file; issued as the last
command of any intermediate <code class="code">troff</code> output.
</p>
</dd>
<dt><code class="code">xt&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>The &lsquo;<samp class="samp">t</samp>&rsquo; stands for <var class="var">trailer</var>.
</p>
<p>Generate trailer information, if any.  In GNU <code class="code">troff</code>, this is
ignored.
</p>
</dd>
<dt><code class="code">xT <var class="var">xxx</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>The &lsquo;<samp class="samp">T</samp>&rsquo; stands for <var class="var">Typesetter</var>.
</p>
<p>Set the name of the output driver to <var class="var">xxx</var>, a sequence of
non-whitespace characters terminated by whitespace.  The possible names
correspond to those of <code class="code">groff</code>&rsquo;s <samp class="option">-T</samp> option.  This is the
first command of the prologue.
</p>
</dd>
<dt><code class="code">xu <var class="var">n</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>The &lsquo;<samp class="samp">u</samp>&rsquo; stands for <var class="var">underline</var>.
</p>
<p>Configure underlining of spaces.  If <var class="var">n</var> is&nbsp;1, start
underlining of spaces; if <var class="var">n</var> is&nbsp;0, stop underlining of spaces.
This is needed for the <code class="code">cu</code> request in <code class="code">nroff</code> mode and is
ignored otherwise.  This command is a <code class="code">gtroff</code> extension.
</p>
</dd>
<dt><code class="code">xX <var class="var">anything</var>&lsaquo;<span class="r">line break</span>&rsaquo;</code></dt>
<dd><p>The &lsquo;<samp class="samp">x</samp>&rsquo; stands for <var class="var">X-escape</var>.
</p>
<p>Send string <var class="var">anything</var> uninterpreted to the device.  If the line
following this command starts with a &lsquo;<samp class="samp">+</samp>&rsquo; character this line is
interpreted as a continuation line in the following sense.  The &lsquo;<samp class="samp">+</samp>&rsquo;
is ignored, but a newline character is sent instead to the device, the
rest of the line is sent uninterpreted.  The same applies to all
following lines until the first character of a line is not a &lsquo;<samp class="samp">+</samp>&rsquo;
character.  This command is generated by the <code class="code">gtroff</code> escape
sequence <code class="code">\X</code>.  The line-continuing feature is a <code class="code">gtroff</code>
extension.
</p></dd>
</dl>

<hr>
</div>
<div class="subsubsection-level-extent" id="Obsolete-Command">
<div class="nav-panel">
<p>
Previous: <a href="#Device-Control-Commands" accesskey="p" rel="prev">Device Control Commands</a>, Up: <a href="#Command-Reference" accesskey="u" rel="up">Command Reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsubsection" id="Obsolete-Command-1">6.1.2.5 Obsolete Command</h4>
<p>In <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> output, the writing of a single glyph is
mostly done by a very strange command that combines a horizontal move
and a single character giving the glyph name.  It doesn&rsquo;t have a command
code, but is represented by a 3-character argument consisting of exactly
2&nbsp;digits and a character.
</p>
<dl class="table">
<dt><var class="var">dd</var><var class="var">g</var></dt>
<dd><p>Move right <var class="var">dd</var> (exactly two decimal digits) basic units &lsquo;<samp class="samp">u</samp>&rsquo;,
then print glyph&nbsp;<var class="var">g</var> (represented as a single character).
</p>
<p>In GNU <code class="code">troff</code>, arbitrary syntactical space around and within this
command is allowed.  Only when a preceding command on the same line ends
with an argument of variable length is a separating space obligatory.
In <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>, large clusters of these and other
commands are used, mostly without spaces; this made such output almost
unreadable.
</p></dd>
</dl>

<p>For modern high-resolution devices, this command does not make sense
because the width of the glyphs can become much larger than two decimal
digits.  In <code class="code">gtroff</code>, this is only used for the devices <code class="code">X75</code>,
<code class="code">X75-12</code>, <code class="code">X100</code>, and <code class="code">X100-12</code>.  For other devices, the
commands &lsquo;<samp class="samp">t</samp>&rsquo; and &lsquo;<samp class="samp">u</samp>&rsquo; provide a better functionality.
</p>

<hr>
</div>
</div>
<div class="subsection-level-extent" id="Intermediate-Output-Examples">
<div class="nav-panel">
<p>
Next: <a href="#Output-Language-Compatibility" accesskey="n" rel="next">Output Language Compatibility</a>, Previous: <a href="#Command-Reference" accesskey="p" rel="prev">Command Reference</a>, Up: <a href="#gtroff-Output" accesskey="u" rel="up"><code class="code">gtroff</code> Output</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Intermediate-Output-Examples-1">6.1.3 Intermediate Output Examples</h4>

<p>This section presents the intermediate output generated from the same
input for three different devices.  The input is the sentence &lsquo;<samp class="samp">hell
world</samp>&rsquo; fed into <code class="code">gtroff</code> on the command line.
</p>
<dl class="table">
<dt>High-resolution device <code class="code">ps</code></dt>
<dd>
<p>This is the standard output of <code class="code">gtroff</code> if no <samp class="option">-T</samp> option is
given.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">shell&gt; echo &quot;hell world&quot; | groff -Z -T ps

x T ps
x res 72000 1 1
x init
</pre></div><pre class="example-preformatted">p1
x font 5 TR
f5
s10000
V12000
H72000
thell
wh2500
tw
H96620
torld
n12000 0
</pre><div class="group"><pre class="example-preformatted">x trailer
V792000
x stop
</pre></div></div>

<p>This output can be fed into <code class="code">grops</code> to get its representation as a
PostScript file.
</p>
</dd>
<dt>Low-resolution device <code class="code">latin1</code></dt>
<dd>
<p>This is similar to the high-resolution device except that the
positioning is done at a minor scale.  Some comments (lines starting
with &lsquo;<samp class="samp">#</samp>&rsquo;) were added for clarification; they were not generated by
the formatter.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">shell&gt; echo &quot;hell world&quot; | groff -Z -T latin1

# prologue
x T latin1
x res 240 24 40
x init
</pre></div><pre class="example-preformatted"># begin a new page
p1
# font setup
x font 1 R
f1
s10
# initial positioning on the page
V40
H0
# write text 'hell'
thell
# inform about space, and issue a horizontal jump
wh24
# write text 'world'
tworld
# announce line break, but do nothing because...
n40 0
</pre><div class="group"><pre class="example-preformatted"># ...the end of the document has been reached
x trailer
V2640
x stop
</pre></div></div>

<p>This output can be fed into <code class="code">grotty</code> to get a formatted text
document.
</p>
</dd>
<dt><abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> output</dt>
<dd><p>Since a computer monitor has a much lower resolution than modern
printers, the intermediate output for X11 devices can use the
jump-and-write command with its 2-digit displacements.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">shell&gt; echo &quot;hell world&quot; | groff -Z -T X100

x T X100
x res 100 1 1
x init
</pre></div><pre class="example-preformatted">p1
x font 5 TR
f5
s10
V16
H100
# write text with jump-and-write commands
ch07e07l03lw06w11o07r05l03dh7
n16 0
</pre><div class="group"><pre class="example-preformatted">x trailer
V1100
x stop
</pre></div></div>

<p>This output can be fed into <code class="code">xditview</code> or <code class="code">gxditview</code> for
displaying in&nbsp;X.
</p>
<p>Due to the obsolete jump-and-write command, the text clusters in the
<abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> output are almost unreadable.
</p></dd>
</dl>


<hr>
</div>
<div class="subsection-level-extent" id="Output-Language-Compatibility">
<div class="nav-panel">
<p>
Previous: <a href="#Intermediate-Output-Examples" accesskey="p" rel="prev">Intermediate Output Examples</a>, Up: <a href="#gtroff-Output" accesskey="u" rel="up"><code class="code">gtroff</code> Output</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Output-Language-Compatibility-1">6.1.4 Output Language Compatibility</h4>

<p>The intermediate output language of <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> was
first documented in <cite class="cite">A Typesetter-independent TROFF</cite>, by Brian
Kernighan, and by 1992 the <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> manual was
updated to incorprate a description of it.
</p>
<p>The GNU <code class="code">troff</code> intermediate output format is compatible with this
specification except for the following features.
</p>
<ul class="itemize mark-bullet">
<li>The classical quasi-device independence is not yet implemented.

</li><li>The old hardware was very different from what we use today.  So the
<code class="code">groff</code> devices are also fundamentally different from the ones
in <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>.  For example, the <abbr class="acronym">AT&amp;T</abbr>
PostScript device is called <code class="code">post</code> and has a resolution of only 720
units per inch, suitable for printers 20 years ago, while <code class="code">groff</code>&rsquo;s
<code class="code">ps</code> device has a resolution of 72000 units per inch.  Maybe, by
implementing some rescaling mechanism similar to the classical
quasi-device independence, <code class="code">groff</code> could emulate <abbr class="acronym">AT&amp;T</abbr>&rsquo;s
<code class="code">post</code> device.

</li><li>The B-spline command &lsquo;<samp class="samp">D~</samp>&rsquo; is correctly handled by the intermediate
output parser, but the drawing routines aren&rsquo;t implemented in some of
the postprocessor programs.

</li><li>The argument of the commands &lsquo;<samp class="samp">s</samp>&rsquo; and &lsquo;<samp class="samp">x&nbsp;H</samp>&rsquo;<!-- /@w --> has the
implicit unit scaled point &lsquo;<samp class="samp">z</samp>&rsquo; in <code class="code">gtroff</code>, while
<abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> has point (&lsquo;<samp class="samp">p</samp>&rsquo;).  This isn&rsquo;t an
incompatibility but a compatible extension, for both units coincide for
all devices without a <code class="code">sizescale</code> parameter in the <samp class="file">DESC</samp>
file, including all postprocessors from <abbr class="acronym">AT&amp;T</abbr> and
<code class="code">groff</code>&rsquo;s text devices.  The few <code class="code">groff</code> devices with a
<code class="code">sizescale</code> parameter either do not exist for <abbr class="acronym">AT&amp;T</abbr>
<code class="code">troff</code>, have a different name, or seem to have a different
resolution.  So conflicts are very unlikely.

</li><li>The position changing after the commands &lsquo;<samp class="samp">Dp</samp>&rsquo;, &lsquo;<samp class="samp">DP</samp>&rsquo;, and
&lsquo;<samp class="samp">Dt</samp>&rsquo; is illogical, but as old versions of <code class="code">gtroff</code> used this
feature it is kept for compatibility reasons.


</li></ul>



<hr>
</div>
</div>
<div class="section-level-extent" id="Device-and-Font-Description-Files">
<div class="nav-panel">
<p>
Previous: <a href="#gtroff-Output" accesskey="p" rel="prev"><code class="code">gtroff</code> Output</a>, Up: <a href="#File-Formats" accesskey="u" rel="up">File Formats</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Device-and-Font-Description-Files-1">6.2 Device and Font Description Files</h3>
<a class="index-entry-id" id="index-font-files"></a>
<a class="index-entry-id" id="index-files_002c-font"></a>

<p>The <code class="code">groff</code> font and output device description formats are slight
extensions of those used by <abbr class="acronym">AT&amp;T</abbr> device-independent
<code class="code">troff</code>.  In distinction to the <abbr class="acronym">AT&amp;T</abbr> implementation,
<code class="code">groff</code> lacks a binary format; all files are text
files.<a class="footnote" id="DOCF125" href="#FOOT125"><sup>125</sup></a>  The device and font description files for a device <var class="var">name</var>
are stored in a <samp class="file">dev<var class="var">name</var></samp> directory.  The device description
file is called <samp class="file">DESC</samp>, and, for each font supported by the device,
a font description file is called&nbsp;<samp class="file"><var class="var">f</var></samp>, where
<var class="var">f</var>&nbsp;is usually an abbreviation of a font&rsquo;s name and/or style.
For example, the <code class="code">ps</code> (PostScript) device has <code class="code">groff</code> font
description files for Times roman (<samp class="file">TR</samp>) and Zapf Chancery Medium
italic (<samp class="file">ZCMI</samp>), among many others, while the <code class="code">utf8</code> device
(for terminal emulators) has only font descriptions for the roman,
italic, bold, and bold-italic styles (<samp class="file">R</samp>, <samp class="file">I</samp>, <samp class="file">B</samp>, and
<samp class="file">BI</samp>, respectively).
</p>
<p>Device and font description files are read both by the formatter, GNU
<code class="code">troff</code>, and by output drivers.  The programs delegate these files&rsquo;
processing to an internal library, <samp class="file">libgroff</samp>, ensuring their
consistent interpretation.
</p>


<ul class="mini-toc">
<li><a href="#DESC-File-Format" accesskey="1"><samp class="file">DESC</samp> File Format</a></li>
<li><a href="#Font-Description-File-Format" accesskey="2">Font Description File Format</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="DESC-File-Format">
<div class="nav-panel">
<p>
Next: <a href="#Font-Description-File-Format" accesskey="n" rel="next">Font Description File Format</a>, Previous: <a href="#Device-and-Font-Description-Files" accesskey="p" rel="prev">Device and Font Description Files</a>, Up: <a href="#Device-and-Font-Description-Files" accesskey="u" rel="up">Device and Font Description Files</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="DESC-File-Format-1">6.2.1 <samp class="file">DESC</samp> File Format</h4>
<a class="index-entry-id" id="index-DESC-file-format"></a>
<a class="index-entry-id" id="index-font-description-file-format"></a>
<a class="index-entry-id" id="index-format-of-font-description-file"></a>

<p>The <samp class="file">DESC</samp> file contains a series of directives; each begins a
line.  Their order is not important, with two exceptions: (1) the
<code class="code">res</code> directive must precede any <code class="code">papersize</code> directive; and
(2) the <code class="code">charset</code> directive must come last (if at all).  If a
directive name is repeated, later entries in the file override previous
ones (except that the paper dimensions are computed based on the
<code class="code">res</code> directive last seen when <code class="code">papersize</code> is encountered).
Spaces and/or tabs separate words and are ignored at line boundaries.
<a class="index-entry-id" id="index-comments-in-device-description-files"></a>
<a class="index-entry-id" id="index-device-description-files_002c-comments"></a>
<a class="index-entry-id" id="index-_0023"></a>
Comments start with the &lsquo;<samp class="samp">#</samp>&rsquo; character and extend to the end of a
line.  Empty lines are ignored.
</p>
<dl class="table">
<dt id='index-family-1'><span><code class="code">family <var class="var">fam</var></code><a class="copiable-link" href='#index-family-1'> &para;</a></span></dt>
<dd><p>The default font family is <var class="var">fam</var>.
</p>
</dd>
<dt id='index-fonts-2'><span><code class="code">fonts <var class="var">n</var> <var class="var">F1</var> <span class="r">&hellip;</span> <var class="var">Fn</var></code><a class="copiable-link" href='#index-fonts-2'> &para;</a></span></dt>
<dd><p>Fonts <var class="var">F1</var>, &hellip;, <var class="var">Fn</var> are mounted at font positions
<var class="var">m</var>+1, &hellip;, <var class="var">m</var>+<var class="var">n</var> where <var class="var">m</var> is the number of
<code class="code">styles</code> (see below).  This directive may extend over more than one
line.  A font name of&nbsp;<code class="code">0</code> causes no font to be mounted at the
corresponding position.
</p>
</dd>
<dt id='index-hor'><span><code class="code">hor <var class="var">n</var></code><a class="copiable-link" href='#index-hor'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-horizontal-motion-quantum"></a>
<a class="index-entry-id" id="index-motion-quantum_002c-horizontal"></a>
<a class="index-entry-id" id="index-quantum_002c-horizontal-motion"></a>
<a class="index-entry-id" id="index-horizontal-resolution"></a>
<a class="index-entry-id" id="index-resolution_002c-horizontal"></a>
<p>The horizontal motion quantum is <var class="var">n</var>&nbsp;basic units.  All
horizontal quantities are rounded to multiples of&nbsp;<var class="var">n</var>.
</p>
</dd>
<dt id='index-image_005fgenerator'><span><code class="code">image_generator <var class="var">program</var></code><a class="copiable-link" href='#index-image_005fgenerator'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-PostScript_002c-PNG-image-generation"></a>
<a class="index-entry-id" id="index-PNG-image-generation-from-PostScript"></a>
<p>Use <var class="var">program</var> to generate PNG images from PostScript input.  Under
GNU/Linux, this is usually <code class="code">gs</code>, but under other systems (notably
Cygwin) it might be set to another name.  The <code class="code">grohtml</code> driver uses
this directive.
</p>
</dd>
<dt id='index-paperlength'><span><code class="code">paperlength <var class="var">n</var></code><a class="copiable-link" href='#index-paperlength'> &para;</a></span></dt>
<dd><p>The vertical dimension of the output medium is <var class="var">n</var>&nbsp;basic units
(deprecated: use <code class="code">papersize</code> instead).
</p>
</dd>
<dt id='index-papersize'><span><code class="code">papersize <var class="var">format-or-dimension-pair-or-file-name</var> <span class="r">&hellip;</span></code><a class="copiable-link" href='#index-papersize'> &para;</a></span></dt>
<dd><p>The dimensions of the output medium are as according to the
argument, which is either a standard paper format, a pair of dimensions,
or the name of a plain text file containing either of the foregoing.
</p>
<p>Recognized paper formats are the ISO and DIN formats
<code class="code">A0</code>&ndash;<code class="code">A7</code>, <code class="code">B0</code>&ndash;<code class="code">B7</code>, <code class="code">C0</code>&ndash;<code class="code">C7</code>,
<code class="code">D0</code>&ndash;<code class="code">D7</code>; the U.S. paper types <code class="code">letter</code>,
<code class="code">legal</code>, <code class="code">tabloid</code>, <code class="code">ledger</code>, <code class="code">statement</code>, and
<code class="code">executive</code>; and the envelope formats <code class="code">com10</code>, <code class="code">monarch</code>,
and <code class="code">DL</code>.  Matching is performed without regard for lettercase.
</p>
<p>Alternatively, the argument can be a custom paper format in the format
<code class="code"><var class="var">length</var>,<var class="var">width</var></code> (with no spaces before or after the
comma).  Both <var class="var">length</var> and <var class="var">width</var> must have a unit appended;
valid units are &lsquo;<samp class="samp">i</samp>&rsquo; for inches, &lsquo;<samp class="samp">c</samp>&rsquo; for centimeters, &lsquo;<samp class="samp">p</samp>&rsquo;
for points, and &lsquo;<samp class="samp">P</samp>&rsquo; for picas.  Example: &lsquo;<samp class="samp">12c,235p</samp>&rsquo;.  An
argument that starts with a digit is always treated as a custom paper
format.
</p>
<p>Finally, the argument can be a file name (e.g., <samp class="file">/etc/papersize</samp>);
if the file can be opened, the first line is read and a match attempted
against each of the other forms.  No comment syntax is supported.
</p>
<p>More than one argument can be specified;
each is scanned in turn and the first valid paper specification used.
</p>
</dd>
<dt id='index-paperwidth'><span><code class="code">paperwidth <var class="var">n</var></code><a class="copiable-link" href='#index-paperwidth'> &para;</a></span></dt>
<dd><p>The horizontal dimension of the output medium is <var class="var">n</var>&nbsp;basic
units (deprecated: use <code class="code">papersize</code> instead).
</p>
</dd>
<dt id='index-pass_005ffilenames'><span><code class="code">pass_filenames</code><a class="copiable-link" href='#index-pass_005ffilenames'> &para;</a></span></dt>
<dd><p>Direct GNU <code class="code">troff</code> to emit the name of the source file being
processed.  This is achieved with the intermediate output command
&lsquo;<samp class="samp">x F</samp>&rsquo;, which <code class="code">grohtml</code> interprets.
</p>
</dd>
<dt id='index-postpro'><span><code class="code">postpro <var class="var">program</var></code><a class="copiable-link" href='#index-postpro'> &para;</a></span></dt>
<dd><p>Use <var class="var">program</var> as the postprocessor.
</p>
</dd>
<dt id='index-prepro'><span><code class="code">prepro <var class="var">program</var></code><a class="copiable-link" href='#index-prepro'> &para;</a></span></dt>
<dd><p>Use <var class="var">program</var> as a preprocessor.  The <code class="code">html</code> and <code class="code">xhtml</code>
output devices use this directive.
</p>
</dd>
<dt id='index-print'><span><code class="code">print <var class="var">program</var></code><a class="copiable-link" href='#index-print'> &para;</a></span></dt>
<dd><p>Use <var class="var">program</var> as a spooler program for printing.  If omitted, the
<samp class="option">-l</samp> and <samp class="option">-L</samp> options of <code class="code">groff</code> are ignored.
</p>
</dd>
<dt id='index-res'><span><code class="code">res <var class="var">n</var></code><a class="copiable-link" href='#index-res'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-device-resolution-1"></a>
<a class="index-entry-id" id="index-resolution_002c-device-1"></a>
<p>The device resolution is <var class="var">n</var>&nbsp;basic units per inch.
</p>
</dd>
<dt id='index-sizes'><span><code class="code">sizes <var class="var">s1</var> <span class="r">&hellip;</span> <var class="var">sn</var> 0</code><a class="copiable-link" href='#index-sizes'> &para;</a></span></dt>
<dd><p>The device has fonts at <var class="var">s1</var>, &hellip;, <var class="var">sn</var> scaled points (see
below).  The list of sizes must be terminated by&nbsp;<code class="code">0</code>.  Each
<var class="var">si</var> can also be a range of sizes <var class="var">m</var>&ndash;<var class="var">n</var>.  The list can
extend over more than one line.
</p>
</dd>
<dt id='index-sizescale'><span><code class="code">sizescale <var class="var">n</var></code><a class="copiable-link" href='#index-sizescale'> &para;</a></span></dt>
<dd><p>A typographical point is subdivided into <var class="var">n</var>&nbsp;scaled points.
The default is&nbsp;<code class="code">1</code>.  See <a class="xref" href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a>.
</p>
</dd>
<dt id='index-styles-2'><span><code class="code">styles <var class="var">S1</var> <span class="r">&hellip;</span> <var class="var">Sm</var></code><a class="copiable-link" href='#index-styles-2'> &para;</a></span></dt>
<dd><p>The first&nbsp;<var class="var">m</var> mounting positions are associated with styles
<var class="var">S1</var>, &hellip;, <var class="var">Sm</var>.
</p>
</dd>
<dt id='index-tcommand'><span><code class="code">tcommand</code><a class="copiable-link" href='#index-tcommand'> &para;</a></span></dt>
<dd><p>The postprocessor can handle the &lsquo;<samp class="samp">t</samp>&rsquo; and &lsquo;<samp class="samp">u</samp>&rsquo; intermediate
output commands.
</p>
</dd>
<dt id='index-unicode'><span><code class="code">unicode</code><a class="copiable-link" href='#index-unicode'> &para;</a></span></dt>
<dd><p>The output device supports the complete Unicode repertoire.  This
directive is useful only for devices that produce character entities
instead of glyphs.
</p>
<p>If <code class="code">unicode</code> is present, no <code class="code">charset</code> section is required in
the font description files since the Unicode handling built into
<code class="code">groff</code> is used.  However, if there are entries in a font
description file&rsquo;s <code class="code">charset</code> section, they either override the
default mappings for those particular characters or add new mappings
(normally for composite characters).
</p>
<p>The <code class="code">utf8</code>, <code class="code">html</code>, and <code class="code">xhtml</code> output devices use this
directive.
</p>
</dd>
<dt id='index-unitwidth'><span><code class="code">unitwidth <var class="var">n</var></code><a class="copiable-link" href='#index-unitwidth'> &para;</a></span></dt>
<dd><p>Quantities in the font description files are in basic units for fonts
whose type size is <var class="var">n</var>&nbsp;scaled points.
</p>
</dd>
<dt id='index-unscaled_005fcharwidths'><span><code class="code">unscaled_charwidths</code><a class="copiable-link" href='#index-unscaled_005fcharwidths'> &para;</a></span></dt>
<dd><p>Make the font handling module always return unscaled character widths.
The <code class="code">grohtml</code> driver uses this directive.
</p>
</dd>
<dt id='index-use_005fcharnames_005fin_005fspecial-1'><span><code class="code">use_charnames_in_special</code><a class="copiable-link" href='#index-use_005fcharnames_005fin_005fspecial-1'> &para;</a></span></dt>
<dd><p>GNU <code class="code">troff</code> should encode special characters inside device control
commands; see <a class="ref" href="#Postprocessor-Access">Postprocessor Access</a>.  The <code class="code">grohtml</code> driver
uses this directive.
</p>
</dd>
<dt id='index-vert'><span><code class="code">vert <var class="var">n</var></code><a class="copiable-link" href='#index-vert'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-vertical-motion-quantum"></a>
<a class="index-entry-id" id="index-motion-quantum_002c-vertical"></a>
<a class="index-entry-id" id="index-quantum_002c-vertical-motion"></a>
<a class="index-entry-id" id="index-vertical-resolution"></a>
<a class="index-entry-id" id="index-resolution_002c-vertical"></a>
<p>The vertical motion quantum is <var class="var">n</var>&nbsp;basic units.  All vertical
quantities are rounded to multiples of&nbsp;<var class="var">n</var>.
</p>
</dd>
<dt id='index-charset'><span><code class="code">charset</code><a class="copiable-link" href='#index-charset'> &para;</a></span></dt>
<dd><p>This line and everything following it in the file are ignored.  It is
recognized for compatibility with other <code class="code">troff</code> implementations.
In GNU <code class="code">troff</code>, character set repertoire is described on a
per-font basis.
</p></dd>
</dl>

<a class="index-entry-id" id="index-spare1"></a>
<a class="index-entry-id" id="index-spare2"></a>
<a class="index-entry-id" id="index-biggestfont"></a>
<p>GNU <code class="code">troff</code> recognizes but ignores the directives <code class="code">spare1</code>,
<code class="code">spare2</code>, and <code class="code">biggestfont</code>.
</p>
<p>The <code class="code">res</code>, <code class="code">unitwidth</code>, <code class="code">fonts</code>, and <code class="code">sizes</code> lines
are mandatory.  Directives not listed above are ignored by GNU
<code class="code">troff</code> but may be used by postprocessors to obtain further
information about the device.
</p>

<hr>
</div>
<div class="subsection-level-extent" id="Font-Description-File-Format">
<div class="nav-panel">
<p>
Previous: <a href="#DESC-File-Format" accesskey="p" rel="prev"><samp class="file">DESC</samp> File Format</a>, Up: <a href="#Device-and-Font-Description-Files" accesskey="u" rel="up">Device and Font Description Files</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Font-Description-File-Format-1">6.2.2 Font Description File Format</h4>
<a class="index-entry-id" id="index-font-file_002c-format"></a>
<a class="index-entry-id" id="index-font-description-file_002c-format"></a>
<a class="index-entry-id" id="index-format-of-font-files"></a>
<a class="index-entry-id" id="index-format-of-font-description-files"></a>

<p>On typesetting output devices, each font is typically available at
multiple sizes.  While paper measurements in the device description file
are in absolute units, measurements applicable to fonts must be
proportional to the type size.  <code class="code">groff</code> achieves this using the
precedent set by <abbr class="acronym">AT&amp;T</abbr> device-independent <code class="code">troff</code>: one
font size is chosen as a norm, and all others are scaled linearly
relative to that basis.  The &ldquo;unit width&rdquo; is the number of basic units
per point when the font is rendered at this nominal size.
</p>
<p>For instance, <code class="code">groff</code>&rsquo;s <code class="code">lbp</code> device uses a <code class="code">unitwidth</code>
of&nbsp;800.  Its Times roman font &lsquo;<samp class="samp">TR</samp>&rsquo; has a <code class="code">spacewidth</code>
of&nbsp;833; this is also the width of its comma, period, centered
period, and mathematical asterisk, while its &lsquo;<samp class="samp">M</samp>&rsquo; is 2,963 basic
units.  Thus, an &lsquo;<samp class="samp">M</samp>&rsquo; on the <code class="code">lbp</code> device is 2,963 basic units
wide at a notional type size of 800&nbsp;points.<a class="footnote" id="DOCF126" href="#FOOT126"><sup>126</sup></a>
</p>
<p>A font description file has two sections.  The first is a sequence of
directives, and is parsed similarly to the <samp class="file">DESC</samp> file described
above.  Except for the directive names that begin the second section,
their ordering is immaterial.  Later directives of the same name
override earlier ones, spaces and tabs are handled in the same way,
<a class="index-entry-id" id="index-comments-in-font-description-files"></a>
<a class="index-entry-id" id="index-font-description-files_002c-comments"></a>
<a class="index-entry-id" id="index-_0023-1"></a>
and the same comment syntax is supported.  Empty lines are ignored
throughout.
</p>
<dl class="table">
<dt id='index-name'><span><code class="code">name <var class="var">f</var></code><a class="copiable-link" href='#index-name'> &para;</a></span></dt>
<dd><p>The name of the font is&nbsp;<var class="var">f</var>.  &lsquo;<samp class="samp">DESC</samp>&rsquo; is an invalid font
name.  Simple integers are valid, but their use is
discouraged.<a class="footnote" id="DOCF127" href="#FOOT127"><sup>127</sup></a>
</p>
</dd>
<dt id='index-spacewidth'><span><code class="code">spacewidth <var class="var">n</var></code><a class="copiable-link" href='#index-spacewidth'> &para;</a></span></dt>
<dd><p>The width of an unadjusted inter-word space is <var class="var">n</var>&nbsp;basic units.
</p></dd>
</dl>

<p>The directives above must appear in the first section; those below are
optional.
</p>
<dl class="table">
<dt id='index-slant'><span><code class="code">slant <var class="var">n</var></code><a class="copiable-link" href='#index-slant'> &para;</a></span></dt>
<dd><p>The font&rsquo;s glyphs have a slant of <var class="var">n</var>&nbsp;degrees; a positive
<var class="var">n</var> slants in the direction of text flow.
</p>
</dd>
<dt id='index-ligatures'><span><code class="code">ligatures <var class="var">lig1</var> <span class="r">&hellip;</span> <var class="var">lign</var> <span class="r">[</span>0<span class="r">]</span></code><a class="copiable-link" href='#index-ligatures'> &para;</a></span></dt>
<dd><p>Glyphs <var class="var">lig1</var>, &hellip;, <var class="var">lign</var> are ligatures; possible ligatures
are &lsquo;<samp class="samp">ff</samp>&rsquo;, &lsquo;<samp class="samp">fi</samp>&rsquo;, &lsquo;<samp class="samp">fl</samp>&rsquo;, &lsquo;<samp class="samp">ffi</samp>&rsquo; and &lsquo;<samp class="samp">ffl</samp>&rsquo;.  For
compatibility with other <code class="code">troff</code> implementations, the list of
ligatures may be terminated with a&nbsp;<code class="code">0</code>.  The list of ligatures
must not extend over more than one line.
</p>
</dd>
<dt id='index-special-fonts-2'><span><code class="code">special</code><a class="copiable-link" href='#index-special-fonts-2'> &para;</a></span></dt>
<dd><a class="index-entry-id" id="index-special-1"></a>
<p>The font is <em class="dfn">special</em>: when a glyph is requested that is not present
in the current font, it is sought in any mounted fonts that bear this
property.
</p></dd>
</dl>

<p>Other directives in this section are ignored by GNU <code class="code">troff</code>, but
may be used by postprocessors to obtain further information about the
font.
</p>
<p>The second section contains one or two subsections.  These can appear in
either order; the first one encountered commences the second section.
Each starts with a directive on a line by itself.  A <code class="code">charset</code>
subsection is mandatory unless the associated <samp class="file">DESC</samp> file contains
the <code class="code">unicode</code> directive.  Another subsection, <code class="code">kernpairs</code>,
is optional.
</p>
<a class="index-entry-id" id="index-charset-1"></a>
<p>The directive <code class="code">charset</code> starts the character set
subsection.<a class="footnote" id="DOCF128" href="#FOOT128"><sup>128</sup></a>  It precedes a series
of glyph descriptions, one per line.  Each such glyph description
comprises a set of fields separated by spaces or tabs and organized as
follows.
</p>
<blockquote class="quotation">
<p><var class="var">name</var> <var class="var">metrics</var> <var class="var">type</var> <var class="var">code</var> [<var class="var">entity-name</var>]
[<code class="code">--</code> <var class="var">comment</var>]
</p></blockquote>

<a class="index-entry-id" id="index-8_002dbit-input"></a>
<a class="index-entry-id" id="index-input_002c-8_002dbit"></a>
<a class="index-entry-id" id="index-accessing-unnamed-glyphs-with-_005cN"></a>
<a class="index-entry-id" id="index-unnamed-glyphs_002c-accessing-with-_005cN"></a>
<a class="index-entry-id" id="index-characters_002c-unnamed_002c-accessing-with-_005cN"></a>
<a class="index-entry-id" id="index-glyphs_002c-unnamed_002c-accessing-with-_005cN"></a>
<a class="index-entry-id" id="index-_002d_002d_002d"></a>
<p><var class="var">name</var> identifies the glyph:
if <var class="var">name</var> is a printable character&nbsp;<var class="var">c</var>, it corresponds to
the <code class="code">troff</code> ordinary character&nbsp;<var class="var">c</var>.  If <var class="var">name</var> is a
multi-character sequence not beginning with <code class="code">\</code>, it corresponds to
the GNU <code class="code">troff</code> special character escape sequence
&lsquo;<samp class="samp">\[<var class="var">name</var>]</samp>&rsquo;.  A name consisting of three minus signs,
&lsquo;<samp class="samp">---</samp>&rsquo;, is special and indicates that the glyph is unnamed: such
glyphs can be accessed only by the <code class="code">\N</code> escape sequence in
<code class="code">troff</code>.  A special character named &lsquo;<samp class="samp">---</samp>&rsquo; can still be defined
using <code class="code">char</code> and similar requests.  The <var class="var">name</var> &lsquo;<samp class="samp">\-</samp>&rsquo;
defines the minus sign glyph.  Finally, <var class="var">name</var> can be the
unbreakable one-sixth and one-twelfth space escape sequences, <code class="code">\|</code>
and <code class="code">\^</code> (&ldquo;thin&rdquo; and &ldquo;hair&rdquo; spaces, respectively), in which
case only the width metric described below is interpreted; a font can
thus customize the widths of these spaces.
</p>
<p>The form of the <var class="var">metrics</var> field is as follows.
</p>
<div class="display">
<div class="group"><pre class="display-preformatted"><var class="var">width</var>[<code class="code">,</code>[<var class="var">height</var>[<code class="code">,</code>[<var class="var">depth</var>[<code class="code">,</code>[<var class="var">italic-correction</var>
  [<code class="code">,</code>[<var class="var">left-italic-correction</var>[<code class="code">,</code>[<var class="var">subscript-correction</var>]]]]]]]]]]
</pre></div></div>

<p>There must not be any spaces, tabs, or newlines between these
<em class="dfn">subfields</em> (which have been split here into two lines only for
better legibility).  The subfields are in basic units expressed as
decimal integers.  Unspecified subfields default to&nbsp;<code class="code">0</code>.
Since there is no associated binary format, these values are not
required to fit into the C language data type &lsquo;<samp class="samp">char</samp>&rsquo; as they are in
<abbr class="acronym">AT&amp;T</abbr> device-independent <code class="code">troff</code>.
</p>
<p>The <var class="var">width</var> subfield gives the width of the glyph.  The <var class="var">height</var>
subfield gives the height of the glyph (upward is positive); if a glyph
does not extend above the baseline, it should be given a zero height,
rather than a negative height.  The <var class="var">depth</var> subfield gives the depth
of the glyph, that is, the distance below the baseline to which the
glyph extends (downward is positive); if a glyph does not extend below
the baseline, it should be given a zero depth, rather than a negative
depth.  Italic corrections are relevant to glyphs in italic or oblique
styles.  The <var class="var">italic-correction</var> is the amount of space that should
be added after an oblique glyph to be followed immediately by an upright
glyph.  The <var class="var">left-italic-correction</var> is the amount of space that
should be added before an oblique glyph to be preceded immediately by an
upright glyph.  The <var class="var">subscript-correction</var> is the amount of space
that should be added after an oblique glyph to be followed by a
subscript; it should be less than the italic correction.
</p>
<p>For fonts used with typesetting devices, the <var class="var">type</var> field gives a
featural description of the glyph: it is a bit mask recording whether
the glyph is an ascender, descender, both, or neither.  When a <code class="code">\w</code>
escape sequence is interpolated, these values are bitwise or-ed
together for each glyph and stored in the <code class="code">nr</code> register.  In font
descriptions for terminal devices, all glyphs might have a type of zero,
regardless of their appearance.
</p>
<dl class="table">
<dt><code class="code">0</code></dt>
<dd><p>means the glyph lies entirely between the baseline and a horizontal line
at the &ldquo;x-height&rdquo; of the font; typical examples are &lsquo;<samp class="samp">a</samp>&rsquo;,
&lsquo;<samp class="samp">c</samp>&rsquo;, and &lsquo;<samp class="samp">x</samp>&rsquo;;
</p>
</dd>
<dt><code class="code">1</code></dt>
<dd><p>means the glyph descends below the baseline, like &lsquo;<samp class="samp">p</samp>&rsquo;;
</p>
</dd>
<dt><code class="code">2</code></dt>
<dd><p>means the glyph ascends above the font&rsquo;s x-height, like &lsquo;<samp class="samp">A</samp>&rsquo; or
&lsquo;<samp class="samp">b</samp>&rsquo;; and
</p>
</dd>
<dt><code class="code">3</code></dt>
<dd><p>means the glyph is both an ascender and a descender&mdash;this is true of
parentheses in some fonts.
</p></dd>
</dl>

<p>The <var class="var">code</var> field gives a numeric identifier that the postprocessor
uses to render the glyph.  The glyph can be specified to <code class="code">troff</code>
using this code by means of the <code class="code">\N</code> escape sequence.  <var class="var">code</var>
can be any integer.<a class="footnote" id="DOCF129" href="#FOOT129"><sup>129</sup></a>
</p>
<p>The <var class="var">entity-name</var> field defines an identifier for the glyph that the
postprocessor uses to print the GNU <code class="code">troff</code> glyph <var class="var">name</var>.  This
field is optional; it was introduced so that the <code class="code">grohtml</code> output
driver could encode its character set.  For example, the glyph
&lsquo;<samp class="samp">\[Po]</samp>&rsquo; is represented by &lsquo;<samp class="samp">&amp;pound;</samp>&rsquo; in <abbr class="acronym">HTML</abbr> 4.0.
For efficiency, these data are now compiled directly into
<code class="code">grohtml</code>.  <code class="code">grops</code> uses the field to build sub-encoding
arrays for PostScript fonts containing more than 256 glyphs.  Anything
on the line after the <var class="var">entity-name</var> field or &lsquo;<samp class="samp">--</samp>&rsquo; is ignored.
</p>
<p>A line in the <code class="code">charset</code> section can also have the form
</p>
<div class="example">
<div class="group"><pre class="example-preformatted"><var class="var">name</var> &quot;
</pre></div></div>

<p>identifying <var class="var">name</var> as another name for the glyph mentioned in the
preceding line.  Such aliases can be chained.
</p>
<a class="index-entry-id" id="index-kernpairs"></a>
<p>The directive <code class="code">kernpairs</code> starts a list of kerning adjustments to
be made to adjacent glyph pairs from this font.  It contains a sequence
of lines formatted as follows.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted"><var class="var">g1</var> <var class="var">g2</var> <var class="var">n</var>
</pre></div></div>

<p>The foregoing means that when glyph <var class="var">g1</var> is typeset immediately
before <var class="var">g2</var>, the space between them should be increased
by&nbsp;<var class="var">n</var>.  Most kerning pairs should have a negative value
for&nbsp;<var class="var">n</var>.
</p>




<hr>
</div>
</div>
</div>
<div class="appendix-level-extent" id="Copying-This-Manual">
<div class="nav-panel">
<p>
Next: <a href="#Request-Index" accesskey="n" rel="next">Request Index</a>, Previous: <a href="#Font-Description-File-Format" accesskey="p" rel="prev">Font Description File Format</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU <code class="code">troff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="appendix" id="Copying-This-Manual-1">Appendix A Copying This Manual</h2>

<div class="center">Version 1.3, 3 November 2008
</div>

<div class="display">
<pre class="display-preformatted">Copyright &copy; 2000-2018 Free Software Foundation, Inc.
<a class="uref" href="http://fsf.org/">http://fsf.org/</a>

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
</pre></div>

<ol class="enumerate" start="0">
<li> PREAMBLE

<p>The purpose of this License is to make a manual, textbook, or other
functional and useful document <em class="dfn">free</em> in the sense of freedom: to
assure everyone the effective freedom to copy and redistribute it,
with or without modifying it, either commercially or noncommercially.
Secondarily, this License preserves for the author and publisher a way
to get credit for their work, while not being considered responsible
for modifications made by others.
</p>
<p>This License is a kind of &ldquo;copyleft&rdquo;, which means that derivative
works of the document must themselves be free in the same sense.  It
complements the GNU General Public License, which is a copyleft
license designed for free software.
</p>
<p>We have designed this License in order to use it for manuals for free
software, because free software needs free documentation: a free
program should come with manuals providing the same freedoms that the
software does.  But this License is not limited to software manuals;
it can be used for any textual work, regardless of subject matter or
whether it is published as a printed book.  We recommend this License
principally for works whose purpose is instruction or reference.
</p>
</li><li> APPLICABILITY AND DEFINITIONS

<p>This License applies to any manual or other work, in any medium, that
contains a notice placed by the copyright holder saying it can be
distributed under the terms of this License.  Such a notice grants a
world-wide, royalty-free license, unlimited in duration, to use that
work under the conditions stated herein.  The &ldquo;Document&rdquo;, below,
refers to any such manual or work.  Any member of the public is a
licensee, and is addressed as &ldquo;you&rdquo;.  You accept the license if you
copy, modify or distribute the work in a way requiring permission
under copyright law.
</p>
<p>A &ldquo;Modified Version&rdquo; of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.
</p>
<p>A &ldquo;Secondary Section&rdquo; is a named appendix or a front-matter section
of the Document that deals exclusively with the relationship of the
publishers or authors of the Document to the Document&rsquo;s overall
subject (or to related matters) and contains nothing that could fall
directly within that overall subject.  (Thus, if the Document is in
part a textbook of mathematics, a Secondary Section may not explain
any mathematics.)  The relationship could be a matter of historical
connection with the subject or with related matters, or of legal,
commercial, philosophical, ethical or political position regarding
them.
</p>
<p>The &ldquo;Invariant Sections&rdquo; are certain Secondary Sections whose titles
are designated, as being those of Invariant Sections, in the notice
that says that the Document is released under this License.  If a
section does not fit the above definition of Secondary then it is not
allowed to be designated as Invariant.  The Document may contain zero
Invariant Sections.  If the Document does not identify any Invariant
Sections then there are none.
</p>
<p>The &ldquo;Cover Texts&rdquo; are certain short passages of text that are listed,
as Front-Cover Texts or Back-Cover Texts, in the notice that says that
the Document is released under this License.  A Front-Cover Text may
be at most 5 words, and a Back-Cover Text may be at most 25 words.
</p>
<p>A &ldquo;Transparent&rdquo; copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, that is suitable for revising the document
straightforwardly with generic text editors or (for images composed of
pixels) generic paint programs or (for drawings) some widely available
drawing editor, and that is suitable for input to text formatters or
for automatic translation to a variety of formats suitable for input
to text formatters.  A copy made in an otherwise Transparent file
format whose markup, or absence of markup, has been arranged to thwart
or discourage subsequent modification by readers is not Transparent.
An image format is not Transparent if used for any substantial amount
of text.  A copy that is not &ldquo;Transparent&rdquo; is called &ldquo;Opaque&rdquo;.
</p>
<p>Examples of suitable formats for Transparent copies include plain
ASCII without markup, Texinfo input format, LaTeX input
format, SGML or XML using a publicly available
DTD, and standard-conforming simple HTML,
PostScript or PDF designed for human modification.  Examples
of transparent image formats include PNG, XCF and
JPG.  Opaque formats include proprietary formats that can be
read and edited only by proprietary word processors, SGML or
XML for which the DTD and/or processing tools are
not generally available, and the machine-generated HTML,
PostScript or PDF produced by some word processors for
output purposes only.
</p>
<p>The &ldquo;Title Page&rdquo; means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the material
this License requires to appear in the title page.  For works in
formats which do not have any title page as such, &ldquo;Title Page&rdquo; means
the text near the most prominent appearance of the work&rsquo;s title,
preceding the beginning of the body of the text.
</p>
<p>The &ldquo;publisher&rdquo; means any person or entity that distributes copies
of the Document to the public.
</p>
<p>A section &ldquo;Entitled XYZ&rdquo; means a named subunit of the Document whose
title either is precisely XYZ or contains XYZ in parentheses following
text that translates XYZ in another language.  (Here XYZ stands for a
specific section name mentioned below, such as &ldquo;Acknowledgements&rdquo;,
&ldquo;Dedications&rdquo;, &ldquo;Endorsements&rdquo;, or &ldquo;History&rdquo;.)  To &ldquo;Preserve the Title&rdquo;
of such a section when you modify the Document means that it remains a
section &ldquo;Entitled XYZ&rdquo; according to this definition.
</p>
<p>The Document may include Warranty Disclaimers next to the notice which
states that this License applies to the Document.  These Warranty
Disclaimers are considered to be included by reference in this
License, but only as regards disclaiming warranties: any other
implication that these Warranty Disclaimers may have is void and has
no effect on the meaning of this License.
</p>
</li><li> VERBATIM COPYING

<p>You may copy and distribute the Document in any medium, either
commercially or noncommercially, provided that this License, the
copyright notices, and the license notice saying this License applies
to the Document are reproduced in all copies, and that you add no other
conditions whatsoever to those of this License.  You may not use
technical measures to obstruct or control the reading or further
copying of the copies you make or distribute.  However, you may accept
compensation in exchange for copies.  If you distribute a large enough
number of copies you must also follow the conditions in section 3.
</p>
<p>You may also lend copies, under the same conditions stated above, and
you may publicly display copies.
</p>
</li><li> COPYING IN QUANTITY

<p>If you publish printed copies (or copies in media that commonly have
printed covers) of the Document, numbering more than 100, and the
Document&rsquo;s license notice requires Cover Texts, you must enclose the
copies in covers that carry, clearly and legibly, all these Cover
Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
the back cover.  Both covers must also clearly and legibly identify
you as the publisher of these copies.  The front cover must present
the full title with all words of the title equally prominent and
visible.  You may add other material on the covers in addition.
Copying with changes limited to the covers, as long as they preserve
the title of the Document and satisfy these conditions, can be treated
as verbatim copying in other respects.
</p>
<p>If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
reasonably) on the actual cover, and continue the rest onto adjacent
pages.
</p>
<p>If you publish or distribute Opaque copies of the Document numbering
more than 100, you must either include a machine-readable Transparent
copy along with each Opaque copy, or state in or with each Opaque copy
a computer-network location from which the general network-using
public has access to download using public-standard network protocols
a complete Transparent copy of the Document, free of added material.
If you use the latter option, you must take reasonably prudent steps,
when you begin distribution of Opaque copies in quantity, to ensure
that this Transparent copy will remain thus accessible at the stated
location until at least one year after the last time you distribute an
Opaque copy (directly or through your agents or retailers) of that
edition to the public.
</p>
<p>It is requested, but not required, that you contact the authors of the
Document well before redistributing any large number of copies, to give
them a chance to provide you with an updated version of the Document.
</p>
</li><li> MODIFICATIONS

<p>You may copy and distribute a Modified Version of the Document under
the conditions of sections 2 and 3 above, provided that you release
the Modified Version under precisely this License, with the Modified
Version filling the role of the Document, thus licensing distribution
and modification of the Modified Version to whoever possesses a copy
of it.  In addition, you must do these things in the Modified Version:
</p>
<ol class="enumerate" type="A" start="1">
<li> Use in the Title Page (and on the covers, if any) a title distinct
from that of the Document, and from those of previous versions
(which should, if there were any, be listed in the History section
of the Document).  You may use the same title as a previous version
if the original publisher of that version gives permission.

</li><li> List on the Title Page, as authors, one or more persons or entities
responsible for authorship of the modifications in the Modified
Version, together with at least five of the principal authors of the
Document (all of its principal authors, if it has fewer than five),
unless they release you from this requirement.

</li><li> State on the Title page the name of the publisher of the
Modified Version, as the publisher.

</li><li> Preserve all the copyright notices of the Document.

</li><li> Add an appropriate copyright notice for your modifications
adjacent to the other copyright notices.

</li><li> Include, immediately after the copyright notices, a license notice
giving the public permission to use the Modified Version under the
terms of this License, in the form shown in the Addendum below.

</li><li> Preserve in that license notice the full lists of Invariant Sections
and required Cover Texts given in the Document&rsquo;s license notice.

</li><li> Include an unaltered copy of this License.

</li><li> Preserve the section Entitled &ldquo;History&rdquo;, Preserve its Title, and add
to it an item stating at least the title, year, new authors, and
publisher of the Modified Version as given on the Title Page.  If
there is no section Entitled &ldquo;History&rdquo; in the Document, create one
stating the title, year, authors, and publisher of the Document as
given on its Title Page, then add an item describing the Modified
Version as stated in the previous sentence.

</li><li> Preserve the network location, if any, given in the Document for
public access to a Transparent copy of the Document, and likewise
the network locations given in the Document for previous versions
it was based on.  These may be placed in the &ldquo;History&rdquo; section.
You may omit a network location for a work that was published at
least four years before the Document itself, or if the original
publisher of the version it refers to gives permission.

</li><li> For any section Entitled &ldquo;Acknowledgements&rdquo; or &ldquo;Dedications&rdquo;, Preserve
the Title of the section, and preserve in the section all the
substance and tone of each of the contributor acknowledgements and/or
dedications given therein.

</li><li> Preserve all the Invariant Sections of the Document,
unaltered in their text and in their titles.  Section numbers
or the equivalent are not considered part of the section titles.

</li><li> Delete any section Entitled &ldquo;Endorsements&rdquo;.  Such a section
may not be included in the Modified Version.

</li><li> Do not retitle any existing section to be Entitled &ldquo;Endorsements&rdquo; or
to conflict in title with any Invariant Section.

</li><li> Preserve any Warranty Disclaimers.
</li></ol>

<p>If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no material
copied from the Document, you may at your option designate some or all
of these sections as invariant.  To do this, add their titles to the
list of Invariant Sections in the Modified Version&rsquo;s license notice.
These titles must be distinct from any other section titles.
</p>
<p>You may add a section Entitled &ldquo;Endorsements&rdquo;, provided it contains
nothing but endorsements of your Modified Version by various
parties&mdash;for example, statements of peer review or that the text has
been approved by an organization as the authoritative definition of a
standard.
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</p>
<p>The author(s) and publisher(s) of the Document do not by this License
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</p>
</li><li> COMBINING DOCUMENTS

<p>You may combine the Document with other documents released under this
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versions, provided that you include in the combination all of the
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list them all as Invariant Sections of your combined work in its
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</p>
<p>The combined work need only contain one copy of this License, and
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Make the same adjustment to the section titles in the list of
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<p>In the combination, you must combine any sections Entitled &ldquo;History&rdquo;
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</li><li> COLLECTIONS OF DOCUMENTS

<p>You may make a collection consisting of the Document and other documents
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<p>You may extract a single document from such a collection, and distribute
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</p>
</li><li> AGGREGATION WITH INDEPENDENT WORKS

<p>A compilation of the Document or its derivatives with other separate
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resulting from the compilation is not used to limit the legal rights
of the compilation&rsquo;s users beyond what the individual works permit.
When the Document is included in an aggregate, this License does not
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</p>
<p>If the Cover Text requirement of section 3 is applicable to these
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</p>
</li><li> TRANSLATION

<p>Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of section 4.
Replacing Invariant Sections with translations requires special
permission from their copyright holders, but you may include
translations of some or all Invariant Sections in addition to the
original versions of these Invariant Sections.  You may include a
translation of this License, and all the license notices in the
Document, and any Warranty Disclaimers, provided that you also include
the original English version of this License and the original versions
of those notices and disclaimers.  In case of a disagreement between
the translation and the original version of this License or a notice
or disclaimer, the original version will prevail.
</p>
<p>If a section in the Document is Entitled &ldquo;Acknowledgements&rdquo;,
&ldquo;Dedications&rdquo;, or &ldquo;History&rdquo;, the requirement (section 4) to Preserve
its Title (section 1) will typically require changing the actual
title.
</p>
</li><li> TERMINATION

<p>You may not copy, modify, sublicense, or distribute the Document
except as expressly provided under this License.  Any attempt
otherwise to copy, modify, sublicense, or distribute it is void, and
will automatically terminate your rights under this License.
</p>
<p>However, if you cease all violation of this License, then your license
from a particular copyright holder is reinstated (a) provisionally,
unless and until the copyright holder explicitly and finally
terminates your license, and (b) permanently, if the copyright holder
fails to notify you of the violation by some reasonable means prior to
60 days after the cessation.
</p>
<p>Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from that
copyright holder, and you cure the violation prior to 30 days after
your receipt of the notice.
</p>
<p>Termination of your rights under this section does not terminate the
licenses of parties who have received copies or rights from you under
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reinstated, receipt of a copy of some or all of the same material does
not give you any rights to use it.
</p>
</li><li> FUTURE REVISIONS OF THIS LICENSE

<p>The Free Software Foundation may publish new, revised versions
of the GNU Free Documentation License from time to time.  Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns.  See
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</p>
<p>Each version of the License is given a distinguishing version number.
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number of this License, you may choose any version ever published (not
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specifies that a proxy can decide which future versions of this
License can be used, that proxy&rsquo;s public statement of acceptance of a
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</li><li> RELICENSING

<p>&ldquo;Massive Multiauthor Collaboration Site&rdquo; (or &ldquo;MMC Site&rdquo;) means any
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site means any set of copyrightable works thus published on the MMC
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</p>
<p>&ldquo;CC-BY-SA&rdquo; means the Creative Commons Attribution-Share Alike 3.0
license published by Creative Commons Corporation, a not-for-profit
corporation with a principal place of business in San Francisco,
California, as well as future copyleft versions of that license
published by that same organization.
</p>
<p>&ldquo;Incorporate&rdquo; means to publish or republish a Document, in whole or
in part, as part of another Document.
</p>
<p>An MMC is &ldquo;eligible for relicensing&rdquo; if it is licensed under this
License, and if all works that were first published under this License
somewhere other than this MMC, and subsequently incorporated in whole
or in part into the MMC, (1) had no cover texts or invariant sections,
and (2) were thus incorporated prior to November 1, 2008.
</p>
<p>The operator of an MMC Site may republish an MMC contained in the site
under CC-BY-SA on the same site at any time before August 1, 2009,
provided the MMC is eligible for relicensing.
</p>
</li></ol>

<h3 class="heading" id="ADDENDUM_003a-How-to-use-this-License-for-your-documents">ADDENDUM: How to use this License for your documents</h3>

<p>To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and
license notices just after the title page:
</p>
<div class="example smallexample">
<div class="group"><pre class="example-preformatted">  Copyright (C)  <var class="var">year</var>  <var class="var">your name</var>.
  Permission is granted to copy, distribute and/or modify this document
  under the terms of the GNU Free Documentation License, Version 1.3
  or any later version published by the Free Software Foundation;
  with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
  Texts.  A copy of the license is included in the section entitled ``GNU
  Free Documentation License''.
</pre></div></div>

<p>If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts,
replace the &ldquo;with&hellip;Texts.&rdquo; line with this:
</p>
<div class="example smallexample">
<div class="group"><pre class="example-preformatted">    with the Invariant Sections being <var class="var">list their titles</var>, with
    the Front-Cover Texts being <var class="var">list</var>, and with the Back-Cover Texts
    being <var class="var">list</var>.
</pre></div></div>

<p>If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.
</p>
<p>If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
free software license, such as the GNU General Public License,
to permit their use in free software.
</p>





<hr>
</div>
<div class="appendix-level-extent" id="Request-Index">
<div class="nav-panel">
<p>
Next: <a href="#Escape-Sequence-Index" accesskey="n" rel="next">Escape Sequence Index</a>, Previous: <a href="#Copying-This-Manual" accesskey="p" rel="prev">Copying This Manual</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU <code class="code">troff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="appendix" id="Request-Index-1">Appendix B Request Index</h2>

<p>Request names appear without a leading control character; the defaults
are <code class="code">.</code> for the regular control character and <code class="code">'</code> for the
no-break control character.
</p>
<div class="printindex rq-printindex">
<table class="rq-letters-header-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#Request-Index_rq_letter-A"><b>A</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-B"><b>B</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-C"><b>C</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-D"><b>D</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-E"><b>E</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-G"><b>G</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-H"><b>H</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-I"><b>I</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-K"><b>K</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-L"><b>L</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-M"><b>M</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-N"><b>N</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-O"><b>O</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-P"><b>P</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-R"><b>R</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-S"><b>S</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-T"><b>T</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-U"><b>U</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-V"><b>V</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-W"><b>W</b></a>
 &nbsp; 
</td></tr></table>
<table class="rq-entries-printindex" border="0">
<tr><td></td><th class="entries-header-printindex">Index Entry</th><td>&nbsp;</td><th class="sections-header-printindex"> Section</th></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-A">A</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ab"><code>ab</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ad"><code>ad</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-af"><code>af</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Assigning-Register-Formats">Assigning Register Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-aln"><code>aln</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-als"><code>als</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-am"><code>am</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Writing-Macros">Writing Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-am1"><code>am1</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Writing-Macros">Writing Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ami"><code>ami</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Writing-Macros">Writing Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ami1"><code>ami1</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Writing-Macros">Writing Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-as"><code>as</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-as1"><code>as1</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-asciify"><code>asciify</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-B">B</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-backtrace"><code>backtrace</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-bd"><code>bd</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-blm"><code>blm</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Blank-Line-Traps">Blank Line Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-box"><code>box</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-boxa"><code>boxa</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-bp"><code>bp</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-br"><code>br</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-break-2"><code>break</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#while">while</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-brp"><code>brp</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-C">C</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-c2"><code>c2</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Control-Characters">Control Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cc"><code>cc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Control-Characters">Control Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ce"><code>ce</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cf"><code>cf</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cflags"><code>cflags</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ch"><code>ch</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-char"><code>char</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-chop"><code>chop</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-class"><code>class</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Classes">Character Classes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-close"><code>close</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-color"><code>color</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-composite"><code>composite</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-continue"><code>continue</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#while">while</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cp"><code>cp</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Compatibility-Mode">Compatibility Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cs"><code>cs</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cu"><code>cu</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-D">D</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-da"><code>da</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-de"><code>de</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Writing-Macros">Writing Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-de1"><code>de1</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Writing-Macros">Writing Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-defcolor"><code>defcolor</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dei"><code>dei</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Writing-Macros">Writing Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dei1"><code>dei1</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Writing-Macros">Writing Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-device"><code>device</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Postprocessor-Access">Postprocessor Access</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-devicem"><code>devicem</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Postprocessor-Access">Postprocessor Access</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-di"><code>di</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-do"><code>do</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Compatibility-Mode">Compatibility Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ds"><code>ds</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ds-1"><code>ds</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ds1"><code>ds1</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dt"><code>dt</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversion-Traps">Diversion Traps</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-E">E</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ec"><code>ec</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Escape-Sequences">Using Escape Sequences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ecr"><code>ecr</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Escape-Sequences">Using Escape Sequences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ecs"><code>ecs</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Escape-Sequences">Using Escape Sequences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-el"><code>el</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#if_002delse">if-else</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-em"><code>em</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#End_002dof_002dinput-Traps">End-of-input Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-eo"><code>eo</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Escape-Sequences">Using Escape Sequences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ev"><code>ev</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-evc"><code>evc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ex"><code>ex</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-F">F</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fam"><code>fam</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fc"><code>fc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Fields">Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fchar"><code>fchar</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fcolor"><code>fcolor</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fi"><code>fi</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fl"><code>fl</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fp"><code>fp</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Positions">Font Positions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fschar"><code>fschar</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fspecial"><code>fspecial</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Special-Fonts">Special Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ft"><code>ft</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ftr"><code>ftr</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fzoom"><code>fzoom</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-G">G</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-gcolor"><code>gcolor</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-H">H</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hc"><code>hc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hcode"><code>hcode</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hla"><code>hla</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hlm"><code>hlm</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hpf"><code>hpf</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hpfa"><code>hpfa</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hpfcode"><code>hpfcode</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hw"><code>hw</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hy"><code>hy</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hym"><code>hym</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hys"><code>hys</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-I">I</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ie"><code>ie</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#if_002delse">if-else</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-if"><code>if</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#if_002dthen">if-then</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ig"><code>ig</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Comments">Comments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-in-1"><code>in</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-it"><code>it</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Line-Traps">Input Line Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-itc"><code>itc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Line-Traps">Input Line Traps</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-K">K</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-kern"><code>kern</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-L">L</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lc"><code>lc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leaders">Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-length"><code>length</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lf"><code>lf</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lg"><code>lg</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-linetabs"><code>linetabs</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ll-1"><code>ll</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ls"><code>ls</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Spacing">Manipulating Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lsm"><code>lsm</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leading-Space-Traps">Leading Space Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lt"><code>lt</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-M">M</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mc"><code>mc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mk"><code>mk</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mso"><code>mso</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-msoquiet"><code>msoquiet</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-N">N</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-na"><code>na</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ne"><code>ne</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nf"><code>nf</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nh"><code>nh</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nm"><code>nm</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nn"><code>nn</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nop"><code>nop</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#if_002dthen">if-then</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nr"><code>nr</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nr-1"><code>nr</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nr-2"><code>nr</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nr-3"><code>nr</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Auto_002dincrement">Auto-increment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nroff"><code>nroff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#troff-and-nroff-Modes"><code class="code">troff</code> and <code class="code">nroff</code> Modes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ns"><code>ns</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Spacing">Manipulating Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nx"><code>nx</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-O">O</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-open"><code>open</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-opena"><code>opena</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-os"><code>os</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output"><code>output</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-P">P</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pc"><code>pc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pev"><code>pev</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pi"><code>pi</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pl"><code>pl</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pm"><code>pm</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pn"><code>pn</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pnr"><code>pnr</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-po-1"><code>po</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ps"><code>ps</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Type-Size">Changing the Type Size</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-psbb"><code>psbb</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pso"><code>pso</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ptr"><code>ptr</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pvs"><code>pvs</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-R">R</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rchar"><code>rchar</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rd"><code>rd</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-return"><code>return</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Writing-Macros">Writing Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rfschar"><code>rfschar</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rj"><code>rj</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rm"><code>rm</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rn"><code>rn</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rnn"><code>rnn</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rr"><code>rr</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rs"><code>rs</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Spacing">Manipulating Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rt"><code>rt</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-S">S</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-schar"><code>schar</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-shc"><code>shc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-shift"><code>shift</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Parameters">Parameters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sizes-1"><code>sizes</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Type-Size">Changing the Type Size</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-so"><code>so</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-soquiet"><code>soquiet</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sp"><code>sp</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Spacing">Manipulating Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-special-2"><code>special</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Special-Fonts">Special Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-spreadwarn"><code>spreadwarn</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ss"><code>ss</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-stringdown"><code>stringdown</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-stringup"><code>stringup</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sty"><code>sty</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-substring"><code>substring</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sv"><code>sv</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sy"><code>sy</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-T">T</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ta"><code>ta</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tag"><code>tag</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Postprocessor-Access">Postprocessor Access</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-taga"><code>taga</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Postprocessor-Access">Postprocessor Access</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tc"><code>tc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ti"><code>ti</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tkf"><code>tkf</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tl"><code>tl</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tm"><code>tm</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tm1"><code>tm1</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tmc"><code>tmc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tr"><code>tr</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trf"><code>trf</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trin"><code>trin</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trnt"><code>trnt</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-troff"><code>troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#troff-and-nroff-Modes"><code class="code">troff</code> and <code class="code">nroff</code> Modes</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-U">U</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-uf"><code>uf</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ul"><code>ul</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unformat"><code>unformat</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-V">V</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vpt"><code>vpt</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Vertical-Position-Traps">Vertical Position Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vs"><code>vs</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Request-Index_rq_letter-W">W</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-warn"><code>warn</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-warnscale"><code>warnscale</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-wh"><code>wh</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-while-1"><code>while</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#while">while</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-write"><code>write</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-writec"><code>writec</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-writem"><code>writem</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
</table>
<table class="rq-letters-footer-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#Request-Index_rq_letter-A"><b>A</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-B"><b>B</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-C"><b>C</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-D"><b>D</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-E"><b>E</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-G"><b>G</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-H"><b>H</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-I"><b>I</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-K"><b>K</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-L"><b>L</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-M"><b>M</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-N"><b>N</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-O"><b>O</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-P"><b>P</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-R"><b>R</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-S"><b>S</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-T"><b>T</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-U"><b>U</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-V"><b>V</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Request-Index_rq_letter-W"><b>W</b></a>
 &nbsp; 
</td></tr></table>
</div>




<hr>
</div>
<div class="appendix-level-extent" id="Escape-Sequence-Index">
<div class="nav-panel">
<p>
Next: <a href="#Operator-Index" accesskey="n" rel="next">Operator Index</a>, Previous: <a href="#Request-Index" accesskey="p" rel="prev">Request Index</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU <code class="code">troff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="appendix" id="Escape-Sequence-Index-1">Appendix C Escape Sequence Index</h2>

<p>The escape character, <code class="code">\</code> by default, is always followed by at
least one more input character, making an escape <em class="emph">sequence</em>.  Any
input token <code class="code">\<var class="var">X</var></code> with <var class="var">X</var> not in the list below emits a
warning and interpolates glyph <var class="var">X</var>.  Note the entries for <code class="code">\.</code>,
which may be obscured by the leader dots, and for <code class="code">\<kbd class="key">RET</kbd></code> and
<code class="code">\<kbd class="key">SP</kbd></code>, which are sorted alphabetically, not by code point
order.
</p>
<div class="printindex es-printindex">
<table class="es-entries-printindex" border="0">
<tr><td></td><th class="entries-header-printindex">Index Entry</th><td>&nbsp;</td><th class="sections-header-printindex"> Section</th></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Escape-Sequence-Index_es_symbol-1">\</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c"><code>\</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Escape-Sequences">Using Escape Sequences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c-1"><code>\</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0021"><code>\!</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0022"><code>\&quot;</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Comments">Comments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0023"><code>\#</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Comments">Comments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0024"><code>\$</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Parameters">Parameters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0024_002a"><code>\$*</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Parameters">Parameters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_00240"><code>\$0</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Parameters">Parameters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0024_0040"><code>\$@</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Parameters">Parameters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0024_005e"><code>\$^</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Parameters">Parameters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0025"><code>\%</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0026"><code>\&amp;</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Dummy-Characters">Dummy Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0027"><code>\<code class="code">'</code></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0028"><code>\(</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0029"><code>\)</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Dummy-Characters">Dummy Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_002a"><code>\*</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_002c"><code>\,</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Italic-Corrections">Italic Corrections</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_002d"><code>\-</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_002e"><code>\.</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Copy-Mode">Copy Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_002f"><code>\/</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Italic-Corrections">Italic Corrections</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c0"><code>\0</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_003a"><code>\:</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_003f"><code>\?</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cA"><code>\A</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005ca"><code>\a</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leaders">Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cB"><code>\B</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cb"><code>\b</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cc"><code>\c</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cC"><code>\C</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cd"><code>\d</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cD"><code>\D</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005ce"><code>\e</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Escape-Sequences">Using Escape Sequences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cE"><code>\E</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Copy-Mode">Copy Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cf"><code>\f</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cF"><code>\F</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cg"><code>\g</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Assigning-Register-Formats">Assigning Register Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cH"><code>\H</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005ch"><code>\h</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005ck"><code>\k</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cl"><code>\l</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cL"><code>\L</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cm"><code>\m</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cM"><code>\M</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cn"><code>\n</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Interpolating-Registers">Interpolating Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cn-1"><code>\n</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Auto_002dincrement">Auto-increment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cN"><code>\N</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cnewline"><code>\<i class="slanted">newline</i></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005co"><code>\o</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cO"><code>\O</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Suppressing-Output">Suppressing Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cp"><code>\p</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cR"><code>\R</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cR-1"><code>\R</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cr"><code>\r</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cRET"><code>\<kbd class="key">RET</kbd></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cS"><code>\S</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cs"><code>\s</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Type-Size">Changing the Type Size</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cSP"><code>\<kbd class="key">SP</kbd></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cspace"><code>\<i class="slanted">space</i></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005ct"><code>\t</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cu"><code>\u</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cv"><code>\v</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cV"><code>\V</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cw"><code>\w</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cx"><code>\x</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Spacing">Manipulating Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cX"><code>\X</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Postprocessor-Access">Postprocessor Access</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cY"><code>\Y</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Postprocessor-Access">Postprocessor Access</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cz"><code>\z</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cZ"><code>\Z</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_005b"><code>\[</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_005c"><code>\\</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Copy-Mode">Copy Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_005e"><code>\^</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_005f"><code>\_</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0060"><code>\<code class="code">`</code></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_007b"><code>\{</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditional-Blocks">Conditional Blocks</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_007b-1"><code>\{</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditional-Blocks">Conditional Blocks</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_007c"><code>\|</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_007d"><code>\}</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditional-Blocks">Conditional Blocks</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_007e"><code>\~</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
</table>
</div>




<hr>
</div>
<div class="appendix-level-extent" id="Operator-Index">
<div class="nav-panel">
<p>
Next: <a href="#Register-Index" accesskey="n" rel="next">Register Index</a>, Previous: <a href="#Escape-Sequence-Index" accesskey="p" rel="prev">Escape Sequence Index</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU <code class="code">troff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="appendix" id="Operator-Index-1">Appendix D Operator Index</h2>

<div class="printindex op-printindex">
<table class="op-letters-header-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#Operator-Index_op_symbol-1"><b>!</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-2"><b>%</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-3"><b>&amp;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-4"><b>(</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-5"><b>)</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-6"><b>*</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-7"><b>+</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-8"><b>-</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-9"><b>/</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-10"><b>:</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-11"><b>;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-12"><b>&lt;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-13"><b>=</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-14"><b>&gt;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-15"><b>|</b></a>
</td></tr></table>
<table class="op-entries-printindex" border="0">
<tr><td></td><th class="entries-header-printindex">Index Entry</th><td>&nbsp;</td><th class="sections-header-printindex"> Section</th></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Operator-Index_op_symbol-1">!</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0021"><code>!</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Operator-Index_op_symbol-2">%</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0025"><code>%</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Operator-Index_op_symbol-3">&amp;</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0026"><code>&amp;</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Operator-Index_op_symbol-4">(</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0028"><code>(</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Operator-Index_op_symbol-5">)</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0029"><code>)</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Operator-Index_op_symbol-6">*</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002a"><code>*</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Operator-Index_op_symbol-7">+</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002b"><code>+</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002b-1"><code>+</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002b-_0028unary_0029"><code>+ <span class="r">(unary)</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Operator-Index_op_symbol-8">-</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002d"><code>-</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002d-1"><code>-</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002d-_0028unary_0029"><code>- <span class="r">(unary)</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Operator-Index_op_symbol-9">/</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002f"><code>/</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Operator-Index_op_symbol-10">:</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003a"><code>:</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Operator-Index_op_symbol-11">;</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003b"><code>;</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Operator-Index_op_symbol-12">&lt;</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003c"><code>&lt;</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003c_003d"><code>&lt;=</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003c_003f"><code>&lt;?</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Operator-Index_op_symbol-13">=</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003d"><code>=</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003d_003d"><code>==</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Operator-Index_op_symbol-14">&gt;</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003e"><code>&gt;</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003e_003d"><code>&gt;=</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003e_003f"><code>&gt;?</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Operator-Index_op_symbol-15">|</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_007c"><code>|</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
</table>
<table class="op-letters-footer-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#Operator-Index_op_symbol-1"><b>!</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-2"><b>%</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-3"><b>&amp;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-4"><b>(</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-5"><b>)</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-6"><b>*</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-7"><b>+</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-8"><b>-</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-9"><b>/</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-10"><b>:</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-11"><b>;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-12"><b>&lt;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-13"><b>=</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-14"><b>&gt;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Operator-Index_op_symbol-15"><b>|</b></a>
</td></tr></table>
</div>




<hr>
</div>
<div class="appendix-level-extent" id="Register-Index">
<div class="nav-panel">
<p>
Next: <a href="#Macro-Index" accesskey="n" rel="next">Macro Index</a>, Previous: <a href="#Operator-Index" accesskey="p" rel="prev">Operator Index</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU <code class="code">troff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="appendix" id="Register-Index-1">Appendix E Register Index</h2>

<p>The macro package or program a specific register belongs to is appended
in brackets.
</p>
<p>A register name&nbsp;<code class="code">x</code> consisting of exactly one character can be
accessed as &lsquo;<samp class="samp">\nx</samp>&rsquo;.  A register name <code class="code">xx</code> consisting of exactly
two characters can be accessed as &lsquo;<samp class="samp">\n(xx</samp>&rsquo;.  Register names
<code class="code">xxx</code> of any length can be accessed as &lsquo;<samp class="samp">\n[xxx]</samp>&rsquo;.
</p>
<div class="printindex vr-printindex">
<table class="vr-letters-header-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#Register-Index_vr_symbol-1"><b>$</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_symbol-2"><b>%</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_symbol-3"><b>.</b></a>
 &nbsp; 
<br>
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-C"><b>C</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-D"><b>D</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-G"><b>G</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-H"><b>H</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-L"><b>L</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-M"><b>M</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-N"><b>N</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-O"><b>O</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-P"><b>P</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-Q"><b>Q</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-R"><b>R</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-S"><b>S</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-T"><b>T</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-U"><b>U</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-V"><b>V</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-Y"><b>Y</b></a>
 &nbsp; 
</td></tr></table>
<table class="vr-entries-printindex" border="0">
<tr><td></td><th class="entries-header-printindex">Index Entry</th><td>&nbsp;</td><th class="sections-header-printindex"> Section</th></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_symbol-1">$</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0024_0024"><code>$$</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_symbol-2">%</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0025-1"><code>%</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0025-2"><code>%</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_symbol-3">.</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002e_0024"><code>.$</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Parameters">Parameters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eA"><code>.A</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ea"><code>.a</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Spacing">Manipulating Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eb"><code>.b</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ebr-1"><code>.br</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Control-Characters">Control Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ec"><code>.c</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eC"><code>.C</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Compatibility-Mode">Compatibility Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ecdp"><code>.cdp</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ece-1"><code>.ce</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002echt"><code>.cht</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ecolor-1"><code>.color</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ecp-1"><code>.cp</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Compatibility-Mode">Compatibility Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ecsk"><code>.csk</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ed"><code>.d</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eev-1"><code>.ev</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eF"><code>.F</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ef"><code>.f</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Positions">Font Positions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002efam-1"><code>.fam</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002efn"><code>.fn</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002efp-1"><code>.fp</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Positions">Font Positions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eg"><code>.g</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eH"><code>.H</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Motion-Quanta">Motion Quanta</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eh"><code>.h</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eheight"><code>.height</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ehla-1"><code>.hla</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ehlc"><code>.hlc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ehlm-1"><code>.hlm</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ehy-1"><code>.hy</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ehym-1"><code>.hym</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ehys-1"><code>.hys</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ei"><code>.i</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ein-3"><code>.in</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eint"><code>.int</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ej"><code>.j</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ek"><code>.k</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ekern-1"><code>.kern</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eL"><code>.L</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Spacing">Manipulating Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002el"><code>.l</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002elg-1"><code>.lg</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002elinetabs-1"><code>.linetabs</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ell-3"><code>.ll</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002elt-3"><code>.lt</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002em"><code>.m</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eM"><code>.M</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002en"><code>.n</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ene-1"><code>.ne</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002enm-1"><code>.nm</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002enn-1"><code>.nn</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ens-1"><code>.ns</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Spacing">Manipulating Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eo"><code>.o</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eO"><code>.O</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Suppressing-Output">Suppressing Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eP"><code>.P</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ep"><code>.p</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002epe"><code>.pe</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002epn-3"><code>.pn</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eps-3"><code>.ps</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002epsr"><code>.psr</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002epvs-3"><code>.pvs</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eR-2"><code>.R</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002erj-1"><code>.rj</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002es"><code>.s</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Type-Size">Changing the Type Size</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eslant"><code>.slant</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002esr"><code>.sr</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ess-1"><code>.ss</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002esss"><code>.sss</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002esty-1"><code>.sty</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eT-2"><code>.T</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002et"><code>.t</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002etabs"><code>.tabs</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002etrunc"><code>.trunc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eU"><code>.U</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eu"><code>.u</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eV"><code>.V</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Motion-Quanta">Motion Quanta</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ev"><code>.v</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002evpt-1"><code>.vpt</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Vertical-Position-Traps">Vertical Position Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ew"><code>.w</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ewarn-1"><code>.warn</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ex"><code>.x</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ey"><code>.y</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eY"><code>.Y</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ez"><code>.z</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002ezoom"><code>.zoom</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_letter-C">C</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-c_002e"><code>c.</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ct"><code>ct</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_letter-D">D</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-DD-_005bms_005d"><code>DD <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-DI-_005bms_005d"><code>DI <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dl"><code>dl</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dn"><code>dn</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dw"><code>dw</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dy"><code>dy</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_letter-F">F</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-FF-_005bms_005d"><code>FF <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-FI-_005bms_005d"><code>FI <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-FM-_005bms_005d"><code>FM <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-FPD-_005bms_005d"><code>FPD <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-FPS-_005bms_005d"><code>FPS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-FVS-_005bms_005d"><code>FVS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_letter-G">G</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-GROWPS-_005bms_005d"><code>GROWPS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-GS-_005bms_005d"><code>GS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Differences-from-AT_0026T-ms">Differences from AT&amp;T ms</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_letter-H">H</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-HM-_005bms_005d"><code>HM <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-HORPHANS-_005bms_005d"><code>HORPHANS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hours"><code>hours</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hp"><code>hp</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-HY-_005bms_005d"><code>HY <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_letter-L">L</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-LL-_005bms_005d"><code>LL <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-llx"><code>llx</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lly"><code>lly</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ln"><code>ln</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lsn"><code>lsn</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leading-Space-Traps">Leading Space Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lss"><code>lss</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leading-Space-Traps">Leading Space Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-LT-_005bms_005d"><code>LT <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_letter-M">M</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-MINGW-_005bms_005d"><code>MINGW <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-minutes"><code>minutes</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mo"><code>mo</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_letter-N">N</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nl"><code>nl</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_letter-O">O</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-opmaxx"><code>opmaxx</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Suppressing-Output">Suppressing Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-opmaxy"><code>opmaxy</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Suppressing-Output">Suppressing Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-opminx"><code>opminx</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Suppressing-Output">Suppressing Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-opminy"><code>opminy</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Suppressing-Output">Suppressing Output</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_letter-P">P</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-PD-_005bms_005d"><code>PD <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-PI-_005bms_005d"><code>PI <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-PO-_005bms_005d"><code>PO <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-PORPHANS-_005bms_005d"><code>PORPHANS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-PS-_005bms_005d-1"><code>PS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-PSINCR-_005bms_005d"><code>PSINCR <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_letter-Q">Q</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-QI-_005bms_005d"><code>QI <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_letter-R">R</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rsb"><code>rsb</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rst"><code>rst</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_letter-S">S</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sb"><code>sb</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-seconds"><code>seconds</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-skw"><code>skw</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-slimit"><code>slimit</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ssc"><code>ssc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-st"><code>st</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-systat"><code>systat</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_letter-T">T</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-TC_002dMARGIN-_005bms_005d"><code>TC-MARGIN <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_letter-U">U</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-urx"><code>urx</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ury"><code>ury</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_letter-V">V</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-VS-_005bms_005d"><code>VS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Register-Index_vr_letter-Y">Y</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-year"><code>year</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-yr"><code>yr</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
</table>
<table class="vr-letters-footer-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#Register-Index_vr_symbol-1"><b>$</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_symbol-2"><b>%</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_symbol-3"><b>.</b></a>
 &nbsp; 
<br>
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-C"><b>C</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-D"><b>D</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-G"><b>G</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-H"><b>H</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-L"><b>L</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-M"><b>M</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-N"><b>N</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-O"><b>O</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-P"><b>P</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-Q"><b>Q</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-R"><b>R</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-S"><b>S</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-T"><b>T</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-U"><b>U</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-V"><b>V</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Register-Index_vr_letter-Y"><b>Y</b></a>
 &nbsp; 
</td></tr></table>
</div>




<hr>
</div>
<div class="appendix-level-extent" id="Macro-Index">
<div class="nav-panel">
<p>
Next: <a href="#String-Index" accesskey="n" rel="next">String Index</a>, Previous: <a href="#Register-Index" accesskey="p" rel="prev">Register Index</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU <code class="code">troff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="appendix" id="Macro-Index-1">Appendix F Macro Index</h2>

<p>The macro package a specific macro belongs to is appended in brackets.
They appear without the leading control character (normally &lsquo;<samp class="samp">.</samp>&rsquo;).
</p>
<div class="printindex ma-printindex">
<table class="ma-letters-header-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#Macro-Index_ma_symbol-1"><b>1</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_symbol-2"><b>2</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_symbol-3"><b>[</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_symbol-4"><b>]</b></a>
 &nbsp; 
<br>
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-A"><b>A</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-B"><b>B</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-C"><b>C</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-D"><b>D</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-E"><b>E</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-G"><b>G</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-H"><b>H</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-I"><b>I</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-K"><b>K</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-L"><b>L</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-M"><b>M</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-N"><b>N</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-O"><b>O</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-P"><b>P</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-Q"><b>Q</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-R"><b>R</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-S"><b>S</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-T"><b>T</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-U"><b>U</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-V"><b>V</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-X"><b>X</b></a>
 &nbsp; 
</td></tr></table>
<table class="ma-entries-printindex" border="0">
<tr><td></td><th class="entries-header-printindex">Index Entry</th><td>&nbsp;</td><th class="sections-header-printindex"> Section</th></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_symbol-1">1</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-1C-_005bms_005d"><code>1C <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Multiple-Columns">ms Multiple Columns</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_symbol-2">2</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-2C-_005bms_005d"><code>2C <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Multiple-Columns">ms Multiple Columns</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_symbol-3">[</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005b-_005bms_005d"><code>[ <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_symbol-4">]</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005d-_005bms_005d"><code>] <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-A">A</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-AB-_005bms_005d"><code>AB <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Description-Macros">ms Document Description Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-AE-_005bms_005d"><code>AE <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Description-Macros">ms Document Description Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-AI-_005bms_005d"><code>AI <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Description-Macros">ms Document Description Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-AM-_005bms_005d"><code>AM <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-AU-_005bms_005d"><code>AU <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Description-Macros">ms Document Description Macros</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-B">B</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-B-_005bms_005d"><code>B <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Typeface-and-decoration">Typeface and decoration</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-B1-_005bms_005d"><code>B1 <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-B2-_005bms_005d"><code>B2 <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-BD-_005bms_005d"><code>BD <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-BI-_005bms_005d"><code>BI <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Typeface-and-decoration">Typeface and decoration</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-BT-_005bman_005d"><code>BT <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-BX-_005bms_005d"><code>BX <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Typeface-and-decoration">Typeface and decoration</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-C">C</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CD-_005bms_005d"><code>CD <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CT-_005bman_005d"><code>CT <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CW-_005bman_005d"><code>CW <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CW-_005bms_005d"><code>CW <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Typeface-and-decoration">Typeface and decoration</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-D">D</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-DA-_005bms_005d"><code>DA <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Description-Macros">ms Document Description Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-De-_005bman_005d"><code>De <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-DE-_005bms_005d"><code>DE <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-Ds-_005bman_005d"><code>Ds <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-DS-_005bms_005d"><code>DS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-DS-_005bms_005d-1"><code>DS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-DS-_005bms_005d-2"><code>DS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-DS-_005bms_005d-3"><code>DS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-DS-_005bms_005d-4"><code>DS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-E">E</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-EE-_005bman_005d"><code>EE <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-EF-_005bms_005d"><code>EF <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Headers-and-Footers">ms Headers and Footers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-EH-_005bms_005d"><code>EH <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Headers-and-Footers">ms Headers and Footers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-EN-_005bms_005d"><code>EN <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-EQ-_005bms_005d"><code>EQ <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-EX-_005bman_005d"><code>EX <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-F">F</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-FE-_005bms_005d"><code>FE <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Footnotes">ms Footnotes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-FS-_005bms_005d"><code>FS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Footnotes">ms Footnotes</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-G">G</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-G-_005bman_005d"><code>G <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-GL-_005bman_005d"><code>GL <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-H">H</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-HB-_005bman_005d"><code>HB <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-I">I</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-I-_005bms_005d"><code>I <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Typeface-and-decoration">Typeface and decoration</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ID-_005bms_005d"><code>ID <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-IP-_005bms_005d"><code>IP <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paragraphs-in-ms">Paragraphs in ms</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-K">K</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-KE-_005bms_005d"><code>KE <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-KF-_005bms_005d"><code>KF <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-KS-_005bms_005d"><code>KS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-L">L</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-LD-_005bms_005d"><code>LD <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-LG-_005bms_005d"><code>LG <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Typeface-and-decoration">Typeface and decoration</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-LP-_005bms_005d"><code>LP <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paragraphs-in-ms">Paragraphs in ms</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-M">M</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-MC-_005bms_005d"><code>MC <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Multiple-Columns">ms Multiple Columns</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-MS-_005bman_005d"><code>MS <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-N">N</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ND-_005bms_005d"><code>ND <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Description-Macros">ms Document Description Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-NE-_005bman_005d"><code>NE <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-NH-_005bms_005d"><code>NH <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Headings-in-ms">Headings in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-NL-_005bms_005d"><code>NL <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Typeface-and-decoration">Typeface and decoration</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-NT-_005bman_005d"><code>NT <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-O">O</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-OF-_005bms_005d"><code>OF <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Headers-and-Footers">ms Headers and Footers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-OH-_005bms_005d"><code>OH <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Headers-and-Footers">ms Headers and Footers</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-P">P</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-P1-_005bms_005d"><code>P1 <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Headers-and-Footers">ms Headers and Footers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-PE-_005bms_005d"><code>PE <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-PF-_005bms_005d"><code>PF <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-PN-_005bman_005d"><code>PN <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-Pn-_005bman_005d"><code>Pn <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-PP-_005bms_005d"><code>PP <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paragraphs-in-ms">Paragraphs in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-PS-_005bms_005d"><code>PS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-PT-_005bman_005d"><code>PT <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-PX-_005bms_005d"><code>PX <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-TOC">ms TOC</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-Q">Q</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-QE-_005bms_005d"><code>QE <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paragraphs-in-ms">Paragraphs in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-QP-_005bms_005d"><code>QP <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paragraphs-in-ms">Paragraphs in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-QS-_005bms_005d"><code>QS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paragraphs-in-ms">Paragraphs in ms</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-R">R</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-R-_005bman_005d"><code>R <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-R-_005bms_005d"><code>R <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Typeface-and-decoration">Typeface and decoration</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-RD-_005bms_005d"><code>RD <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-RE-_005bms_005d"><code>RE <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Indented-regions-in-ms">Indented regions in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-RN-_005bman_005d"><code>RN <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-RP-_005bms_005d"><code>RP <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Description-Macros">ms Document Description Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-RS-_005bms_005d"><code>RS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Indented-regions-in-ms">Indented regions in ms</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-S">S</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-SH-_005bms_005d"><code>SH <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Headings-in-ms">Headings in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-SM-_005bms_005d"><code>SM <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Typeface-and-decoration">Typeface and decoration</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-T">T</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-TA-_005bms_005d"><code>TA <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tab-Stops-in-ms">Tab Stops in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-TB-_005bman_005d"><code>TB <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-TC-_005bms_005d"><code>TC <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-TOC">ms TOC</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-TE-_005bms_005d"><code>TE <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-TL-_005bms_005d"><code>TL <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Description-Macros">ms Document Description Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-TS-_005bms_005d"><code>TS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-U">U</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-UL-_005bms_005d"><code>UL <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Typeface-and-decoration">Typeface and decoration</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-V">V</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-VE-_005bman_005d"><code>VE <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-VS-_005bman_005d"><code>VS <span class="r">[</span>man<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Macro-Index_ma_letter-X">X</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-XA-_005bms_005d"><code>XA <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-TOC">ms TOC</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-XE-_005bms_005d"><code>XE <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-TOC">ms TOC</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-XH-_005bms_005d"><code>XH <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-TOC">ms TOC</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-XH_002dREPLACEMENT-_005bms_005d"><code>XH-REPLACEMENT <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-TOC">ms TOC</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-XH_002dUPDATE_002dTOC-_005bms_005d"><code>XH-UPDATE-TOC <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-TOC">ms TOC</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-XN-_005bms_005d"><code>XN <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-TOC">ms TOC</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-XN_002dINIT-_005bms_005d"><code>XN-INIT <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-TOC">ms TOC</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-XN_002dREPLACEMENT-_005bms_005d"><code>XN-REPLACEMENT <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-TOC">ms TOC</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-XP-_005bms_005d"><code>XP <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paragraphs-in-ms">Paragraphs in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-XS-_005bms_005d"><code>XS <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-TOC">ms TOC</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
</table>
<table class="ma-letters-footer-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#Macro-Index_ma_symbol-1"><b>1</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_symbol-2"><b>2</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_symbol-3"><b>[</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_symbol-4"><b>]</b></a>
 &nbsp; 
<br>
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-A"><b>A</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-B"><b>B</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-C"><b>C</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-D"><b>D</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-E"><b>E</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-G"><b>G</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-H"><b>H</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-I"><b>I</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-K"><b>K</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-L"><b>L</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-M"><b>M</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-N"><b>N</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-O"><b>O</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-P"><b>P</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-Q"><b>Q</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-R"><b>R</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-S"><b>S</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-T"><b>T</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-U"><b>U</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-V"><b>V</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Macro-Index_ma_letter-X"><b>X</b></a>
 &nbsp; 
</td></tr></table>
</div>




<hr>
</div>
<div class="appendix-level-extent" id="String-Index">
<div class="nav-panel">
<p>
Next: <a href="#File-Keyword-Index" accesskey="n" rel="next">File Keyword Index</a>, Previous: <a href="#Macro-Index" accesskey="p" rel="prev">Macro Index</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU <code class="code">troff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="appendix" id="String-Index-1">Appendix G String Index</h2>

<p>The macro package or program a that defines or uses each string is
appended in brackets. (Only one string, <code class="code">.T</code>, is defined by the
<code class="code">troff</code> formatter itself.)  See <a class="xref" href="#Strings">Strings</a>.
</p>

<div class="printindex st-printindex">
<table class="st-letters-header-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#String-Index_st_symbol-1"><b>!</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-2"><b>'</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-3"><b>*</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-4"><b>,</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-5"><b>-</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-6"><b>.</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-7"><b>/</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-8"><b>3</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-9"><b>8</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-10"><b>:</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-11"><b>&lt;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-12"><b>&gt;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-13"><b>?</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-14"><b>^</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-15"><b>_</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-16"><b>`</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-17"><b>{</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-18"><b>}</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-19"><b>~</b></a>
 &nbsp; 
<br>
<a class="summary-letter-printindex" href="#String-Index_st_letter-A"><b>A</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-C"><b>C</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-D"><b>D</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-L"><b>L</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-M"><b>M</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-O"><b>O</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-Q"><b>Q</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-R"><b>R</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-S"><b>S</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-T"><b>T</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-U"><b>U</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-V"><b>V</b></a>
 &nbsp; 
</td></tr></table>
<table class="st-entries-printindex" border="0">
<tr><td></td><th class="entries-header-printindex">Index Entry</th><td>&nbsp;</td><th class="sections-header-printindex"> Section</th></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-1">!</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0021-_005bms_005d"><code>! <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-2">'</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0027-_005bms_005d"><code><code class="code">'</code> <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0027-_005bms_005d-1"><code><code class="code">'</code> <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-3">*</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002a-_005bms_005d"><code>* <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Footnotes">ms Footnotes</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-4">,</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002c-_005bms_005d"><code>, <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002c-_005bms_005d-1"><code>, <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-5">-</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002d-_005bms_005d"><code>- <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Typographical-symbols-in-ms">Typographical symbols in ms</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-6">.</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002e-_005bms_005d"><code>. <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eT"><code>.T</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eT-1"><code>.T</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-7">/</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002f-_005bms_005d"><code>/ <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-8">3</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-3-_005bms_005d"><code>3 <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-9">8</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-8-_005bms_005d"><code>8 <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-10">:</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003a-_005bms_005d"><code>: <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003a-_005bms_005d-1"><code>: <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-11">&lt;</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003c-_005bms_005d"><code>&lt; <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Typeface-and-decoration">Typeface and decoration</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-12">&gt;</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003e-_005bms_005d"><code>&gt; <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Typeface-and-decoration">Typeface and decoration</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-13">?</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003f-_005bms_005d"><code>? <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-14">^</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005e-_005bms_005d"><code>^ <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005e-_005bms_005d-1"><code>^ <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-15">_</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005f-_005bms_005d"><code>_ <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-16">`</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0060-_005bms_005d"><code><code class="code">`</code> <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0060-_005bms_005d-1"><code><code class="code">`</code> <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-17">{</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_007b-_005bms_005d"><code>{ <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Typeface-and-decoration">Typeface and decoration</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-18">}</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_007d-_005bms_005d"><code>} <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Typeface-and-decoration">Typeface and decoration</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_symbol-19">~</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_007e-_005bms_005d"><code>~ <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_007e-_005bms_005d-1"><code>~ <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_letter-A">A</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ABSTRACT-_005bms_005d"><code>ABSTRACT <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ae-_005bms_005d"><code>ae <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-Ae-_005bms_005d"><code>Ae <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_letter-C">C</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-C-_005bms_005d"><code>C <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CF-_005bms_005d"><code>CF <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CH-_005bms_005d"><code>CH <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_letter-D">D</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-d_002d-_005bms_005d"><code>d- <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-D_002d-_005bms_005d"><code>D- <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_letter-F">F</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-FAM-_005bms_005d"><code>FAM <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-FR-_005bms_005d"><code>FR <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_letter-L">L</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-LF-_005bms_005d"><code>LF <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-LH-_005bms_005d"><code>LH <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_letter-M">M</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-MONTH1-_005bms_005d"><code>MONTH1 <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-MONTH10-_005bms_005d"><code>MONTH10 <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-MONTH11-_005bms_005d"><code>MONTH11 <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-MONTH12-_005bms_005d"><code>MONTH12 <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-MONTH2-_005bms_005d"><code>MONTH2 <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-MONTH3-_005bms_005d"><code>MONTH3 <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-MONTH4-_005bms_005d"><code>MONTH4 <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-MONTH5-_005bms_005d"><code>MONTH5 <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-MONTH6-_005bms_005d"><code>MONTH6 <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-MONTH7-_005bms_005d"><code>MONTH7 <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-MONTH8-_005bms_005d"><code>MONTH8 <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-MONTH9-_005bms_005d"><code>MONTH9 <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_letter-O">O</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-o-_005bms_005d"><code>o <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-oe-_005bms_005d"><code>oe <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-OE-_005bms_005d"><code>OE <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_letter-Q">Q</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-Q-_005bms_005d"><code>Q <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Typographical-symbols-in-ms">Typographical symbols in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-q-_005bms_005d"><code>q <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_letter-R">R</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-REFERENCES-_005bms_005d"><code>REFERENCES <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-RF-_005bms_005d"><code>RF <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-RH-_005bms_005d"><code>RH <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_letter-S">S</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-SN-_005bms_005d"><code>SN <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Headings-in-ms">Headings in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-SN_002dDOT-_005bms_005d"><code>SN-DOT <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Headings-in-ms">Headings in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-SN_002dNO_002dDOT-_005bms_005d"><code>SN-NO-DOT <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Headings-in-ms">Headings in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-SN_002dSTYLE-_005bms_005d"><code>SN-STYLE <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-SN_002dSTYLE-_005bms_005d-1"><code>SN-STYLE <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Headings-in-ms">Headings in ms</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_letter-T">T</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-th-_005bms_005d"><code>th <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-Th-_005bms_005d"><code>Th <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-TOC-_005bms_005d"><code>TOC <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_letter-U">U</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-U-_005bms_005d"><code>U <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Typographical-symbols-in-ms">Typographical symbols in ms</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="String-Index_st_letter-V">V</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-v-_005bms_005d"><code>v <span class="r">[</span>ms<span class="r">]</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
</table>
<table class="st-letters-footer-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#String-Index_st_symbol-1"><b>!</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-2"><b>'</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-3"><b>*</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-4"><b>,</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-5"><b>-</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-6"><b>.</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-7"><b>/</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-8"><b>3</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-9"><b>8</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-10"><b>:</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-11"><b>&lt;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-12"><b>&gt;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-13"><b>?</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-14"><b>^</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-15"><b>_</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-16"><b>`</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-17"><b>{</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-18"><b>}</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_symbol-19"><b>~</b></a>
 &nbsp; 
<br>
<a class="summary-letter-printindex" href="#String-Index_st_letter-A"><b>A</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-C"><b>C</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-D"><b>D</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-L"><b>L</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-M"><b>M</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-O"><b>O</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-Q"><b>Q</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-R"><b>R</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-S"><b>S</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-T"><b>T</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-U"><b>U</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#String-Index_st_letter-V"><b>V</b></a>
 &nbsp; 
</td></tr></table>
</div>




<hr>
</div>
<div class="appendix-level-extent" id="File-Keyword-Index">
<div class="nav-panel">
<p>
Next: <a href="#Program-and-File-Index" accesskey="n" rel="next">Program and File Index</a>, Previous: <a href="#String-Index" accesskey="p" rel="prev">String Index</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU <code class="code">troff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="appendix" id="File-Keyword-Index-1">Appendix H File Keyword Index</h2>

<div class="printindex ky-printindex">
<table class="ky-letters-header-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#File-Keyword-Index_ky_symbol-1"><b>#</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_symbol-2"><b>-</b></a>
 &nbsp; 
<br>
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-B"><b>B</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-C"><b>C</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-H"><b>H</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-I"><b>I</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-K"><b>K</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-L"><b>L</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-N"><b>N</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-P"><b>P</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-R"><b>R</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-S"><b>S</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-T"><b>T</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-U"><b>U</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-V"><b>V</b></a>
 &nbsp; 
</td></tr></table>
<table class="ky-entries-printindex" border="0">
<tr><td></td><th class="entries-header-printindex">Index Entry</th><td>&nbsp;</td><th class="sections-header-printindex"> Section</th></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="File-Keyword-Index_ky_symbol-1">#</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0023"><code>#</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0023-1"><code>#</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="File-Keyword-Index_ky_symbol-2">-</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002d_002d_002d"><code>---</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="File-Keyword-Index_ky_letter-B">B</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-biggestfont"><code>biggestfont</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="File-Keyword-Index_ky_letter-C">C</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-charset"><code>charset</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-charset-1"><code>charset</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="File-Keyword-Index_ky_letter-F">F</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-family"><code>family</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-family-1"><code>family</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fonts"><code>fonts</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fonts-1"><code>fonts</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Special-Fonts">Special Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fonts-2"><code>fonts</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="File-Keyword-Index_ky_letter-H">H</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hor"><code>hor</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="File-Keyword-Index_ky_letter-I">I</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-image_005fgenerator"><code>image_generator</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="File-Keyword-Index_ky_letter-K">K</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-kernpairs"><code>kernpairs</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="File-Keyword-Index_ky_letter-L">L</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ligatures"><code>ligatures</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="File-Keyword-Index_ky_letter-N">N</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-name"><code>name</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="File-Keyword-Index_ky_letter-P">P</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-paperlength"><code>paperlength</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-papersize"><code>papersize</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-paperwidth"><code>paperwidth</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pass_005ffilenames"><code>pass_filenames</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-postpro"><code>postpro</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-prepro"><code>prepro</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-print"><code>print</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="File-Keyword-Index_ky_letter-R">R</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-res"><code>res</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="File-Keyword-Index_ky_letter-S">S</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sizes"><code>sizes</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sizescale"><code>sizescale</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-slant"><code>slant</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-spacewidth"><code>spacewidth</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-spare1"><code>spare1</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-spare2"><code>spare2</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-special"><code>special</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-special-1"><code>special</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-styles"><code>styles</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-styles-1"><code>styles</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-styles-2"><code>styles</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="File-Keyword-Index_ky_letter-T">T</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tcommand"><code>tcommand</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="File-Keyword-Index_ky_letter-U">U</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unicode"><code>unicode</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unitwidth"><code>unitwidth</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unscaled_005fcharwidths"><code>unscaled_charwidths</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-use_005fcharnames_005fin_005fspecial"><code>use_charnames_in_special</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Postprocessor-Access">Postprocessor Access</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-use_005fcharnames_005fin_005fspecial-1"><code>use_charnames_in_special</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="File-Keyword-Index_ky_letter-V">V</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vert"><code>vert</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
</table>
<table class="ky-letters-footer-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#File-Keyword-Index_ky_symbol-1"><b>#</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_symbol-2"><b>-</b></a>
 &nbsp; 
<br>
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-B"><b>B</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-C"><b>C</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-H"><b>H</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-I"><b>I</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-K"><b>K</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-L"><b>L</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-N"><b>N</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-P"><b>P</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-R"><b>R</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-S"><b>S</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-T"><b>T</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-U"><b>U</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#File-Keyword-Index_ky_letter-V"><b>V</b></a>
 &nbsp; 
</td></tr></table>
</div>




<hr>
</div>
<div class="appendix-level-extent" id="Program-and-File-Index">
<div class="nav-panel">
<p>
Next: <a href="#Concept-Index" accesskey="n" rel="next">Concept Index</a>, Previous: <a href="#File-Keyword-Index" accesskey="p" rel="prev">File Keyword Index</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU <code class="code">troff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="appendix" id="Program-and-File-Index-1">Appendix I Program and File Index</h2>

<div class="printindex pg-printindex">
<table class="pg-letters-header-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-A"><b>A</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-C"><b>C</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-D"><b>D</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-E"><b>E</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-G"><b>G</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-I"><b>I</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-J"><b>J</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-L"><b>L</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-M"><b>M</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-N"><b>N</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-P"><b>P</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-R"><b>R</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-S"><b>S</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-T"><b>T</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-V"><b>V</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-Z"><b>Z</b></a>
 &nbsp; 
</td></tr></table>
<table class="pg-entries-printindex" border="0">
<tr><td></td><th class="entries-header-printindex">Index Entry</th><td>&nbsp;</td><th class="sections-header-printindex"> Section</th></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Program-and-File-Index_pg_letter-A">A</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-an_002etmac"><code>an.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#man">man</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Program-and-File-Index_pg_letter-C">C</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-changebar"><code>changebar</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-composite_002etmac"><code>composite.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cp1047_002etmac"><code>cp1047.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cs_002etmac"><code>cs.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Program-and-File-Index_pg_letter-D">D</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-de_002etmac"><code>de.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-DESC"><code>DESC</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-DESC-1"><code>DESC</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-DESC-2"><code>DESC</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-DESC-3"><code>DESC</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-DESC-4"><code>DESC</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Special-Fonts">Special Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diffmk"><code>diffmk</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Program-and-File-Index_pg_letter-E">E</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ec_002etmac"><code>ec.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-en_002etmac"><code>en.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-eqn"><code>eqn</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Program-and-File-Index_pg_letter-F">F</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fr_002etmac"><code>fr.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-freeeuro_002epfa"><code>freeeuro.pfa</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Program-and-File-Index_pg_letter-G">G</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-gchem"><code>gchem</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-gdiffmk"><code>gdiffmk</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-geqn"><code>geqn</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ggrn"><code>ggrn</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-gpic"><code>gpic</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-grap"><code>grap</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-grefer"><code>grefer</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-groff"><code>groff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-gsoelim"><code>gsoelim</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-gtbl"><code>gtbl</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-gtroff"><code>gtroff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Program-and-File-Index_pg_letter-I">I</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-it_002etmac"><code>it.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Program-and-File-Index_pg_letter-J">J</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ja_002etmac"><code>ja.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Program-and-File-Index_pg_letter-L">L</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-latin1_002etmac"><code>latin1.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-latin2_002etmac"><code>latin2.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-latin5_002etmac"><code>latin5.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-latin9_002etmac"><code>latin9.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Program-and-File-Index_pg_letter-M">M</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-makeindex"><code>makeindex</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Indexing">Indexing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-man_002elocal"><code>man.local</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-man_002etmac"><code>man.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#man">man</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-man_002eultrix"><code>man.ultrix</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Program-and-File-Index_pg_letter-N">N</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nrchbar"><code>nrchbar</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Program-and-File-Index_pg_letter-P">P</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-papersize_002etmac"><code>papersize.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paper-Format">Paper Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-perl"><code>perl</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pic"><code>pic</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-post_002dgrohtml"><code>post-grohtml</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pre_002dgrohtml"><code>pre-grohtml</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-preconv"><code>preconv</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Program-and-File-Index_pg_letter-R">R</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-refer"><code>refer</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Program-and-File-Index_pg_letter-S">S</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-soelim"><code>soelim</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sv_002etmac"><code>sv.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Program-and-File-Index_pg_letter-T">T</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tbl"><code>tbl</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trace_002etmac"><code>trace.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Writing-Macros">Writing Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-troffrc"><code>troffrc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-troffrc-1"><code>troffrc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paper-Format">Paper Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-troffrc-2"><code>troffrc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-troffrc-3"><code>troffrc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-troffrc-4"><code>troffrc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#troff-and-nroff-Modes"><code class="code">troff</code> and <code class="code">nroff</code> Modes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-troffrc_002dend"><code>troffrc-end</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-troffrc_002dend-1"><code>troffrc-end</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-troffrc_002dend-2"><code>troffrc-end</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#troff-and-nroff-Modes"><code class="code">troff</code> and <code class="code">nroff</code> Modes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tty_002etmac"><code>tty.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#troff-and-nroff-Modes"><code class="code">troff</code> and <code class="code">nroff</code> Modes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tty_002etmac-1"><code>tty.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Program-and-File-Index_pg_letter-V">V</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vtroff"><code>vtroff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Operators-in-Conditionals">Operators in Conditionals</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Program-and-File-Index_pg_letter-Z">Z</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-zh_002etmac"><code>zh.tmac</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
</table>
<table class="pg-letters-footer-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-A"><b>A</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-C"><b>C</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-D"><b>D</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-E"><b>E</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-G"><b>G</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-I"><b>I</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-J"><b>J</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-L"><b>L</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-M"><b>M</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-N"><b>N</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-P"><b>P</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-R"><b>R</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-S"><b>S</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-T"><b>T</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-V"><b>V</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Program-and-File-Index_pg_letter-Z"><b>Z</b></a>
 &nbsp; 
</td></tr></table>
</div>




<hr>
</div>
<div class="appendix-level-extent" id="Concept-Index">
<div class="nav-panel">
<p>
Previous: <a href="#Program-and-File-Index" accesskey="p" rel="prev">Program and File Index</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU <code class="code">troff</code></a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="appendix" id="Concept-Index-1">Appendix J Concept Index</h2>

<div class="printindex cp-printindex">
<table class="cp-letters-header-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-1"><b>&quot;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-2"><b>%</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-3"><b>&amp;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-4"><b>'</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-5"><b>(</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-6"><b>)</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-7"><b>*</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-8"><b>+</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-9"><b>-</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-10"><b>.</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-11"><b>/</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-12"><b>8</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-13"><b>:</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-14"><b>&lt;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-15"><b>=</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-16"><b>&gt;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-17"><b>[</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-18"><b>\</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-19"><b>]</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-20"><b>|</b></a>
 &nbsp; 
<br>
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-A"><b>A</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-B"><b>B</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-C"><b>C</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-D"><b>D</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-E"><b>E</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-G"><b>G</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-H"><b>H</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-I"><b>I</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-J"><b>J</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-K"><b>K</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-L"><b>L</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-M"><b>M</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-N"><b>N</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-O"><b>O</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-P"><b>P</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-Q"><b>Q</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-R"><b>R</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-S"><b>S</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-T"><b>T</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-U"><b>U</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-V"><b>V</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-W"><b>W</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-Y"><b>Y</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-Z"><b>Z</b></a>
 &nbsp; 
</td></tr></table>
<table class="cp-entries-printindex" border="0">
<tr><td></td><th class="entries-header-printindex">Index Entry</th><td>&nbsp;</td><th class="sections-header-printindex"> Section</th></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-1">&quot;</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0022_002c-as-delimiter"><code class="code">&quot;</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0022_002c-at-end-of-sentence"><code class="code">&quot;</code>, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0022_002c-at-end-of-sentence-1"><code class="code">&quot;</code>, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0022_002c-embedding-in-a-macro-argument"><code class="code">&quot;</code>, embedding in a macro argument</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Calling-Macros">Calling Macros</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-2">%</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0025_002c-as-delimiter"><code class="code">%</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-3">&amp;</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0026_002c-as-delimiter"><code class="code">&amp;</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-4">'</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0027_002c-as-a-comment"><code class="code">'</code>, as a comment</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Comments">Comments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0027_002c-as-delimiter"><code class="code">'</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0027_002c-at-end-of-sentence"><code class="code">'</code>, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0027_002c-at-end-of-sentence-1"><code class="code">'</code>, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-5">(</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0028_002c-as-delimiter"><code class="code">(</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-6">)</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0029_002c-as-delimiter"><code class="code">)</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0029_002c-at-end-of-sentence"><code class="code">)</code>, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_0029_002c-at-end-of-sentence-1"><code class="code">)</code>, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-7">*</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002a_002c-as-delimiter"><code class="code">*</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002a_002c-at-end-of-sentence"><code class="code">*</code>, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002a_002c-at-end-of-sentence-1"><code class="code">*</code>, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-8">+</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002b_002c-and-page-motion"><code class="code">+</code>, and page motion</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002b_002c-as-delimiter"><code class="code">+</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-9">-</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002d_002c-and-page-motion"><code class="code">-</code>, and page motion</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002d_002c-as-delimiter"><code class="code">-</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-10">.</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002e_002c-as-delimiter"><code class="code">.</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eh-register_002c-difference-from-nl"><code class="code">.h</code> register, difference from <code class="code">nl</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eps-register_002c-in-comparison-with-_002epsr"><code class="code">.ps</code> register, in comparison with <code class="code">.psr</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002es-register_002c-in-comparison-with-_002esr"><code class="code">.s</code> register, in comparison with <code class="code">.sr</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eS-register_002c-Plan-9-alias-for-_002etabs"><code class="code">.S</code> register, Plan&nbsp;9 alias for <code class="code">.tabs</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002et-register_002c-and-diversions"><code class="code">.t</code> register, and diversions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversion-Traps">Diversion Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002etabs-register_002c-Plan-9-alias-_0028_002eS_0029"><code class="code">.tabs</code> register, Plan&nbsp;9 alias (<code class="code">.S</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002eV-register_002c-and-vs"><code class="code">.V</code> register, and <code class="code">vs</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-11">/</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_002f_002c-as-delimiter"><code class="code">/</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-12">8</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-8_002dbit-input">8-bit input</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-13">:</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003a_002c-as-delimiter"><code class="code">:</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-14">&lt;</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003c_002c-as-delimiter"><code class="code">&lt;</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-15">=</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003d_002c-as-delimiter"><code class="code">=</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-16">&gt;</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_003e_002c-as-delimiter"><code class="code">&gt;</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-17">[</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005b_002c-macro-names-starting-with_002c-and-refer"><code class="code">[</code>, macro names starting with, and <code class="code">refer</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-18">\</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0021_002c-and-copy-mode"><code class="code">\!</code>, and copy mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0021_002c-and-output-request"><code class="code">\!</code>, and <code class="code">output</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0021_002c-and-trnt"><code class="code">\!</code>, and <code class="code">trnt</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0021_002c-as-delimiter"><code class="code">\!</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0021_002c-as-delimiter-1"><code class="code">\!</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0021_002c-in-top_002dlevel-diversion"><code class="code">\!</code>, in top-level diversion</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0021_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\!</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0021_002c-incompatibilities-with-AT_0026T-troff-1"><code class="code">\!</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0024_002c-when-reading-text-for-a-macro"><code class="code">\$</code>, when reading text for a macro</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Copy-Mode">Copy Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0025_002c-and-translations"><code class="code">\%</code>, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0025_002c-as-delimiter"><code class="code">\%</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0025_002c-as-delimiter-1"><code class="code">\%</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0025_002c-following-_005cX-or-_005cY"><code class="code">\%</code>, following <code class="code">\X</code> or <code class="code">\Y</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0025_002c-in-_005cX"><code class="code">\%</code>, in <code class="code">\X</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Postprocessor-Access">Postprocessor Access</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0025_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\%</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0026_002c-and-glyph-definitions"><code class="code">\&amp;</code>, and glyph definitions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0026_002c-and-translations"><code class="code">\&amp;</code>, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0026_002c-as-delimiter"><code class="code">\&amp;</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0026_002c-at-end-of-sentence"><code class="code">\&amp;</code>, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0026_002c-in-_005cX"><code class="code">\&amp;</code>, in <code class="code">\X</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Postprocessor-Access">Postprocessor Access</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0026_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\&amp;</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0027_002c-and-translations"><code class="code">\'</code>, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0027_002c-as-delimiter"><code class="code">\'</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0027_002c-as-delimiter-1"><code class="code">\'</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0027_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\'</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0028_002c-and-translations"><code class="code">\(</code>, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0029_002c-as-delimiter"><code class="code">\)</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0029_002c-in-_005cX"><code class="code">\)</code>, in <code class="code">\X</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Postprocessor-Access">Postprocessor Access</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_002a_002c-and-warnings"><code class="code">\*</code>, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_002a_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\*</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Compatibility-Mode">Compatibility Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_002a_002c-when-reading-text-for-a-macro"><code class="code">\*</code>, when reading text for a macro</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Copy-Mode">Copy Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_002c-disabling-_0028eo_0029"><code class="code">\</code>, disabling (<code class="code">eo</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Escape-Sequences">Using Escape Sequences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_002c-embedding-in-a-macro-argument"><code class="code">\</code>, embedding in a macro argument</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Calling-Macros">Calling Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_002c_002c-as-delimiter"><code class="code">\,</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_002d-glyph_002c-and-cflags"><code class="code">\-</code> glyph, and <code class="code">cflags</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_002d_002c-and-translations"><code class="code">\-</code>, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_002d_002c-as-delimiter"><code class="code">\-</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_002d_002c-as-delimiter-1"><code class="code">\-</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_002d_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\-</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_002f_002c-as-delimiter"><code class="code">\/</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_002f_002c-as-delimiter-1"><code class="code">\/</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c0_002c-as-delimiter"><code class="code">\0</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_003a_002c-as-delimiter"><code class="code">\:</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_003a_002c-as-delimiter-1"><code class="code">\:</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_003a_002c-in-_005cX"><code class="code">\:</code>, in <code class="code">\X</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Postprocessor-Access">Postprocessor Access</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_003f_002c-and-copy-mode"><code class="code">\?</code>, and copy mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Operators-in-Conditionals">Operators in Conditionals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_003f_002c-and-copy-mode-1"><code class="code">\?</code>, and copy mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_003f_002c-as-delimiter"><code class="code">\?</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_003f_002c-in-top_002dlevel-diversion"><code class="code">\?</code>, in top-level diversion</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_003f_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\?</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005ca_002c-and-copy-mode"><code class="code">\a</code>, and copy mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leaders">Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005ca_002c-and-translations"><code class="code">\a</code>, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005ca_002c-as-delimiter"><code class="code">\a</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cA_002c-delimiters-allowed-by"><code class="code">\A</code>, delimiters allowed by</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cA_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\A</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cb_002c-delimiters-allowed-by"><code class="code">\b</code>, delimiters allowed by</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cb_002c-limitations-of"><code class="code">\b</code>, limitations of</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cC_002c-and-translations"><code class="code">\C</code>, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cc_002c-as-delimiter"><code class="code">\c</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cc_002c-as-delimiter-1"><code class="code">\c</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cc_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\c</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cc_002c-when-filling-disabled"><code class="code">\c</code>, when filling disabled</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cc_002c-when-filling-enabled"><code class="code">\c</code>, when filling enabled</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cd_002c-as-delimiter"><code class="code">\d</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cD_002c-delimiters-allowed-by"><code class="code">\D</code>, delimiters allowed by</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005ce_002c-and-glyph-definitions"><code class="code">\e</code>, and glyph definitions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005ce_002c-and-translations"><code class="code">\e</code>, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005ce_002c-as-delimiter"><code class="code">\e</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cE_002c-as-delimiter"><code class="code">\E</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005ce_002c-as-delimiter-1"><code class="code">\e</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005ce_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\e</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cF_002c-and-changing-fonts"><code class="code">\F</code>, and changing fonts</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cf_002c-and-font-translations"><code class="code">\f</code>, and font translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cf_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\f</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Compatibility-Mode">Compatibility Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005ch_002c-delimiters-allowed-by"><code class="code">\h</code>, delimiters allowed by</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cH_002c-delimiters-allowed-by"><code class="code">\H</code>, delimiters allowed by</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cH_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\H</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Compatibility-Mode">Compatibility Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cH_002c-using-_002b-and-_002d-with"><code class="code">\H</code>, using <code class="code">+</code> and&nbsp;<code class="code">-</code> with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cH_002c-with-fractional-type-sizes"><code class="code">\H</code>, with fractional type sizes</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cl_002c-and-glyph-definitions"><code class="code">\l</code>, and glyph definitions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cL_002c-and-glyph-definitions"><code class="code">\L</code>, and glyph definitions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cl_002c-delimiters-allowed-by"><code class="code">\l</code>, delimiters allowed by</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cL_002c-delimiters-allowed-by"><code class="code">\L</code>, delimiters allowed by</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cN_002c-and-translations"><code class="code">\N</code>, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cn_002c-and-warnings"><code class="code">\n</code>, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cN_002c-delimiters-allowed-by"><code class="code">\N</code>, delimiters allowed by</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cn_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\n</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Compatibility-Mode">Compatibility Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cn_002c-when-reading-text-for-a-macro"><code class="code">\n</code>, when reading text for a macro</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Copy-Mode">Copy Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005co_002c-delimiters-allowed-by"><code class="code">\o</code>, delimiters allowed by</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cp_002c-as-delimiter"><code class="code">\p</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cp_002c-as-delimiter-1"><code class="code">\p</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cR_002c-after-_005cc"><code class="code">\R</code>, after <code class="code">\c</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cR_002c-and-warnings"><code class="code">\R</code>, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cr_002c-as-delimiter"><code class="code">\r</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cR_002c-delimiters-allowed-by"><code class="code">\R</code>, delimiters allowed by</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cR_002c-difference-from-nr"><code class="code">\R</code>, difference from <code class="code">nr</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Auto_002dincrement">Auto-increment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cR_002c-using-_002b-and-_002d-with"><code class="code">\R</code>, using <code class="code">+</code> and&nbsp;<code class="code">-</code> with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cRET_002c-when-reading-text-for-a-macro">\<kbd class="key">RET</kbd>, when reading text for a macro</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Copy-Mode">Copy Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cs_002c-delimiters-allowed-by"><code class="code">\s</code>, delimiters allowed by</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cS_002c-delimiters-allowed-by"><code class="code">\S</code>, delimiters allowed by</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cs_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\s</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Compatibility-Mode">Compatibility Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cS_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\S</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Compatibility-Mode">Compatibility Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cs_002c-incompatibilities-with-AT_0026T-troff-1"><code class="code">\s</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Compatibility-Mode">Compatibility Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cs_002c-using-_002b-and-_002d-with"><code class="code">\s</code>, using <code class="code">+</code> and&nbsp;<code class="code">-</code> with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cs_002c-with-fractional-type-sizes"><code class="code">\s</code>, with fractional type sizes</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cSP_002c-as-delimiter"><code class="code">\<kbd class="key">SP</kbd></code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cSP_002c-difference-from-_005c_007e"><code class="code">\<kbd class="key">SP</kbd></code>, difference from <code class="code">\~</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Calling-Macros">Calling Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cSP_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\<kbd class="key">SP</kbd></code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005ct_002c-and-copy-mode"><code class="code">\t</code>, and copy mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005ct_002c-and-translations"><code class="code">\t</code>, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005ct_002c-and-warnings"><code class="code">\t</code>, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005ct_002c-as-delimiter"><code class="code">\t</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cu_002c-as-delimiter"><code class="code">\u</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cV_002c-and-copy-mode"><code class="code">\V</code>, and copy mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cv_002c-delimiters-allowed-by"><code class="code">\v</code>, delimiters allowed by</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cv_002c-internal-representation"><code class="code">\v</code>, internal representation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Gtroff-Internals">Gtroff Internals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cw_002c-delimiters-allowed-by"><code class="code">\w</code>, delimiters allowed by</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cX_002c-and-special-characters"><code class="code">\X</code>, and special characters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Postprocessor-Access">Postprocessor Access</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cX_002c-delimiters-allowed-by"><code class="code">\X</code>, delimiters allowed by</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cx_002c-delimiters-allowed-by"><code class="code">\x</code>, delimiters allowed by</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cX_002c-followed-by-_005c_0025"><code class="code">\X</code>, followed by <code class="code">\%</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cY_002c-followed-by-_005c_0025"><code class="code">\Y</code>, followed by <code class="code">\%</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005cZ_002c-delimiters-allowed-by"><code class="code">\Z</code>, delimiters allowed by</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_005b_002c-and-translations"><code class="code">\[</code>, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_005c_002c-when-reading-text-for-a-macro"><code class="code">\\</code>, when reading text for a macro</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Copy-Mode">Copy Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_005e_002c-as-delimiter"><code class="code">\^</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_005e_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\^</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_005f_002c-and-translations"><code class="code">\_</code>, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_005f_002c-as-delimiter"><code class="code">\_</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_005f_002c-as-delimiter-1"><code class="code">\_</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_005f_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\_</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0060_002c-and-translations"><code class="code">\`</code>, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0060_002c-as-delimiter"><code class="code">\`</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0060_002c-as-delimiter-1"><code class="code">\`</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_0060_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\`</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_007b_002c-as-delimiter"><code class="code">\{</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_007b_002c-as-delimiter-1"><code class="code">\{</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_007b_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\{</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_007c_002c-as-delimiter"><code class="code">\|</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_007c_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\|</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_007d_002c-and-warnings"><code class="code">\}</code>, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_007d_002c-as-delimiter"><code class="code">\}</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_007d_002c-as-delimiter-1"><code class="code">\}</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_007d_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\}</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_007e_002c-and-translations"><code class="code">\~</code>, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_007e_002c-as-delimiter"><code class="code">\~</code>, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_007e_002c-difference-from-_005cSP"><code class="code">\~</code>, difference from <code class="code">\<kbd class="key">SP</kbd></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Calling-Macros">Calling Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005c_007e_002c-incompatibilities-with-AT_0026T-troff"><code class="code">\~</code>, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-19">]</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005d_002c-as-part-of-an-identifier"><code class="code">]</code>, as part of an identifier</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005d_002c-at-end-of-sentence"><code class="code">]</code>, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005d_002c-at-end-of-sentence-1"><code class="code">]</code>, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_005d_002c-macro-names-starting-with_002c-and-refer"><code class="code">]</code>, macro names starting with, and <code class="code">refer</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_symbol-20">|</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-_007c_002c-and-page-motion"><code class="code">|</code>, and page motion</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-A">A</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ab-request_002c-incompatibilities-with-AT_0026T-troff"><code class="code">ab</code> request, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-aborting-_0028ab_0029">aborting (<code class="code">ab</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-absolute-_0028sic_0029-position-operator-_0028_007c_0029">absolute <i class="slanted">(sic)</i> position operator (<code class="code">|</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-abstract-font-style">abstract font style</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-abstract-font-style_002c-setting-up-_0028sty_0029">abstract font style, setting up (<code class="code">sty</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-accent-marks-_005bms_005d">accent marks [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-access-to-postprocessor">access to postprocessor</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Postprocessor-Access">Postprocessor Access</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-accessing-unnamed-glyphs-with-_005cN">accessing unnamed glyphs with <code class="code">\N</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-activating-kerning-_0028kern_0029">activating kerning (<code class="code">kern</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-activating-ligatures-_0028lg_0029">activating ligatures (<code class="code">lg</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-activating-track-kerning-_0028tkf_0029">activating track kerning (<code class="code">tkf</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ad-request_002c-and-hyphenation-margin"><code class="code">ad</code> request, and hyphenation margin</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ad-request_002c-and-hyphenation-space"><code class="code">ad</code> request, and hyphenation space</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-addition">addition</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-additional-inter_002dsentence-space">additional inter-sentence space</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-adjustment-and-filling_002c-manipulating">adjustment and filling, manipulating</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-adjustment-mode-register-_0028_002ej_0029">adjustment mode register (<code class="code">.j</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-adjustment-to-both-margins_002c-difference-from-AT_0026T-troff">adjustment to both margins, difference from <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-Adobe-Glyph-List-_0028AGL_0029">Adobe Glyph List (AGL)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-alias_002c-diversion_002c-creating-_0028als_0029">alias, diversion, creating (<code class="code">als</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-alias_002c-diversion_002c-removing-_0028rm_0029">alias, diversion, removing (<code class="code">rm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-alias_002c-macro_002c-creating-_0028als_0029">alias, macro, creating (<code class="code">als</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-alias_002c-macro_002c-removing-_0028rm_0029">alias, macro, removing (<code class="code">rm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-alias_002c-register_002c-creating-_0028aln_0029">alias, register, creating (<code class="code">aln</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-alias_002c-register_002c-removing-_0028rr_0029">alias, register, removing (<code class="code">rr</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-alias_002c-string_002c-creating-_0028als_0029">alias, string, creating (<code class="code">als</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-alias_002c-string_002c-removing-_0028rm_0029">alias, string, removing (<code class="code">rm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-aliasing-fonts-with-third-argument-to-fp-request">aliasing fonts with third argument to <code class="code">fp</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Positions">Font Positions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-als-request_002c-and-_005c_00240"><code class="code">als</code> request, and <code class="code">\$0</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Parameters">Parameters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-am_002c-am1_002c-ami-requests_002c-and-warnings"><code class="code">am</code>, <code class="code">am1</code>, <code class="code">ami</code> requests, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-appending-to-a-diversion-_0028da_002c-boxa_0029">appending to a diversion (<code class="code">da</code>, <code class="code">boxa</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-appending-to-a-file-_0028opena_0029">appending to a file (<code class="code">opena</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-appending-to-a-macro-_0028am_0029">appending to a macro (<code class="code">am</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Writing-Macros">Writing Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-appending-to-a-string-_0028as_0029">appending to a string (<code class="code">as</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-approximation-output-register-_0028_002eA_0029">approximation output register (<code class="code">.A</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-arc_002c-drawing-_0028_005cD_0027a-_2026_0027_0029">arc, drawing (&lsquo;<samp class="samp">\D'a &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-argument">argument</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Requests-and-Macros">Requests and Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-arguments-to-macros">arguments to macros</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Calling-Macros">Calling Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-arguments-to-macros_002c-and-tabs">arguments to macros, and tabs</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-Requests">Invoking Requests</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-arguments-to-requests">arguments to requests</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-Requests">Invoking Requests</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-arguments-to-requests_002c-and-tabs">arguments to requests, and tabs</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-Requests">Invoking Requests</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-arguments_002c-and-compatibility-mode">arguments, and compatibility mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Gtroff-Internals">Gtroff Internals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-arguments_002c-to-escape-sequences_002c-delimiting">arguments, to escape sequences, delimiting</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-arguments_002c-to-strings">arguments, to strings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-arithmetic-operators">arithmetic operators</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-artificial-fonts">artificial fonts</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-as_002c-as1-requests_002c-and-comments"><code class="code">as</code>, <code class="code">as1</code> requests, and comments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Comments">Comments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-as_002c-as1-requests_002c-and-warnings"><code class="code">as</code>, <code class="code">as1</code> requests, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ASCII-output-encoding"><abbr class="acronym">ASCII</abbr> output encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-asciify-request_002c-and-writem"><code class="code">asciify</code> request, and <code class="code">writem</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-assertion-_0028arithmetic-operator_0029">assertion (arithmetic operator)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-assign-number-format-to-register-_0028af_0029">assign number format to register (<code class="code">af</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Assigning-Register-Formats">Assigning Register Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-assignments_002c-indirect">assignments, indirect</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Interpolating-Registers">Interpolating Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-assignments_002c-nested">assignments, nested</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Interpolating-Registers">Interpolating Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-AT_0026T-ms_002c-macro-package-differences"><abbr class="acronym">AT&amp;T</abbr> <samp class="file">ms</samp>, macro package differences</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Differences-from-AT_0026T-ms">Differences from AT&amp;T ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-attributes_002c-character-cell">attributes, character cell</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-auto_002dincrementation-of-a-register">auto-incrementation of a register</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Auto_002dincrement">Auto-increment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-automatic-font-mounting">automatic font mounting</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-automatic-hyphenation">automatic hyphenation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-automatic-hyphenation-parameters">automatic hyphenation parameters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-auxiliary-macro-package">auxiliary macro package</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Major-Macro-Packages">Major Macro Packages</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-available-glyphs_002c-list-of-_0028groff_005fchar_00287_0029-man-page_0029">available glyphs, list of (<cite class="cite">groff_char<span class="r">(7)</span></cite> man page)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-B">B</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-background">background</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Background">Background</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-background-color-name-register-_0028_002eM_0029">background color name register (<code class="code">.M</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-backslash-glyph_002c-formatting-_0028_005c_005brs_005d_0029">backslash glyph, formatting (<code class="code">\[rs]</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Escape-Sequences">Using Escape Sequences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-backslash_002c-embedding-in-a-macro-argument">backslash, embedding in a macro argument</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Calling-Macros">Calling Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-backslash_002c-printing-_0028_005c_005c_002c-_005ce_002c-_005cE_002c-_005c_005brs_005d_0029">backslash, printing (<code class="code">\\</code>, <code class="code">\e</code>, <code class="code">\E</code>, <code class="code">\[rs]</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-backspace-character_002c-and-translations">backspace character, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-backtrace-of-input-stack-_0028backtrace_0029">backtrace of input stack (<code class="code">backtrace</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-baseline-rule-special-character_0028_005c_005bru_005d_0029">baseline rule special character(<code class="code">\[ru]</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-baseline_002c-text">baseline, text</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-baseline_002c-text-1">baseline, text</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Type-Size-and-Vertical-Spacing">Manipulating Type Size and Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-basic-scaling-unit-_0028u_0029">basic scaling unit (<code class="code">u</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-basic-units">basic units</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-basic-units_002c-conversion-to">basic units, conversion to</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-basics-of-macro-package-usage">basics of macro package usage</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Basics">Basics</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-bd-request_002c-and-font-styles"><code class="code">bd</code> request, and font styles</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-bd-request_002c-and-font-translations"><code class="code">bd</code> request, and font translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-bd-request_002c-incompatibilities-with-AT_0026T-troff"><code class="code">bd</code> request, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-beginning-diversion-_0028di_002c-box_0029">beginning diversion (<code class="code">di</code>, <code class="code">box</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-beginning-of-conditional-block-_0028_005c_007b_0029">beginning of conditional block (<code class="code">\{</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditional-Blocks">Conditional Blocks</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-blank-line">blank line</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Breaking">Breaking</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-blank-line-macro-_0028blm_0029">blank line macro (<code class="code">blm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Breaking">Breaking</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-blank-line-macro-_0028blm_0029-1">blank line macro (<code class="code">blm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-Requests">Invoking Requests</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-blank-line-macro-_0028blm_0029-2">blank line macro (<code class="code">blm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Blank-Line-Traps">Blank Line Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-blank-line-trap-_0028blm_0029">blank line trap (<code class="code">blm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-Requests">Invoking Requests</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-blank-line-traps">blank line traps</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Blank-Line-Traps">Blank Line Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-blank-lines_002c-disabling">blank lines, disabling</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Spacing">Manipulating Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-block_002c-conditional_002c-beginning-_0028_005c_007b_0029">block, conditional, beginning (<code class="code">\{</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditional-Blocks">Conditional Blocks</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-block_002c-conditional_002c-end-_0028_005c_007d_0029">block, conditional, end (<code class="code">\}</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditional-Blocks">Conditional Blocks</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-blocks_002c-conditional">blocks, conditional</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditional-Blocks">Conditional Blocks</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-body_002c-of-a-while-request">body, of a while request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#while">while</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-boldface_002c-imitating-_0028bd_0029">boldface, imitating (<code class="code">bd</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-bottom-margin">bottom margin</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-boundary_002drelative-motion-operator-_0028_007c_0029">boundary-relative motion operator (<code class="code">|</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-bounding-box">bounding box</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-box-_0028diversion-operation_0029">box (diversion operation)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-box-request_002c-and-warnings"><code class="code">box</code> request, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-box-rule-glyph-_0028_005c_005bbr_005d_0029">box rule glyph (<code class="code">\[br]</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-box_002c-boxa-requests_002c-and-warnings"><code class="code">box</code>, <code class="code">boxa</code> requests, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-boxa-request_002c-and-dn-_0028dl_0029"><code class="code">boxa</code> request, and <code class="code">dn</code> (<code class="code">dl</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-boxa-request_002c-and-warnings"><code class="code">boxa</code> request, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-boxes-_005bms_005d">boxes [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-bp-request_002c-and-top_002dlevel-diversion"><code class="code">bp</code> request, and top-level diversion</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-bp-request_002c-and-traps-_0028_002epe_0029"><code class="code">bp</code> request, and traps (<code class="code">.pe</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-bp-request_002c-causing-implicit-break"><code class="code">bp</code> request, causing implicit break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-bp-request_002c-incompatibilities-with-AT_0026T-troff"><code class="code">bp</code> request, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-bp-request_002c-using-_002b-and-_002d-with"><code class="code">bp</code> request, using <code class="code">+</code> and&nbsp;<code class="code">-</code> with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-br-glyph_002c-and-cflags"><code class="code">br</code> glyph, and <code class="code">cflags</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-brace-escape-sequence_002c-closing-_0028_005c_007d_0029">brace escape sequence, closing (<code class="code">\})</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditional-Blocks">Conditional Blocks</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-brace-escape-sequence_002c-opening-_0028_005c_007d_0029">brace escape sequence, opening (<code class="code">\})</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditional-Blocks">Conditional Blocks</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-brace-escape-sequences-_0028_005c_007b_002c-_005c_007d_0029">brace escape sequences (<code class="code">\{</code>, <code class="code">\}</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditional-Blocks">Conditional Blocks</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-break">break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Breaking">Breaking</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-break-1">break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-break-_0028introduction_0029">break (introduction)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Basics">Basics</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-break-request_002c-in-a-while-loop"><code class="code">break</code> request, in a <code class="code">while</code> loop</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#while">while</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-break_002c-page">break, page</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-break_002c-page-1">break, page</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-break_002c-page-2">break, page</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#The-Implicit-Page-Trap">The Implicit Page Trap</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-break_002c-page-_0028introduction_0029">break, page (introduction)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Basics">Basics</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-break_002c-page_002c-final">break, page, final</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#End_002dof_002dinput-Traps">End-of-input Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-break_002c-page_002c-prevented-by-vpt">break, page, prevented by <code class="code">vpt</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Vertical-Position-Traps">Vertical Position Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-breaking-file-names-_0028_005c_003a_0029">breaking file names (<code class="code">\:</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-breaking-URLs-_0028_005c_003a_0029">breaking URLs (<code class="code">\:</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-breaking-without-hyphens-_0028_005c_003a_0029">breaking without hyphens (<code class="code">\:</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-built_002din-register_002c-removing">built-in register, removing</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-built_002din-registers">built-in registers</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-bulleted-list_002c-example-markup-_005bms_005d">bulleted list, example markup [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Lists-in-ms">Lists in ms</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-C">C</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-c-scaling-unit"><code class="code">c</code> scaling unit</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-calling-a-macro">calling a macro</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Requests-and-Macros">Requests and Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-calling-macros">calling macros</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Calling-Macros">Calling Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-capabilities-of-groff">capabilities of <code class="code">groff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#groff-Capabilities"><code class="code">groff</code> Capabilities</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-case_002dtransforming-a-string-_0028stringdown_002c-stringup_0029">case-transforming a string (<code class="code">stringdown</code>, <code class="code">stringup</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-categories_002c-warning">categories, warning</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CCSID-1047-output-encoding-_0028EBCDIC_0029">CCSID 1047 output encoding (EBCDIC)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ce-request_002c-causing-implicit-break"><code class="code">ce</code> request, causing implicit break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ce-request_002c-difference-from-_002ead-c"><code class="code">ce</code> request, difference from &lsquo;<samp class="samp">.ad&nbsp;c</samp>&rsquo;<!-- /@w --></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cell_002c-character_002c-attributes">cell, character, attributes</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-centered-text-_0028filled_0029">centered text (filled)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-centered-text-_0028unfilled_0029">centered text (unfilled)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-centering-lines-_0028ce_0029">centering lines (<code class="code">ce</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-centering-lines-_0028introduction_0029">centering lines (introduction)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Basics">Basics</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-centimeter-scaling-unit-_0028c_0029">centimeter scaling unit (<code class="code">c</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cf-request_002c-and-copy-mode"><code class="code">cf</code> request, and copy mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cf-request_002c-causing-implicit-break"><code class="code">cf</code> request, causing implicit break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-changing-control-characters">changing control characters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Control-Characters">Control Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-changing-font-family-_0028fam_002c-_005cF_0029">changing font family (<code class="code">fam</code>, <code class="code">\F</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-changing-fonts-_0028ft_002c-_005cf_0029">changing fonts (<code class="code">ft</code>, <code class="code">\f</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-changing-format_002c-and-read_002donly-registers">changing format, and read-only registers</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Assigning-Register-Formats">Assigning Register Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-changing-the-font-height-_0028_005cH_0029">changing the font height (<code class="code">\H</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-changing-the-font-slant-_0028_005cS_0029">changing the font slant (<code class="code">\S</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-changing-the-page-number-character-_0028pc_0029">changing the page number character (<code class="code">pc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-changing-trap-location-_0028ch_0029">changing trap location (<code class="code">ch</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-changing-type-sizes-_0028ps_002c-_005cs_0029">changing type sizes (<code class="code">ps</code>, <code class="code">\s</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Type-Size">Changing the Type Size</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-changing-vertical-line-spacing-_0028vs_0029">changing vertical line spacing (<code class="code">vs</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-char-request_002c-and-soft-hyphen-character"><code class="code">char</code> request, and soft hyphen character</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-char-request_002c-and-translations"><code class="code">char</code> request, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-char-request_002c-used-with-_005cN"><code class="code">char</code> request, used with <code class="code">\N</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character">character</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character-cell-attributes">character cell attributes</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character-class-_0028class_0029">character class (<code class="code">class</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Classes">Character Classes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character-classes">character classes</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Classes">Character Classes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character-properties-_0028cflags_0029">character properties (<code class="code">cflags</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character-translations">character translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-backspace_002c-and-translations">character, backspace, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-control-_0028_002e_0029">character, control (<code class="code">.</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Requests-and-Macros">Requests and Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-control_002c-changing-_0028cc_0029">character, control, changing (<code class="code">cc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Control-Characters">Control Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-defining-_0028char_0029">character, defining (<code class="code">char</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-defining-fallback-_0028fchar_002c-fschar_002c-schar_0029">character, defining fallback (<code class="code">fchar</code>, <code class="code">fschar</code>, <code class="code">schar</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-distinguished-from-glyph">character, distinguished from glyph</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-dummy-_0028_005c_0026_0029">character, dummy (<code class="code">\&amp;</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Dummy-Characters">Dummy Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-dummy-_0028_005c_0026_0029_002c-as-control-character-suppressor">character, dummy (<code class="code">\&amp;</code>), as control character suppressor</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Requests-and-Macros">Requests and Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-dummy-_0028_005c_0026_0029_002c-effect-on-kerning">character, dummy (<code class="code">\&amp;</code>), effect on kerning</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-dummy-_0028_005c_0026_0029_002c-effect-on-_005cl-escape-sequence">character, dummy (<code class="code">\&amp;</code>), effect on <code class="code">\l</code> escape sequence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-escape_002c-changing-_0028ec_0029">character, escape, changing (<code class="code">ec</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Escape-Sequences">Using Escape Sequences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-escape_002c-while-defining-glyph">character, escape, while defining glyph</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-field-delimiting-_0028fc_0029">character, field delimiting (<code class="code">fc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Fields">Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-field-padding-_0028fc_0029">character, field padding (<code class="code">fc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Fields">Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-horizontal-tab">character, horizontal tab</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Leaders">Tabs and Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-hyphenation-_0028_005c_0025_0029">character, hyphenation (<code class="code">\%</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-leader">character, leader</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Leaders">Tabs and Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-leader-repetition-_0028lc_0029">character, leader repetition (<code class="code">lc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leaders">Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-leader_002c-and-translations">character, leader, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-leader_002c-non_002dinterpreted-_0028_005ca_0029">character, leader, non-interpreted (<code class="code">\a</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leaders">Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-named-_0028_005cC_0029">character, named (<code class="code">\C</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-newline_002c-and-translations">character, newline, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-no_002dbreak-control-_0028_0027_0029">character, no-break control (<code class="code">'</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Requests-and-Macros">Requests and Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-no_002dbreak-control_002c-changing-_0028c2_0029">character, no-break control, changing (<code class="code">c2</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Control-Characters">Control Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-ordinary">character, ordinary</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-soft-hyphen_002c-setting-_0028shc_0029">character, soft hyphen, setting (<code class="code">shc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-special">character, special</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-tab-repetition-_0028tc_0029">character, tab repetition (<code class="code">tc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-tab_002c-and-translations">character, tab, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-tab_002c-non_002dinterpreted-_0028_005ct_0029">character, tab, non-interpreted (<code class="code">\t</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-transparent">character, transparent</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-character_002c-transparent-dummy-_0028_005c_0029_0029">character, transparent dummy (<code class="code">\)</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Dummy-Characters">Dummy Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-characters_002c-end_002dof_002dsentence">characters, end-of-sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-characters_002c-end_002dof_002dsentence-transparent">characters, end-of-sentence transparent</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-characters_002c-hyphenation">characters, hyphenation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-characters_002c-input_002c-and-output-glyphs_002c-compatibility-with-AT_0026T-troff">characters, input, and output glyphs, compatibility with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-characters_002c-invalid-for-trf-request">characters, invalid for <code class="code">trf</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-characters_002c-invalid-input">characters, invalid input</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-characters_002c-overlapping">characters, overlapping</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-characters_002c-special">characters, special</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-characters_002c-special_002c-list-of-_0028groff_005fchar_00287_0029-man-page_0029">characters, special, list of (<cite class="cite">groff_char<span class="r">(7)</span></cite> man page)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-characters_002c-unnamed_002c-accessing-with-_005cN">characters, unnamed, accessing with <code class="code">\N</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-circle_002c-filled_002c-drawing-_0028_005cD_0027C-_2026_0027_0029">circle, filled, drawing (&lsquo;<samp class="samp">\D'C &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-circle_002c-outlined_002c-drawing-_0028_005cD_0027c-_2026_0027_0029">circle, outlined, drawing (&lsquo;<samp class="samp">\D'c &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-circle_002c-solid_002c-drawing-_0028_005cD_0027C-_2026_0027_0029">circle, solid, drawing (&lsquo;<samp class="samp">\D'C &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-circle_002c-stroked_002c-drawing-_0028_005cD_0027c-_2026_0027_0029">circle, stroked, drawing (&lsquo;<samp class="samp">\D'c &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-class-of-characters-_0028class_0029">class of characters (<code class="code">class</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Classes">Character Classes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-classes_002c-character">classes, character</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Classes">Character Classes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-clearing-input-line-trap-_0028it_002c-itc_0029">clearing input line trap (<code class="code">it</code>, <code class="code">itc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Line-Traps">Input Line Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-closing-brace-escape-sequence-_0028_005c_007d_0029">closing brace escape sequence (<code class="code">\})</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditional-Blocks">Conditional Blocks</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-closing-file-_0028close_0029">closing file (<code class="code">close</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-code-page-1047-output-encoding">code page 1047 output encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-code-page-1047_002c-input-encoding">code page 1047, input encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-code_002c-hyphenation-_0028hcode_0029">code, hyphenation (<code class="code">hcode</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-color-name_002c-background_002c-register-_0028_002eM_0029">color name, background, register (<code class="code">.M</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-color-name_002c-fill_002c-register-_0028_002eM_0029">color name, fill, register (<code class="code">.M</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-color-name_002c-stroke_002c-register-_0028_002em_0029">color name, stroke, register (<code class="code">.m</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-color_002c-default">color, default</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-color_002c-fill">color, fill</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-color_002c-stroke">color, stroke</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-colors">colors</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-command-prefix">command prefix</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environment">Environment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-command_002dline-options">command-line options</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-comments">comments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Comments">Comments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-comments-in-device-description-files">comments in device description files</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-comments-in-font-description-files">comments in font description files</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-comments_002c-lining-up-with-tabs">comments, lining up with tabs</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Comments">Comments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-comments_002c-with-ds">comments, with <code class="code">ds</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-common-features">common features</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Common-Features">Common Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-common-name-space-of-macros_002c-diversions_002c-and-strings">common name space of macros, diversions, and strings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-comparison-of-strings">comparison of strings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Operators-in-Conditionals">Operators in Conditionals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-comparison-operators">comparison operators</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-compatibility-mode">compatibility mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-compatibility-mode-1">compatibility mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Compatibility-Mode">Compatibility Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-compatibility-mode_002c-and-parameters">compatibility mode, and parameters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Gtroff-Internals">Gtroff Internals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-complementation_002c-logical">complementation, logical</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-composite-glyph-names">composite glyph names</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-conditional-block_002c-beginning-_0028_005c_007b_0029">conditional block, beginning (<code class="code">\{</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditional-Blocks">Conditional Blocks</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-conditional-block_002c-end-_0028_005c_007d_0029">conditional block, end (<code class="code">\}</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditional-Blocks">Conditional Blocks</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-conditional-blocks">conditional blocks</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditional-Blocks">Conditional Blocks</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-conditional-expressions">conditional expressions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Operators-in-Conditionals">Operators in Conditionals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-conditional-output-for-terminal-_0028TTY_0029">conditional output for terminal (TTY)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Operators-in-Conditionals">Operators in Conditionals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-conditional-page-break-_0028ne_0029">conditional page break (<code class="code">ne</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-conditionals-and-loops">conditionals and loops</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditionals-and-Loops">Conditionals and Loops</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-configuring-control-characters">configuring control characters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Control-Characters">Control Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-configuring-the-page-length-_0028pl_0029">configuring the page length (<code class="code">pl</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-consecutive-hyphenated-lines-_0028hlm_0029">consecutive hyphenated lines (<code class="code">hlm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-constant-glyph-space-mode-_0028cs_0029">constant glyph space mode (<code class="code">cs</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-contents_002c-table-of">contents, table of</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Table-of-Contents">Table of Contents</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-contents_002c-table-of-1">contents, table of</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leaders">Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-continuation_002c-input-line-_0028_005cRET_0029">continuation, input line (<code class="code">\<kbd class="key">RET</kbd></code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-continuation_002c-output-line-_0028_005cc_0029">continuation, output line (<code class="code">\c</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-continue-request_002c-in-a-while-loop"><code class="code">continue</code> request, in a <code class="code">while</code> loop</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#while">while</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-continued-output-line-register-_0028_002eint_0029">continued output line register (<code class="code">.int</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-continuous-underlining-_0028cu_0029">continuous underlining (<code class="code">cu</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-control-character-_0028_002e_0029">control character (<code class="code">.</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Requests-and-Macros">Requests and Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-control-character_002c-changing-_0028cc_0029">control character, changing (<code class="code">cc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Control-Characters">Control Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-control-character_002c-no_002dbreak-_0028_0027_0029">control character, no-break (<code class="code">'</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Requests-and-Macros">Requests and Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-control-character_002c-no_002dbreak_002c-changing-_0028c2_0029">control character, no-break, changing (<code class="code">c2</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Control-Characters">Control Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-control-characters">control characters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Control-Characters">Control Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-control-line">control line</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Requests-and-Macros">Requests and Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-control_002c-line">control, line</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-control_002c-page">control, page</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-conventions-for-input">conventions for input</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Conventions">Input Conventions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-conversion-to-basic-units">conversion to basic units</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-copy-mode">copy mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Copy-Mode">Copy Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-copy-mode-1">copy mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Copy-Mode">Copy Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-copy-mode_002c-and-cf-request">copy mode, and <code class="code">cf</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-copy-mode_002c-and-device-request">copy mode, and <code class="code">device</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Postprocessor-Access">Postprocessor Access</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-copy-mode_002c-and-length-request">copy mode, and <code class="code">length</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-copy-mode_002c-and-macro-parameters">copy mode, and macro parameters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Parameters">Parameters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-copy-mode_002c-and-output-request">copy mode, and <code class="code">output</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-copy-mode_002c-and-trf-request">copy mode, and <code class="code">trf</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-copy-mode_002c-and-write-request">copy mode, and <code class="code">write</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-copy-mode_002c-and-writec-request">copy mode, and <code class="code">writec</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-copy-mode_002c-and-writem-request">copy mode, and <code class="code">writem</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-copy-mode_002c-and-_005c_0021">copy mode, and <code class="code">\!</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-copy-mode_002c-and-_005c_003f">copy mode, and <code class="code">\?</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Operators-in-Conditionals">Operators in Conditionals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-copy-mode_002c-and-_005c_003f-1">copy mode, and <code class="code">\?</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-copy-mode_002c-and-_005ca">copy mode, and <code class="code">\a</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leaders">Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-copy-mode_002c-and-_005ct">copy mode, and <code class="code">\t</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-copy-mode_002c-and-_005cV">copy mode, and <code class="code">\V</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-copying-environment-_0028evc_0029">copying environment (<code class="code">evc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-correction-between-oblique-and-upright-glyph-_0028_005c_002f_002c-_005c_002c_0029">correction between oblique and upright glyph (<code class="code">\/</code>, <code class="code">\,</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Italic-Corrections">Italic Corrections</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-correction-between-upright-and-oblique-glyph-_0028_005c_002f_002c-_005c_002c_0029">correction between upright and oblique glyph (<code class="code">\/</code>, <code class="code">\,</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Italic-Corrections">Italic Corrections</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-correction_002c-italic-_0028_005c_002f_0029">correction, italic (<code class="code">\/</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Italic-Corrections">Italic Corrections</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-correction_002c-left-italic-_0028_005c_002c_0029">correction, left italic (<code class="code">\,</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Italic-Corrections">Italic Corrections</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cover-page-in-_005bms_005d_002c-example-markup">cover page in [<samp class="file">ms</samp>], example markup</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Description-Macros">ms Document Description Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cp-request_002c-and-glyph-definitions"><code class="code">cp</code> request, and glyph definitions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cq-glyph_002c-at-end-of-sentence"><code class="code">cq</code> glyph, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cq-glyph_002c-at-end-of-sentence-1"><code class="code">cq</code> glyph, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-creating-alias-for-register-_0028aln_0029">creating alias for register (<code class="code">aln</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-creating-alias_002c-for-diversion-_0028als_0029">creating alias, for diversion (<code class="code">als</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-creating-alias_002c-for-macro-_0028als_0029">creating alias, for macro (<code class="code">als</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-creating-alias_002c-for-string-_0028als_0029">creating alias, for string (<code class="code">als</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-creating-new-characters-_0028char_0029">creating new characters (<code class="code">char</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-credits">credits</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Credits">Credits</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cs-request_002c-and-font-styles"><code class="code">cs</code> request, and font styles</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cs-request_002c-and-font-translations"><code class="code">cs</code> request, and font translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cs-request_002c-incompatibilities-with-AT_0026T-troff"><code class="code">cs</code> request, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-cs-request_002c-with-fractional-type-sizes"><code class="code">cs</code> request, with fractional type sizes</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CSTR-_002354-errata">CSTR&nbsp;#54 errata</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CSTR-_002354-errata-1">CSTR&nbsp;#54 errata</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CSTR-_002354-errata-2">CSTR&nbsp;#54 errata</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CSTR-_002354-errata-3">CSTR&nbsp;#54 errata</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CSTR-_002354-errata-4">CSTR&nbsp;#54 errata</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Type-Size">Changing the Type Size</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CSTR-_002354-errata-5">CSTR&nbsp;#54 errata</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CSTR-_002354-erratum_002c-bp-request">CSTR&nbsp;#54 erratum, <code class="code">bp</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CSTR-_002354-erratum_002c-po-request">CSTR&nbsp;#54 erratum, <code class="code">po</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CSTR-_002354-erratum_002c-ps-request">CSTR&nbsp;#54 erratum, <code class="code">ps</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Type-Size">Changing the Type Size</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CSTR-_002354-erratum_002c-sb-register">CSTR&nbsp;#54 erratum, <code class="code">sb</code> register</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CSTR-_002354-erratum_002c-st-register">CSTR&nbsp;#54 erratum, <code class="code">st</code> register</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CSTR-_002354-erratum_002c-yr-register">CSTR&nbsp;#54 erratum, <code class="code">yr</code> register</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CSTR-_002354-erratum_002c-_005cS-escape">CSTR&nbsp;#54 erratum, <code class="code">\S</code> escape</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-CSTR-_002354-erratum_002c-_005cs-escape-sequence">CSTR&nbsp;#54 erratum, <code class="code">\s</code> escape sequence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Type-Size">Changing the Type Size</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-current-directory">current directory</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-current-input-file-name-register-_0028_002eF_0029">current input file name register (<code class="code">.F</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-current-page-number-_0028_0025_0029">current page number (<code class="code">%</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-current-time_002c-hours-_0028hours_0029">current time, hours (<code class="code">hours</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-current-time_002c-minutes-_0028minutes_0029">current time, minutes (<code class="code">minutes</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-current-time_002c-seconds-_0028seconds_0029">current time, seconds (<code class="code">seconds</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-D">D</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-da-request_002c-and-dn-_0028dl_0029"><code class="code">da</code> request, and <code class="code">dn</code> (<code class="code">dl</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-da-request_002c-and-warnings"><code class="code">da</code> request, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-da-request_002c-and-warnings-1"><code class="code">da</code> request, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-date_002c-day-of-the-month-register-_0028dy_0029">date, day of the month register (<code class="code">dy</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-date_002c-day-of-the-week-register-_0028dw_0029">date, day of the week register (<code class="code">dw</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-date_002c-month-of-the-year-register-_0028mo_0029">date, month of the year register (<code class="code">mo</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-date_002c-year-register-_0028year_002c-yr_0029">date, year register (<code class="code">year</code>, <code class="code">yr</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-day-of-the-month-register-_0028dy_0029">day of the month register (<code class="code">dy</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-day-of-the-week-register-_0028dw_0029">day of the week register (<code class="code">dw</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dd-glyph_002c-at-end-of-sentence"><code class="code">dd</code> glyph, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dd-glyph_002c-at-end-of-sentence-1"><code class="code">dd</code> glyph, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-de-request_002c-and-while"><code class="code">de</code> request, and <code class="code">while</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#while">while</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-de_002c-de1_002c-dei-requests_002c-and-warnings"><code class="code">de</code>, <code class="code">de1</code>, <code class="code">dei</code> requests, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-debugging">debugging</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-debugging-page-location-traps">debugging page location traps</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-decimal-point_002c-as-delimiter">decimal point, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-decrementation_002c-automatic_002c-of-a-register">decrementation, automatic, of a register</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Auto_002dincrement">Auto-increment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-default-color">default color</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-default-tab-stops">default tab stops</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-default-units">default units</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Default-Units">Default Units</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-deferred-output">deferred output</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Deferring-Output">Deferring Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-defining-character-_0028char_0029">defining character (<code class="code">char</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-defining-character-class-_0028class_0029">defining character class (<code class="code">class</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Classes">Character Classes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-defining-fallback-character-_0028fchar_002c-fschar_002c-schar_0029">defining fallback character (<code class="code">fchar</code>, <code class="code">fschar</code>, <code class="code">schar</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-defining-glyph-_0028char_0029">defining glyph (<code class="code">char</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-defining-symbol-_0028char_0029">defining symbol (<code class="code">char</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-delimited-arguments_002c-incompatibilities-with-AT_0026T-troff">delimited arguments, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Compatibility-Mode">Compatibility Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-delimiters_002c-for-escape-sequence-arguments">delimiters, for escape sequence arguments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-delimiting-character_002c-for-fields-_0028fc_0029">delimiting character, for fields (<code class="code">fc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Fields">Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-delimiting-escape-sequence-arguments">delimiting escape sequence arguments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-depth_002c-interpolation">depth, interpolation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Calling-Macros">Calling Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-depth_002c-of-last-glyph-_0028_002ecdp_0029">depth, of last glyph (<code class="code">.cdp</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-DESC-file-format"><samp class="file">DESC</samp> file format</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-DESC-file_002c-and-font-mounting"><samp class="file">DESC</samp> file, and font mounting</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Positions">Font Positions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-DESC-file_002c-and-use_005fcharnames_005fin_005fspecial-keyword"><samp class="file">DESC</samp> file, and <code class="code">use_charnames_in_special</code> keyword</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Postprocessor-Access">Postprocessor Access</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-description-file_002c-font">description file, font</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-device-description-files_002c-comments">device description files, comments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-device-request_002c-and-copy-mode"><code class="code">device</code> request, and copy mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Postprocessor-Access">Postprocessor Access</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-device-resolution">device resolution</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-device-resolution-1">device resolution</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-device-resolution_002c-obtaining-in-the-formatter">device resolution, obtaining in the formatter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-devices-for-output">devices for output</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Output-Device-Intro">Output Device Intro</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dg-glyph_002c-at-end-of-sentence"><code class="code">dg</code> glyph, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dg-glyph_002c-at-end-of-sentence-1"><code class="code">dg</code> glyph, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-di-request_002c-and-warnings"><code class="code">di</code> request, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-di-request_002c-and-warnings-1"><code class="code">di</code> request, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-differences-in-implementation">differences in implementation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Implementation-Differences">Implementation Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-digit_002dwidth-space-_0028_005c0_0029">digit-width space (<code class="code">\0</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-digits_002c-as-delimiters">digits, as delimiters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dimensions_002c-line">dimensions, line</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-directories-for-fonts">directories for fonts</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Directories">Font Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-directories-for-macros">directories for macros</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-directory_002c-current">directory, current</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-directory_002c-for-tmac-files">directory, for tmac files</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-directory_002c-home">directory, home</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-directory_002c-platform_002dspecific">directory, platform-specific</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-directory_002c-site_002dlocal">directory, site-local</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-directory_002c-site_002dlocal-1">directory, site-local</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Directories">Font Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-disabling-hyphenation-_0028_005c_0025_0029">disabling hyphenation (<code class="code">\%</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-disabling-_005c-_0028eo_0029">disabling <code class="code">\</code> (<code class="code">eo</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Escape-Sequences">Using Escape Sequences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-discardable-horizontal-space">discardable horizontal space</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-displays">displays</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Displays-and-Keeps">Displays and Keeps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-displays-_005bms_005d">displays [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-displays_002c-and-footnotes-_005bms_005d">displays, and footnotes [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Footnotes">ms Footnotes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-distance-to-next-vertical-position-trap-register-_0028_002et_0029">distance to next vertical position trap register (<code class="code">.t</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion">diversion</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Deferring-Output">Deferring Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion-name-register-_0028_002ez_0029">diversion name register (<code class="code">.z</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion-trap_002c-setting-_0028dt_0029">diversion trap, setting (<code class="code">dt</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversion-Traps">Diversion Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion-traps">diversion traps</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversion-Traps">Diversion Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion_002c-appending-to-_0028da_002c-boxa_0029">diversion, appending to (<code class="code">da</code>, <code class="code">boxa</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion_002c-beginning-_0028di_002c-box_0029">diversion, beginning (<code class="code">di</code>, <code class="code">box</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion_002c-creating-alias-for-_0028als_0029">diversion, creating alias for (<code class="code">als</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion_002c-ending-_0028di_002c-box_0029">diversion, ending (<code class="code">di</code>, <code class="code">box</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion_002c-nested">diversion, nested</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion_002c-removing-_0028rm_0029">diversion, removing (<code class="code">rm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion_002c-removing-alias-for-_0028rm_0029">diversion, removing alias for (<code class="code">rm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion_002c-renaming-_0028rn_0029">diversion, renaming (<code class="code">rn</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion_002c-stripping-final-newline">diversion, stripping final newline</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Punning-Names">Punning Names</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion_002c-top_002dlevel">diversion, top-level</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion_002c-top_002dlevel_002c-and-bp">diversion, top-level, and <code class="code">bp</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion_002c-top_002dlevel_002c-and-_005c_0021">diversion, top-level, and <code class="code">\!</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion_002c-top_002dlevel_002c-and-_005c_003f">diversion, top-level, and <code class="code">\?</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion_002c-unformatting-_0028asciify_0029">diversion, unformatting (<code class="code">asciify</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversion_002c-vertical-position-in_002c-register-_0028_002ed_0029">diversion, vertical position in, register (<code class="code">.d</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversions">diversions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversions-1">diversions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Punning-Names">Punning Names</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversions_002c-and-traps">diversions, and traps</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-diversions_002c-shared-name-space-with-macros-and-strings">diversions, shared name space with macros and strings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-division_002c-truncating">division, truncating</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dl-register_002c-and-da-_0028boxa_0029"><code class="code">dl</code> register, and <code class="code">da</code> (<code class="code">boxa</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dn-register_002c-and-da-_0028boxa_0029"><code class="code">dn</code> register, and <code class="code">da</code> (<code class="code">boxa</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-document-description-macros_002c-_005bms_005d">document description macros, [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Description-Macros">ms Document Description Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-document-formats">document formats</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Document-Formats">Document Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-documents_002c-multi_002dfile">documents, multi-file</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-documents_002c-structuring-the-source-of">documents, structuring the source of</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-Requests">Invoking Requests</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dot_002c-as-delimiter">dot, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-double-quote_002c-embedding-in-a-macro-argument">double quote, embedding in a macro argument</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Calling-Macros">Calling Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-double-quotes_002c-trailing_002c-in-strings">double quotes, trailing, in strings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-double_002dspacing-_0028ls_0029">double-spacing (<code class="code">ls</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Spacing">Manipulating Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-double_002dspacing-_0028vs_002c-pvs_0029">double-spacing (<code class="code">vs</code>, <code class="code">pvs</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-down_002dcasing-a-string-_0028stringdown_0029">down-casing a string (<code class="code">stringdown</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-a-filled-circle-_0028_005cD_0027C-_2026_0027_0029">drawing a filled circle (&lsquo;<samp class="samp">\D'C &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-a-filled-ellipse-_0028_005cD_0027E-_2026_0027_0029">drawing a filled ellipse (&lsquo;<samp class="samp">\D'E &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-a-filled-polygon-_0028_005cD_0027P-_2026_0027_0029">drawing a filled polygon (&lsquo;<samp class="samp">\D'P &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-a-line-_0028_005cD_0027l-_2026_0027_0029">drawing a line (&lsquo;<samp class="samp">\D'l &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-a-solid-circle-_0028_005cD_0027C-_2026_0027_0029">drawing a solid circle (&lsquo;<samp class="samp">\D'C &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-a-solid-ellipse-_0028_005cD_0027E-_2026_0027_0029">drawing a solid ellipse (&lsquo;<samp class="samp">\D'E &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-a-solid-polygon-_0028_005cD_0027P-_2026_0027_0029">drawing a solid polygon (&lsquo;<samp class="samp">\D'P &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-a-spline-_0028_005cD_0027_007e-_2026_0027_0029">drawing a spline (&lsquo;<samp class="samp">\D'~ &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-a-stroked-circle-_0028_005cD_0027c-_2026_0027_0029">drawing a stroked circle (&lsquo;<samp class="samp">\D'c &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-a-stroked-ellipse-_0028_005cD_0027e-_2026_0027_0029">drawing a stroked ellipse (&lsquo;<samp class="samp">\D'e &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-a-stroked-polygon-_0028_005cD_0027p-_2026_0027_0029">drawing a stroked polygon (&lsquo;<samp class="samp">\D'p &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-an-arc-_0028_005cD_0027a-_2026_0027_0029">drawing an arc (&lsquo;<samp class="samp">\D'a &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-an-outlined-circle-_0028_005cD_0027c-_2026_0027_0029">drawing an outlined circle (&lsquo;<samp class="samp">\D'c &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-an-outlined-ellipse-_0028_005cD_0027e-_2026_0027_0029">drawing an outlined ellipse (&lsquo;<samp class="samp">\D'e &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-an-outlined-polygon-_0028_005cD_0027p-_2026_0027_0029">drawing an outlined polygon (&lsquo;<samp class="samp">\D'p &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-horizontal-lines-_0028_005cl_0029">drawing horizontal lines (<code class="code">\l</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-position">drawing position</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-position_002c-vertical-_0028nl_0029">drawing position, vertical (<code class="code">nl</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-requests">drawing requests</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-drawing-vertical-lines-_0028_005cL_0029">drawing vertical lines (<code class="code">\L</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ds-request_002c-and-comments"><code class="code">ds</code> request, and comments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ds-request_002c-and-double-quotes"><code class="code">ds</code> request, and double quotes</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ds-request_002c-and-leading-spaces"><code class="code">ds</code> request, and leading spaces</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ds_002c-ds1-requests_002c-and-comments"><code class="code">ds</code>, <code class="code">ds1</code> requests, and comments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Comments">Comments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ds_002c-ds1-requests_002c-and-warnings"><code class="code">ds</code>, <code class="code">ds1</code> requests, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dummy-character-_0028_005c_0026_0029">dummy character (<code class="code">\&amp;</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Dummy-Characters">Dummy Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dummy-character-_0028_005c_0026_0029_002c-as-control-character-suppressor">dummy character (<code class="code">\&amp;</code>), as control character suppressor</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Requests-and-Macros">Requests and Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dummy-character-_0028_005c_0026_0029_002c-effect-on-kerning">dummy character (<code class="code">\&amp;</code>), effect on kerning</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dummy-character-_0028_005c_0026_0029_002c-effect-on-_005cl-escape-sequence">dummy character (<code class="code">\&amp;</code>), effect on <code class="code">\l</code> escape sequence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dummy-character_002c-transparent-_0028_005c_0029_0029">dummy character, transparent (<code class="code">\)</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Dummy-Characters">Dummy Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dummy-environment_002c-used-by-_005cw-escape-sequence">dummy environment, used by <code class="code">\w</code> escape sequence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dumping-environments-_0028pev_0029">dumping environments (<code class="code">pev</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dumping-page-location-traps-_0028ptr_0029">dumping page location traps (<code class="code">ptr</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dumping-registers-_0028pnr_0029">dumping registers (<code class="code">pnr</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-dumping-symbol-table-_0028pm_0029">dumping symbol table (<code class="code">pm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-E">E</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-EBCDIC-output-encoding"><abbr class="acronym">EBCDIC</abbr> output encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-EBCDIC_002c-input-encoding"><abbr class="acronym">EBCDIC</abbr>, input encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ejection_002c-page">ejection, page</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ejection_002c-page-1">ejection, page</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ejection_002c-page-2">ejection, page</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#The-Implicit-Page-Trap">The Implicit Page Trap</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ejection_002c-page_002c-of-final-page">ejection, page, of final page</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#End_002dof_002dinput-Traps">End-of-input Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ejection_002c-page_002c-prevented-by-vpt">ejection, page, prevented by <code class="code">vpt</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Vertical-Position-Traps">Vertical Position Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-el-request_002c-and-warnings"><code class="code">el</code> request, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ellipse_002c-filled_002c-drawing-_0028_005cD_0027E-_2026_0027_0029">ellipse, filled, drawing (&lsquo;<samp class="samp">\D'E &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ellipse_002c-outlined_002c-drawing-_0028_005cD_0027e-_2026_0027_0029">ellipse, outlined, drawing (&lsquo;<samp class="samp">\D'e &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ellipse_002c-solid_002c-drawing-_0028_005cD_0027E-_2026_0027_0029">ellipse, solid, drawing (&lsquo;<samp class="samp">\D'E &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ellipse_002c-stroked_002c-drawing-_0028_005cD_0027e-_2026_0027_0029">ellipse, stroked, drawing (&lsquo;<samp class="samp">\D'e &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-em-glyph_002c-and-cflags"><code class="code">em</code> glyph, and <code class="code">cflags</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-em-scaling-unit-_0028m_0029">em scaling unit (<code class="code">m</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-embolding-of-special-fonts">embolding of special fonts</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-empty-line">empty line</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Breaking">Breaking</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-en-scaling-unit-_0028n_0029">en scaling unit (<code class="code">n</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-enabling-vertical-position-traps-_0028vpt_0029">enabling vertical position traps (<code class="code">vpt</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Vertical-Position-Traps">Vertical Position Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-encoding_002c-input_002c-code-page-1047">encoding, input, code page 1047</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-encoding_002c-input_002c-EBCDIC">encoding, input, <abbr class="acronym">EBCDIC</abbr></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-encoding_002c-input_002c-Latin_002d1-_0028ISO-8859_002d1_0029">encoding, input, <span class="w-nolinebreak-text">Latin-1</span><!-- /@w --> (ISO <span class="w-nolinebreak-text">8859-1</span><!-- /@w -->)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-encoding_002c-input_002c-Latin_002d2-_0028ISO-8859_002d2_0029">encoding, input, <span class="w-nolinebreak-text">Latin-2</span><!-- /@w --> (ISO <span class="w-nolinebreak-text">8859-2</span><!-- /@w -->)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-encoding_002c-input_002c-Latin_002d5-_0028ISO-8859_002d9_0029">encoding, input, <span class="w-nolinebreak-text">Latin-5</span><!-- /@w --> (ISO <span class="w-nolinebreak-text">8859-9</span><!-- /@w -->)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-encoding_002c-input_002c-Latin_002d9-_0028ISO-8859_002d15_0029">encoding, input, <span class="w-nolinebreak-text">Latin-9</span><!-- /@w --> (ISO <span class="w-nolinebreak-text">8859-15</span><!-- /@w -->)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-encoding_002c-output_002c-ASCII">encoding, output, <abbr class="acronym">ASCII</abbr></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-encoding_002c-output_002c-code-page-1047">encoding, output, code page 1047</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-encoding_002c-output_002c-EBCDIC">encoding, output, <abbr class="acronym">EBCDIC</abbr></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-encoding_002c-output_002c-ISO-646">encoding, output, ISO&nbsp;646</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-encoding_002c-output_002c-Latin_002d1-_0028ISO-8859_002d1_0029">encoding, output, <span class="w-nolinebreak-text">Latin-1</span><!-- /@w --> (ISO <span class="w-nolinebreak-text">8859-1</span><!-- /@w -->)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-encoding_002c-output_002c-UTF_002d8">encoding, output, <span class="w-nolinebreak-text">UTF-8</span><!-- /@w --></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-end-of-conditional-block-_0028_005c_007d_0029">end of conditional block (<code class="code">\}</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditional-Blocks">Conditional Blocks</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-end_002dof_002dinput-macro-_0028em_0029">end-of-input macro (<code class="code">em</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#End_002dof_002dinput-Traps">End-of-input Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-end_002dof_002dinput-trap_002c-setting-_0028em_0029">end-of-input trap, setting (<code class="code">em</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#End_002dof_002dinput-Traps">End-of-input Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-end_002dof_002dinput-traps">end-of-input traps</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#End_002dof_002dinput-Traps">End-of-input Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-end_002dof_002dsentence-characters">end-of-sentence characters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-end_002dof_002dsentence-characters-1">end-of-sentence characters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-end_002dof_002dsentence-transparent-characters">end-of-sentence transparent characters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ending-diversion-_0028di_002c-box_0029">ending diversion (<code class="code">di</code>, <code class="code">box</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-endnotes">endnotes</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Footnotes-and-Endnotes">Footnotes and Endnotes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-environment">environment</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Deferring-Output">Deferring Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-environment-availability-and-naming_002c-incompatibilities-with">environment availability and naming, incompatibilities with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-environment-number_002fname-register-_0028_002eev_0029">environment number/name register (<code class="code">.ev</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-environment-variables">environment variables</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environment">Environment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-environment_002c-copying-_0028evc_0029">environment, copying (<code class="code">evc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-environment_002c-dimensions-of-last-glyph-_0028_002ew_002c-_002echt_002c-_002ecdp_002c-_002ecsk_0029">environment, dimensions of last glyph (<code class="code">.w</code>, <code class="code">.cht</code>, <code class="code">.cdp</code>, <code class="code">.csk</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-environment_002c-dummy_002c-used-by-_005cw-escape-sequence">environment, dummy, used by <code class="code">\w</code> escape sequence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-environment_002c-previous-line-length-_0028_002en_0029">environment, previous line length (<code class="code">.n</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-environment_002c-switching-_0028ev_0029">environment, switching (<code class="code">ev</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-environments">environments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-environments_002c-dumping-_0028pev_0029">environments, dumping (<code class="code">pev</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-equality-operator">equality operator</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-equation-example-_005bms_005d">equation example [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-equations-_005bms_005d">equations [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-escape-character_002c-changing-_0028ec_0029">escape character, changing (<code class="code">ec</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Escape-Sequences">Using Escape Sequences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-escape-character_002c-formatting-_0028_005ce_0029">escape character, formatting (<code class="code">\e</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Escape-Sequences">Using Escape Sequences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-escape-character_002c-while-defining-glyph">escape character, while defining glyph</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-escape-sequence">escape sequence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Formatter-Instructions">Formatter Instructions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-escape-sequence-argument-delimiters">escape sequence argument delimiters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-escape-sequences">escape sequences</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Escape-Sequences">Using Escape Sequences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-escape-sequences_002c-brace-_0028_005c_007b_002c-_005c_007d_0029">escape sequences, brace (<code class="code">\{</code>, <code class="code">\}</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditional-Blocks">Conditional Blocks</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-escaping-newline-characters_002c-in-strings">escaping newline characters, in strings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ex-request_002c-use-in-debugging"><code class="code">ex</code> request, use in debugging</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ex-request_002c-used-with-nx-and-rd"><code class="code">ex</code> request, used with <code class="code">nx</code> and <code class="code">rd</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-example-markup_002c-bulleted-list-_005bms_005d">example markup, bulleted list [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Lists-in-ms">Lists in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-example-markup_002c-cover-page-in-_005bms_005d">example markup, cover page in [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Description-Macros">ms Document Description Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-example-markup_002c-glossary_002dstyle-list-_005bms_005d">example markup, glossary-style list [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Lists-in-ms">Lists in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-example-markup_002c-numbered-list-_005bms_005d">example markup, numbered list [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Lists-in-ms">Lists in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-examples-of-invocation">examples of invocation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invocation-Examples">Invocation Examples</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-exiting-_0028ex_0029">exiting (<code class="code">ex</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-expansion-of-strings-_0028_005c_002a_0029">expansion of strings (<code class="code">\*</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-explicit-hyphen-_0028_005c_0025_0029">explicit hyphen (<code class="code">\%</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-explicit-hyphenation">explicit hyphenation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-expression_002c-limitation-of-logical-not-in">expression, limitation of logical not in</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-expression_002c-order-of-evaluation">expression, order of evaluation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-expressions_002c-and-register-format">expressions, and register format</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Assigning-Register-Formats">Assigning Register Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-expressions_002c-and-space-characters">expressions, and space characters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-expressions_002c-conditional">expressions, conditional</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Operators-in-Conditionals">Operators in Conditionals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-expressions_002c-numeric">expressions, numeric</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-extra-post_002dvertical-line-space-_0028_005cx_0029">extra post-vertical line space (<code class="code">\x</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-extra-post_002dvertical-line-space-register-_0028_002ea_0029">extra post-vertical line space register (<code class="code">.a</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Spacing">Manipulating Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-extra-pre_002dvertical-line-space-_0028_005cx_0029">extra pre-vertical line space (<code class="code">\x</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-extra-spaces-between-words">extra spaces between words</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Adjustment">Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-extreme-values-representable-with-Roman-numerals">extreme values representable with Roman numerals</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Assigning-Register-Formats">Assigning Register Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-extremum-operators-_0028_003e_003f_002c-_003c_003f_0029">extremum operators (<code class="code">&gt;?</code>, <code class="code">&lt;?</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-F">F</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-f-scaling-unit"><code class="code">f</code> scaling unit</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-factor_002c-zoom_002c-of-a-font-_0028fzoom_0029">factor, zoom, of a font (<code class="code">fzoom</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fallback-character_002c-defining-_0028fchar_002c-fschar_002c-schar_0029">fallback character, defining (<code class="code">fchar</code>, <code class="code">fschar</code>, <code class="code">schar</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fallback-glyph_002c-removing-definition-_0028rchar_002c-rfschar_0029">fallback glyph, removing definition (<code class="code">rchar</code>, <code class="code">rfschar</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fam-request_002c-and-changing-fonts"><code class="code">fam</code> request, and changing fonts</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-families_002c-font">families, font</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-family_002c-font">family, font</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-features_002c-common">features, common</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Common-Features">Common Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fi-request_002c-causing-implicit-break"><code class="code">fi</code> request, causing implicit break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-field-delimiting-character-_0028fc_0029">field delimiting character (<code class="code">fc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Fields">Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-field-padding-character-_0028fc_0029">field padding character (<code class="code">fc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Fields">Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fields">fields</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Fields">Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fields_002c-and-tabs">fields, and tabs</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-figure-space-_0028_005c0_0029">figure space (<code class="code">\0</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-figures-_005bms_005d">figures [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-file-formats">file formats</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#File-Formats">File Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-file-names_002c-breaking-_0028_005c_003a_0029">file names, breaking (<code class="code">\:</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-file_002c-appending-to-_0028opena_0029">file, appending to (<code class="code">opena</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-file_002c-closing-_0028close_0029">file, closing (<code class="code">close</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-file_002c-font-description">file, font description</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-file_002c-inclusion-_0028so_0029">file, inclusion (<code class="code">so</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-file_002c-macro_002c-search-path">file, macro, search path</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-file_002c-opening-_0028open_0029">file, opening (<code class="code">open</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-file_002c-processing-next-_0028nx_0029">file, processing next (<code class="code">nx</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-file_002c-writing-to-_0028write_002c-writec_0029">file, writing to (<code class="code">write</code>, <code class="code">writec</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-files_002c-font">files, font</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Device-and-Font-Description-Files">Device and Font Description Files</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fill-color">fill color</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fill-color-name-register-_0028_002eM_0029">fill color name register (<code class="code">.M</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fill-mode-_0028fi_0029_002c-enabling">fill mode (<code class="code">fi</code>), enabling</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fill-mode_002c-and-_005cc">fill mode, and <code class="code">\c</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fill-mode_002c-disabling">fill mode, disabling</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-filled-circle_002c-drawing-_0028_005cD_0027C-_2026_0027_0029">filled circle, drawing (&lsquo;<samp class="samp">\D'C &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-filled-ellipse_002c-drawing-_0028_005cD_0027E-_2026_0027_0029">filled ellipse, drawing (&lsquo;<samp class="samp">\D'E &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-filled-polygon_002c-drawing-_0028_005cD_0027P-_2026_0027_0029">filled polygon, drawing (&lsquo;<samp class="samp">\D'P &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-filling">filling</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Filling">Filling</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-filling-and-adjustment_002c-manipulating">filling and adjustment, manipulating</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-filling-of-output_002c-disabling-_0028nf_0029">filling of output, disabling (<code class="code">nf</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-filling-of-output_002c-enabling-_0028fi_0029">filling of output, enabling (<code class="code">fi</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-filling_002c-and-break-warnings">filling, and <code class="code">break</code> warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-filling_002c-and-inter_002dsentence-space">filling, and inter-sentence space</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-final-newline_002c-stripping-in-diversions">final newline, stripping in diversions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Punning-Names">Punning Names</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fl-request_002c-causing-implicit-break"><code class="code">fl</code> request, causing implicit break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-floating-keep">floating keep</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Displays-and-Keeps">Displays and Keeps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-flush-output-_0028fl_0029">flush output (<code class="code">fl</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font">font</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-aliasing-with-third-argument-to-fp-request">font aliasing with third argument to <code class="code">fp</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Positions">Font Positions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-description-file">font description file</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-description-file-format">font description file format</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-description-file_002c-format">font description file, format</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-description-files_002c-comments">font description files, comments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-directories">font directories</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Directories">Font Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-families">font families</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-family">font family</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-family_002c-changing-_0028fam_002c-_005cF_0029">font family, changing (<code class="code">fam</code>, <code class="code">\F</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-file_002c-format">font file, format</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-files">font files</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Device-and-Font-Description-Files">Device and Font Description Files</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-for-underlining-_0028uf_0029">font for underlining (<code class="code">uf</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-height_002c-changing-_0028_005cH_0029">font height, changing (<code class="code">\H</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-metrics">font metrics</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-mounting_002c-automatic">font mounting, automatic</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-path">font path</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Directories">Font Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-position-register-_0028_002ef_0029">font position register (<code class="code">.f</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Positions">Font Positions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-positions">font positions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Positions">Font Positions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-slant_002c-changing-_0028_005cS_0029">font slant, changing (<code class="code">\S</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-style">font style</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-style_002c-abstract">font style, abstract</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-style_002c-abstract_002c-setting-up-_0028sty_0029">font style, abstract, setting up (<code class="code">sty</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-styles">font styles</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font-translation-_0028ftr_0029">font translation (<code class="code">ftr</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font_002c-magnification-_0028fzoom_0029">font, magnification (<code class="code">fzoom</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font_002c-mounting-_0028fp_0029">font, mounting (<code class="code">fp</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Positions">Font Positions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font_002c-optical-size">font, optical size</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font_002c-previous_002c-selecting-_0028_005cf_005b_005d_002c-_005cfP_0029">font, previous, selecting (<code class="code">\f[]</code>, <code class="code">\fP</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font_002c-previous_002c-slecting-_0028ft_0029">font, previous, slecting (<code class="code">ft</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font_002c-selection">font, selection</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font_002c-special">font, special</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font_002c-text">font, text</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font_002c-unstyled">font, unstyled</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-font_002c-zoom-factor-_0028fzoom_0029">font, zoom factor (<code class="code">fzoom</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fonts_002c-artificial">fonts, artificial</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fonts_002c-changing-_0028ft_002c-_005cf_0029">fonts, changing (<code class="code">ft</code>, <code class="code">\f</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fonts_002c-searching">fonts, searching</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Directories">Font Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fonts_002c-special">fonts, special</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Special-Fonts">Special Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-footers">footers</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-footers-1">footers</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-footers-_005bms_005d">footers [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Headers-and-Footers">ms Headers and Footers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-footnote-marker-_005bms_005d">footnote marker [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Footnotes">ms Footnotes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-footnotes">footnotes</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Footnotes-and-Endnotes">Footnotes and Endnotes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-footnotes-_005bms_005d">footnotes [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Footnotes">ms Footnotes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-footnotes_002c-and-displays-_005bms_005d">footnotes, and displays [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Footnotes">ms Footnotes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-footnotes_002c-and-keeps-_005bms_005d">footnotes, and keeps [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Footnotes">ms Footnotes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-form-letters">form letters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-format-of-font-description-file">format of font description file</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-format-of-font-description-files">format of font description files</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-format-of-font-files">format of font files</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-format-of-register-_0028_005cg_0029">format of register (<code class="code">\g</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Assigning-Register-Formats">Assigning Register Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-format_002c-paper">format, paper</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paper-Format">Paper Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-formats_002c-file">formats, file</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#File-Formats">File Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-formatter-instructions">formatter instructions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Formatter-Instructions">Formatter Instructions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-formatting-a-backslash-glyph-_0028_005c_005brs_005d_0029">formatting a backslash glyph (<code class="code">\[rs]</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Escape-Sequences">Using Escape Sequences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-formatting-a-title-line-_0028tl_0029">formatting a title line (<code class="code">tl</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-formatting-the-escape-character-_0028_005ce_0029">formatting the escape character (<code class="code">\e</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Escape-Sequences">Using Escape Sequences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-formatting-the-time">formatting the time</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fp-request_002c-and-font-translations"><code class="code">fp</code> request, and font translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fp-request_002c-incompatibilities-with-AT_0026T-troff"><code class="code">fp</code> request, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fractional-point-sizes">fractional point sizes</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fractional-point-sizes-1">fractional point sizes</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fractional-type-sizes">fractional type sizes</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fractional-type-sizes-1">fractional type sizes</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fractional-type-sizes-in-ms-macros">fractional type sizes in <samp class="file">ms</samp> macros</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Differences-from-AT_0026T-ms">Differences from AT&amp;T ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-French-spacing">French spacing</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fspecial-request_002c-and-font-styles"><code class="code">fspecial</code> request, and font styles</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fspecial-request_002c-and-font-translations"><code class="code">fspecial</code> request, and font translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fspecial-request_002c-and-glyph-search-order"><code class="code">fspecial</code> request, and glyph search order</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-fspecial-request_002c-and-imitating-bold"><code class="code">fspecial</code> request, and imitating bold</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ft-request_002c-and-font-translations"><code class="code">ft</code> request, and font translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-full_002dservice-macro-package">full-service macro package</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Major-Macro-Packages">Major Macro Packages</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-G">G</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-geometry_002c-page">geometry, page</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-GGL-_0028groff-glyph-list_0029">GGL (<code class="code">groff</code> glyph list)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-GGL-_0028groff-glyph-list_0029-1">GGL (<code class="code">groff</code> glyph list)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Classes">Character Classes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glossary_002dstyle-list_002c-example-markup-_005bms_005d">glossary-style list, example markup [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Lists-in-ms">Lists in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph">glyph</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph-for-line-drawing">glyph for line drawing</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph-names_002c-composite">glyph names, composite</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph-pile-_0028_005cb_0029">glyph pile (<code class="code">\b</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph-properties-_0028cflags_0029">glyph properties (<code class="code">cflags</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph_002c-box-rule-_0028_005c_005bbr_005d_0029">glyph, box rule (<code class="code">\[br]</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph_002c-constant-space">glyph, constant space</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph_002c-defining-_0028char_0029">glyph, defining (<code class="code">char</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph_002c-distinguished-from-character">glyph, distinguished from character</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph_002c-for-line-drawing">glyph, for line drawing</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph_002c-for-margins-_0028mc_0029">glyph, for margins (<code class="code">mc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph_002c-last_002c-dimensions-_0028_002ew_002c-_002echt_002c-_002ecdp_002c-_002ecsk_0029">glyph, last, dimensions (<code class="code">.w</code>, <code class="code">.cht</code>, <code class="code">.cdp</code>, <code class="code">.csk</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph_002c-leader-repetition-_0028lc_0029">glyph, leader repetition (<code class="code">lc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leaders">Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph_002c-numbered-_0028_005cN_0029">glyph, numbered (<code class="code">\N</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph_002c-numbered-_0028_005cN_0029-1">glyph, numbered (<code class="code">\N</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph_002c-removing-definition-_0028rchar_002c-rfschar_0029">glyph, removing definition (<code class="code">rchar</code>, <code class="code">rfschar</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph_002c-soft-hyphen-_0028hy_0029">glyph, soft hyphen (<code class="code">hy</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph_002c-tab-repetition-_0028tc_0029">glyph, tab repetition (<code class="code">tc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyph_002c-underscore-_0028_005c_005bru_005d_0029">glyph, underscore (<code class="code">\[ru]</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyphs_002c-available_002c-list-of-_0028groff_005fchar_00287_0029-man-page_0029">glyphs, available, list of (<cite class="cite">groff_char<span class="r">(7)</span></cite> man page)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyphs_002c-output_002c-and-input-characters_002c-compatibility-with-AT_0026T-troff">glyphs, output, and input characters, compatibility with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyphs_002c-overstriking-_0028_005co_0029">glyphs, overstriking (<code class="code">\o</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyphs_002c-unnamed">glyphs, unnamed</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-glyphs_002c-unnamed_002c-accessing-with-_005cN">glyphs, unnamed, accessing with <code class="code">\N</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-GNU-troff_002c-identification-register-_0028_002eg_0029">GNU <code class="code">troff</code>, identification register (<code class="code">.g</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-GNU-troff_002c-PID-register-_0028_0024_0024_0029">GNU <code class="code">troff</code>, PID register (<code class="code">$$</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-GNU-troff_002c-process-ID-register-_0028_0024_0024_0029">GNU <code class="code">troff</code>, process ID register (<code class="code">$$</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-GNU_002dspecific-register-_0028_002eg_0029">GNU-specific register (<code class="code">.g</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-graphic-renditions">graphic renditions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-greater-than-_0028or-equal-to_0029-operator">greater than (or equal to) operator</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-groff-capabilities"><code class="code">groff</code> capabilities</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#groff-Capabilities"><code class="code">groff</code> Capabilities</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-groff-glyph-list-_0028GGL_0029"><code class="code">groff</code> glyph list (GGL)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-groff-glyph-list-_0028GGL_0029-1"><code class="code">groff</code> glyph list (GGL)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Classes">Character Classes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-groff-invocation"><code class="code">groff</code> invocation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-groff">Invoking groff</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-groff_002c-and-pi-request"><code class="code">groff</code>, and <code class="code">pi</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-groff_002d_002d_002dwhat-is-it_003f"><code class="code">groff</code>&mdash;what is it?</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#What-Is-groff_003f">What Is <code class="code">groff</code>?</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-GROFF_005fBIN_005fPATH_002c-environment-variable"><code>GROFF_BIN_PATH<span class="r">, environment variable</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environment">Environment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-GROFF_005fCOMMAND_005fPREFIX_002c-environment-variable"><code>GROFF_COMMAND_PREFIX<span class="r">, environment variable</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environment">Environment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-GROFF_005fENCODING_002c-environment-variable"><code>GROFF_ENCODING<span class="r">, environment variable</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environment">Environment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-GROFF_005fFONT_005fPATH_002c-environment-variable"><code>GROFF_FONT_PATH<span class="r">, environment variable</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environment">Environment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-GROFF_005fFONT_005fPATH_002c-environment-variable-1"><code>GROFF_FONT_PATH<span class="r">, environment variable</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Directories">Font Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-GROFF_005fTMAC_005fPATH_002c-environment-variable"><code>GROFF_TMAC_PATH<span class="r">, environment variable</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environment">Environment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-GROFF_005fTMAC_005fPATH_002c-environment-variable-1"><code>GROFF_TMAC_PATH<span class="r">, environment variable</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-GROFF_005fTMPDIR_002c-environment-variable"><code>GROFF_TMPDIR<span class="r">, environment variable</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environment">Environment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-GROFF_005fTYPESETTER_002c-environment-variable"><code>GROFF_TYPESETTER<span class="r">, environment variable</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environment">Environment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-grohtml_002c-the-program"><code class="code">grohtml</code>, the program</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-gtroff_002c-interactive-use"><code class="code">gtroff</code>, interactive use</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-gtroff_002c-output"><code class="code">gtroff</code>, output</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#gtroff-Output">gtroff Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-gtroff_002c-reference"><code class="code">gtroff</code>, reference</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#GNU-troff-Reference">GNU troff Reference</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-H">H</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hair-space-_0028_005c_005e_0029">hair space (<code class="code">\^</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hcode-request_002c-and-glyph-definitions"><code class="code">hcode</code> request, and glyph definitions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-headers">headers</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-headers-1">headers</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-headers-_005bms_005d">headers [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Headers-and-Footers">ms Headers and Footers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-height_002c-font_002c-changing-_0028_005cH_0029">height, font, changing (<code class="code">\H</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-height_002c-of-last-glyph-_0028_002echt_0029">height, of last glyph (<code class="code">.cht</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-high_002dwater-mark-register-_0028_002eh_0029">high-water mark register (<code class="code">.h</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-home-directory">home directory</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-horizontal-discardable-space">horizontal discardable space</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-horizontal-input-line-position-register-_0028hp_0029">horizontal input line position register (<code class="code">hp</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-horizontal-input-line-position_002c-saving-_0028_005ck_0029">horizontal input line position, saving (<code class="code">\k</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-horizontal-line_002c-drawing-_0028_005cl_0029">horizontal line, drawing (<code class="code">\l</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-horizontal-motion-_0028_005ch_0029">horizontal motion (<code class="code">\h</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-horizontal-motion-quantum">horizontal motion quantum</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-horizontal-motion-quantum-register-_0028_002eH_0029">horizontal motion quantum register (<code class="code">.H</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Motion-Quanta">Motion Quanta</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-horizontal-output-line-position-register-_0028_002ek_0029">horizontal output line position register (<code class="code">.k</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-horizontal-resolution">horizontal resolution</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-horizontal-resolution-register-_0028_002eH_0029">horizontal resolution register (<code class="code">.H</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Motion-Quanta">Motion Quanta</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-horizontal-space-_0028_005ch_0029">horizontal space (<code class="code">\h</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-horizontal-space_002c-unformatting">horizontal space, unformatting</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Punning-Names">Punning Names</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-horizontal-tab-character">horizontal tab character</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Leaders">Tabs and Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hours_002c-current-time-_0028hours_0029">hours, current time (<code class="code">hours</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hpf-request_002c-and-hyphenation-language"><code class="code">hpf</code> request, and hyphenation language</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hw-request_002c-and-hy-restrictions"><code class="code">hw</code> request, and <code class="code">hy</code> restrictions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hw-request_002c-and-hyphenation-language"><code class="code">hw</code> request, and hyphenation language</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hy-glyph_002c-and-cflags"><code class="code">hy</code> glyph, and <code class="code">cflags</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphen_002c-explicit-_0028_005c_0025_0029">hyphen, explicit (<code class="code">\%</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenated-lines_002c-consecutive-_0028hlm_0029">hyphenated lines, consecutive (<code class="code">hlm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenating-characters">hyphenating characters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation">hyphenation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Hyphenation">Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation-character-_0028_005c_0025_0029">hyphenation character (<code class="code">\%</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation-code-_0028hcode_0029">hyphenation code (<code class="code">hcode</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation-consecutive-line-count-register-_0028_002ehlc_0029">hyphenation consecutive line count register (<code class="code">.hlc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation-consecutive-line-limit-register-_0028_002ehlm_0029">hyphenation consecutive line limit register (<code class="code">.hlm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation-exceptions">hyphenation exceptions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation-language-register-_0028_002ehla_0029">hyphenation language register (<code class="code">.hla</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation-margin-_0028hym_0029">hyphenation margin (<code class="code">hym</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation-margin-register-_0028_002ehym_0029">hyphenation margin register (<code class="code">.hym</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation-mode-register-_0028_002ehy_0029">hyphenation mode register (<code class="code">.hy</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation-parameters_002c-automatic">hyphenation parameters, automatic</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation-pattern-files">hyphenation pattern files</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation-patterns-_0028hpf_0029">hyphenation patterns (<code class="code">hpf</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation-space-_0028hys_0029">hyphenation space (<code class="code">hys</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation-space-adjustment-threshold">hyphenation space adjustment threshold</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation-space-adjustment-threshold-register-_0028_002ehys_0029">hyphenation space adjustment threshold register (<code class="code">.hys</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation_002c-automatic">hyphenation, automatic</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation_002c-disabling-_0028_005c_0025_0029">hyphenation, disabling (<code class="code">\%</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation_002c-explicit">hyphenation, explicit</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation_002c-incompatibilities-with-AT_0026T-troff">hyphenation, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation_002c-manipulating">hyphenation, manipulating</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-hyphenation_002c-manual">hyphenation, manual</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-I">I</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-i-scaling-unit"><code class="code">i</code> scaling unit</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-i_002fo">i/o</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-IBM-code-page-1047-input-encoding">IBM code page 1047 input encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-IBM-code-page-1047-output-encoding">IBM code page 1047 output encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-identifiers">identifiers</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-identifiers_002c-undefined">identifiers, undefined</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ie-request_002c-and-font-translations"><code class="code">ie</code> request, and font translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ie-request_002c-and-warnings"><code class="code">ie</code> request, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ie-request_002c-operators-to-use-with"><code class="code">ie</code> request, operators to use with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Operators-in-Conditionals">Operators in Conditionals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-if-request_002c-and-font-translations"><code class="code">if</code> request, and font translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-if-request_002c-and-the-_0021-operator"><code class="code">if</code> request, and the &lsquo;<samp class="samp">!</samp>&rsquo; operator</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-if-request_002c-operators-to-use-with"><code class="code">if</code> request, operators to use with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Operators-in-Conditionals">Operators in Conditionals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-if_002delse">if-else</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#if_002delse">if-else</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-if_002dthen">if-then</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#if_002dthen">if-then</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-imitating-boldface-_0028bd_0029">imitating boldface (<code class="code">bd</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-implementation-differences">implementation differences</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Implementation-Differences">Implementation Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-implicit-line-break">implicit line break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Breaking">Breaking</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-implicit-trap">implicit trap</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#The-Implicit-Page-Trap">The Implicit Page Trap</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-in-request_002c-causing-implicit-break"><code class="code">in</code> request, causing implicit break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-in-request_002c-using-_002b-and-_002d-with"><code class="code">in</code> request, using <code class="code">+</code> and&nbsp;<code class="code">-</code> with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-inch-scaling-unit-_0028i_0029">inch scaling unit (<code class="code">i</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-including-a-file-_0028so_0029">including a file (<code class="code">so</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-incompatibilities-with-AT_0026T-troff">incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Implementation-Differences">Implementation Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-increment-value-without-changing-the-register">increment value without changing the register</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Auto_002dincrement">Auto-increment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-incrementation_002c-automatic_002c-of-a-register">incrementation, automatic, of a register</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Auto_002dincrement">Auto-increment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-indentation-_0028in_0029">indentation (<code class="code">in</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-indentation_002c-of-roff-source-code">indentation, of <code class="code">roff</code> source code</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-Requests">Invoking Requests</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-index_002c-in-macro-package">index, in macro package</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Indexing">Indexing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-indicator_002c-scaling">indicator, scaling</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-indirect-assignments">indirect assignments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Interpolating-Registers">Interpolating Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-and-output-requests">input and output requests</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-characters-and-output-glyphs_002c-compatibility-with-AT_0026T-troff">input characters and output glyphs, compatibility with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-characters_002c-invalid">input characters, invalid</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-conventions">input conventions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Conventions">Input Conventions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-encoding_002c-code-page-1047">input encoding, code page 1047</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-encoding_002c-EBCDIC">input encoding, <abbr class="acronym">EBCDIC</abbr></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-encoding_002c-Latin_002d1-_0028ISO-8859_002d1_0029">input encoding, <span class="w-nolinebreak-text">Latin-1</span><!-- /@w --> (ISO <span class="w-nolinebreak-text">8859-1</span><!-- /@w -->)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-encoding_002c-Latin_002d2-_0028ISO-8859_002d2_0029">input encoding, <span class="w-nolinebreak-text">Latin-2</span><!-- /@w --> (ISO <span class="w-nolinebreak-text">8859-2</span><!-- /@w -->)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-encoding_002c-Latin_002d5-_0028ISO-8859_002d9_0029">input encoding, <span class="w-nolinebreak-text">Latin-5</span><!-- /@w --> (ISO <span class="w-nolinebreak-text">8859-9</span><!-- /@w -->)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-encoding_002c-Latin_002d9-_0028ISO-8859_002d15_0029">input encoding, <span class="w-nolinebreak-text">Latin-9</span><!-- /@w --> (ISO <span class="w-nolinebreak-text">8859-15</span><!-- /@w -->)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-file-name_002c-current_002c-register-_0028_002eF_0029">input file name, current, register (<code class="code">.F</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-level">input level</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Calling-Macros">Calling Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-level-in-delimited-arguments">input level in delimited arguments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Compatibility-Mode">Compatibility Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-line-continuation-_0028_005cRET_0029">input line continuation (<code class="code">\<kbd class="key">RET</kbd></code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-line-number-register-_0028_002ec_002c-c_002e_0029">input line number register (<code class="code">.c</code>, <code class="code">c.</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-line-number_002c-setting-_0028lf_0029">input line number, setting (<code class="code">lf</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-line-position_002c-horizontal_002c-saving-_0028_005ck_0029">input line position, horizontal, saving (<code class="code">\k</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-line-trap_002c-clearing-_0028it_002c-itc_0029">input line trap, clearing (<code class="code">it</code>, <code class="code">itc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Line-Traps">Input Line Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-line-trap_002c-setting-_0028it_002c-itc_0029">input line trap, setting (<code class="code">it</code>, <code class="code">itc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Line-Traps">Input Line Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-line-traps">input line traps</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Line-Traps">Input Line Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-line-traps-and-interrupted-lines-_0028itc_0029">input line traps and interrupted lines (<code class="code">itc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Line-Traps">Input Line Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-line_002c-horizontal-position_002c-register-_0028hp_0029">input line, horizontal position, register (<code class="code">hp</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-line_002c-productive">input line, productive</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-stack_002c-backtrace-_0028backtrace_0029">input stack, backtrace (<code class="code">backtrace</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-stack_002c-setting-limit">input stack, setting limit</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input-token">input token</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Gtroff-Internals">Gtroff Internals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input_002c-8_002dbit">input, 8-bit</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-input_002c-standard_002c-reading-from-_0028rd_0029">input, standard, reading from (<code class="code">rd</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-inserting-horizontal-space-_0028_005ch_0029">inserting horizontal space (<code class="code">\h</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-installation">installation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Installation">Installation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-instructing-the-formatter">instructing the formatter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Formatter-Instructions">Formatter Instructions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-inter_002dsentence-space-size-register-_0028_002esss_0029">inter-sentence space size register (<code class="code">.sss</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-inter_002dsentence-space_002c-additional">inter-sentence space, additional</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-inter_002dword-spacing_002c-minimal">inter-word spacing, minimal</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-interactive-use-of-gtroff">interactive use of <code class="code">gtroff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-intercepting-requests">intercepting requests</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Control-Characters">Control Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-intermediate-output">intermediate output</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#gtroff-Output">gtroff Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-interpolating-registers-_0028_005cn_0029">interpolating registers (<code class="code">\n</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Interpolating-Registers">Interpolating Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-interpolation">interpolation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Requests-and-Macros">Requests and Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-interpolation-depth">interpolation depth</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Calling-Macros">Calling Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-interpolation-depth-in-delimited-arguments">interpolation depth in delimited arguments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Compatibility-Mode">Compatibility Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-interpolation-of-strings-_0028_005c_002a_0029">interpolation of strings (<code class="code">\*</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-interpretation-mode">interpretation mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Copy-Mode">Copy Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-interrupted-line">interrupted line</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-interrupted-line-register-_0028_002eint_0029">interrupted line register (<code class="code">.int</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-interrupted-lines-and-input-line-traps-_0028itc_0029">interrupted lines and input line traps (<code class="code">itc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Line-Traps">Input Line Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-introduction">introduction</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Introduction">Introduction</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-invalid-characters-for-trf-request">invalid characters for <code class="code">trf</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-invalid-input-characters">invalid input characters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-invocation-examples">invocation examples</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invocation-Examples">Invocation Examples</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-invoking-groff">invoking <code class="code">groff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-groff">Invoking groff</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-invoking-requests">invoking requests</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-Requests">Invoking Requests</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ISO-646-output-encoding">ISO&nbsp;646 output encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ISO-8859_002d1-_0028Latin_002d1_0029-output-encoding">ISO <span class="w-nolinebreak-text">8859-1</span><!-- /@w --> (<span class="w-nolinebreak-text">Latin-1</span><!-- /@w -->) output encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ISO-8859_002d1-_0028Latin_002d1_0029_002c-input-encoding">ISO <span class="w-nolinebreak-text">8859-1</span><!-- /@w --> (<span class="w-nolinebreak-text">Latin-1</span><!-- /@w -->), input encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ISO-8859_002d15-_0028Latin_002d9_0029_002c-input-encoding">ISO <span class="w-nolinebreak-text">8859-15</span><!-- /@w --> (<span class="w-nolinebreak-text">Latin-9</span><!-- /@w -->), input encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ISO-8859_002d2-_0028Latin_002d2_0029_002c-input-encoding">ISO <span class="w-nolinebreak-text">8859-2</span><!-- /@w --> (<span class="w-nolinebreak-text">Latin-2</span><!-- /@w -->), input encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ISO-8859_002d9-_0028Latin_002d5_0029_002c-input-encoding">ISO <span class="w-nolinebreak-text">8859-9</span><!-- /@w --> (<span class="w-nolinebreak-text">Latin-5</span><!-- /@w -->), input encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-italic-correction-_0028_005c_002f_0029">italic correction (<code class="code">\/</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Italic-Corrections">Italic Corrections</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-J">J</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-justifying-text">justifying text</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-justifying-text-_0028rj_0029">justifying text (<code class="code">rj</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-K">K</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-keep_002c-floating">keep, floating</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Displays-and-Keeps">Displays and Keeps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-keeps-_0028introduction_0029">keeps (introduction)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Displays-and-Keeps">Displays and Keeps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-keeps-_005bms_005d">keeps [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-keeps_002c-and-footnotes-_005bms_005d">keeps, and footnotes [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Footnotes">ms Footnotes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-kerning-and-ligatures">kerning and ligatures</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-kerning-enabled-register-_0028_002ekern_0029">kerning enabled register (<code class="code">.kern</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-kerning_002c-activating-_0028kern_0029">kerning, activating (<code class="code">kern</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-kerning_002c-track">kerning, track</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-L">L</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-landscape-page-orientation">landscape page orientation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paper-Format">Paper Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-language-_005bms_005d">language [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-last-glyph_002c-dimensions-_0028_002ew_002c-_002echt_002c-_002ecdp_002c-_002ecsk_0029">last glyph, dimensions (<code class="code">.w</code>, <code class="code">.cht</code>, <code class="code">.cdp</code>, <code class="code">.csk</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-last_002drequested-point-size-registers-_0028_002epsr_002c-_002esr_0029">last-requested point size registers (<code class="code">.psr</code>, <code class="code">.sr</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-last_002drequested-type-size-registers-_0028_002epsr_002c-_002esr_0029">last-requested type size registers (<code class="code">.psr</code>, <code class="code">.sr</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-Latin_002d1-_0028ISO-8859_002d1_0029-output-encoding"><span class="w-nolinebreak-text">Latin-1</span><!-- /@w --> (ISO <span class="w-nolinebreak-text">8859-1</span><!-- /@w -->) output encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-Latin_002d1-_0028ISO-8859_002d1_0029_002c-input-encoding"><span class="w-nolinebreak-text">Latin-1</span><!-- /@w --> (ISO <span class="w-nolinebreak-text">8859-1</span><!-- /@w -->), input encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-Latin_002d2-_0028ISO-8859_002d2_0029_002c-input-encoding"><span class="w-nolinebreak-text">Latin-2</span><!-- /@w --> (ISO <span class="w-nolinebreak-text">8859-2</span><!-- /@w -->), input encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-Latin_002d5-_0028ISO-8859_002d9_0029_002c-input-encoding"><span class="w-nolinebreak-text">Latin-5</span><!-- /@w --> (ISO <span class="w-nolinebreak-text">8859-9</span><!-- /@w -->), input encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-Latin_002d9-_0028ISO-8859_002d15_0029_002c-input-encoding"><span class="w-nolinebreak-text">Latin-9</span><!-- /@w --> (ISO <span class="w-nolinebreak-text">8859-15</span><!-- /@w -->), input encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Encodings">Input Encodings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-layout_002c-line">layout, line</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-layout_002c-page">layout, page</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lc-request_002c-and-glyph-definitions"><code class="code">lc</code> request, and glyph definitions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-leader-character">leader character</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Leaders">Tabs and Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-leader-character-1">leader character</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leaders">Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-leader-character_002c-and-translations">leader character, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-leader-character_002c-non_002dinterpreted-_0028_005ca_0029">leader character, non-interpreted (<code class="code">\a</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leaders">Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-leader-repetition-character-_0028lc_0029">leader repetition character (<code class="code">lc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leaders">Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-leaders">leaders</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leaders">Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-leading">leading</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Type-Size-and-Vertical-Spacing">Manipulating Type Size and Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-leading-space-macro-_0028lsm_0029">leading space macro (<code class="code">lsm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Breaking">Breaking</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-leading-space-traps">leading space traps</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leading-Space-Traps">Leading Space Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-leading-spaces">leading spaces</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Breaking">Breaking</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-leading-spaces-macro-_0028lsm_0029">leading spaces macro (<code class="code">lsm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leading-Space-Traps">Leading Space Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-leading-spaces-with-ds">leading spaces with <code class="code">ds</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-left-italic-correction-_0028_005c_002c_0029">left italic correction (<code class="code">\,</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Italic-Corrections">Italic Corrections</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-left-margin-_0028po_0029">left margin (<code class="code">po</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-length-of-a-string-_0028length_0029">length of a string (<code class="code">length</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-length-of-line-_0028ll_0029">length of line (<code class="code">ll</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-length-of-previous-line-_0028_002en_0029">length of previous line (<code class="code">.n</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-length-of-the-page_002c-configuring-_0028pl_0029">length of the page, configuring (<code class="code">pl</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-length-of-title-line_002c-configuring-_0028lt_0029">length of title line, configuring (<code class="code">lt</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-length-request_002c-and-copy-mode"><code class="code">length</code> request, and copy mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-less-than-_0028or-equal-to_0029-operator">less than (or equal to) operator</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-letters_002c-form">letters, form</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-level_002c-input">level, input</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Calling-Macros">Calling Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-level_002c-suppression-nesting_002c-register">level, suppression nesting, register</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Suppressing-Output">Suppressing Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lf-request_002c-incompatibilities-with-AT_0026T-troff"><code class="code">lf</code> request, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ligature">ligature</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ligatures-and-kerning">ligatures and kerning</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ligatures-enabled-register-_0028_002elg_0029">ligatures enabled register (<code class="code">.lg</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ligatures_002c-activating-_0028lg_0029">ligatures, activating (<code class="code">lg</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-limitations-of-_005cb-escape-sequence">limitations of <code class="code">\b</code> escape sequence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-break">line break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-break-_0028introduction_0029">line break (introduction)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Basics">Basics</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-break_002c-output">line break, output</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Breaking">Breaking</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-control">line control</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-dimensions">line dimensions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-drawing-glyph">line drawing glyph</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-drawing-glyph-1">line drawing glyph</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-indentation-_0028in_0029">line indentation (<code class="code">in</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-layout">line layout</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-length-_0028ll_0029">line length (<code class="code">ll</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-length-register-_0028_002el_0029">line length register (<code class="code">.l</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-length_002c-previous-_0028_002en_0029">line length, previous (<code class="code">.n</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-number_002c-input_002c-register-_0028_002ec_002c-c_002e_0029">line number, input, register (<code class="code">.c</code>, <code class="code">c.</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-number_002c-output_002c-register-_0028ln_0029">line number, output, register (<code class="code">ln</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-numbers_002c-printing-_0028nm_0029">line numbers, printing (<code class="code">nm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-space_002c-extra-post_002dvertical-_0028_005cx_0029">line space, extra post-vertical (<code class="code">\x</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-space_002c-extra-pre_002dvertical-_0028_005cx_0029">line space, extra pre-vertical (<code class="code">\x</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-spacing-register-_0028_002eL_0029">line spacing register (<code class="code">.L</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Spacing">Manipulating Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-spacing_002c-post_002dvertical-_0028pvs_0029">line spacing, post-vertical (<code class="code">pvs</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line-thickness-_0028_005cD_0027t-_2026_0027_0029">line thickness (&lsquo;<samp class="samp">\D't &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line_002c-blank">line, blank</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Breaking">Breaking</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line_002c-drawing-_0028_005cD_0027l-_2026_0027_0029">line, drawing (&lsquo;<samp class="samp">\D'l &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line_002c-horizontal_002c-drawing-_0028_005cl_0029">line, horizontal, drawing (<code class="code">\l</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line_002c-input_002c-continuation-_0028_005cRET_0029">line, input, continuation (<code class="code">\<kbd class="key">RET</kbd></code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line_002c-input_002c-horizontal-position_002c-register-_0028hp_0029">line, input, horizontal position, register (<code class="code">hp</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line_002c-input_002c-horizontal-position_002c-saving-_0028_005ck_0029">line, input, horizontal position, saving (<code class="code">\k</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line_002c-interrupted">line, interrupted</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line_002c-output_002c-continuation-_0028_005cc_0029">line, output, continuation (<code class="code">\c</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line_002c-output_002c-horizontal-position_002c-register-_0028_002ek_0029">line, output, horizontal position, register (<code class="code">.k</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line_002c-productive-input">line, productive input</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line_002c-vertical_002c-drawing-_0028_005cL_0029">line, vertical, drawing (<code class="code">\L</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-line_002dtabs-mode">line-tabs mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lines_002c-blank_002c-disabling">lines, blank, disabling</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Spacing">Manipulating Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lines_002c-centering-_0028ce_0029">lines, centering (<code class="code">ce</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lines_002c-centering-_0028introduction_0029">lines, centering (introduction)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Basics">Basics</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lines_002c-consecutive-hyphenated-_0028hlm_0029">lines, consecutive hyphenated (<code class="code">hlm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lines_002c-interrupted_002c-and-input-line-traps-_0028itc_0029">lines, interrupted, and input line traps (<code class="code">itc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Line-Traps">Input Line Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lines_002c-right_002daligning-_0028introduction_0029">lines, right-aligning (introduction)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Basics">Basics</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lines_002c-right_002djustifying-_0028introduction_0029">lines, right-justifying (introduction)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Basics">Basics</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-list-of-special-characters-_0028groff_005fchar_00287_0029-man-page_0029">list of special characters (<cite class="cite">groff_char<span class="r">(7)</span></cite> man page)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-listing-page-location-traps-_0028ptr_0029">listing page location traps (<code class="code">ptr</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lists">lists</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paragraphs">Paragraphs</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ll-request_002c-using-_002b-and-_002d-with"><code class="code">ll</code> request, using <code class="code">+</code> and&nbsp;<code class="code">-</code> with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-localization">localization</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-localization-_005bms_005d">localization [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-locating-macro-files">locating macro files</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-locating-macro-packages">locating macro packages</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-location_002c-vertical_002c-page_002c-marking-_0028mk_0029">location, vertical, page, marking (<code class="code">mk</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-location_002c-vertical_002c-page_002c-returning-to-marked-_0028rt_0029">location, vertical, page, returning to marked (<code class="code">rt</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-logical-_0060_0060and_0027_0027-operator">logical &ldquo;and&rdquo; operator</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-logical-_0060_0060or_0027_0027-operator">logical &ldquo;or&rdquo; operator</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-logical-complementation-operator">logical complementation operator</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-logical-conjunction-operator">logical conjunction operator</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-logical-disjunction-operator">logical disjunction operator</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-logical-not_002c-limitation-in-expression">logical not, limitation in expression</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-logical-operators">logical operators</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-long-names">long names</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Compatibility-Mode">Compatibility Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-loops-and-conditionals">loops and conditionals</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditionals-and-Loops">Conditionals and Loops</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lowercasing-a-string-_0028stringdown_0029">lowercasing a string (<code class="code">stringdown</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ls-request_002c-alternative-to-_0028pvs_0029"><code class="code">ls</code> request, alternative to (<code class="code">pvs</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-lt-request_002c-using-_002b-and-_002d-with"><code class="code">lt</code> request, using <code class="code">+</code> and&nbsp;<code class="code">-</code> with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-M">M</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-m-scaling-unit"><code class="code">m</code> scaling unit</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-M-scaling-unit"><code class="code">M</code> scaling unit</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-machine-units">machine units</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro">macro</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Requests-and-Macros">Requests and Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro-arguments">macro arguments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Calling-Macros">Calling Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro-arguments_002c-and-compatibility-mode">macro arguments, and compatibility mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Gtroff-Internals">Gtroff Internals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro-arguments_002c-and-tabs">macro arguments, and tabs</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-Requests">Invoking Requests</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro-directories">macro directories</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro-file-search-path">macro file search path</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro-name-register-_0028_005c_00240_0029">macro name register (<code class="code">\$0</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Parameters">Parameters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro-names_002c-starting-with-_005b-or-_005d_002c-and-refer">macro names, starting with <code class="code">[</code> or <code class="code">]</code>, and <code class="code">refer</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro-package">macro package</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Packages">Macro Packages</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro-package-search-path">macro package search path</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro-package-usage_002c-basics-of">macro package usage, basics of</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Basics">Basics</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro-package_002c-auxiliary">macro package, auxiliary</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Major-Macro-Packages">Major Macro Packages</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro-package_002c-full_002dservice">macro package, full-service</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Major-Macro-Packages">Major Macro Packages</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro-package_002c-introduction">macro package, introduction</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Package-Intro">Macro Package Intro</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro-package_002c-major">macro package, major</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Major-Macro-Packages">Major Macro Packages</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro-package_002c-minor">macro package, minor</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Major-Macro-Packages">Major Macro Packages</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro-package_002c-structuring-the-source-of">macro package, structuring the source of</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-Requests">Invoking Requests</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro_002c-appending-to-_0028am_0029">macro, appending to (<code class="code">am</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Writing-Macros">Writing Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro_002c-creating-alias-for-_0028als_0029">macro, creating alias for (<code class="code">als</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro_002c-end_002dof_002dinput-_0028em_0029">macro, end-of-input (<code class="code">em</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#End_002dof_002dinput-Traps">End-of-input Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro_002c-parameters-_0028_005c_0024_0029">macro, parameters (<code class="code">\$</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Parameters">Parameters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro_002c-removing-_0028rm_0029">macro, removing (<code class="code">rm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro_002c-removing-alias-for-_0028rm_0029">macro, removing alias for (<code class="code">rm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macro_002c-renaming-_0028rn_0029">macro, renaming (<code class="code">rn</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macros_002c-recursive">macros, recursive</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#while">while</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macros_002c-searching">macros, searching</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macros_002c-shared-name-space-with-strings-and-diversions">macros, shared name space with strings and diversions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macros_002c-tutorial-for-users">macros, tutorial for users</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tutorial-for-Macro-Users">Tutorial for Macro Users</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-macros_002c-writing">macros, writing</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Writing-Macros">Writing Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-magnification-of-a-font-_0028fzoom_0029">magnification of a font (<code class="code">fzoom</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-major-macro-package">major macro package</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Major-Macro-Packages">Major Macro Packages</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-major-version-number-register-_0028_002ex_0029">major version number register (<code class="code">.x</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-man-macros_002c-custom-headers-and-footers"><code class="code">man</code> macros, custom headers and footers</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-man-macros_002c-Ultrix_002dspecific"><code class="code">man</code> macros, Ultrix-specific</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-man-pages">man pages</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#man">man</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-manipulating-filling-and-adjustment">manipulating filling and adjustment</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-manipulating-hyphenation">manipulating hyphenation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-manipulating-spacing">manipulating spacing</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Spacing">Manipulating Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-manipulating-type-size-and-vertical-spacing">manipulating type size and vertical spacing</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Type-Size-and-Vertical-Spacing">Manipulating Type Size and Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-manual-hyphenation">manual hyphenation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-manual-pages">manual pages</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#man">man</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-margin-for-hyphenation-_0028hym_0029">margin for hyphenation (<code class="code">hym</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-margin-glyph-_0028mc_0029">margin glyph (<code class="code">mc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-margin_002c-bottom">margin, bottom</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-margin_002c-left-_0028po_0029">margin, left (<code class="code">po</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-margin_002c-right">margin, right</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-margin_002c-top">margin, top</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mark_002c-high_002dwater_002c-register-_0028_002eh_0029">mark, high-water, register (<code class="code">.h</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-marker_002c-footnote-_005bms_005d">marker, footnote [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Footnotes">ms Footnotes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-marking-vertical-page-location-_0028mk_0029">marking vertical page location (<code class="code">mk</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-maximum-operator">maximum operator</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-maximum-value-representable-with-Roman-numerals">maximum value representable with Roman numerals</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Assigning-Register-Formats">Assigning Register Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mdoc-macros"><code class="code">mdoc</code> macros</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#mdoc">mdoc</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-me-macro-package"><code class="code">me</code> macro package</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#me">me</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-measurement-units">measurement units</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-measurements">measurements</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-measurements_002c-specifying-safely">measurements, specifying safely</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Default-Units">Default Units</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-metrics_002c-font">metrics, font</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-minimal-inter_002dword-spacing">minimal inter-word spacing</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-minimum-operator">minimum operator</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-minimum-value-representable-with-Roman-numerals">minimum value representable with Roman numerals</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Assigning-Register-Formats">Assigning Register Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-minor-macro-package">minor macro package</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Major-Macro-Packages">Major Macro Packages</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-minor-version-number-register-_0028_002ey_0029">minor version number register (<code class="code">.y</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-minutes_002c-current-time-_0028minutes_0029">minutes, current time (<code class="code">minutes</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mm-macro-package"><code class="code">mm</code> macro package</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#mm">mm</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode-for-constant-glyph-space-_0028cs_0029">mode for constant glyph space (<code class="code">cs</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-compatibility">mode, compatibility</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Compatibility-Mode">Compatibility Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-compatibility_002c-and-parameters">mode, compatibility, and parameters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Gtroff-Internals">Gtroff Internals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-copy">mode, copy</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Copy-Mode">Copy Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-copy-1">mode, copy</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Copy-Mode">Copy Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-copy_002c-and-cf-request">mode, copy, and <code class="code">cf</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-copy_002c-and-device-request">mode, copy, and <code class="code">device</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Postprocessor-Access">Postprocessor Access</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-copy_002c-and-length-request">mode, copy, and <code class="code">length</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-copy_002c-and-macro-parameters">mode, copy, and macro parameters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Parameters">Parameters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-copy_002c-and-output-request">mode, copy, and <code class="code">output</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-copy_002c-and-trf-request">mode, copy, and <code class="code">trf</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-copy_002c-and-write-request">mode, copy, and <code class="code">write</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-copy_002c-and-writec-request">mode, copy, and <code class="code">writec</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-copy_002c-and-writem-request">mode, copy, and <code class="code">writem</code> request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-copy_002c-and-_005c_0021">mode, copy, and <code class="code">\!</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-copy_002c-and-_005c_003f">mode, copy, and <code class="code">\?</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Operators-in-Conditionals">Operators in Conditionals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-copy_002c-and-_005c_003f-1">mode, copy, and <code class="code">\?</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-copy_002c-and-_005ca">mode, copy, and <code class="code">\a</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leaders">Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-copy_002c-and-_005ct">mode, copy, and <code class="code">\t</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-copy_002c-and-_005cV">mode, copy, and <code class="code">\V</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-fill-_0028fi_0029_002c-enabling">mode, fill (<code class="code">fi</code>), enabling</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-fill_002c-and-break-warnings">mode, fill, and <code class="code">break</code> warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-fill_002c-and-inter_002dsentence-space">mode, fill, and inter-sentence space</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-fill_002c-and-_005cc">mode, fill, and <code class="code">\c</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-fill_002c-disabling">mode, fill, disabling</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-interpretation">mode, interpretation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Copy-Mode">Copy Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-line_002dtabs">mode, line-tabs</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-no_002dfill">mode, no-fill</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-no_002dfill_002c-and-_005cc">mode, no-fill, and <code class="code">\c</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-no_002dspace-_0028ns_0029">mode, no-space (<code class="code">ns</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Spacing">Manipulating Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-nroff">mode, <code class="code">nroff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#troff-and-nroff-Modes"><code class="code">troff</code> and <code class="code">nroff</code> Modes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-safer">mode, safer</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-safer-1">mode, safer</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-safer-2">mode, safer</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-safer-3">mode, safer</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-safer-4">mode, safer</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-safer-5">mode, safer</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-safer-6">mode, safer</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-safer-7">mode, safer</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Safer-Mode">Safer Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-troff">mode, <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#troff-and-nroff-Modes"><code class="code">troff</code> and <code class="code">nroff</code> Modes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-unsafe">mode, unsafe</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-unsafe-1">mode, unsafe</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-unsafe-2">mode, unsafe</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-unsafe-3">mode, unsafe</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-unsafe-4">mode, unsafe</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-unsafe-5">mode, unsafe</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mode_002c-unsafe-6">mode, unsafe</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-modifying-requests">modifying requests</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Control-Characters">Control Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-modulus">modulus</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mom-macro-package"><code class="code">mom</code> macro package</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#mom">mom</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-month-of-the-year-register-_0028mo_0029">month of the year register (<code class="code">mo</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-motion-operators">motion operators</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-motion-quanta">motion quanta</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Motion-Quanta">Motion Quanta</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-motion-quantum_002c-horizontal">motion quantum, horizontal</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-motion-quantum_002c-horizontal_002c-register-_0028_002eH_0029">motion quantum, horizontal, register (<code class="code">.H</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Motion-Quanta">Motion Quanta</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-motion-quantum_002c-vertical">motion quantum, vertical</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-motion_002c-horizontal-_0028_005ch_0029">motion, horizontal (<code class="code">\h</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-motion_002c-vertical-_0028_005cv_0029">motion, vertical (<code class="code">\v</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-motions_002c-page">motions, page</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mounting-a-font-_0028fp_0029">mounting a font (<code class="code">fp</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Positions">Font Positions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mounting-position">mounting position</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mounting-position-1">mounting position</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-mounting_002c-font_002c-automatic">mounting, font, automatic</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros"><samp class="file">ms</samp> macros</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms">ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-accent-marks"><samp class="file">ms</samp> macros, accent marks</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-body-text"><samp class="file">ms</samp> macros, body text</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Body-Text">ms Body Text</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-creating-table-of-contents"><samp class="file">ms</samp> macros, creating table of contents</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-TOC">ms TOC</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-displays"><samp class="file">ms</samp> macros, displays</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-document-control-settings"><samp class="file">ms</samp> macros, document control settings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Control-Settings">ms Document Control Settings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-document-description"><samp class="file">ms</samp> macros, document description</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Description-Macros">ms Document Description Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-equations"><samp class="file">ms</samp> macros, equations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-figures"><samp class="file">ms</samp> macros, figures</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-footers"><samp class="file">ms</samp> macros, footers</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Headers-and-Footers">ms Headers and Footers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-footnotes"><samp class="file">ms</samp> macros, footnotes</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Footnotes">ms Footnotes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-fractional-type-sizes-in"><samp class="file">ms</samp> macros, fractional type sizes in</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Differences-from-AT_0026T-ms">Differences from AT&amp;T ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-general-structure"><samp class="file">ms</samp> macros, general structure</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Document-Structure">ms Document Structure</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-groff-differences-from-AT_0026T"><samp class="file">ms</samp> macros, <code class="code">groff</code> differences from <abbr class="acronym">AT&amp;T</abbr></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Differences-from-AT_0026T-ms">Differences from AT&amp;T ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-headers"><samp class="file">ms</samp> macros, headers</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Headers-and-Footers">ms Headers and Footers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-headings"><samp class="file">ms</samp> macros, headings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Headings-in-ms">Headings in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-keeps"><samp class="file">ms</samp> macros, keeps</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-keeps-and-displays">ms keeps and displays</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-language"><samp class="file">ms</samp> macros, language</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-lists"><samp class="file">ms</samp> macros, lists</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Lists-in-ms">Lists in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-localization"><samp class="file">ms</samp> macros, localization</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-language-and-localization">ms language and localization</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-margins"><samp class="file">ms</samp> macros, margins</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Margins">ms Margins</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-multiple-columns"><samp class="file">ms</samp> macros, multiple columns</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Multiple-Columns">ms Multiple Columns</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-naming-conventions"><samp class="file">ms</samp> macros, naming conventions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Naming-Conventions">ms Naming Conventions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-nested-lists"><samp class="file">ms</samp> macros, nested lists</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Indented-regions-in-ms">Indented regions in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-obtaining-typographical-symbols"><samp class="file">ms</samp> macros, obtaining typographical symbols</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Typographical-symbols-in-ms">Typographical symbols in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-page-layout"><samp class="file">ms</samp> macros, page layout</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Page-Layout">ms Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-paragraph-handling"><samp class="file">ms</samp> macros, paragraph handling</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paragraphs-in-ms">Paragraphs in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-references"><samp class="file">ms</samp> macros, references</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-special-characters"><samp class="file">ms</samp> macros, special characters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-strings"><samp class="file">ms</samp> macros, strings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-tables"><samp class="file">ms</samp> macros, tables</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ms-macros_002c-text-settings"><samp class="file">ms</samp> macros, text settings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Text-settings-in-ms">Text settings in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-multi_002dfile-documents">multi-file documents</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-multi_002dline-strings">multi-line strings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-multi_002dpage-table-example-_005bms_005d">multi-page table example [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-multiple-columns-_005bms_005d">multiple columns [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Multiple-Columns">ms Multiple Columns</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-multiplication">multiplication</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-N">N</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-n-scaling-unit"><code class="code">n</code> scaling unit</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-name-space_002c-common_002c-of-macros_002c-diversions_002c-and-strings">name space, common, of macros, diversions, and strings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-name_002c-background-color_002c-register-_0028_002eM_0029">name, background color, register (<code class="code">.M</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-name_002c-fill-color_002c-register-_0028_002eM_0029">name, fill color, register (<code class="code">.M</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-name_002c-stroke-color_002c-register-_0028_002em_0029">name, stroke color, register (<code class="code">.m</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-named-character-_0028_005cC_0029">named character (<code class="code">\C</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-names_002c-long">names, long</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Compatibility-Mode">Compatibility Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-naming-conventions_002c-ms-macros">naming conventions, <samp class="file">ms</samp> macros</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Naming-Conventions">ms Naming Conventions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ne-request_002c-and-the-_002etrunc-register"><code class="code">ne</code> request, and the <code class="code">.trunc</code> register</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ne-request_002c-comparison-with-sv"><code class="code">ne</code> request, comparison with <code class="code">sv</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-negating-register-values">negating register values</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-negation">negation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nested-assignments">nested assignments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Interpolating-Registers">Interpolating Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nested-diversions">nested diversions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nested-lists-_005bms_005d">nested lists [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Indented-regions-in-ms">Indented regions in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nesting-level_002c-suppression_002c-register">nesting level, suppression, register</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Suppressing-Output">Suppressing Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-new-page-_0028bp_0029">new page (<code class="code">bp</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-newline-character_002c-and-translations">newline character, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-newline-character_002c-in-strings_002c-escaping">newline character, in strings, escaping</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-newline_002c-as-delimiter">newline, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-newline_002c-final_002c-stripping-in-diversions">newline, final, stripping in diversions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Punning-Names">Punning Names</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-next-file_002c-processing-_0028nx_0029">next file, processing (<code class="code">nx</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-next-free-font-position-register-_0028_002efp_0029">next free font position register (<code class="code">.fp</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Positions">Font Positions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-next-page-number-register-_0028_002epn_0029">next page number register (<code class="code">.pn</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-next-page-number_002c-configuring-_0028pn_0029">next page number, configuring (<code class="code">pn</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nf-request_002c-causing-implicit-break"><code class="code">nf</code> request, causing implicit break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nl-register_002c-and-_002ed"><code class="code">nl</code> register, and <code class="code">.d</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nl-register_002c-difference-from-_002eh"><code class="code">nl</code> register, difference from <code class="code">.h</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nm-request_002c-using-_002b-and-_002d-with"><code class="code">nm</code> request, using <code class="code">+</code> and&nbsp;<code class="code">-</code> with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-no_002dbreak-control-character-_0028_0027_0029">no-break control character (<code class="code">'</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Requests-and-Macros">Requests and Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-no_002dbreak-control-character_002c-changing-_0028c2_0029">no-break control character, changing (<code class="code">c2</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Control-Characters">Control Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-no_002dfill-mode">no-fill mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-no_002dfill-mode_002c-and-_005cc">no-fill mode, and <code class="code">\c</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-no_002dspace-mode-_0028ns_0029">no-space mode (<code class="code">ns</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Spacing">Manipulating Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-node_002c-output">node, output</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Gtroff-Internals">Gtroff Internals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-non_002dprinting-break-point-_0028_005c_003a_0029">non-printing break point (<code class="code">\:</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nr-request_002c-and-warnings"><code class="code">nr</code> request, and warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nr-request_002c-using-_002b-and-_002d-with"><code class="code">nr</code> request, using <code class="code">+</code> and&nbsp;<code class="code">-</code> with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-nroff-mode"><code class="code">nroff</code> mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#troff-and-nroff-Modes"><code class="code">troff</code> and <code class="code">nroff</code> Modes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-number-formats_002c-assigning-to-register-_0028af_0029">number formats, assigning to register (<code class="code">af</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Assigning-Register-Formats">Assigning Register Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-number-of-registers-register-_0028_002eR_0029">number of registers register (<code class="code">.R</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-number_002c-input-line_002c-setting-_0028lf_0029">number, input line, setting (<code class="code">lf</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-number_002c-page_002c-next_002c-configuring-_0028pn_0029">number, page, next, configuring (<code class="code">pn</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-numbered-glyph-_0028_005cN_0029">numbered glyph (<code class="code">\N</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-numbered-glyph-_0028_005cN_0029-1">numbered glyph (<code class="code">\N</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-numbered-list_002c-example-markup-_005bms_005d">numbered list, example markup [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Lists-in-ms">Lists in ms</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-numbers_002c-line_002c-printing-_0028nm_0029">numbers, line, printing (<code class="code">nm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-numeral_002dwidth-space-_0028_005c0_0029">numeral-width space (<code class="code">\0</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-numerals_002c-as-delimiters">numerals, as delimiters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-numerals_002c-Roman">numerals, Roman</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Assigning-Register-Formats">Assigning Register Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-numeric-expression_002c-valid">numeric expression, valid</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-numeric-expressions">numeric expressions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-O">O</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-object-creation">object creation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Writing-Macros">Writing Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-offset_002c-page">offset, page</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-offset_002c-page-_0028po_0029">offset, page (<code class="code">po</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-open-request_002c-and-safer-mode"><code class="code">open</code> request, and safer mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-opena-request_002c-and-safer-mode"><code class="code">opena</code> request, and safer mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-opening-brace-escape-sequence-_0028_005c_007d_0029">opening brace escape sequence (<code class="code">\}</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Conditional-Blocks">Conditional Blocks</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-opening-file-_0028open_0029">opening file (<code class="code">open</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-operator_002c-scaling">operator, scaling</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-operators_002c-arithmetic">operators, arithmetic</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-operators_002c-as-delimiters">operators, as delimiters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-operators_002c-comparison">operators, comparison</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-operators_002c-extremum-_0028_003e_003f_002c-_003c_003f_0029">operators, extremum (<code class="code">&gt;?</code>, <code class="code">&lt;?</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-operators_002c-logical">operators, logical</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-operators_002c-motion">operators, motion</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-operators_002c-unary-arithmetic">operators, unary arithmetic</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-optical-size-of-a-font">optical size of a font</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-options">options</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-order-of-evaluation-in-expressions">order of evaluation in expressions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ordinary-character">ordinary character</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-orientation_002c-landscape">orientation, landscape</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paper-Format">Paper Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-orphan">orphan</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-orphan-lines_002c-preventing-with-ne">orphan lines, preventing with <code class="code">ne</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-os-request_002c-and-no_002dspace-mode"><code class="code">os</code> request, and no-space mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-outlined-circle_002c-drawing-_0028_005cD_0027c-_2026_0027_0029">outlined circle, drawing (&lsquo;<samp class="samp">\D'c &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-outlined-ellipse_002c-drawing-_0028_005cD_0027e-_2026_0027_0029">outlined ellipse, drawing (&lsquo;<samp class="samp">\D'e &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-outlined-polygon_002c-drawing-_0028_005cD_0027p-_2026_0027_0029">outlined polygon, drawing (&lsquo;<samp class="samp">\D'p &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-and-input-requests">output and input requests</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-comparison-operator">output comparison operator</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Operators-in-Conditionals">Operators in Conditionals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-device-name-string-_0028_002eT_0029">output device name string (<code class="code">.T</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-device-name-string-_0028_002eT_0029-1">output device name string (<code class="code">.T</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-device-name-string-_0028_002eT_0029_002c-in-other-implementations">output device name string (<code class="code">.T</code>), in other implementations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-device-usage-register-_0028_002eT_0029">output device usage register (<code class="code">.T</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-device-usage-register-_0028_002eT_0029_002c-incompatibility-with-AT_0026T-troff">output device usage register (<code class="code">.T</code>), incompatibility with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-devices">output devices</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Output-Device-Intro">Output Device Intro</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-encoding_002c-ASCII">output encoding, <abbr class="acronym">ASCII</abbr></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-encoding_002c-code-page-1047">output encoding, code page 1047</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-encoding_002c-EBCDIC">output encoding, <abbr class="acronym">EBCDIC</abbr></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-encoding_002c-ISO-646">output encoding, ISO&nbsp;646</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-encoding_002c-Latin_002d1-_0028ISO-8859_002d1_0029">output encoding, <span class="w-nolinebreak-text">Latin-1</span><!-- /@w --> (ISO <span class="w-nolinebreak-text">8859-1</span><!-- /@w -->)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-encoding_002c-UTF_002d8">output encoding, <span class="w-nolinebreak-text">UTF-8</span><!-- /@w --></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-glyphs_002c-and-input-characters_002c-compatibility-with-AT_0026T-troff">output glyphs, and input characters, compatibility with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-line-break">output line break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Breaking">Breaking</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-line-number-register-_0028ln_0029">output line number register (<code class="code">ln</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-line-properties">output line properties</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-line_002c-continuation-_0028_005cc_0029">output line, continuation (<code class="code">\c</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Continuation">Line Continuation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-line_002c-horizontal-position_002c-register-_0028_002ek_0029">output line, horizontal position, register (<code class="code">.k</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-node">output node</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Gtroff-Internals">Gtroff Internals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-request_002c-and-copy-mode"><code class="code">output</code> request, and copy mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output-request_002c-and-_005c_0021"><code class="code">output</code> request, and <code class="code">\!</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output_002c-filling_002c-disablement-of-_0028nf_0029">output, filling, disablement of (<code class="code">nf</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output_002c-filling_002c-enablement-of-_0028fi_0029">output, filling, enablement of (<code class="code">fi</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output_002c-flush-_0028fl_0029">output, flush (<code class="code">fl</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output_002c-gtroff">output, <code class="code">gtroff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#gtroff-Output">gtroff Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output_002c-intermediate">output, intermediate</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#gtroff-Output">gtroff Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output_002c-suppressing-_0028_005cO_0029">output, suppressing (<code class="code">\O</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Suppressing-Output">Suppressing Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output_002c-transparent-_0028cf_002c-trf_0029">output, transparent (<code class="code">cf</code>, <code class="code">trf</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output_002c-transparent-_0028_005c_0021_002c-_005c_003f_0029">output, transparent (<code class="code">\!</code>, <code class="code">\?</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output_002c-transparent_002c-incompatibilities-with-AT_0026T-troff">output, transparent, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-output_002c-troff">output, <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#gtroff-Output">gtroff Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-overlapping-characters">overlapping characters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-overstriking-glyphs-_0028_005co_0029">overstriking glyphs (<code class="code">\o</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-P">P</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-p-scaling-unit"><code class="code">p</code> scaling unit</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-P-scaling-unit"><code class="code">P</code> scaling unit</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-package_002c-macro">package, macro</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Packages">Macro Packages</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-package_002c-macro_002c-auxiliary">package, macro, auxiliary</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Major-Macro-Packages">Major Macro Packages</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-package_002c-macro_002c-full_002dservice">package, macro, full-service</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Major-Macro-Packages">Major Macro Packages</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-package_002c-macro_002c-introduction">package, macro, introduction</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Package-Intro">Macro Package Intro</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-package_002c-macro_002c-major">package, macro, major</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Major-Macro-Packages">Major Macro Packages</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-package_002c-macro_002c-minor">package, macro, minor</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Major-Macro-Packages">Major Macro Packages</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-package_002c-macro_002c-search-path">package, macro, search path</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-package_002c-package_002c-structuring-the-source-of">package, package, structuring the source of</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-Requests">Invoking Requests</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-padding-character_002c-for-fields-_0028fc_0029">padding character, for fields (<code class="code">fc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Fields">Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page">page</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-break">page break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-break-1">page break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-break-2">page break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#The-Implicit-Page-Trap">The Implicit Page Trap</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-break-_0028introduction_0029">page break (introduction)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Basics">Basics</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-break_002c-conditional-_0028ne_0029">page break, conditional (<code class="code">ne</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-break_002c-final">page break, final</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#End_002dof_002dinput-Traps">End-of-input Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-break_002c-prevented-by-vpt">page break, prevented by <code class="code">vpt</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Vertical-Position-Traps">Vertical Position Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-control">page control</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-ejection">page ejection</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-ejection-1">page ejection</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-ejection-2">page ejection</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#The-Implicit-Page-Trap">The Implicit Page Trap</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-ejection-status-register-_0028_002epe_0029">page ejection status register (<code class="code">.pe</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-ejection_002c-of-final-page">page ejection, of final page</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#End_002dof_002dinput-Traps">End-of-input Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-ejection_002c-prevented-by-vpt">page ejection, prevented by <code class="code">vpt</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Vertical-Position-Traps">Vertical Position Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-footers">page footers</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-headers">page headers</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-layout">page layout</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-layout-_005bms_005d">page layout [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Page-Layout">ms Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-length-register-_0028_002ep_0029">page length register (<code class="code">.p</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-length_002c-configuring-_0028pl_0029">page length, configuring (<code class="code">pl</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-location-traps">page location traps</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-location-traps_002c-debugging">page location traps, debugging</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-location_002c-vertical_002c-marking-_0028mk_0029">page location, vertical, marking (<code class="code">mk</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-location_002c-vertical_002c-returning-to-marked-_0028rt_0029">page location, vertical, returning to marked (<code class="code">rt</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-motions">page motions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-number-character-_0028_0025_0029">page number character (<code class="code">%</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-number-character_002c-changing-_0028pc_0029">page number character, changing (<code class="code">pc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-number-register-_0028_0025_0029">page number register (<code class="code">%</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-number_002c-configuring-next-_0028pn_0029">page number, configuring next (<code class="code">pn</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-number_002c-next_002c-register-_0028_002epn_0029">page number, next, register (<code class="code">.pn</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-offset">page offset</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-offset-_0028po_0029">page offset (<code class="code">po</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page-orientation_002c-landscape">page orientation, landscape</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paper-Format">Paper Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page_002c-geometry-of">page, geometry of</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-page_002c-new-_0028bp_0029">page, new (<code class="code">bp</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-paper-format">paper format</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paper-Format">Paper Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-paper-size">paper size</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paper-Format">Paper Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-paragraphs">paragraphs</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paragraphs">Paragraphs</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-parameter-count-register-_0028_002e_0024_0029">parameter count register (<code class="code">.$</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Parameters">Parameters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-parameters">parameters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Parameters">Parameters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-parameters_002c-and-compatibility-mode">parameters, and compatibility mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Gtroff-Internals">Gtroff Internals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-parameters_002c-macro-_0028_005c_0024_0029">parameters, macro (<code class="code">\$</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Parameters">Parameters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-parentheses">parentheses</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-partially-collected-line">partially collected line</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-path_002c-for-font-files">path, for font files</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Directories">Font Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-path_002c-for-tmac-files">path, for tmac files</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pattern-files_002c-for-hyphenation">pattern files, for hyphenation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-patterns-for-hyphenation-_0028hpf_0029">patterns for hyphenation (<code class="code">hpf</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pending-output-line">pending output line</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pi-request_002c-and-groff"><code class="code">pi</code> request, and <code class="code">groff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pi-request_002c-and-safer-mode"><code class="code">pi</code> request, and safer mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pi-request_002c-disabled-by-default"><code class="code">pi</code> request, disabled by default</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Safer-Mode">Safer Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pica-scaling-unit-_0028P_0029">pica scaling unit (<code class="code">P</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-PID-of-GNU-troff-register-_0028_0024_0024_0029">PID of GNU <code class="code">troff</code> register (<code class="code">$$</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pile_002c-glyph-_0028_005cb_0029">pile, glyph (<code class="code">\b</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pl-request_002c-using-_002b-and-_002d-with"><code class="code">pl</code> request, using <code class="code">+</code> and&nbsp;<code class="code">-</code> with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-plain-text-approximation-output-register-_0028_002eA_0029">plain text approximation output register (<code class="code">.A</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-plain-text-approximation-output-register-_0028_002eA_0029-1">plain text approximation output register (<code class="code">.A</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-planting-a-trap">planting a trap</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Traps">Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-platform_002dspecific-directory">platform-specific directory</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pm-request_002c-incompatibilities-with-AT_0026T-troff"><code class="code">pm</code> request, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pn-request_002c-using-_002b-and-_002d-with"><code class="code">pn</code> request, using <code class="code">+</code> and&nbsp;<code class="code">-</code> with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-PNG-image-generation-from-PostScript">PNG image generation from PostScript</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-po-request_002c-using-_002b-and-_002d-with"><code class="code">po</code> request, using <code class="code">+</code> and&nbsp;<code class="code">-</code> with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-point-scaling-unit-_0028p_0029">point scaling unit (<code class="code">p</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-point-size-registers-_0028_002es_002c-_002eps_0029">point size registers (<code class="code">.s</code>, <code class="code">.ps</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Type-Size">Changing the Type Size</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-point-size-registers_002c-last_002drequested-_0028_002epsr_002c-_002esr_0029">point size registers, last-requested (<code class="code">.psr</code>, <code class="code">.sr</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-point-sizes_002c-changing-_0028ps_002c-_005cs_0029">point sizes, changing (<code class="code">ps</code>, <code class="code">\s</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Type-Size">Changing the Type Size</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-point-sizes_002c-fractional">point sizes, fractional</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-point-sizes_002c-fractional-1">point sizes, fractional</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-polygon_002c-filled_002c-drawing-_0028_005cD_0027P-_2026_0027_0029">polygon, filled, drawing (&lsquo;<samp class="samp">\D'P &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-polygon_002c-outlined_002c-drawing-_0028_005cD_0027p-_2026_0027_0029">polygon, outlined, drawing (&lsquo;<samp class="samp">\D'p &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-polygon_002c-solid_002c-drawing-_0028_005cD_0027P-_2026_0027_0029">polygon, solid, drawing (&lsquo;<samp class="samp">\D'P &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-polygon_002c-stroked_002c-drawing-_0028_005cD_0027p-_2026_0027_0029">polygon, stroked, drawing (&lsquo;<samp class="samp">\D'p &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-position-of-lowest-text-line-_0028_002eh_0029">position of lowest text line (<code class="code">.h</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-position_002c-absolute-_0028sic_0029-operator-_0028_007c_0029">position, absolute <i class="slanted">(sic)</i> operator (<code class="code">|</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-position_002c-drawing">position, drawing</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-position_002c-horizontal-input-line_002c-saving-_0028_005ck_0029">position, horizontal input line, saving (<code class="code">\k</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-position_002c-horizontal_002c-in-input-line_002c-register-_0028hp_0029">position, horizontal, in input line, register (<code class="code">hp</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-position_002c-horizontal_002c-in-output-line_002c-register-_0028_002ek_0029">position, horizontal, in output line, register (<code class="code">.k</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-position_002c-mounting">position, mounting</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-position_002c-vertical_002c-in-diversion_002c-register-_0028_002ed_0029">position, vertical, in diversion, register (<code class="code">.d</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-positions_002c-font">positions, font</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Positions">Font Positions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-post_002dvertical-line-spacing">post-vertical line spacing</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-post_002dvertical-line-spacing-register-_0028_002epvs_0029">post-vertical line spacing register (<code class="code">.pvs</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-post_002dvertical-line-spacing_002c-changing-_0028pvs_0029">post-vertical line spacing, changing (<code class="code">pvs</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-postprocessor-access">postprocessor access</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Postprocessor-Access">Postprocessor Access</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-postprocessors">postprocessors</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Output-Device-Intro">Output Device Intro</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-PostScript_002c-bounding-box">PostScript, bounding box</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-PostScript_002c-PNG-image-generation">PostScript, PNG image generation</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-prefix_002c-for-commands">prefix, for commands</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environment">Environment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-preprocessors">preprocessors</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Preprocessor-Intro">Preprocessor Intro</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-previous-font_002c-selecting-_0028ft_0029">previous font, selecting (<code class="code">ft</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-previous-font_002c-selecting-_0028_005cf_005b_005d_002c-_005cfP_0029">previous font, selecting (<code class="code">\f[]</code>, <code class="code">\fP</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-previous-line-length-_0028_002en_0029">previous line length (<code class="code">.n</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-print-current-page-register-_0028_002eP_0029">print current page register (<code class="code">.P</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-printing-backslash-_0028_005c_005c_002c-_005ce_002c-_005cE_002c-_005c_005brs_005d_0029">printing backslash (<code class="code">\\</code>, <code class="code">\e</code>, <code class="code">\E</code>, <code class="code">\[rs]</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-printing-line-numbers-_0028nm_0029">printing line numbers (<code class="code">nm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-printing-to-stderr-_0028tm_002c-tm1_002c-tmc_0029">printing to stderr (<code class="code">tm</code>, <code class="code">tm1</code>, <code class="code">tmc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-printing_002c-zero_002dwidth-_0028_005cz_002c-_005cZ_0029">printing, zero-width (<code class="code">\z</code>, <code class="code">\Z</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-printing_002c-zero_002dwidth-_0028_005cz_002c-_005cZ_0029-1">printing, zero-width (<code class="code">\z</code>, <code class="code">\Z</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-process-ID-of-GNU-troff-register-_0028_0024_0024_0029">process ID of GNU <code class="code">troff</code> register (<code class="code">$$</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-processing-next-file-_0028nx_0029">processing next file (<code class="code">nx</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-productive-input-line">productive input line</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-properties-of-characters-_0028cflags_0029">properties of characters (<code class="code">cflags</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-properties-of-glyphs-_0028cflags_0029">properties of glyphs (<code class="code">cflags</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-properties-of-output-lines">properties of output lines</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ps-request_002c-and-constant-glyph-space-mode"><code class="code">ps</code> request, and constant glyph space mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ps-request_002c-incompatibilities-with-AT_0026T-troff"><code class="code">ps</code> request, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ps-request_002c-using-_002b-and-_002d-with"><code class="code">ps</code> request, using <code class="code">+</code> and&nbsp;<code class="code">-</code> with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ps-request_002c-with-fractional-type-sizes"><code class="code">ps</code> request, with fractional type sizes</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pso-request_002c-and-safer-mode"><code class="code">pso</code> request, and safer mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-pvs-request_002c-using-_002b-and-_002d-with"><code class="code">pvs</code> request, using <code class="code">+</code> and&nbsp;<code class="code">-</code> with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-Q">Q</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-quanta_002c-motion">quanta, motion</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Motion-Quanta">Motion Quanta</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-quantum_002c-horizontal-motion">quantum, horizontal motion</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-quantum_002c-vertical-motion">quantum, vertical motion</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-R">R</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-radicalex-glyph_002c-and-cflags"><code class="code">radicalex</code> glyph, and <code class="code">cflags</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ragged_002dleft-text">ragged-left text</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ragged_002dright-text">ragged-right text</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rc-request_002c-and-glyph-definitions"><code class="code">rc</code> request, and glyph definitions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-read_002donly-register-removal_002c-incompatibility-with-AT_0026T-troff">read-only register removal, incompatibility with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-read_002donly-register_002c-changing-format">read-only register, changing format</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Assigning-Register-Formats">Assigning Register Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-reading-from-standard-input-_0028rd_0029">reading from standard input (<code class="code">rd</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-recursive-macros">recursive macros</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#while">while</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-refer_002c-and-macro-names-starting-with-_005b-or-_005d"><code class="code">refer</code>, and macro names starting with <code class="code">[</code> or <code class="code">]</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-reference_002c-gtroff">reference, <code class="code">gtroff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#GNU-troff-Reference">GNU troff Reference</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-references-_005bms_005d">references [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-register-format_002c-in-expressions">register format, in expressions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Assigning-Register-Formats">Assigning Register Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-register_002c-assigning-number-format-to-_0028af_0029">register, assigning number format to (<code class="code">af</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Assigning-Register-Formats">Assigning Register Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-register_002c-built_002din_002c-removing">register, built-in, removing</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-register_002c-creating-alias-for-_0028aln_0029">register, creating alias for (<code class="code">aln</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-register_002c-format-_0028_005cg_0029">register, format (<code class="code">\g</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Assigning-Register-Formats">Assigning Register Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-register_002c-read_002donly_002c-removal_002c-incompatibility-with-AT_0026T-troff">register, read-only, removal, incompatibility with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-register_002c-removing-_0028rr_0029">register, removing (<code class="code">rr</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-register_002c-removing-alias-for-_0028rr_0029">register, removing alias for (<code class="code">rr</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-register_002c-renaming-_0028rnn_0029">register, renaming (<code class="code">rnn</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-registers">registers</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Registers">Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-registers_002c-built_002din">registers, built-in</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-registers_002c-dumping-_0028pnr_0029">registers, dumping (<code class="code">pnr</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-registers_002c-interpolating-_0028_005cn_0029">registers, interpolating (<code class="code">\n</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Interpolating-Registers">Interpolating Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-registers_002c-number-of_002c-register-_0028_002eR_0029">registers, number of, register (<code class="code">.R</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-registers_002c-setting-_0028nr_002c-_005cR_0029">registers, setting (<code class="code">nr</code>, <code class="code">\R</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-removal-of-read_002donly-registers_002c-incompatibility-with-AT_0026T-troff">removal of read-only registers, incompatibility with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-removing-a-built_002din-register">removing a built-in register</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-removing-a-register-_0028rr_0029">removing a register (<code class="code">rr</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-removing-alias-for-register-_0028rr_0029">removing alias for register (<code class="code">rr</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-removing-alias_002c-for-diversion-_0028rm_0029">removing alias, for diversion (<code class="code">rm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-removing-alias_002c-for-macro-_0028rm_0029">removing alias, for macro (<code class="code">rm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-removing-alias_002c-for-string-_0028rm_0029">removing alias, for string (<code class="code">rm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-removing-diversion-_0028rm_0029">removing diversion (<code class="code">rm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-removing-glyph-definition-_0028rchar_002c-rfschar_0029">removing glyph definition (<code class="code">rchar</code>, <code class="code">rfschar</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-removing-macro-_0028rm_0029">removing macro (<code class="code">rm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-removing-request-_0028rm_0029">removing request (<code class="code">rm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-removing-string-_0028rm_0029">removing string (<code class="code">rm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-renaming-a-register-_0028rnn_0029">renaming a register (<code class="code">rnn</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-renaming-diversion-_0028rn_0029">renaming diversion (<code class="code">rn</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-renaming-macro-_0028rn_0029">renaming macro (<code class="code">rn</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-renaming-request-_0028rn_0029">renaming request (<code class="code">rn</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-renaming-string-_0028rn_0029">renaming string (<code class="code">rn</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-renditions_002c-graphic">renditions, graphic</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-request">request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Requests-and-Macros">Requests and Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-request-1">request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Formatter-Instructions">Formatter Instructions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-request-arguments">request arguments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-Requests">Invoking Requests</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-request-arguments_002c-and-compatibility-mode">request arguments, and compatibility mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Gtroff-Internals">Gtroff Internals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-request-arguments_002c-and-tabs">request arguments, and tabs</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-Requests">Invoking Requests</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-request_002c-removing-_0028rm_0029">request, removing (<code class="code">rm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-request_002c-renaming-_0028rn_0029">request, renaming (<code class="code">rn</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-request_002c-undefined">request, undefined</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Comments">Comments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-requests-for-drawing">requests for drawing</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-requests-for-input-and-output">requests for input and output</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-requests_002c-intercepting">requests, intercepting</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Control-Characters">Control Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-requests_002c-invoking">requests, invoking</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-Requests">Invoking Requests</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-requests_002c-modifying">requests, modifying</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Control-Characters">Control Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-resolution_002c-device">resolution, device</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-resolution_002c-device-1">resolution, device</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-resolution_002c-device_002c-obtaining-in-the-formatter">resolution, device, obtaining in the formatter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-resolution_002c-horizontal">resolution, horizontal</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-resolution_002c-horizontal_002c-register-_0028_002eH_0029">resolution, horizontal, register (<code class="code">.H</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Motion-Quanta">Motion Quanta</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-resolution_002c-vertical">resolution, vertical</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-returning-to-marked-vertical-page-location-_0028rt_0029">returning to marked vertical page location (<code class="code">rt</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-revision-number-register-_0028_002eY_0029">revision number register (<code class="code">.Y</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-right-margin">right margin</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Line-Layout">Line Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-right_002daligning-lines-_0028introduction_0029">right-aligning lines (introduction)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Basics">Basics</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-right_002djustifying-_0028rj_0029">right-justifying (<code class="code">rj</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-right_002djustifying-lines-_0028introduction_0029">right-justifying lines (introduction)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Basics">Basics</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rivers">rivers</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rj-request_002c-causing-implicit-break"><code class="code">rj</code> request, causing implicit break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rn-glyph_002c-and-cflags"><code class="code">rn</code> glyph, and <code class="code">cflags</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-roman-glyph_002c-correction-after-italic-glyph-_0028_005c_002f_0029">roman glyph, correction after italic glyph (<code class="code">\/</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Italic-Corrections">Italic Corrections</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-roman-glyph_002c-correction-before-italic-glyph-_0028_005c_002c_0029">roman glyph, correction before italic glyph (<code class="code">\,</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Italic-Corrections">Italic Corrections</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-Roman-numerals">Roman numerals</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Assigning-Register-Formats">Assigning Register Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-Roman-numerals_002c-extrema-_0028maximum-and-minimum_0029">Roman numerals, extrema (maximum and minimum)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Assigning-Register-Formats">Assigning Register Formats</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rq-glyph_002c-at-end-of-sentence"><code class="code">rq</code> glyph, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rq-glyph_002c-at-end-of-sentence-1"><code class="code">rq</code> glyph, at end of sentence</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-rt-request_002c-using-_002b-and-_002d-with"><code class="code">rt</code> request, using <code class="code">+</code> and&nbsp;<code class="code">-</code> with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ru-glyph_002c-and-cflags"><code class="code">ru</code> glyph, and <code class="code">cflags</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-running-system-commands">running system commands</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-S">S</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-s-scaling-unit"><code class="code">s</code> scaling unit</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-safer-mode">safer mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-safer-mode-1">safer mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-safer-mode-2">safer mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-safer-mode-3">safer mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-safer-mode-4">safer mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-safer-mode-5">safer mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-safer-mode-6">safer mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-safer-mode-7">safer mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Safer-Mode">Safer Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-saving-horizontal-input-line-position-_0028_005ck_0029">saving horizontal input line position (<code class="code">\k</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-scaling-indicator">scaling indicator</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-scaling-operator">scaling operator</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-scaling-unit-c">scaling unit <code class="code">c</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-scaling-unit-f">scaling unit <code class="code">f</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-scaling-unit-i">scaling unit <code class="code">i</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-scaling-unit-m">scaling unit <code class="code">m</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-scaling-unit-M">scaling unit <code class="code">M</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-scaling-unit-n">scaling unit <code class="code">n</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-scaling-unit-p">scaling unit <code class="code">p</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-scaling-unit-P">scaling unit <code class="code">P</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-scaling-unit-s">scaling unit <code class="code">s</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-scaling-unit-u">scaling unit <code class="code">u</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-scaling-unit-v">scaling unit <code class="code">v</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-scaling-unit-z">scaling unit <code class="code">z</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-searching-fonts">searching fonts</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Directories">Font Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-searching-macros">searching macros</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-seconds_002c-current-time-_0028seconds_0029">seconds, current time (<code class="code">seconds</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-selecting-the-previous-font-_0028ft_0029">selecting the previous font (<code class="code">ft</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sentence-space">sentence space</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sentence-space-size-register-_0028_002esss_0029">sentence space size register (<code class="code">.sss</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sentences">sentences</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sequence_002c-escape">sequence, escape</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Formatter-Instructions">Formatter Instructions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-setting-diversion-trap-_0028dt_0029">setting diversion trap (<code class="code">dt</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversion-Traps">Diversion Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-setting-end_002dof_002dinput-trap-_0028em_0029">setting end-of-input trap (<code class="code">em</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#End_002dof_002dinput-Traps">End-of-input Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-setting-input-line-number-_0028lf_0029">setting input line number (<code class="code">lf</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-setting-input-line-trap-_0028it_002c-itc_0029">setting input line trap (<code class="code">it</code>, <code class="code">itc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Line-Traps">Input Line Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-setting-registers-_0028nr_002c-_005cR_0029">setting registers (<code class="code">nr</code>, <code class="code">\R</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Setting-Registers">Setting Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-setting-the-page-length-_0028pl_0029">setting the page length (<code class="code">pl</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-setting-up-an-abstract-font-style-_0028sty_0029">setting up an abstract font style (<code class="code">sty</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-shc-request_002c-and-translations"><code class="code">shc</code> request, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-site_002dlocal-directory">site-local directory</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-site_002dlocal-directory-1">site-local directory</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Directories">Font Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-size-of-sentence-space-register-_0028_002esss_0029">size of sentence space register (<code class="code">.sss</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-size-of-word-space-register-_0028_002ess_0029">size of word space register (<code class="code">.ss</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-size_002c-optical_002c-of-a-font">size, optical, of a font</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-size_002c-paper">size, paper</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paper-Format">Paper Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-size_002c-size">size, size</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Type-Size-and-Vertical-Spacing">Manipulating Type Size and Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sizes_002c-fractional">sizes, fractional</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sizes_002c-fractional-type">sizes, fractional type</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-skew_002c-of-last-glyph-_0028_002ecsk_0029">skew, of last glyph (<code class="code">.csk</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-slant_002c-font_002c-changing-_0028_005cS_0029">slant, font, changing (<code class="code">\S</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-soft-hyphen-character_002c-setting-_0028shc_0029">soft hyphen character, setting (<code class="code">shc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-soft-hyphen-glyph-_0028hy_0029">soft hyphen glyph (<code class="code">hy</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-solid-circle_002c-drawing-_0028_005cD_0027C-_2026_0027_0029">solid circle, drawing (&lsquo;<samp class="samp">\D'C &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-solid-ellipse_002c-drawing-_0028_005cD_0027E-_2026_0027_0029">solid ellipse, drawing (&lsquo;<samp class="samp">\D'E &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-solid-polygon_002c-drawing-_0028_005cD_0027P-_2026_0027_0029">solid polygon, drawing (&lsquo;<samp class="samp">\D'P &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-SOURCE_005fDATE_005fEPOCH_002c-environment-variable"><code>SOURCE_DATE_EPOCH<span class="r">, environment variable</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environment">Environment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sp-request_002c-and-no_002dspace-mode"><code class="code">sp</code> request, and no-space mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Spacing">Manipulating Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sp-request_002c-causing-implicit-break"><code class="code">sp</code> request, causing implicit break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-space-between-sentences">space between sentences</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-space-between-sentences-register-_0028_002esss_0029">space between sentences register (<code class="code">.sss</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-space-between-words-register-_0028_002ess_0029">space between words register (<code class="code">.ss</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-space-character_002c-as-delimiter">space character, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-space-characters_002c-in-expressions">space characters, in expressions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-space_002c-between-sentences">space, between sentences</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-space_002c-between-words">space, between words</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-space_002c-discardable_002c-horizontal">space, discardable, horizontal</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-space_002c-hair-_0028_005c_005e_0029">space, hair (<code class="code">\^</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-space_002c-horizontal-_0028_005ch_0029">space, horizontal (<code class="code">\h</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-space_002c-horizontal_002c-unformatting">space, horizontal, unformatting</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Punning-Names">Punning Names</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-space_002c-thin-_0028_005c_007c_0029">space, thin (<code class="code">\|</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-space_002c-unbreakable-_0028_005c_007e_0029">space, unbreakable (<code class="code">\~</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-space_002c-unbreakable-and-unadjustable-_0028_005cSP_0029">space, unbreakable and unadjustable (<code class="code">\<kbd class="key">SP</kbd></code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-space_002c-vertical_002c-unit-_0028v_0029">space, vertical, unit (<code class="code">v</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-space_002c-width-of-a-digit-_0028numeral_0029-_0028_005c0_0029">space, width of a digit (numeral) (<code class="code">\0</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-spaces-with-ds">spaces with <code class="code">ds</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-spaces_002c-in-a-macro-argument">spaces, in a macro argument</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Calling-Macros">Calling Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-spaces_002c-leading-and-trailing">spaces, leading and trailing</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Breaking">Breaking</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-spacing-_0028introduction_0029">spacing (introduction)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Basics">Basics</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-spacing_002c-manipulating">spacing, manipulating</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Spacing">Manipulating Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-spacing_002c-vertical">spacing, vertical</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-spacing_002c-vertical-1">spacing, vertical</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Type-Size-and-Vertical-Spacing">Manipulating Type Size and Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-spacing_002c-vertical-_0028introduction_0029">spacing, vertical (introduction)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Basics">Basics</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-special-characters">special characters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Sentences">Sentences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-special-characters-1">special characters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-special-characters-_005bms_005d">special characters [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-special-characters_002c-list-of-_0028groff_005fchar_00287_0029-man-page_0029">special characters, list of (<cite class="cite">groff_char<span class="r">(7)</span></cite> man page)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-special-font">special font</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-special-fonts">special fonts</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-special-fonts-1">special fonts</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Special-Fonts">Special Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-special-fonts-2">special fonts</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-special-fonts_002c-emboldening">special fonts, emboldening</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-special-request_002c-and-font-translations"><code class="code">special</code> request, and font translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-special-request_002c-and-glyph-search-order"><code class="code">special</code> request, and glyph search order</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-spline_002c-drawing-_0028_005cD_0027_007e-_2026_0027_0029">spline, drawing (&lsquo;<samp class="samp">\D'~ &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-springing-a-trap">springing a trap</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Traps">Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sqrtex-glyph_002c-and-cflags"><code class="code">sqrtex</code> glyph, and <code class="code">cflags</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ss-request_002c-incompatibilities-with-AT_0026T-troff"><code class="code">ss</code> request, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-stack">stack</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-stacking-glyphs-_0028_005cb_0029">stacking glyphs (<code class="code">\b</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-standard-input_002c-reading-from-_0028rd_0029">standard input, reading from (<code class="code">rd</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-stderr_002c-printing-to-_0028tm_002c-tm1_002c-tmc_0029">stderr, printing to (<code class="code">tm</code>, <code class="code">tm1</code>, <code class="code">tmc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-stops_002c-tab">stops, tab</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Leaders">Tabs and Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-string-arguments">string arguments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-string-comparison">string comparison</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Operators-in-Conditionals">Operators in Conditionals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-string-expansion-_0028_005c_002a_0029">string expansion (<code class="code">\*</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-string-interpolation-_0028_005c_002a_0029">string interpolation (<code class="code">\*</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-string_002c-appending-_0028as_0029">string, appending (<code class="code">as</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-string_002c-creating-alias-for-_0028als_0029">string, creating alias for (<code class="code">als</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-string_002c-length-of-_0028length_0029">string, length of (<code class="code">length</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-string_002c-removing-_0028rm_0029">string, removing (<code class="code">rm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-string_002c-removing-alias-for-_0028rm_0029">string, removing alias for (<code class="code">rm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-string_002c-renaming-_0028rn_0029">string, renaming (<code class="code">rn</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-strings">strings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-strings-_005bms_005d">strings [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Legacy-Features">ms Legacy Features</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-strings_002c-multi_002dline">strings, multi-line</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-strings_002c-shared-name-space-with-macros-and-diversions">strings, shared name space with macros and diversions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-stripping-final-newline-in-diversions">stripping final newline in diversions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Punning-Names">Punning Names</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-stroke-color">stroke color</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-stroke-color-name-register-_0028_002em_0029">stroke color name register (<code class="code">.m</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-stroked-circle_002c-drawing-_0028_005cD_0027c-_2026_0027_0029">stroked circle, drawing (&lsquo;<samp class="samp">\D'c &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-stroked-ellipse_002c-drawing-_0028_005cD_0027e-_2026_0027_0029">stroked ellipse, drawing (&lsquo;<samp class="samp">\D'e &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-stroked-polygon_002c-drawing-_0028_005cD_0027p-_2026_0027_0029">stroked polygon, drawing (&lsquo;<samp class="samp">\D'p &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-structuring-source-code-of-documents-or-macro-packages">structuring source code of documents or macro packages</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-Requests">Invoking Requests</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sty-request_002c-and-changing-fonts"><code class="code">sty</code> request, and changing fonts</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sty-request_002c-and-font-translations"><code class="code">sty</code> request, and font translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-style_002c-font">style, font</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-style_002c-font_002c-abstract">style, font, abstract</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-style_002c-font_002c-abstract_002c-setting-up-_0028sty_0029">style, font, abstract, setting up (<code class="code">sty</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-styles_002c-font">styles, font</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-substring-_0028substring_0029">substring (<code class="code">substring</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-subtraction">subtraction</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-suppressing-output-_0028_005cO_0029">suppressing output (<code class="code">\O</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Suppressing-Output">Suppressing Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-suppression-nesting-level-register">suppression nesting level register</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Suppressing-Output">Suppressing Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sv-request_002c-and-no_002dspace-mode"><code class="code">sv</code> request, and no-space mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-switching-environments-_0028ev_0029">switching environments (<code class="code">ev</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sy-request_002c-and-safer-mode"><code class="code">sy</code> request, and safer mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-sy-request_002c-disabled-by-default"><code class="code">sy</code> request, disabled by default</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Safer-Mode">Safer Mode</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-symbol">symbol</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-symbol-table_002c-dumping-_0028pm_0029">symbol table, dumping (<code class="code">pm</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-symbol_002c-defining-_0028char_0029">symbol, defining (<code class="code">char</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-symbols_002c-using">symbols, using</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-system-commands_002c-running">system commands, running</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-system_0028_0029-return-value-register-_0028systat_0029"><code class="code">system()</code> return value register (<code class="code">systat</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-T">T</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tab-character">tab character</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Leaders">Tabs and Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tab-character-encoding">tab character encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tab-character_002c-and-translations">tab character, and translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tab-character_002c-as-delimiter">tab character, as delimiter</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Delimiters">Delimiters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tab-character_002c-non_002dinterpreted-_0028_005ct_0029">tab character, non-interpreted (<code class="code">\t</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tab-repetition-character-_0028tc_0029">tab repetition character (<code class="code">tc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tab-stop-settings-register-_0028_002etabs_0029">tab stop settings register (<code class="code">.tabs</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tab-stops">tab stops</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Leaders">Tabs and Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tab-stops_002c-default">tab stops, default</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tab_002c-line_002dtabs-mode">tab, line-tabs mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-table-of-contents">table of contents</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Table-of-Contents">Table of Contents</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-table-of-contents-1">table of contents</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leaders">Leaders</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-table-of-contents_002c-creating-_005bms_005d">table of contents, creating [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-TOC">ms TOC</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-table_002c-multi_002dpage_002c-example-_005bms_005d">table, multi-page, example [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tables-_005bms_005d">tables [<samp class="file">ms</samp>]</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#ms-Insertions">ms Insertions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tabs_002c-and-fields">tabs, and fields</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tabs-and-Fields">Tabs and Fields</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tabs_002c-and-macro-arguments">tabs, and macro arguments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-Requests">Invoking Requests</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tabs_002c-and-request-arguments">tabs, and request arguments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Invoking-Requests">Invoking Requests</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tabs_002c-before-comments">tabs, before comments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Comments">Comments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tagged-paragraphs">tagged paragraphs</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paragraphs">Paragraphs</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tags_002c-paragraph">tags, paragraph</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Paragraphs">Paragraphs</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-terminal_002c-conditional-output-for">terminal, conditional output for</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Operators-in-Conditionals">Operators in Conditionals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-text-baseline">text baseline</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-text-baseline-1">text baseline</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Type-Size-and-Vertical-Spacing">Manipulating Type Size and Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-text-font">text font</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-text-line">text line</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Requests-and-Macros">Requests and Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-text-line_002c-position-of-lowest-_0028_002eh_0029">text line, position of lowest (<code class="code">.h</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-text_002c-GNU-troff-processing">text, GNU <code class="code">troff</code> processing</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Text">Text</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-text_002c-justifying">text, justifying</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-text_002c-justifying-_0028rj_0029">text, justifying (<code class="code">rj</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-thickness-of-lines-_0028_005cD_0027t-_2026_0027_0029">thickness of lines (&lsquo;<samp class="samp">\D't &hellip;'</samp>&rsquo;)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-thin-space-_0028_005c_007c_0029">thin space (<code class="code">\|</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-three_002dpart-title-_0028tl_0029">three-part title (<code class="code">tl</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ti-request_002c-causing-implicit-break"><code class="code">ti</code> request, causing implicit break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ti-request_002c-using-_002b-and-_002d-with"><code class="code">ti</code> request, using <code class="code">+</code> and&nbsp;<code class="code">-</code> with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-time_002c-current_002c-hours-_0028hours_0029">time, current, hours (<code class="code">hours</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-time_002c-current_002c-minutes-_0028minutes_0029">time, current, minutes (<code class="code">minutes</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-time_002c-current_002c-seconds-_0028seconds_0029">time, current, seconds (<code class="code">seconds</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-time_002c-formatting">time, formatting</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-title-length_002c-configuring-_0028lt_0029">title length, configuring (<code class="code">lt</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-title-line-length-register-_0028_002elt_0029">title line length register (<code class="code">.lt</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-title-line_002c-formatting-_0028tl_0029">title line, formatting (<code class="code">tl</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-titles">titles</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Layout">Page Layout</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tkf-request_002c-and-font-styles"><code class="code">tkf</code> request, and font styles</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tkf-request_002c-and-font-translations"><code class="code">tkf</code> request, and font translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tkf-request_002c-with-fractional-type-sizes"><code class="code">tkf</code> request, with fractional type sizes</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tl-request_002c-and-mc"><code class="code">tl</code> request, and <code class="code">mc</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Miscellaneous">Miscellaneous</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tmac_002c-directory">tmac, directory</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tmac_002c-path">tmac, path</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-TMPDIR_002c-environment-variable"><code>TMPDIR<span class="r">, environment variable</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environment">Environment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-token_002c-input">token, input</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Gtroff-Internals">Gtroff Internals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-top-margin">top margin</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-top_002dlevel-diversion">top-level diversion</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-top_002dlevel-diversion_002c-and-bp">top-level diversion, and <code class="code">bp</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-top_002dlevel-diversion_002c-and-_005c_0021">top-level diversion, and <code class="code">\!</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-top_002dlevel-diversion_002c-and-_005c_003f">top-level diversion, and <code class="code">\?</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tr-request_002c-and-glyph-definitions"><code class="code">tr</code> request, and glyph definitions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tr-request_002c-and-soft-hyphen-character"><code class="code">tr</code> request, and soft hyphen character</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tr-request_002c-incompatibilities-with-AT_0026T-troff"><code class="code">tr</code> request, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-track-kerning">track kerning</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-track-kerning_002c-activating-_0028tkf_0029">track kerning, activating (<code class="code">tkf</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Ligatures-and-Kerning">Ligatures and Kerning</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trailing-double-quotes-in-strings">trailing double quotes in strings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trailing-spaces-in-string-definitions-and-appendments">trailing spaces in string definitions and appendments</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trailing-spaces-on-text-lines">trailing spaces on text lines</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Breaking">Breaking</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-translations-of-characters">translations of characters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Character-Translations">Character Translations</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-transparent-characters">transparent characters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-transparent-dummy-character-_0028_005c_0029_0029">transparent dummy character (<code class="code">\)</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Dummy-Characters">Dummy Characters</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-transparent-output-_0028cf_002c-trf_0029">transparent output (<code class="code">cf</code>, <code class="code">trf</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-transparent-output-_0028_005c_0021_002c-_005c_003f_0029">transparent output (<code class="code">\!</code>, <code class="code">\?</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-transparent-output_002c-incompatibilities-with-AT_0026T-troff">transparent output, incompatibilities with <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trap">trap</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Deferring-Output">Deferring Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trap_002c-changing-location-_0028ch_0029">trap, changing location (<code class="code">ch</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trap_002c-distance-to-next-vertical-position_002c-register-_0028_002et_0029">trap, distance to next vertical position, register (<code class="code">.t</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trap_002c-diversion_002c-setting-_0028dt_0029">trap, diversion, setting (<code class="code">dt</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversion-Traps">Diversion Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trap_002c-end_002dof_002dinput_002c-setting-_0028em_0029">trap, end-of-input, setting (<code class="code">em</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#End_002dof_002dinput-Traps">End-of-input Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trap_002c-implicit">trap, implicit</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#The-Implicit-Page-Trap">The Implicit Page Trap</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trap_002c-input-line_002c-clearing-_0028it_002c-itc_0029">trap, input line, clearing (<code class="code">it</code>, <code class="code">itc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Line-Traps">Input Line Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trap_002c-input-line_002c-setting-_0028it_002c-itc_0029">trap, input line, setting (<code class="code">it</code>, <code class="code">itc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Line-Traps">Input Line Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trap_002c-planting">trap, planting</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Traps">Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trap_002c-springing">trap, springing</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Traps">Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-traps">traps</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Traps">Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-traps_002c-and-diversions">traps, and diversions</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-traps_002c-blank-line">traps, blank line</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Blank-Line-Traps">Blank Line Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-traps_002c-diversion">traps, diversion</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversion-Traps">Diversion Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-traps_002c-end_002dof_002dinput">traps, end-of-input</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#End_002dof_002dinput-Traps">End-of-input Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-traps_002c-input-line">traps, input line</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Line-Traps">Input Line Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-traps_002c-input-line_002c-and-interrupted-lines-_0028itc_0029">traps, input line, and interrupted lines (<code class="code">itc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Input-Line-Traps">Input Line Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-traps_002c-leading-space">traps, leading space</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Leading-Space-Traps">Leading Space Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-traps_002c-page-location">traps, page location</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-traps_002c-page-location_002c-dumping-_0028ptr_0029">traps, page location, dumping (<code class="code">ptr</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-traps_002c-page-location_002c-listing-_0028ptr_0029">traps, page location, listing (<code class="code">ptr</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-traps_002c-sprung-by-bp-request-_0028_002epe_0029">traps, sprung by <code class="code">bp</code> request (<code class="code">.pe</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-traps_002c-vertical-position">traps, vertical position</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Vertical-Position-Traps">Vertical Position Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trf-request_002c-and-copy-mode"><code class="code">trf</code> request, and copy mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trf-request_002c-and-invalid-characters"><code class="code">trf</code> request, and invalid characters</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trf-request_002c-causing-implicit-break"><code class="code">trf</code> request, causing implicit break</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-trin-request_002c-and-asciify"><code class="code">trin</code> request, and <code class="code">asciify</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-troff-mode"><code class="code">troff</code> mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#troff-and-nroff-Modes"><code class="code">troff</code> and <code class="code">nroff</code> Modes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-troff-output"><code class="code">troff</code> output</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#gtroff-Output">gtroff Output</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-truncated-vertical-space-register-_0028_002etrunc_0029">truncated vertical space register (<code class="code">.trunc</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Location-Traps">Page Location Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-truncating-division">truncating division</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-TTY_002c-conditional-output-for">TTY, conditional output for</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Operators-in-Conditionals">Operators in Conditionals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-tutorial-for-macro-users">tutorial for macro users</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tutorial-for-Macro-Users">Tutorial for Macro Users</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-type-size">type size</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Type-Size-and-Vertical-Spacing">Manipulating Type Size and Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-type-size-registers-_0028_002es_002c-_002eps_0029">type size registers (<code class="code">.s</code>, <code class="code">.ps</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Type-Size">Changing the Type Size</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-type-size-registers_002c-last_002drequested-_0028_002epsr_002c-_002esr_0029">type size registers, last-requested (<code class="code">.psr</code>, <code class="code">.sr</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-type-sizes_002c-changing-_0028ps_002c-_005cs_0029">type sizes, changing (<code class="code">ps</code>, <code class="code">\s</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Type-Size">Changing the Type Size</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-type-sizes_002c-fractional">type sizes, fractional</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-type-sizes_002c-fractional-1">type sizes, fractional</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Other-Differences">Other Differences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-typeface">typeface</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-TZ_002c-environment-variable"><code>TZ<span class="r">, environment variable</span></code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environment">Environment</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-U">U</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-u-scaling-unit"><code class="code">u</code> scaling unit</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-uf-request_002c-and-font-styles"><code class="code">uf</code> request, and font styles</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Families">Font Families</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ul-glyph_002c-and-cflags"><code class="code">ul</code> glyph, and <code class="code">cflags</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-ul-request_002c-and-font-translations"><code class="code">ul</code> request, and font translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-Ultrix_002dspecific-man-macros">Ultrix-specific <code class="code">man</code> macros</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Optional-man-extensions">Optional man extensions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unadjustable-and-unbreakable-space-_0028_005cSP_0029">unadjustable and unbreakable space (<code class="code">\<kbd class="key">SP</kbd></code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unary-arithmetic-operators">unary arithmetic operators</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unbreakable-and-unadjustable-space-_0028_005cSP_0029">unbreakable and unadjustable space (<code class="code">\<kbd class="key">SP</kbd></code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unbreakable-space-_0028_005c_007e_0029">unbreakable space (<code class="code">\~</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-undefined-identifiers">undefined identifiers</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-undefined-request">undefined request</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Comments">Comments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-underline-font-_0028uf_0029">underline font (<code class="code">uf</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-underlining-_0028ul_0029">underlining (<code class="code">ul</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-underlining_002c-continuous-_0028cu_0029">underlining, continuous (<code class="code">cu</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Artificial-Fonts">Artificial Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unformatting-diversions-_0028asciify_0029">unformatting diversions (<code class="code">asciify</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unformatting-horizontal-space">unformatting horizontal space</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Punning-Names">Punning Names</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-Unicode">Unicode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Identifiers">Identifiers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-Unicode-1">Unicode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unit_002c-scaling_002c-c">unit, scaling, <code class="code">c</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unit_002c-scaling_002c-f">unit, scaling, <code class="code">f</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Colors">Colors</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unit_002c-scaling_002c-i">unit, scaling, <code class="code">i</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unit_002c-scaling_002c-m">unit, scaling, <code class="code">m</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unit_002c-scaling_002c-M">unit, scaling, <code class="code">M</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unit_002c-scaling_002c-n">unit, scaling, <code class="code">n</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unit_002c-scaling_002c-p">unit, scaling, <code class="code">p</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unit_002c-scaling_002c-P">unit, scaling, <code class="code">P</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unit_002c-scaling_002c-s">unit, scaling, <code class="code">s</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unit_002c-scaling_002c-u">unit, scaling, <code class="code">u</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unit_002c-scaling_002c-v">unit, scaling, <code class="code">v</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unit_002c-scaling_002c-z">unit, scaling, <code class="code">z</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-units-of-measurement">units of measurement</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-units_002c-basic">units, basic</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-units_002c-basic_002c-conversion-to">units, basic, conversion to</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-units_002c-default">units, default</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Default-Units">Default Units</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-units_002c-machine">units, machine</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unnamed-glyphs">unnamed glyphs</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unnamed-glyphs_002c-accessing-with-_005cN">unnamed glyphs, accessing with <code class="code">\N</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Font-Description-File-Format">Font Description File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unsafe-mode">unsafe mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unsafe-mode-1">unsafe mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Macro-Directories">Macro Directories</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unsafe-mode-2">unsafe mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unsafe-mode-3">unsafe mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unsafe-mode-4">unsafe mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unsafe-mode-5">unsafe mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unsafe-mode-6">unsafe mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unstyled-font">unstyled font</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fonts">Using Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-up_002dcasing-a-string-_0028stringup_0029">up-casing a string (<code class="code">stringup</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-uppercasing-a-string-_0028stringup_0029">uppercasing a string (<code class="code">stringup</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Strings">Strings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-upright-glyph_002c-correction-after-oblique-glyph-_0028_005c_002f_0029">upright glyph, correction after oblique glyph (<code class="code">\/</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Italic-Corrections">Italic Corrections</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-upright-glyph_002c-correction-before-oblique-glyph-_0028_005c_002c_0029">upright glyph, correction before oblique glyph (<code class="code">\,</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Italic-Corrections">Italic Corrections</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-URLs_002c-breaking-_0028_005c_003a_0029">URLs, breaking (<code class="code">\:</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Hyphenation">Manipulating Hyphenation</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-user_0027s-macro-tutorial">user&rsquo;s macro tutorial</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tutorial-for-Macro-Users">Tutorial for Macro Users</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-user_0027s-tutorial-for-macros">user&rsquo;s tutorial for macros</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Tutorial-for-Macro-Users">Tutorial for Macro Users</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-using-escape-sequences">using escape sequences</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Escape-Sequences">Using Escape Sequences</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-using-symbols">using symbols</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Symbols">Using Symbols</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-UTF_002d8-output-encoding"><span class="w-nolinebreak-text">UTF-8</span><!-- /@w --> output encoding</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Groff-Options">Groff Options</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-V">V</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-v-scaling-unit"><code class="code">v</code> scaling unit</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-valid-numeric-expression">valid numeric expression</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-value_002c-incrementing-without-changing-the-register">value, incrementing without changing the register</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Auto_002dincrement">Auto-increment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-variables-in-environment">variables in environment</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environment">Environment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vee">vee</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vee-scaling-unit-_0028v_0029">vee scaling unit (<code class="code">v</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-version-number_002c-major_002c-register-_0028_002ex_0029">version number, major, register (<code class="code">.x</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-version-number_002c-minor_002c-register-_0028_002ey_0029">version number, minor, register (<code class="code">.y</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-drawing-position-_0028nl_0029">vertical drawing position (<code class="code">nl</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-line-drawing-_0028_005cL_0029">vertical line drawing (<code class="code">\L</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-line-spacing-register-_0028_002ev_0029">vertical line spacing register (<code class="code">.v</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-line-spacing_002c-changing-_0028vs_0029">vertical line spacing, changing (<code class="code">vs</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-line-spacing_002c-effective-value">vertical line spacing, effective value</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Changing-the-Vertical-Spacing">Changing the Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-motion-_0028_005cv_0029">vertical motion (<code class="code">\v</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-motion-quantum">vertical motion quantum</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-page-location_002c-marking-_0028mk_0029">vertical page location, marking (<code class="code">mk</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-page-location_002c-returning-to-marked-_0028rt_0029">vertical page location, returning to marked (<code class="code">rt</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-position-in-diversion-register-_0028_002ed_0029">vertical position in diversion register (<code class="code">.d</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Diversions">Diversions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-position-trap-enable-register-_0028_002evpt_0029">vertical position trap enable register (<code class="code">.vpt</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Vertical-Position-Traps">Vertical Position Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-position-traps">vertical position traps</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Vertical-Position-Traps">Vertical Position Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-position-traps_002c-enabling-_0028vpt_0029">vertical position traps, enabling (<code class="code">vpt</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Vertical-Position-Traps">Vertical Position Traps</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-position_002c-drawing-_0028nl_0029">vertical position, drawing (<code class="code">nl</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-resolution">vertical resolution</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#DESC-File-Format">DESC File Format</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-space-unit-_0028v_0029">vertical space unit (<code class="code">v</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Measurements">Measurements</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-spacing">vertical spacing</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Geometry">Page Geometry</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-spacing-1">vertical spacing</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Type-Size-and-Vertical-Spacing">Manipulating Type Size and Vertical Spacing</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-vertical-spacing-_0028introduction_0029">vertical spacing (introduction)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Basics">Basics</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-W">W</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-warning-categories">warning categories</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-warning-level-_0028warn_0029">warning level (<code class="code">warn</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-warnings">warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Debugging">Debugging</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-warnings-1">warnings</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Warnings">Warnings</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-what-is-groff_003f">what is <code class="code">groff</code>?</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#What-Is-groff_003f">What Is <code class="code">groff</code>?</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-while">while</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#while">while</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-while-request_002c-and-font-translations"><code class="code">while</code> request, and font translations</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-while-request_002c-and-the-_0021-operator"><code class="code">while</code> request, and the &lsquo;<samp class="samp">!</samp>&rsquo; operator</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Numeric-Expressions">Numeric Expressions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-while-request_002c-confusing-with-br"><code class="code">while</code> request, confusing with <code class="code">br</code></a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#while">while</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-while-request_002c-operators-to-use-with"><code class="code">while</code> request, operators to use with</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Operators-in-Conditionals">Operators in Conditionals</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-widow">widow</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-widow-1">widow</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Control">Page Control</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-width-escape-_0028_005cw_0029">width escape (<code class="code">\w</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-width_002c-of-last-glyph-_0028_002ew_0029">width, of last glyph (<code class="code">.w</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Environments">Environments</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-word-space-size-register-_0028_002ess_0029">word space size register (<code class="code">.ss</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Manipulating-Filling-and-Adjustment">Manipulating Filling and Adjustment</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-word_002c-definition-of">word, definition of</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Filling">Filling</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-write-request_002c-and-copy-mode"><code class="code">write</code> request, and copy mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-writec-request_002c-and-copy-mode"><code class="code">writec</code> request, and copy mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-writem-request_002c-and-copy-mode"><code class="code">writem</code> request, and copy mode</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-writing-macros">writing macros</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Writing-Macros">Writing Macros</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-writing-to-file-_0028write_002c-writec_0029">writing to file (<code class="code">write</code>, <code class="code">writec</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#I_002fO">I/O</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-Y">Y</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-year_002c-current_002c-register-_0028year_002c-yr_0029">year, current, register (<code class="code">year</code>, <code class="code">yr</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Built_002din-Registers">Built-in Registers</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th id="Concept-Index_cp_letter-Z">Z</th><td></td><td></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-z-scaling-unit"><code class="code">z</code> scaling unit</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Using-Fractional-Type-Sizes">Using Fractional Type Sizes</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-zero_002dwidth-printing-_0028_005cz_002c-_005cZ_0029">zero-width printing (<code class="code">\z</code>, <code class="code">\Z</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-zero_002dwidth-printing-_0028_005cz_002c-_005cZ_0029-1">zero-width printing (<code class="code">\z</code>, <code class="code">\Z</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Page-Motions">Page Motions</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-zoom-factor-of-a-font-_0028fzoom_0029">zoom factor of a font (<code class="code">fzoom</code>)</a>:</td><td>&nbsp;</td><td class="printindex-index-section"><a href="#Selecting-Fonts">Selecting Fonts</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
</table>
<table class="cp-letters-footer-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-1"><b>&quot;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-2"><b>%</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-3"><b>&amp;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-4"><b>'</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-5"><b>(</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-6"><b>)</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-7"><b>*</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-8"><b>+</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-9"><b>-</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-10"><b>.</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-11"><b>/</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-12"><b>8</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-13"><b>:</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-14"><b>&lt;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-15"><b>=</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-16"><b>&gt;</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-17"><b>[</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-18"><b>\</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-19"><b>]</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_symbol-20"><b>|</b></a>
 &nbsp; 
<br>
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-A"><b>A</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-B"><b>B</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-C"><b>C</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-D"><b>D</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-E"><b>E</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-G"><b>G</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-H"><b>H</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-I"><b>I</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-J"><b>J</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-K"><b>K</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-L"><b>L</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-M"><b>M</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-N"><b>N</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-O"><b>O</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-P"><b>P</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-Q"><b>Q</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-R"><b>R</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-S"><b>S</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-T"><b>T</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-U"><b>U</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-V"><b>V</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-W"><b>W</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-Y"><b>Y</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-Z"><b>Z</b></a>
 &nbsp; 
</td></tr></table>
</div>


<hr>
</div>
</div>
<div class="element-footnotes" id="SEC_Footnotes">
<div class="nav-panel">
<p>
 &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Request-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="footnotes-heading">Footnotes</h4>

<h5 class="footnote-body-heading"><a id="FOOT1" href="#DOCF1">(1)</a></h5>
<p>The &lsquo;<samp class="samp">g</samp>&rsquo; prefix is
not used on all systems; see <a class="ref" href="#Invoking-groff">Invoking <code class="code">groff</code></a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT2" href="#DOCF2">(2)</a></h5>
<p>Unix and related operating systems distinguish
standard output and standard error streams <em class="emph">because</em> of
<code class="code">troff</code>:
<a class="uref" href="https://minnie.tuhs.org/pipermail/tuhs/2013-December/006113.html">https://minnie.tuhs.org/pipermail/tuhs/2013-December/006113.html</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT3" href="#DOCF3">(3)</a></h5>
<p>See <a class="xref" href="#Line-Layout">Line Layout</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT4" href="#DOCF4">(4)</a></h5>
<p>Besides <code class="code">groff</code>, <code class="code">neatroff</code> is an
exception.</p>
<h5 class="footnote-body-heading"><a id="FOOT5" href="#DOCF5">(5)</a></h5>
<p>The
<code class="code">mso</code> request does not have these limitations.  See <a class="xref" href="#I_002fO">I/O</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT6" href="#DOCF6">(6)</a></h5>
<p>The remainder of this chapter is based on
<cite class="cite">Writing Papers with nroff using -me</cite> by Eric&nbsp;P. Allman,
which is distributed with <code class="code">groff</code> as <samp class="file">meintro.me</samp>.</p>
<h5 class="footnote-body-heading"><a id="FOOT7" href="#DOCF7">(7)</a></h5>
<p>While manual <em class="emph">pages</em> are older, early ones used
macros supplanted by the <samp class="file">man</samp> package of Seventh Edition Unix
(1979).  <samp class="file">ms</samp> shipped with Sixth Edition (1975) and was documented
by Mike Lesk in a Bell Labs internal memorandum.</p>
<h5 class="footnote-body-heading"><a id="FOOT8" href="#DOCF8">(8)</a></h5>
<p>defined in <a class="ref" href="#ms-Footnotes">Footnotes</a></p>
<h5 class="footnote-body-heading"><a id="FOOT9" href="#DOCF9">(9)</a></h5>
<p>Distinguish a
document title from &ldquo;titles&rdquo;, which are what <code class="code">roff</code> systems call
headers and footers collectively.</p>
<h5 class="footnote-body-heading"><a id="FOOT10" href="#DOCF10">(10)</a></h5>
<p>This idiosyncrasy arose through
feature accretion; for example, the <code class="code">B</code> macro in Version&nbsp;6
Unix <samp class="file">ms</samp> (1975) accepted only one argument, the text to be set in
boldface.  By Version&nbsp;7 (1979) it recognized a second argument; in
1990, <code class="code">groff</code> <samp class="file">ms</samp> added a &ldquo;pre&rdquo; argument, placing it third
to avoid breaking support for older documents.</p>
<h5 class="footnote-body-heading"><a id="FOOT11" href="#DOCF11">(11)</a></h5>
<p>&ldquo;Portable Document Format Publishing with GNU
Troff&rdquo;, <samp class="file">pdfmark.ms</samp> in the <code class="code">groff</code> distribution, uses this
technique.</p>
<h5 class="footnote-body-heading"><a id="FOOT12" href="#DOCF12">(12)</a></h5>
<p>Unix Version&nbsp;7 <samp class="file">ms</samp>, its descendants, and GNU
<samp class="file">ms</samp> prior to <code class="code">groff</code> version 1.23.0</p>
<h5 class="footnote-body-heading"><a id="FOOT13" href="#DOCF13">(13)</a></h5>
<p>You could reset it
after each call to <code class="code">.1C</code>, <code class="code">.2C</code>, or <code class="code">.MC</code>.</p>
<h5 class="footnote-body-heading"><a id="FOOT14" href="#DOCF14">(14)</a></h5>
<p><cite class="cite">Typing Documents on the UNIX System: Using the
-ms Macros with Troff and Nroff</cite>, M.&nbsp;E. Lesk, Bell Laboratories,
1978</p>
<h5 class="footnote-body-heading"><a id="FOOT15" href="#DOCF15">(15)</a></h5>
<p>Register values are converted to and stored as
basic units.  See <a class="xref" href="#Measurements">Measurements</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT16" href="#DOCF16">(16)</a></h5>
<p>If you redefine the <samp class="file">ms</samp> <code class="code">PT</code> macro
and desire special treatment of certain page numbers (like &lsquo;<samp class="samp">1</samp>&rsquo;),
you may need to handle a non-Arabic page number format, as <code class="code">groff</code>
<samp class="file">ms</samp>&rsquo;s <code class="code">PT</code> does; see the macro package source.  <code class="code">groff</code>
<samp class="file">ms</samp> aliases the <code class="code">PN</code> register to <code class="code">%</code>.</p>
<h5 class="footnote-body-heading"><a id="FOOT17" href="#DOCF17">(17)</a></h5>
<p>The removal beforehand is necessary
because <code class="code">groff</code> <samp class="file">ms</samp> aliases these macros to a diagnostic
macro, and you want to redefine the aliased name, not its target.</p>
<h5 class="footnote-body-heading"><a id="FOOT18" href="#DOCF18">(18)</a></h5>
<p>See <a class="xref" href="#Device-and-Font-Description-Files">Device and Font Description Files</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT19" href="#DOCF19">(19)</a></h5>
<p><i class="slanted">Tabs</i> and <i class="slanted">leaders</i> also separate
words.  <i class="slanted">Escape sequences</i> can function as word characters, word
separators, or neither&mdash;the last simply have no effect on GNU
<code class="code">troff</code>&rsquo;s idea of whether an input character is within a word.
We&rsquo;ll discuss all of these in due course.</p>
<h5 class="footnote-body-heading"><a id="FOOT20" href="#DOCF20">(20)</a></h5>
<p>A
well-researched jeremiad appreciated by <code class="code">groff</code> contributors on
both sides of the sentence-spacing debate can be found at
<a class="uref" href="https://web.archive.org/web/20171217060354/http://www.heracliteanriver.com/?p=324">https://web.archive.org/web/20171217060354/http://www.heracliteanriver.com/?p=324</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT21" href="#DOCF21">(21)</a></h5>
<p>This statement oversimplifies; there are
escape sequences whose purpose is precisely to produce glyphs on the
output device, and input characters that <em class="emph">aren&rsquo;t</em> part of escape
sequences can undergo a great deal of processing before getting to the
output.</p>
<h5 class="footnote-body-heading"><a id="FOOT22" href="#DOCF22">(22)</a></h5>
<p>The mnemonics for the special
characters shown here are &ldquo;dagger&rdquo;, &ldquo;double dagger&rdquo;, &ldquo;right
(double) quote&rdquo;, and &ldquo;closing (single) quote&rdquo;.  See the
<cite class="cite">groff_char<span class="r">(7)</span></cite> man page.</p>
<h5 class="footnote-body-heading"><a id="FOOT23" href="#DOCF23">(23)</a></h5>
<p>&ldquo;Text lines&rdquo; are defined in <a class="ref" href="#Requests-and-Macros">Requests and Macros</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT24" href="#DOCF24">(24)</a></h5>
<p>&ldquo;Tab&rdquo;
is short for &ldquo;tabulation&rdquo;, revealing the term&rsquo;s origin as a spacing
mechanism for table arrangement.</p>
<h5 class="footnote-body-heading"><a id="FOOT25" href="#DOCF25">(25)</a></h5>
<p>The <code class="code">\<kbd class="key">RET</kbd></code> escape sequence can alter how an
input line is classified; see <a class="ref" href="#Line-Continuation">Line Continuation</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT26" href="#DOCF26">(26)</a></h5>
<p>Argument handling in
macros is more flexible but also more complex.  See <a class="xref" href="#Calling-Macros">Calling Macros</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT27" href="#DOCF27">(27)</a></h5>
<p>Some escape sequences undergo
interpolation as well.</p>
<h5 class="footnote-body-heading"><a id="FOOT28" href="#DOCF28">(28)</a></h5>
<p>GNU <code class="code">troff</code> offers additional ones.  See <a class="xref" href="#Writing-Macros">Writing Macros</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT29" href="#DOCF29">(29)</a></h5>
<p>Macro files and packages
frequently define registers and strings as well.</p>
<h5 class="footnote-body-heading"><a id="FOOT30" href="#DOCF30">(30)</a></h5>
<p>The
<em class="emph">semantics</em> of certain punctuation code points have gotten stricter
with the successive standards, a cause of some frustration among man
page writers; see the <cite class="cite">groff_char<span class="r">(7)</span></cite> man page.</p>
<h5 class="footnote-body-heading"><a id="FOOT31" href="#DOCF31">(31)</a></h5>
<p>The
DVI output device defaults to using the Computer Modern (CM) fonts;
<samp class="file">ec.tmac</samp> loads the EC fonts instead, which provide Euro
&lsquo;<samp class="samp">\[Eu]</samp>&rsquo; and per mille &lsquo;<samp class="samp">\[%0]</samp>&rsquo; glyphs.</p>
<h5 class="footnote-body-heading"><a id="FOOT32" href="#DOCF32">(32)</a></h5>
<p>Emacs: <code class="code">fill-column: 72</code>; Vim: <code class="code">textwidth=72</code></p>
<h5 class="footnote-body-heading"><a id="FOOT33" href="#DOCF33">(33)</a></h5>
<p><code class="code">groff</code> does not yet support right-to-left
scripts.</p>
<h5 class="footnote-body-heading"><a id="FOOT34" href="#DOCF34">(34)</a></h5>
<p><code class="code">groff</code>&rsquo;s terminal output devices have page
offsets of zero.</p>
<h5 class="footnote-body-heading"><a id="FOOT35" href="#DOCF35">(35)</a></h5>
<p>Provision is made for interpreting and
reporting decimal fractions in certain cases.</p>
<h5 class="footnote-body-heading"><a id="FOOT36" href="#DOCF36">(36)</a></h5>
<p>If that&rsquo;s not enough, see the <cite class="cite">groff_tmac<span class="r">(5)</span></cite>
man page for the <samp class="file">62bit.tmac</samp> macro package.</p>
<h5 class="footnote-body-heading"><a id="FOOT37" href="#DOCF37">(37)</a></h5>
<p>See <a class="xref" href="#Conditionals-and-Loops">Conditionals and Loops</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT38" href="#DOCF38">(38)</a></h5>
<p>Control structure syntax
creates an exception to this rule, but is designed to remain useful:
recalling our example, &lsquo;<samp class="samp">.if 1 .Underline this</samp>&rsquo; would underline only
&ldquo;this&rdquo;, precisely.  See <a class="xref" href="#Conditionals-and-Loops">Conditionals and Loops</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT39" href="#DOCF39">(39)</a></h5>
<p>See <a class="xref" href="#Diversions">Diversions</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT40" href="#DOCF40">(40)</a></h5>
<p>Historically, control characters like
ASCII STX, ETX, and BEL (<kbd class="key">Control+B</kbd>, <kbd class="key">Control+C</kbd>, and
<kbd class="key">Control+G</kbd>) have been observed in <code class="code">roff</code> documents,
particularly in macro packages employing them as delimiters with the
output comparison operator to try to avoid collisions with the content
of arbitrary user-supplied parameters (see <a class="pxref" href="#Operators-in-Conditionals">Operators in Conditionals</a>).  We discourage this expedient; in GNU <code class="code">troff</code> it is
unnecessary (outside of compatibility mode) because delimited arguments
are parsed at a different input level than the surrounding context.
See <a class="xref" href="#Implementation-Differences">Implementation Differences</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT41" href="#DOCF41">(41)</a></h5>
<p>Consider what happens when a C1 control
<code class="code">0x80</code>&ndash;<code class="code">0x9F</code> is necessary as a continuation byte in a UTF-8
sequence.</p>
<h5 class="footnote-body-heading"><a id="FOOT42" href="#DOCF42">(42)</a></h5>
<p>Recall <a class="ref" href="#Identifiers">Identifiers</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT43" href="#DOCF43">(43)</a></h5>
<p>In compatibility
mode, a space is not necessary after a request or macro name of two
characters&rsquo; length.  Also, Plan&nbsp;9 <code class="code">troff</code> allows tabs to
separate arguments.</p>
<h5 class="footnote-body-heading"><a id="FOOT44" href="#DOCF44">(44)</a></h5>
<p><code class="code">\~</code> is fairly
portable; see <a class="ref" href="#Other-Differences">Other Differences</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT45" href="#DOCF45">(45)</a></h5>
<p>Strictly, you can neglect to
close the last quoted macro argument, relying on the end of the control
line to do so.   We consider this lethargic practice poor style.</p>
<h5 class="footnote-body-heading"><a id="FOOT46" href="#DOCF46">(46)</a></h5>
<p>The omission of spaces before the comment
escape sequences is necessary; see <a class="ref" href="#Strings">Strings</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT47" href="#DOCF47">(47)</a></h5>
<p>TeX does have such a mechanism.</p>
<h5 class="footnote-body-heading"><a id="FOOT48" href="#DOCF48">(48)</a></h5>
<p>This claim may be more aspirational than descriptive.</p>
<h5 class="footnote-body-heading"><a id="FOOT49" href="#DOCF49">(49)</a></h5>
<p>See <a class="xref" href="#Conditional-Blocks">Conditional Blocks</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT50" href="#DOCF50">(50)</a></h5>
<p>Exception: auto-incrementing registers defined outside
the ignored region <em class="emph">will</em> be modified if interpolated with
<code class="code">\n</code> inside it.  See <a class="xref" href="#Auto_002dincrement">Auto-increment</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT51" href="#DOCF51">(51)</a></h5>
<p>A negative auto-increment can be
considered an &ldquo;auto-decrement&rdquo;.</p>
<h5 class="footnote-body-heading"><a id="FOOT52" href="#DOCF52">(52)</a></h5>
<p>GNU <code class="code">troff</code> dynamically allocates memory for
as many registers as required.</p>
<h5 class="footnote-body-heading"><a id="FOOT53" href="#DOCF53">(53)</a></h5>
<p>unless diverted; see <a class="ref" href="#Diversions">Diversions</a></p>
<h5 class="footnote-body-heading"><a id="FOOT54" href="#DOCF54">(54)</a></h5>
<p>See <a class="xref" href="#Line-Continuation">Line Continuation</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT55" href="#DOCF55">(55)</a></h5>
<p>Recall <a class="ref" href="#Filling">Filling</a> and <a class="ref" href="#Sentences">Sentences</a> for the
definitions of word and sentence boundaries, respectively.</p>
<h5 class="footnote-body-heading"><a id="FOOT56" href="#DOCF56">(56)</a></h5>
<p>Whether a perfect algorithm for this application is
even possible is an unsolved problem in computer science:
<a class="url" href="https://tug.org/docs/liang/liang-thesis.pdf">https://tug.org/docs/liang/liang-thesis.pdf</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT57" href="#DOCF57">(57)</a></h5>
<p><code class="code">\%</code> itself stops marking
hyphenation points but still produces no output glyph.</p>
<h5 class="footnote-body-heading"><a id="FOOT58" href="#DOCF58">(58)</a></h5>
<p>&ldquo;Soft&rdquo; because it appears in output
only where a hyphenation break is performed; a &ldquo;hard&rdquo; hyphen, as in
&ldquo;long-term&rdquo;, always appears.</p>
<h5 class="footnote-body-heading"><a id="FOOT59" href="#DOCF59">(59)</a></h5>
<p>The mode is a vector of Booleans encoded as an integer.
To a programmer, this fact is easily deduced from the exclusive use of
powers of two for the configuration parameters; they are computationally
easy to &ldquo;mask off&rdquo; and compare to zero.  To almost everyone else, the
arrangement seems recondite and unfriendly.</p>
<h5 class="footnote-body-heading"><a id="FOOT60" href="#DOCF60">(60)</a></h5>
<p>Hyphenation is
prevented if the next page location trap is closer to the vertical
drawing position than the next text baseline would be.  See <a class="xref" href="#Page-Location-Traps">Page Location Traps</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT61" href="#DOCF61">(61)</a></h5>
<p>For more on localization, see the
<cite class="cite">groff_tmac<span class="r">(5)</span></cite> man page.</p>
<h5 class="footnote-body-heading"><a id="FOOT62" href="#DOCF62">(62)</a></h5>
<p>See <a class="xref" href="#Page-Location-Traps">Page Location Traps</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT63" href="#DOCF63">(63)</a></h5>
<p>See <a class="xref" href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT64" href="#DOCF64">(64)</a></h5>
<p>or geometric objects; see <a class="ref" href="#Drawing-Geometric-Objects">Drawing Geometric Objects</a></p>
<h5 class="footnote-body-heading"><a id="FOOT65" href="#DOCF65">(65)</a></h5>
<p>to the top-level diversion;
see <a class="ref" href="#Diversions">Diversions</a></p>
<h5 class="footnote-body-heading"><a id="FOOT66" href="#DOCF66">(66)</a></h5>
<p>Plan&nbsp;9 <code class="code">troff</code>
uses the register <code class="code">.S</code> for this purpose.</p>
<h5 class="footnote-body-heading"><a id="FOOT67" href="#DOCF67">(67)</a></h5>
<p>This is pronounced to rhyme with &ldquo;feeder&rdquo;, and
refers to how the glyphs &ldquo;lead&rdquo; the eye across the page to the
corresponding page number or other datum.</p>
<h5 class="footnote-body-heading"><a id="FOOT68" href="#DOCF68">(68)</a></h5>
<p>A
GNU <code class="command">nroff</code> program is available for convenience; it calls GNU
<code class="code">troff</code> to perform the formatting.</p>
<h5 class="footnote-body-heading"><a id="FOOT69" href="#DOCF69">(69)</a></h5>
<p>Historically, the <code class="code">\c</code>
escape sequence has proven challenging to characterize.  Some sources
say it &ldquo;connects the next input text&rdquo; (to the input line on which it
appears); others describe it as &ldquo;interrupting&rdquo; text, on the grounds
that a text line is interrupted without breaking, perhaps to inject a
request invocation or macro call.</p>
<h5 class="footnote-body-heading"><a id="FOOT70" href="#DOCF70">(70)</a></h5>
<p>See <a class="xref" href="#Traps">Traps</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT71" href="#DOCF71">(71)</a></h5>
<p>See <a class="xref" href="#Diversions">Diversions</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT72" href="#DOCF72">(72)</a></h5>
<p>Terminals and some output devices have fonts that render
at only one or two sizes.  As examples of the latter, take the
<code class="code">groff</code> <code class="code">lj4</code> device&rsquo;s Lineprinter, and <code class="code">lbp</code>&rsquo;s Courier
and Elite faces.</p>
<h5 class="footnote-body-heading"><a id="FOOT73" href="#DOCF73">(73)</a></h5>
<p>Font designers prepare families such that the styles
share esthetic properties.</p>
<h5 class="footnote-body-heading"><a id="FOOT74" href="#DOCF74">(74)</a></h5>
<p>Historically, the fonts
<code class="code">troff</code>s dealt with were not Free Software or, as with the Graphic
Systems C/A/T, did not even exist in the digital domain.</p>
<h5 class="footnote-body-heading"><a id="FOOT75" href="#DOCF75">(75)</a></h5>
<p>See <a class="xref" href="#Font-Description-File-Format">Font Description File Format</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT76" href="#DOCF76">(76)</a></h5>
<p>See <a class="xref" href="#DESC-File-Format"><samp class="file">DESC</samp> File Format</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT77" href="#DOCF77">(77)</a></h5>
<p>Not all versions of the <code class="code">man</code> program
support the <samp class="option">-T</samp> option; use the subsequent example for an
alternative.</p>
<h5 class="footnote-body-heading"><a id="FOOT78" href="#DOCF78">(78)</a></h5>
<p>This is &ldquo;Normalization Form D&rdquo;
as documented in Unicode Standard Annex #15
(<a class="uref" href="https://unicode.org/reports/tr15/">https://unicode.org/reports/tr15/</a>).</p>
<h5 class="footnote-body-heading"><a id="FOOT79" href="#DOCF79">(79)</a></h5>
<p>See <a class="xref" href="#Compatibility-Mode">Compatibility Mode</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT80" href="#DOCF80">(80)</a></h5>
<p>Output glyphs
don&rsquo;t&mdash;to GNU <code class="code">troff</code>, a glyph is simply a box with an index into
a font, a given height above and depth below the baseline, and a width.</p>
<h5 class="footnote-body-heading"><a id="FOOT81" href="#DOCF81">(81)</a></h5>
<p>Opinions of this escape sequence&rsquo;s name abound.
&ldquo;Zero-width space&rdquo; is a popular misnomer: <code class="code">roff</code> formatters do
not treat it like a space.  Ossanna called it a &ldquo;non-printing,
zero-width character&rdquo;, but the character causes <em class="emph">output</em> even
though it does not &ldquo;print&rdquo;.  If no output line is pending, the dummy
character starts one.  Contrast an empty input document with one
containing only <code class="code">\&amp;</code>.  The former produces no output; the latter, a
blank page.</p>
<h5 class="footnote-body-heading"><a id="FOOT82" href="#DOCF82">(82)</a></h5>
<p>In text fonts, the tallest glyphs are typically
parentheses.  Unfortunately, in many cases the actual dimensions of the
glyphs in a font do not closely match its declared type size!  For
example, in the standard PostScript font families, 10-point Times sets
better with 9-point Helvetica and 11-point Courier than if all three
were used at 10&nbsp;points.</p>
<h5 class="footnote-body-heading"><a id="FOOT83" href="#DOCF83">(83)</a></h5>
<p>Rhyme with &ldquo;sledding&rdquo;; mechanical typography
used lead metal (Latin <em class="emph">plumbum</em>).</p>
<h5 class="footnote-body-heading"><a id="FOOT84" href="#DOCF84">(84)</a></h5>
<p>The claim appears to have been true of Ossanna
<code class="code">troff</code> for the C/A/T device; Kernighan made device-independent
<code class="code">troff</code> more flexible.</p>
<h5 class="footnote-body-heading"><a id="FOOT85" href="#DOCF85">(85)</a></h5>
<p>See <a class="xref" href="#Device-and-Font-Description-Files">Device and Font Description Files</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT86" href="#DOCF86">(86)</a></h5>
<p>also
known vulgarly as &ldquo;ANSI colors&rdquo;</p>
<h5 class="footnote-body-heading"><a id="FOOT87" href="#DOCF87">(87)</a></h5>
<p>See <a class="xref" href="#Copy-Mode">Copy Mode</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT88" href="#DOCF88">(88)</a></h5>
<p>This refers to
<code class="code">vtroff</code>, a translator that would convert the C/A/T output from
early-vintage <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code> to a form suitable for
Versatec and Benson-Varian plotters.</p>
<h5 class="footnote-body-heading"><a id="FOOT89" href="#DOCF89">(89)</a></h5>
<p>Strictly, letters not otherwise recognized <em class="emph">are</em> treated
as output comparison delimiters.  For portability, it is wise to avoid
using letters not in the list above; for example, Plan&nbsp;9
<code class="code">troff</code> uses &lsquo;<samp class="samp">h</samp>&rsquo; to test a mode it calls <code class="code">htmlroff</code>, and
GNU <code class="code">troff</code> may provide additional operators in the future.</p>
<h5 class="footnote-body-heading"><a id="FOOT90" href="#DOCF90">(90)</a></h5>
<p>Because formatting of the comparands takes place
in a dummy environment, vertical motions within them cannot spring
traps.</p>
<h5 class="footnote-body-heading"><a id="FOOT91" href="#DOCF91">(91)</a></h5>
<p>All
of this is to say that the lists of output nodes created by formatting
<var class="var">xxx</var> and <var class="var">yyy</var> must be identical.  See <a class="xref" href="#Gtroff-Internals"><code class="code">gtroff</code> Internals</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT92" href="#DOCF92">(92)</a></h5>
<p>This bizarre behavior maintains compatibility with
<abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>.</p>
<h5 class="footnote-body-heading"><a id="FOOT93" href="#DOCF93">(93)</a></h5>
<p>See <a class="xref" href="#while">while</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT94" href="#DOCF94">(94)</a></h5>
<p>See <a class="xref" href="#Copy-Mode">Copy Mode</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT95" href="#DOCF95">(95)</a></h5>
<p>unless you redefine it</p>
<h5 class="footnote-body-heading"><a id="FOOT96" href="#DOCF96">(96)</a></h5>
<p>&ldquo;somewhat less&rdquo; because
things other than macro calls can be on the input stack</p>
<h5 class="footnote-body-heading"><a id="FOOT97" href="#DOCF97">(97)</a></h5>
<p>See <a class="xref" href="#Copy-Mode">Copy Mode</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT98" href="#DOCF98">(98)</a></h5>
<p>While it is possible to define and
call a macro &lsquo;<samp class="samp">.</samp>&rsquo;, you can&rsquo;t use it as an end macro: during a macro
definition, &lsquo;<samp class="samp">..</samp>&rsquo; is never handled as calling &lsquo;<samp class="samp">.</samp>&rsquo;, even if
&lsquo;<samp class="samp">.de <var class="var">name</var> .</samp>&rsquo; explicitly precedes it.</p>
<h5 class="footnote-body-heading"><a id="FOOT99" href="#DOCF99">(99)</a></h5>
<p>Its structure is
adapted from, and isomorphic to, part of a solution by Tadziu Hoffman to
the problem of reflowing text multiple times to find an optimal
configuration for it.
<a class="uref" href="https://lists.gnu.org/archive/html/groff/2008-12/msg00006.html">https://lists.gnu.org/archive/html/groff/2008-12/msg00006.html</a></p>
<h5 class="footnote-body-heading"><a id="FOOT100" href="#DOCF100">(100)</a></h5>
<p>If they were not,
parameter interpolations would be similar to command-line
parameters&mdash;fixed for the entire duration of a <code class="code">roff</code> program&rsquo;s
run.  The advantage of interpolating <code class="code">\$</code> escape sequences even in
copy mode is that they can interpolate different contents from one call
to the next, like function parameters in a procedural language.  The
additional escape character is the price of this power.</p>
<h5 class="footnote-body-heading"><a id="FOOT101" href="#DOCF101">(101)</a></h5>
<p>Compare this to the <code class="code">\def</code> and <code class="code">\edef</code>
commands in TeX.</p>
<h5 class="footnote-body-heading"><a id="FOOT102" href="#DOCF102">(102)</a></h5>
<p>These are lightly adapted from the <code class="code">groff</code>
implementation of the <samp class="file">ms</samp> macros.</p>
<h5 class="footnote-body-heading"><a id="FOOT103" href="#DOCF103">(103)</a></h5>
<p>At the
<code class="code">grops</code> defaults of 10-point type on 12-point vertical spacing, the
difference between half a vee and half an em can be subtle: large
spacings like &lsquo;<samp class="samp">.vs .5i</samp>&rsquo; make it obvious.</p>
<h5 class="footnote-body-heading"><a id="FOOT104" href="#DOCF104">(104)</a></h5>
<p>See <a class="xref" href="#Strings">Strings</a>, for an explanation of the trailing
&lsquo;<samp class="samp">\&quot;</samp>&rsquo;.</p>
<h5 class="footnote-body-heading"><a id="FOOT105" href="#DOCF105">(105)</a></h5>
<p>(<var class="var">hc</var>, <var class="var">vc</var>) is adjusted to the point nearest
the perpendicular bisector of the arc&rsquo;s chord.</p>
<h5 class="footnote-body-heading"><a id="FOOT106" href="#DOCF106">(106)</a></h5>
<p>See <a class="xref" href="#The-Implicit-Page-Trap">The Implicit Page Trap</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT107" href="#DOCF107">(107)</a></h5>
<p>A trap planted at &lsquo;<samp class="samp">20i</samp>&rsquo; or
&lsquo;<samp class="samp">-30i</samp>&rsquo; will not be sprung on a page of length &lsquo;<samp class="samp">11i</samp>&rsquo;.</p>
<h5 class="footnote-body-heading"><a id="FOOT108" href="#DOCF108">(108)</a></h5>
<p>It may help to think of each trap location as
maintaining a queue; <code class="code">wh</code> operates on the head of the queue, and
<code class="code">ch</code> operates on its tail.  Only the trap at the head of the queue
is visible.</p>
<h5 class="footnote-body-heading"><a id="FOOT109" href="#DOCF109">(109)</a></h5>
<p>See <a class="xref" href="#Debugging">Debugging</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT110" href="#DOCF110">(110)</a></h5>
<p>See <a class="xref" href="#Diversions">Diversions</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT111" href="#DOCF111">(111)</a></h5>
<p>While processing an
end-of-input macro, the formatter assumes that the next page break must
be the last; it goes into &ldquo;sudden death overtime&rdquo;.</p>
<h5 class="footnote-body-heading"><a id="FOOT112" href="#DOCF112">(112)</a></h5>
<p>Another, taken by the <code class="code">groff</code> <code class="code">man</code> macros, is
to intercept <code class="code">ne</code> requests and wrap <code class="code">bp</code> ones.</p>
<h5 class="footnote-body-heading"><a id="FOOT113" href="#DOCF113">(113)</a></h5>
<p>Thus, the &ldquo;water&rdquo;
gets &ldquo;higher&rdquo; proceeding <em class="emph">down</em> the page.</p>
<h5 class="footnote-body-heading"><a id="FOOT114" href="#DOCF114">(114)</a></h5>
<p>The backslash is doubled.  See <a class="xref" href="#Copy-Mode">Copy Mode</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT115" href="#DOCF115">(115)</a></h5>
<p>that is, ISO&nbsp;646:1991-IRV or,
popularly, &ldquo;US-ASCII&rdquo;</p>
<h5 class="footnote-body-heading"><a id="FOOT116" href="#DOCF116">(116)</a></h5>
<p>They are bypassed because these parameters are not
rendered as glyphs in the output; instead, they remain abstract
characters&mdash;in a PDF bookmark or a URL, for example.</p>
<h5 class="footnote-body-heading"><a id="FOOT117" href="#DOCF117">(117)</a></h5>
<p>Recall <a class="ref" href="#Line-Layout">Line Layout</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT118" href="#DOCF118">(118)</a></h5>
<p>Historically,
tools named <code class="command">nrchbar</code> and <code class="command">changebar</code> were developed for
marking changes with margin characters and could be found in archives of
the <code class="code">comp.sources.unix</code> <abbr class="acronym">USENET</abbr> group.  Some proprietary
Unices also offer(ed) a <code class="command">diffmk</code> program.</p>
<h5 class="footnote-body-heading"><a id="FOOT119" href="#DOCF119">(119)</a></h5>
<p>Except the
escape sequences <code class="code">\f</code>, <code class="code">\F</code>, <code class="code">\H</code>, <code class="code">\m</code>, <code class="code">\M</code>,
<code class="code">\R</code>, <code class="code">\s</code>, and <code class="code">\S</code>, which are processed immediately if
not in copy mode.</p>
<h5 class="footnote-body-heading"><a id="FOOT120" href="#DOCF120">(120)</a></h5>
<p>The
Graphic Systems C/A/T phototypesetter (the original device target for
<abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>) supported only a few discrete type sizes
in the range 6&ndash;36 points, so Ossanna contrived a special case in the
parser to do what the user must have meant.  Kernighan warned of this in
the 1992 revision of CSTR&nbsp;#54 (2.3), and more recently, McIlroy
referred to it as a &ldquo;living fossil&rdquo;.</p>
<h5 class="footnote-body-heading"><a id="FOOT121" href="#DOCF121">(121)</a></h5>
<p>DWB&nbsp;3.3, Solaris, Heirloom Doctools, and
Plan&nbsp;9 <code class="code">troff</code> all support it.</p>
<h5 class="footnote-body-heading"><a id="FOOT122" href="#DOCF122">(122)</a></h5>
<p>Naturally, if you&rsquo;ve changed
the escape character, you need to prefix the <code class="code">e</code> with whatever it
is&mdash;and you&rsquo;ll likely get something other than a backslash in the
output.</p>
<h5 class="footnote-body-heading"><a id="FOOT123" href="#DOCF123">(123)</a></h5>
<p>The <code class="code">rs</code> special character identifier was not
defined in <abbr class="acronym">AT&amp;T</abbr> <code class="code">troff</code>&rsquo;s font description files, but is
in those of its lineal descendant, Heirloom Doctools <code class="code">troff</code>, as of
the latter&rsquo;s 060716 release (July 2006).</p>
<h5 class="footnote-body-heading"><a id="FOOT124" href="#DOCF124">(124)</a></h5>
<p>The parser
and postprocessor for intermediate output can be found in the file<br>
<samp class="file"><var class="var">groff-source-dir</var>/src/libs/libdriver/input.cpp</samp>.</p>
<h5 class="footnote-body-heading"><a id="FOOT125" href="#DOCF125">(125)</a></h5>
<p>Plan&nbsp;9 <code class="code">troff</code> has also abandoned the binary
format.</p>
<h5 class="footnote-body-heading"><a id="FOOT126" href="#DOCF126">(126)</a></h5>
<p>800-point type
is not practical for most purposes, but using it enables the quantities
in the font description files to be expressed as integers.</p>
<h5 class="footnote-body-heading"><a id="FOOT127" href="#DOCF127">(127)</a></h5>
<p><code class="code">groff</code> requests and escape sequences
interpret non-negative font names as mounting positions instead.
Further, a font named &lsquo;<samp class="samp">0</samp>&rsquo; cannot be automatically mounted by the
<code class="code">fonts</code> directive of a <samp class="file">DESC</samp> file.</p>
<h5 class="footnote-body-heading"><a id="FOOT128" href="#DOCF128">(128)</a></h5>
<p>For typesetter devices, this directive is misnamed
since it starts a list of glyphs, not characters.</p>
<h5 class="footnote-body-heading"><a id="FOOT129" href="#DOCF129">(129)</a></h5>
<p>that is, any integer parsable by the C
standard library&rsquo;s <cite class="cite">strtol<span class="r">(3)</span></cite> function</p>
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