ten using <a href="../../../../../../../libs/phoenix/doc/html/index.html" target="_top">Boost.Phoenix</a>
            use the placeholders defined in the namespace <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span></code>.
            Please note that all existing placeholders for your convenience are also
            available from the namespace <code class="computeroutput"><span class="identifier">boost</span><span class=