 </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              there must be a specialization of <code class="computeroutput"><span class="identifier">traits</span><span class="special">::</span><span class="identifier">tag</span></code>,
              defining <code class="computeroutput"><span class="identifier">box_tag</span></code> as
              type
            </li>
<li class="listitem">
              there must be a specialization of <