e to tell from the name of a header file, what version it belongs
        to. While all main include files for <a href="../../../../../../libs/spirit/classic/index.html" target="_top"><span class="emphasis"><em>Spirit.Classic</em></span></a>
        have the string 'classic_' in their name, for instance:
      </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier"