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Previous: <a href="Glyphs-for-Programming.html" accesskey="p" rel="prev">Glyphs for Programming</a>, Up: <a href="Insertions.html" accesskey="u" rel="up">Insertions</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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<span id="Inserting-Unicode_003a-_0040U"></span><h3 class="section">12.10 Inserting Unicode: <code>@U</code></h3>
<span id="index-Unicode-character_002c-inserting"></span>
<span id="index-Code-point-of-Unicode-character_002c-inserting-by"></span>
<span id="index-U"></span>
<p>The command <code>@U{<var>hex</var>}</code> inserts a representation of the
Unicode character U+<var>hex</var>. For example, <code>@U{0132}</code>
inserts the Dutch ‘IJ’ ligature (‘IJ’).
</p>
<p>The <var>hex</var> value should be at least four hex digits; leading zeros
are <em>not</em> added. In general, <var>hex</var> must specify a valid
normal Unicode character; e.g., U+10FFFF (the very last code point) is
invalid by definition, and thus cannot be inserted this way.
</p>
<span id="index-ASCII_002c-source-document-portability-using"></span>
<p><code>@U</code> is useful for inserting occasional glyphs for which Texinfo
has no dedicated command, while allowing the Texinfo source to remain
purely 7-bit ASCII for maximum portability.
</p>
<span id="index-Unicode-and-TeX"></span>
<p>This command has many limitations—the same limitations as inserting
Unicode characters in UTF-8 or another binary form. First and most
importantly, TeX knows nothing about most of Unicode. Supporting
specific additional glyphs upon request is possible, but it’s not
viable for <samp>texinfo.tex</samp> to support whole additional scripts
(Japanese, Urdu, …). The <code>@U</code> command does nothing to
change this. If the specified character is not supported in TeX,
an error is given. (See <a href="_0040documentencoding.html"><code>@documentencoding</code></a>.)
</p>
<span id="index-Entity-reference-in-HTML-et-al_002e"></span>
<span id="index-_0026_0023xhex_003b_002c-output-from-_0040U"></span>
<p>In HTML, XML, and Docbook, the output from <code>@U</code> is always an
entity reference of the form ‘<samp>&#x<var>hex</var>;</samp>’, as in
‘<samp>&#x0132;</samp>’ for the example above. This should work even when an
HTML document uses some other encoding (say, Latin 1) and the
given character is not supported in that encoding.
</p>
<p>In Info and plain text, if the output encoding is not UTF-8, the output
is the ASCII sequence ‘<samp>U+<var>hex</var></samp>’, as in the six ASCII characters
‘<samp>U+0132</samp>’ for the example above.
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