class="special">\</span><span class="identifier">p</span><span class="special">{</span><span class="identifier">digit</span><span class="special">}</span></code>.
      </p>
<h6>
<a name="boost_regex.syntax.basic_extended.h20"></a>
        <span class="phrase"><a name="boost_regex.syntax.basic_extended.word_boundaries"></a></span><a class="link" href="basic_extended.html#boost_regex.syntax.basic_extended.word_boundaries">Word
        Boundaries</a>
      </h6>
<p>
        The following escape sequences matc