an class="special">);</span>
</pre>
<a name="boost_regex.posix_extended_syntax"></a><h4>
<a name="boost_regex.syntax.basic_extended.h1"></a>
        <span class="phrase"><a name="boost_regex.syntax.basic_extended.posix_extended_syntax"></a></span><a class="link" href="basic_extended.html#boost_regex.syntax.basic_extended.posix_extended_syntax">POSIX Extended
        Syntax</a>
      </h4>
<p>
        In POSIX-Extended regular expressions, all characters match themselves except
        for the following spec