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<title>HTML Xref 8-bit Character Expansion (GNU Texinfo 6.7)</title>

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<span id="HTML-Xref-8_002dbit-Character-Expansion"></span><div class="header">
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<span id="HTML-Cross_002dreference-8_002dbit-Character-Expansion"></span><h4 class="subsection">22.4.4 HTML Cross-reference 8-bit Character Expansion</h4>
<span id="index-HTML-cross_002dreference-8_002dbit-character-expansion"></span>
<span id="index-8_002dbit-characters_002c-in-HTML-cross_002dreferences"></span>
<span id="index-Expansion-of-8_002dbit-characters-in-HTML-cross_002dreferences"></span>
<span id="index-Transliteration-of-8_002dbit-characters-in-HTML-cross_002dreferences"></span>

<p>Usually, characters other than plain 7-bit ASCII are transformed into
the corresponding Unicode code point(s) in Normalization Form&nbsp;C,
which uses precomposed characters where available.  (This is the
normalization form recommended by the W3C and other bodies.)  This
holds when that code point is <code>0xffff</code> or less, as it almost
always is.
</p>
<p>These will then be further transformed by the rules above into the
string &lsquo;<samp>_<var>hhhh</var></samp>&rsquo;, where <var>hhhh</var> is the code point in hex.
</p>
<p>For example, combining this rule and the previous section:
</p>
<div class="example">
<pre class="example">@node @b{A} @TeX{} @u{B} @point{}@enddots{}
&rArr; A-TeX-B_0306-_2605_002e_002e_002e
</pre></div>

<p>Notice: 1)&nbsp;<code>@enddots</code> expands to three periods which in
turn expands to three &lsquo;<samp>_002e</samp>&rsquo;&rsquo;s; 2)&nbsp;<code>@u{B}</code> is a &lsquo;B&rsquo;
with a breve accent, which does not exist as a pre-accented Unicode
character, therefore expands to &lsquo;<samp>B_0306</samp>&rsquo; (B with combining
breve).
</p>
<p>When the Unicode code point is above <code>0xffff</code>, the transformation
is &lsquo;<samp>__<var>xxxxxx</var></samp>&rsquo;, that is, two leading underscores followed by
six hex digits.  Since Unicode has declared that their highest code
point is <code>0x10ffff</code>, this is sufficient.  (We felt it was better
to define this extra escape than to always use six hex digits, since
the first two would nearly always be zeros.)
</p>
<p>This method works fine if the node name consists mostly of ASCII
characters and contains only few 8-bit ones.  But if the document is
written in a language whose script is not based on the Latin alphabet
(for example, Ukrainian), it will create file names consisting almost
entirely of &lsquo;<samp>_<var>xxxx</var></samp>&rsquo; notations, which is inconvenient and
all but unreadable.  To handle such cases, <code>makeinfo</code> offers
the <samp>--transliterate-file-names</samp> command line option.  This
option enables <em>transliteration</em> of node names into ASCII
characters for the purposes of file name creation and referencing.
The transliteration is based on phonetic principles, which makes the
generated file names more easily understanable.
</p>
<span id="index-Normalization-Form-C_002c-Unicode"></span>
<p>For the definition of Unicode Normalization Form&nbsp;C, see Unicode
report UAX#15, <a href="http://www.unicode.org/reports/tr15/">http://www.unicode.org/reports/tr15/</a>.  Many
related documents and implementations are available elsewhere on the
web.
</p>

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Next: <a href="HTML-Xref-Mismatch.html" accesskey="n" rel="next">HTML Xref Mismatch</a>, Previous: <a href="HTML-Xref-Command-Expansion.html" accesskey="p" rel="prev">HTML Xref Command Expansion</a>, Up: <a href="HTML-Xref.html" accesskey="u" rel="up">HTML Xref</a> &nbsp; [<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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