e.html" title="syntax_option_type">option flag</a> - in
        which case whether a character appears within a range is determined by comparing
        the code points of the characters only.
      </p>
<h6>
<a name="boost_regex.syntax.basic_extended.h11"></a>
        <span class="phrase"><a name="boost_regex.syntax.basic_extended.negation"></a></span><a class="link" href="basic_extended.html#boost_regex.syntax.basic_extended.negation">Negation:</a>
      </h6>
<p>
        If the bracket-expression begins 