cales on one platform.
      </p>
<h6>
<a name="boost_regex.syntax.basic_extended.h15"></a>
        <span class="phrase"><a name="boost_regex.syntax.basic_extended.combinations"></a></span><a class="link" href="basic_extended.html#boost_regex.syntax.basic_extended.combinations">Combinations:</a>
      </h6>
<p>
        All of the above can be combined in one character set declaration, for example:
        <code class="computeroutput"><span class="special">[[:</span><span class="identifier">digit</span><span