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<hr>
<h4 class="footnotes-heading">Footnotes</h4>
<h5 class="footnote-body-heading"><a id="FOOT1" href="Preprocessor-Intro.html#DOCF1">(1)</a></h5>
<p>The ‘<samp class="samp">g</samp>’ prefix is
not used on all systems; see <a class="ref" href="Invoking-groff.html">Invoking <code class="code">groff</code></a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT2" href="Conventions-Used-in-This-Manual.html#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="Conventions-Used-in-This-Manual.html#DOCF3">(3)</a></h5>
<p>See <a class="xref" href="Line-Layout.html">Line Layout</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT4" href="Invoking-groff.html#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="Macro-Directories.html#DOCF5">(5)</a></h5>
<p>The
<code class="code">mso</code> request does not have these limitations. See <a class="xref" href="I_002fO.html">I/O</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT6" href="Basics.html#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 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="ms-Introduction.html#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="ms-Document-Control-Settings.html#DOCF8">(8)</a></h5>
<p>defined in <a class="ref" href="ms-Footnotes.html">Footnotes</a></p>
<h5 class="footnote-body-heading"><a id="FOOT9" href="ms-Document-Description-Macros.html#DOCF9">(9)</a></h5>
<p>Distinguish a
document title from “titles”, which are what <code class="code">roff</code> systems call
headers and footers collectively.</p>
<h5 class="footnote-body-heading"><a id="FOOT10" href="Typeface-and-decoration.html#DOCF10">(10)</a></h5>
<p>This idiosyncrasy arose through
feature accretion; for example, the <code class="code">B</code> macro in Version 6
Unix <samp class="file">ms</samp> (1975) accepted only one argument, the text to be set in
boldface. By Version 7 (1979) it recognized a second argument; in
1990, <code class="code">groff</code> <samp class="file">ms</samp> added a “pre” argument, placing it third
to avoid breaking support for older documents.</p>
<h5 class="footnote-body-heading"><a id="FOOT11" href="ms-Footnotes.html#DOCF11">(11)</a></h5>
<p>“Portable Document Format Publishing with GNU
Troff”, <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="ms-Footnotes.html#DOCF12">(12)</a></h5>
<p>Unix Version 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="ms-Footnotes.html#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="Differences-from-AT_0026T-ms.html#DOCF14">(14)</a></h5>
<p><cite class="cite">Typing Documents on the UNIX System: Using the
-ms Macros with Troff and Nroff</cite>, M. E. Lesk, Bell Laboratories,
1978</p>
<h5 class="footnote-body-heading"><a id="FOOT15" href="Differences-from-AT_0026T-ms.html#DOCF15">(15)</a></h5>
<p>Register values are converted to and stored as
basic units. See <a class="xref" href="Measurements.html">Measurements</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT16" href="Differences-from-AT_0026T-ms.html#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 ‘<samp class="samp">1</samp>’),
you may need to handle a non-Arabic page number format, as <code class="code">groff</code>
<samp class="file">ms</samp>’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="Missing-Unix-Version-7-ms-Macros.html#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="Filling.html#DOCF18">(18)</a></h5>
<p>See <a class="xref" href="Device-and-Font-Description-Files.html">Device and Font Description Files</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT19" href="Filling.html#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—the last simply have no effect on GNU
<code class="code">troff</code>’s idea of whether an input character is within a word.
We’ll discuss all of these in due course.</p>
<h5 class="footnote-body-heading"><a id="FOOT20" href="Sentences.html#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="Sentences.html#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’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="Sentences.html#DOCF22">(22)</a></h5>
<p>The mnemonics for the special
characters shown here are “dagger”, “double dagger”, “right
(double) quote”, and “closing (single) quote”. 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="Breaking.html#DOCF23">(23)</a></h5>
<p>“Text lines” are defined in <a class="ref" href="Requests-and-Macros.html">Requests and Macros</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT24" href="Tabs-and-Leaders.html#DOCF24">(24)</a></h5>
<p>“Tab”
is short for “tabulation”, revealing the term’s origin as a spacing
mechanism for table arrangement.</p>
<h5 class="footnote-body-heading"><a id="FOOT25" href="Requests-and-Macros.html#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.html">Line Continuation</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT26" href="Requests-and-Macros.html#DOCF26">(26)</a></h5>
<p>Argument handling in
macros is more flexible but also more complex. See <a class="xref" href="Calling-Macros.html">Calling Macros</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT27" href="Requests-and-Macros.html#DOCF27">(27)</a></h5>
<p>Some escape sequences undergo
interpolation as well.</p>
<h5 class="footnote-body-heading"><a id="FOOT28" href="Requests-and-Macros.html#DOCF28">(28)</a></h5>
<p>GNU <code class="code">troff</code> offers additional ones. See <a class="xref" href="Writing-Macros.html">Writing Macros</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT29" href="Macro-Packages.html#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="Input-Encodings.html#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="Input-Encodings.html#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
‘<samp class="samp">\[Eu]</samp>’ and per mille ‘<samp class="samp">\[%0]</samp>’ glyphs.</p>
<h5 class="footnote-body-heading"><a id="FOOT32" href="Input-Conventions.html#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="Page-Geometry.html#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="Page-Geometry.html#DOCF34">(34)</a></h5>
<p><code class="code">groff</code>’s terminal output devices have page
offsets of zero.</p>
<h5 class="footnote-body-heading"><a id="FOOT35" href="Numeric-Expressions.html#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="Numeric-Expressions.html#DOCF36">(36)</a></h5>
<p>If that’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="Numeric-Expressions.html#DOCF37">(37)</a></h5>
<p>See <a class="xref" href="Conditionals-and-Loops.html">Conditionals and Loops</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT38" href="Numeric-Expressions.html#DOCF38">(38)</a></h5>
<p>Control structure syntax
creates an exception to this rule, but is designed to remain useful:
recalling our example, ‘<samp class="samp">.if 1 .Underline this</samp>’ would underline only
“this”, precisely. See <a class="xref" href="Conditionals-and-Loops.html">Conditionals and Loops</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT39" href="Numeric-Expressions.html#DOCF39">(39)</a></h5>
<p>See <a class="xref" href="Diversions.html">Diversions</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT40" href="Identifiers.html#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.html">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.html">Implementation Differences</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT41" href="Identifiers.html#DOCF41">(41)</a></h5>
<p>Consider what happens when a C1 control
<code class="code">0x80</code>–<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="Control-Characters.html#DOCF42">(42)</a></h5>
<p>Recall <a class="ref" href="Identifiers.html">Identifiers</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT43" href="Invoking-Requests.html#DOCF43">(43)</a></h5>
<p>In compatibility
mode, a space is not necessary after a request or macro name of two
characters’ length. Also, Plan 9 <code class="code">troff</code> allows tabs to
separate arguments.</p>
<h5 class="footnote-body-heading"><a id="FOOT44" href="Calling-Macros.html#DOCF44">(44)</a></h5>
<p><code class="code">\~</code> is fairly
portable; see <a class="ref" href="Other-Differences.html">Other Differences</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT45" href="Calling-Macros.html#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="Using-Escape-Sequences.html#DOCF46">(46)</a></h5>
<p>The omission of spaces before the comment
escape sequences is necessary; see <a class="ref" href="Strings.html">Strings</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT47" href="Using-Escape-Sequences.html#DOCF47">(47)</a></h5>
<p>TeX does have such a mechanism.</p>
<h5 class="footnote-body-heading"><a id="FOOT48" href="Comments.html#DOCF48">(48)</a></h5>
<p>This claim may be more aspirational than descriptive.</p>
<h5 class="footnote-body-heading"><a id="FOOT49" href="Comments.html#DOCF49">(49)</a></h5>
<p>See <a class="xref" href="Conditional-Blocks.html">Conditional Blocks</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT50" href="Comments.html#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.html">Auto-increment</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT51" href="Auto_002dincrement.html#DOCF51">(51)</a></h5>
<p>A negative auto-increment can be
considered an “auto-decrement”.</p>
<h5 class="footnote-body-heading"><a id="FOOT52" href="Built_002din-Registers.html#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="Manipulating-Filling-and-Adjustment.html#DOCF53">(53)</a></h5>
<p>unless diverted; see <a class="ref" href="Diversions.html">Diversions</a></p>
<h5 class="footnote-body-heading"><a id="FOOT54" href="Manipulating-Filling-and-Adjustment.html#DOCF54">(54)</a></h5>
<p>See <a class="xref" href="Line-Continuation.html">Line Continuation</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT55" href="Manipulating-Filling-and-Adjustment.html#DOCF55">(55)</a></h5>
<p>Recall <a class="ref" href="Filling.html">Filling</a> and <a class="ref" href="Sentences.html">Sentences</a> for the
definitions of word and sentence boundaries, respectively.</p>
<h5 class="footnote-body-heading"><a id="FOOT56" href="Manipulating-Hyphenation.html#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="Manipulating-Hyphenation.html#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="Manipulating-Hyphenation.html#DOCF58">(58)</a></h5>
<p>“Soft” because it appears in output
only where a hyphenation break is performed; a “hard” hyphen, as in
“long-term”, always appears.</p>
<h5 class="footnote-body-heading"><a id="FOOT59" href="Manipulating-Hyphenation.html#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 “mask off” and compare to zero. To almost everyone else, the
arrangement seems recondite and unfriendly.</p>
<h5 class="footnote-body-heading"><a id="FOOT60" href="Manipulating-Hyphenation.html#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.html">Page Location Traps</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT61" href="Manipulating-Hyphenation.html#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="Manipulating-Spacing.html#DOCF62">(62)</a></h5>
<p>See <a class="xref" href="Page-Location-Traps.html">Page Location Traps</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT63" href="Manipulating-Spacing.html#DOCF63">(63)</a></h5>
<p>See <a class="xref" href="Drawing-Geometric-Objects.html">Drawing Geometric Objects</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT64" href="Manipulating-Spacing.html#DOCF64">(64)</a></h5>
<p>or geometric objects; see <a class="ref" href="Drawing-Geometric-Objects.html">Drawing Geometric Objects</a></p>
<h5 class="footnote-body-heading"><a id="FOOT65" href="Manipulating-Spacing.html#DOCF65">(65)</a></h5>
<p>to the top-level diversion;
see <a class="ref" href="Diversions.html">Diversions</a></p>
<h5 class="footnote-body-heading"><a id="FOOT66" href="Tabs-and-Fields.html#DOCF66">(66)</a></h5>
<p>Plan 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="Leaders.html#DOCF67">(67)</a></h5>
<p>This is pronounced to rhyme with “feeder”, and
refers to how the glyphs “lead” the eye across the page to the
corresponding page number or other datum.</p>
<h5 class="footnote-body-heading"><a id="FOOT68" href="troff-and-nroff-Modes.html#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="Line-Continuation.html#DOCF69">(69)</a></h5>
<p>Historically, the <code class="code">\c</code>
escape sequence has proven challenging to characterize. Some sources
say it “connects the next input text” (to the input line on which it
appears); others describe it as “interrupting” 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="Page-Layout.html#DOCF70">(70)</a></h5>
<p>See <a class="xref" href="Traps.html">Traps</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT71" href="Page-Control.html#DOCF71">(71)</a></h5>
<p>See <a class="xref" href="Diversions.html">Diversions</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT72" href="Using-Fonts.html#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’s Lineprinter, and <code class="code">lbp</code>’s Courier
and Elite faces.</p>
<h5 class="footnote-body-heading"><a id="FOOT73" href="Using-Fonts.html#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="Using-Fonts.html#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="Using-Fonts.html#DOCF75">(75)</a></h5>
<p>See <a class="xref" href="Font-Description-File-Format.html">Font Description File Format</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT76" href="Font-Families.html#DOCF76">(76)</a></h5>
<p>See <a class="xref" href="DESC-File-Format.html"><samp class="file">DESC</samp> File Format</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT77" href="Using-Symbols.html#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="Using-Symbols.html#DOCF78">(78)</a></h5>
<p>This is “Normalization Form D”
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="Using-Symbols.html#DOCF79">(79)</a></h5>
<p>See <a class="xref" href="Compatibility-Mode.html">Compatibility Mode</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT80" href="Using-Symbols.html#DOCF80">(80)</a></h5>
<p>Output glyphs
don’t—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="Dummy-Characters.html#DOCF81">(81)</a></h5>
<p>Opinions of this escape sequence’s name abound.
“Zero-width space” is a popular misnomer: <code class="code">roff</code> formatters do
not treat it like a space. Ossanna called it a “non-printing,
zero-width character”, but the character causes <em class="emph">output</em> even
though it does not “print”. If no output line is pending, the dummy
character starts one. Contrast an empty input document with one
containing only <code class="code">\&</code>. The former produces no output; the latter, a
blank page.</p>
<h5 class="footnote-body-heading"><a id="FOOT82" href="Manipulating-Type-Size-and-Vertical-Spacing.html#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 points.</p>
<h5 class="footnote-body-heading"><a id="FOOT83" href="Manipulating-Type-Size-and-Vertical-Spacing.html#DOCF83">(83)</a></h5>
<p>Rhyme with “sledding”; mechanical typography
used lead metal (Latin <em class="emph">plumbum</em>).</p>
<h5 class="footnote-body-heading"><a id="FOOT84" href="Changing-the-Type-Size.html#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="Using-Fractional-Type-Sizes.html#DOCF85">(85)</a></h5>
<p>See <a class="xref" href="Device-and-Font-Description-Files.html">Device and Font Description Files</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT86" href="Colors.html#DOCF86">(86)</a></h5>
<p>also
known vulgarly as “ANSI colors”</p>
<h5 class="footnote-body-heading"><a id="FOOT87" href="Strings.html#DOCF87">(87)</a></h5>
<p>See <a class="xref" href="Copy-Mode.html">Copy Mode</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT88" href="Operators-in-Conditionals.html#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&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="Operators-in-Conditionals.html#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 9
<code class="code">troff</code> uses ‘<samp class="samp">h</samp>’ 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="Operators-in-Conditionals.html#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="Operators-in-Conditionals.html#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.html"><code class="code">gtroff</code> Internals</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT92" href="Operators-in-Conditionals.html#DOCF92">(92)</a></h5>
<p>This bizarre behavior maintains compatibility with
<abbr class="acronym">AT&T</abbr> <code class="code">troff</code>.</p>
<h5 class="footnote-body-heading"><a id="FOOT93" href="Conditional-Blocks.html#DOCF93">(93)</a></h5>
<p>See <a class="xref" href="while.html">while</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT94" href="while.html#DOCF94">(94)</a></h5>
<p>See <a class="xref" href="Copy-Mode.html">Copy Mode</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT95" href="while.html#DOCF95">(95)</a></h5>
<p>unless you redefine it</p>
<h5 class="footnote-body-heading"><a id="FOOT96" href="while.html#DOCF96">(96)</a></h5>
<p>“somewhat less” because
things other than macro calls can be on the input stack</p>
<h5 class="footnote-body-heading"><a id="FOOT97" href="Writing-Macros.html#DOCF97">(97)</a></h5>
<p>See <a class="xref" href="Copy-Mode.html">Copy Mode</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT98" href="Writing-Macros.html#DOCF98">(98)</a></h5>
<p>While it is possible to define and
call a macro ‘<samp class="samp">.</samp>’, you can’t use it as an end macro: during a macro
definition, ‘<samp class="samp">..</samp>’ is never handled as calling ‘<samp class="samp">.</samp>’, even if
‘<samp class="samp">.de <var class="var">name</var> .</samp>’ explicitly precedes it.</p>
<h5 class="footnote-body-heading"><a id="FOOT99" href="Writing-Macros.html#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="Parameters.html#DOCF100">(100)</a></h5>
<p>If they were not,
parameter interpolations would be similar to command-line
parameters—fixed for the entire duration of a <code class="code">roff</code> program’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="Copy-Mode.html#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="Copy-Mode.html#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="Page-Motions.html#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 ‘<samp class="samp">.vs .5i</samp>’ make it obvious.</p>
<h5 class="footnote-body-heading"><a id="FOOT104" href="Page-Motions.html#DOCF104">(104)</a></h5>
<p>See <a class="xref" href="Strings.html">Strings</a>, for an explanation of the trailing
‘<samp class="samp">\"</samp>’.</p>
<h5 class="footnote-body-heading"><a id="FOOT105" href="Drawing-Geometric-Objects.html#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’s chord.</p>
<h5 class="footnote-body-heading"><a id="FOOT106" href="Page-Location-Traps.html#DOCF106">(106)</a></h5>
<p>See <a class="xref" href="The-Implicit-Page-Trap.html">The Implicit Page Trap</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT107" href="Page-Location-Traps.html#DOCF107">(107)</a></h5>
<p>A trap planted at ‘<samp class="samp">20i</samp>’ or
‘<samp class="samp">-30i</samp>’ will not be sprung on a page of length ‘<samp class="samp">11i</samp>’.</p>
<h5 class="footnote-body-heading"><a id="FOOT108" href="Page-Location-Traps.html#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="The-Implicit-Page-Trap.html#DOCF109">(109)</a></h5>
<p>See <a class="xref" href="Debugging.html">Debugging</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT110" href="The-Implicit-Page-Trap.html#DOCF110">(110)</a></h5>
<p>See <a class="xref" href="Diversions.html">Diversions</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT111" href="End_002dof_002dinput-Traps.html#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 “sudden death overtime”.</p>
<h5 class="footnote-body-heading"><a id="FOOT112" href="End_002dof_002dinput-Traps.html#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="Diversions.html#DOCF113">(113)</a></h5>
<p>Thus, the “water”
gets “higher” proceeding <em class="emph">down</em> the page.</p>
<h5 class="footnote-body-heading"><a id="FOOT114" href="Punning-Names.html#DOCF114">(114)</a></h5>
<p>The backslash is doubled. See <a class="xref" href="Copy-Mode.html">Copy Mode</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT115" href="Postprocessor-Access.html#DOCF115">(115)</a></h5>
<p>that is, ISO 646:1991-IRV or,
popularly, “US-ASCII”</p>
<h5 class="footnote-body-heading"><a id="FOOT116" href="Postprocessor-Access.html#DOCF116">(116)</a></h5>
<p>They are bypassed because these parameters are not
rendered as glyphs in the output; instead, they remain abstract
characters—in a PDF bookmark or a URL, for example.</p>
<h5 class="footnote-body-heading"><a id="FOOT117" href="Miscellaneous.html#DOCF117">(117)</a></h5>
<p>Recall <a class="ref" href="Line-Layout.html">Line Layout</a>.</p>
<h5 class="footnote-body-heading"><a id="FOOT118" href="Miscellaneous.html#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="Gtroff-Internals.html#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="Compatibility-Mode.html#DOCF120">(120)</a></h5>
<p>The
Graphic Systems C/A/T phototypesetter (the original device target for
<abbr class="acronym">AT&T</abbr> <code class="code">troff</code>) supported only a few discrete type sizes
in the range 6–36 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 #54 (�2.3), and more recently, McIlroy
referred to it as a “living fossil”.</p>
<h5 class="footnote-body-heading"><a id="FOOT121" href="Other-Differences.html#DOCF121">(121)</a></h5>
<p>DWB 3.3, Solaris, Heirloom Doctools, and
Plan 9 <code class="code">troff</code> all support it.</p>
<h5 class="footnote-body-heading"><a id="FOOT122" href="Other-Differences.html#DOCF122">(122)</a></h5>
<p>Naturally, if you’ve changed
the escape character, you need to prefix the <code class="code">e</code> with whatever it
is—and you’ll likely get something other than a backslash in the
output.</p>
<h5 class="footnote-body-heading"><a id="FOOT123" href="Other-Differences.html#DOCF123">(123)</a></h5>
<p>The <code class="code">rs</code> special character identifier was not
defined in <abbr class="acronym">AT&T</abbr> <code class="code">troff</code>’s font description files, but is
in those of its lineal descendant, Heirloom Doctools <code class="code">troff</code>, as of
the latter’s 060716 release (July 2006).</p>
<h5 class="footnote-body-heading"><a id="FOOT124" href="gtroff-Output.html#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="Device-and-Font-Description-Files.html#DOCF125">(125)</a></h5>
<p>Plan 9 <code class="code">troff</code> has also abandoned the binary
format.</p>
<h5 class="footnote-body-heading"><a id="FOOT126" href="Font-Description-File-Format.html#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="Font-Description-File-Format.html#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 ‘<samp class="samp">0</samp>’ 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="Font-Description-File-Format.html#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="Font-Description-File-Format.html#DOCF129">(129)</a></h5>
<p>that is, any integer parsable by the C
standard library’s <cite class="cite">strtol<span class="r">(3)</span></cite> function</p>
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