 <span class="phrase"><a name="boost_regex.syntax.basic_extended.single_characters"></a></span><a class="link" href="basic_extended.html#boost_regex.syntax.basic_extended.single_characters">Single
        characters:</a>
      </h6>
<p>
        For example <code class="computeroutput"><span class="special">[</span><span class="identifier">abc</span><span class="special">]</span></code>, will match any of the characters 'a', 'b',
        or 'c'.
      </p>
<h6>
<a name="boost_regex.syntax.basic_extended.h10"