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<title>HTML Xref Node Name Expansion (GNU Texinfo 6.7)</title>
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<span id="HTML-Xref-Node-Name-Expansion"></span><div class="header">
<p>
Next: <a href="HTML-Xref-Command-Expansion.html" accesskey="n" rel="next">HTML Xref Command Expansion</a>, Previous: <a href="HTML-Xref-Link-Basics.html" accesskey="p" rel="prev">HTML Xref Link Basics</a>, Up: <a href="HTML-Xref.html" accesskey="u" rel="up">HTML Xref</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Command-and-Variable-Index.html" title="Index" rel="index">Index</a>]</p>
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<hr>
<span id="HTML-Cross_002dreference-Node-Name-Expansion"></span><h4 class="subsection">22.4.2 HTML Cross-reference Node Name Expansion</h4>
<span id="index-HTML-cross_002dreference-node-name-expansion"></span>
<span id="index-node-name-expansion_002c-in-HTML-cross_002dreferences"></span>
<span id="index-expansion_002c-of-node-names-in-HTML-cross_002dreferences"></span>
<p>As mentioned in the previous section, the key part of the HTML cross
reference algorithm is the conversion of node names in the Texinfo
source into strings suitable for XHTML identifiers and filenames. The
restrictions are similar for each: plain ASCII letters, numbers, and
the ‘<samp>-</samp>’ and ‘<samp>_</samp>’ characters are all that can be used.
(Although HTML anchors can contain most characters, XHTML is more
restrictive.)
</p>
<p>Cross-references in Texinfo can refer either to nodes or anchors
(see <a href="_0040anchor.html"><code>@anchor</code></a>). However, anchors are treated identically
to nodes in this context, so we’ll continue to say “node” names for
simplicity.
</p>
<p>A special exception: the Top node (see <a href="The-Top-Node.html">The Top Node</a>) is always
mapped to the file <samp>index.html</samp>, to match web server software.
However, the HTML <em>target</em> is ‘<samp>Top</samp>’. Thus (in the split case):
</p>
<div class="example">
<pre class="example">@xref{Top,,, emacs, The GNU Emacs Manual}.
⇒ <a href="emacs/index.html#Top">
</pre></div>
<ol>
<li> The standard ASCII letters (a-z and A-Z) are not modified. All other
characters may be changed as specified below.
</li><li> The standard ASCII numbers (0-9) are not modified except when a number
is the first character of the node name. In that case, see below.
</li><li> Multiple consecutive space, tab and newline characters are transformed
into just one space. (It’s not possible to have newlines in node
names with the current implementation, but we specify it anyway, just
in case.)
</li><li> Leading and trailing spaces are removed.
</li><li> After the above has been applied, each remaining space character is
converted into a ‘<samp>-</samp>’ character.
</li><li> Other ASCII 7-bit characters are transformed into ‘<samp>_00<var>xx</var></samp>’,
where <var>xx</var> is the ASCII character code in (lowercase) hexadecimal.
This includes ‘<samp>_</samp>’, which is mapped to ‘<samp>_005f</samp>’.
</li><li> If the node name does not begin with a letter, the literal string
‘<samp>g_t</samp>’ is prefixed to the result. (Due to the rules above, that
string can never occur otherwise; it is an arbitrary choice, standing
for “GNU Texinfo”.) This is necessary because XHTML requires that
identifiers begin with a letter.
</li></ol>
<p>For example:
</p>
<div class="example">
<pre class="example">@node A node --- with _'%
⇒ A-node-_002d_002d_002d-with-_005f_0027_0025
</pre></div>
<p>Example translations of common characters:
</p>
<ul>
<li> ‘<samp>_</samp>’ ⇒ ‘<samp>_005f</samp>’
</li><li> ‘<samp>-</samp>’ ⇒ ‘<samp>_002d</samp>’
</li><li> ‘<samp>A node</samp>’ ⇒ ‘<samp>A-node</samp>’
</li></ul>
<p>On case-folding computer systems, nodes differing only by case will be
mapped to the same file. In particular, as mentioned above, Top
always maps to the file <samp>index.html</samp>. Thus, on a case-folding
system, Top and a node named ‘Index’ will both be written to
<samp>index.html</samp>. Fortunately, the targets serve to distinguish
these cases, since HTML target names are always case-sensitive,
independent of operating system.
</p>
<hr>
<div class="header">
<p>
Next: <a href="HTML-Xref-Command-Expansion.html" accesskey="n" rel="next">HTML Xref Command Expansion</a>, Previous: <a href="HTML-Xref-Link-Basics.html" accesskey="p" rel="prev">HTML Xref Link Basics</a>, Up: <a href="HTML-Xref.html" accesskey="u" rel="up">HTML Xref</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Command-and-Variable-Index.html" title="Index" rel="index">Index</a>]</p>
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