de class="computeroutput"><span class="identifier">headers_container</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span></code>
        to determine what container type holds the header fields. We note some problems
        with the container declaration:
      </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
            The header and body containers may only be default-constructed.
         