_top">Boost.Phoenix</a>
          placeholders to important information from the <code class="computeroutput"><span class="identifier">Attrib</span></code>
          and <code class="computeroutput"><span class="identifier">Context</span></code> that are otherwise
          fiddly to extract.
        </p>
<div class="variablelist">
<p class="title"><b>Spirit.Qi specific Phoenix placeholders</b></p>
<dl>
<dt><span class="term"><code class="computeroutput"><span class="identifier">_1</span><span class="specia