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<title>Leaders (The GNU Troff Manual)</title>
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<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="groff.html_fot.html#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 1, also known as <abbr class="acronym">SOH</abbr> or “start of heading”),
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 ‘<samp class="samp">.</samp>’.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-_005ca-1"><span class="category-def">Escape 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'> ¶</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.html">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'> ¶</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.html">Tabs and Leaders</a>: when encountering a leader
character in the input, the formatter writes as many dots ‘<samp class="samp">.</samp>’ 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.html">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]
⇒ 19. The Prophet............................. 98
⇒ 20. All Astir............................... 101
</pre></div></div>
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