and multiple keys.
    </p>
<p>
      The memory overhead of these containers with Boost.Intrusive hooks is 3 pointers.
    </p>
<p>
      An empty, <code class="computeroutput"><a class="link" href="../boost/intrusive/sg_set.html" title="Class template sg_set">sg_set</a></code>, <code class="computeroutput"><a class="link" href="../boost/intrusive/sg_multiset.html" title="Class template sg_multiset">sg_multiset</a></code> or <code class="computeroutput"><a class="link" href="../boost/intrusive/sgtree.html"