1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
|
<!DOCTYPE html>
<html>
<!-- Created by GNU Texinfo 7.0.3, https://www.gnu.org/software/texinfo/ -->
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<!-- This manual documents GNU troff version 1.23.0.
Copyright 1994-2023 Free Software Foundation, Inc.
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". -->
<title>Measurements (The GNU Troff Manual)</title>
<meta name="description" content="Measurements (The GNU Troff Manual)">
<meta name="keywords" content="Measurements (The GNU Troff Manual)">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<meta name="viewport" content="width=device-width,initial-scale=1">
<link href="index.html" rel="start" title="Top">
<link href="Request-Index.html" rel="index" title="Request Index">
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
<link href="GNU-troff-Reference.html" rel="up" title="GNU troff Reference">
<link href="Numeric-Expressions.html" rel="next" title="Numeric Expressions">
<link href="Text.html" rel="prev" title="Text">
<style type="text/css">
<!--
a.copiable-link {visibility: hidden; text-decoration: none; line-height: 0em}
span:hover a.copiable-link {visibility: visible}
-->
</style>
</head>
<body lang="en">
<div class="section-level-extent" id="Measurements">
<div class="nav-panel">
<p>
Next: <a href="Numeric-Expressions.html" accesskey="n" rel="next">Numeric Expressions</a>, Previous: <a href="Text.html" accesskey="p" rel="prev">Text</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>
</div>
<hr>
<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
‘<samp class="samp">10.5p</samp>’, ‘<samp class="samp">11i</samp>’, and ‘<samp class="samp">3.c</samp>’.
</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
‘<samp class="samp">1i</samp>’ 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'> ¶</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 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'> ¶</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 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'> ¶</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’s unit used for measuring type size.
There are 72 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'> ¶</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’s unit. There are 6 picas to an inch and
12 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.html">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.html">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'> ¶</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 ‘<samp class="samp">M</samp>’.
</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'> ¶</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'> ¶</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.html">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'> ¶</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.html" accesskey="1">Motion Quanta</a></li>
<li><a href="Default-Units.html" accesskey="2">Default Units</a></li>
</ul>
</div>
<hr>
<div class="nav-panel">
<p>
Next: <a href="Numeric-Expressions.html">Numeric Expressions</a>, Previous: <a href="Text.html">Text</a>, Up: <a href="GNU-troff-Reference.html">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>
</div>
</body>
</html>
|
