>
</div>
<div class="section" id="predicate-requirements">
<h5>2.1.5.6.2&nbsp;&nbsp;&nbsp;Predicate Requirements</h5>
<p>The requirements on other arguments are a bit more interesting than
those on <tt class="docutils literal">root_vertex</tt>; they can't be described in terms of simple
type matching.  Instead, they must be described in terms of <a class="reference external" href="../../../mpl/doc/refmanual/metafunction.html">MPL
Metafunctions</a>.  There's no space to give a complete description
of metafun