is"><em><span class="identifier">unspecified</span></em></span>                     <a name="boost.heap.skew_heap.implementation_defined.reference"></a><span class="identifier">reference</span><span class="special">;</span>          
  <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">unspecified</span></em></span>                     <a name="boost.heap.skew_heap.implementation_defined.handle_type"></a><span class="identifier">handle_type</span><span class="special">;