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<span id="Indexing-Commands"></span><div class="header">
<p>
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<hr>
<span id="Defining-the-Entries-of-an-Index"></span><h3 class="section">11.2 Defining the Entries of an Index</h3>
<span id="index-Defining-indexing-entries"></span>
<span id="index-Index-entries"></span>
<span id="index-Entries-for-an-index"></span>
<span id="index-Specifying-index-entries"></span>
<span id="index-Creating-index-entries"></span>
<p>The data to make an index come from many individual indexing commands
scattered throughout the Texinfo source file. Each command says to add
one entry to a particular index; after formatting, the index will give
the current page number or node name as the reference.
</p>
<p>An index entry consists of an indexing command at the beginning of a
line followed, on the rest of the line, by the entry.
</p>
<p>For example, this section begins with the following five entries for
the concept index:
</p>
<div class="example">
<pre class="example">@cindex Defining indexing entries
@cindex Index entries, defining
@cindex Entries for an index
@cindex Specifying index entries
@cindex Creating index entries
</pre></div>
<p>Each predefined index has its own indexing command—<code>@cindex</code>
for the concept index, <code>@findex</code> for the function index, and so
on, as listed in the previous section.
</p>
<p>Index entries should precede the visible material that is being
indexed. For instance:
</p>
<div class="example">
<pre class="example">@cindex hello
Hello, there!
</pre></div>
<p>Among other reasons, that way following indexing links (in
whatever context) ends up before the material, where readers want to
be, instead of after.
</p>
<p>Try to avoid using a colon in index entries, as this may confuse some
Info readers. See <a href="Menu-Parts.html">Menu Parts</a> for more information about the
structure of a menu entry.
</p>
<span id="index-Index-font-types"></span>
<p>By default, entries for a concept index are printed in a small roman
font and entries for the other indices are printed in a small
<code>@code</code> font. You may change the way part of an entry is
printed with the usual Texinfo commands, such as <code>@file</code> for
file names (see <a href="Marking-Text.html">Marking Text</a>), and <code>@r</code> for the normal roman
font (see <a href="Fonts.html">Fonts</a>).
</p>
<span id="index-sortas"></span>
<span id="index-sort-keys-for-index-entries"></span>
<span id="index-index-sorting"></span>
<p>For the printed output, you may specify an explicit sort key for an
index entry using <code>@sortas</code> following either the index command
or the text of the entry. For example: ‘<samp>@findex @sortas{\}
\ @r{(literal \ in @code{@@math})</samp>’ sorts the index entry this
produces under backslash.
</p>
<span id="index-txiindexbackslashignore"></span>
<span id="index-txiindexhyphenignore"></span>
<span id="index-txiindexlessthanignore"></span>
<span id="index-txiindexatsignignore"></span>
<p>To reduce the quantity of sort keys you need to provide explicitly,
you may choose to ignore certain characters in index entries
for the purposes of sorting. The characters that you can
currently choose to ignore are ‘<samp>\</samp>’, ‘<samp>-</samp>’, ‘<samp><</samp>’
and ‘<samp>@</samp>’, which are ignored by giving as an argument to the
<code>@set</code> command, respectively, <code>txiindexbackslashignore</code>,
<code>txiindexhyphenignore</code>, <code>txiindexlessthanignore</code> and
<code>txiindexatsignignore</code>. For example, specifying ‘<samp>@set
txiindexbackslashignore</samp>’ causes the ‘<samp>\mathopsup</samp>’ entry in the
index for this manual to be sorted as if it were ‘<samp>mathopsup</samp>’,
so that it appears among the other entries beginning with ‘M’.
</p>
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<p>
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