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+<head>
+<title>UK TeX FAQ -- question label atsigns</title>
+</head><body>
+<h3><code>\</code><code>@</code> and <code>@</code> in macro names</h3>
+<p/>Macro names containing <code>@</code> are <em>internal</em> to LaTeX, and
+without special treatment just don&rsquo;t work in ordinary use. A nice
+example of the problems caused is discussed in
+<a href="FAQ-atvert.html"><code>\</code><code>@</code> in vertical mode</a>&rdquo;.
+<p/>The problems users see are caused by copying bits of a class
+(<code>.cls</code> file) or
+package (<code>.sty</code> file) into a document, or by including a class or
+package file into a LaTeX document by some means other than
+<code>\</code><code>documentclass</code> or <code>\</code><code>usepackage</code>. LaTeX defines internal
+commands whose names contain the character <code>@</code> to
+avoid clashes between its internal names and names that we would
+normally use in our documents. In order that these commands may work
+at all, <code>\</code><code>documentclass</code> and <code>\</code><code>usepackage</code> play around with the
+meaning of <code>@</code>.
+<p/>If you&rsquo;ve included a file some other way (for example, using
+<code>\</code><code>input</code>), you can probably solve the problem by using the correct
+command.
+<p/>If you&rsquo;re using a fragment of a package or class, you may well feel
+confused: books such as the first edition of the
+<a href="FAQ-books.html">The LaTeX Companion</a>
+are full of fragments of packages as examples for you to employ.
+The second edition of the <em>Companion</em> makes clearer how you
+should use these fragments, and in addition, the code of
+all the examples is now available on CTAN.
+To see the technique in practice, look at the example below, from file
+<i>2-2-7.ltx</i> in the <em>Companion</em> examples directory:
+<blockquote>
+<pre>
+\makeatletter
+\renewcommand\subsection{\@startsection
+ {subsection}{2}{0mm}%name, level, indent
+ {-\baselineskip}% beforeskip
+ {0.5\baselineskip}% afterskip
+ {\normalfont\normalsize\itshape}}% style
+\makeatother
+</pre>
+</blockquote><p>
+(That example appears on page 29 of <em>The LaTeX Companion</em>,
+second edition.)
+<p/>The alternative is to treat all these fragments as a package proper,
+bundling them up into a <code>.sty</code> file and including them with
+<code>\</code><code>usepackage</code>; this way you hide your LaTeX internal code somewhere
+that LaTeX internal code is expected, which often looks &lsquo;tidier&rsquo;.
+<dl>
+<dt><tt><i>Examples from the Companion</i></tt><dd><a href="ftp://cam.ctan.org/tex-archive/info/examples/tlc2.zip">info/examples/tlc2</a> (<a href="ftp://cam.ctan.org/tex-archive/info/examples/tlc2.tar.gz">gzipped tar</a>, <a href="http://www.tex.ac.uk/tex-archive/info/examples/tlc2/">browse</a>)
+</dl>
+<p/><p>This question on the Web: <a href="http://www.tex.ac.uk/cgi-bin/texfaq2html?label=atsigns">http://www.tex.ac.uk/cgi-bin/texfaq2html?label=atsigns</a>
+</body>