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<title>Line Layout (The GNU Troff Manual)</title>
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<p>
Next: <a href="Line-Continuation.html" accesskey="n" rel="next">Line Continuation</a>, Previous: <a href="troff-and-nroff-Modes.html" accesskey="p" rel="prev"><code class="code">troff</code> and <code class="code">nroff</code> Modes</a>, Up: <a href="GNU-troff-Reference.html" accesskey="u" rel="up">GNU <code class="code">troff</code> Reference</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Request-Index.html" title="Index" rel="index">Index</a>]</p>
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<hr>
<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"> -->| in |<--
|<-----------ll------------>|
+----+----+----------------------+----+
| : : : |
+----+----+----------------------+----+
-->| po |<--
|<--------paper width---------------->|
</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'> ¶</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>—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'> ¶</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>—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'> ¶</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>—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"> ⇒ This is text without indenta-
⇒ tion. The line length has
⇒ been set to 3 inches.
⇒ Now the left and
⇒ right margins are
⇒ both increased.
⇒ Calling .in and .ll without
⇒ parameters restores the previ-
⇒ 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'> ¶</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'> ¶</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'> ¶</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'> ¶</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.html">Manipulating Filling and Adjustment</a>). The initial value is 1<span class="dmn">i</span> and the default scaling
unit is ‘<samp class="samp">m</samp>’. 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 ‘<samp class="samp">.o</samp>’.
<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&T</abbr>
<code class="code">troff</code> manual as using a default scaling unit of ‘<samp class="samp">v</samp>’.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">.po 3i
\n[.o]
⇒ 720
.po -1i
\n[.o]
⇒ 480
.po
\n[.o]
⇒ 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'> ¶</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'> ¶</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'> ¶</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'> ¶</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 ‘<samp class="samp">m</samp>’.
</p>
<p>If a negative indentation value is specified (which is not allowed),
<code class="code">gtroff</code> emits a warning in category ‘<samp class="samp">range</samp>’ 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 ‘<samp class="samp">.i</samp>’. The indentation is associated with the
environment (see <a class="pxref" href="Environments.html">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'> ¶</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'> ¶</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'> ¶</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'> ¶</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.html">Environments</a>). The default scaling unit is
‘<samp class="samp">m</samp>’. 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 ‘<samp class="samp">range</samp>’ and sets the
temporary indentation to zero. ‘Total indentation’ 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'> ¶</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'> ¶</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'> ¶</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'> ¶</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'> ¶</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
‘<samp class="samp">m</samp>’.
</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 ‘<samp class="samp">range</samp>’ and sets the line length to zero. The
line length is associated with the environment (see <a class="pxref" href="Environments.html">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 ‘<samp class="samp">.l</samp>’. 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>
</div>
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