te_time::period</a><span class="special">&lt;</span> <span class="identifier">date_type</span><span class="special">,</span> <span class="identifier">duration_type</span> <span class="special">&gt;</span> <a name="boost.date_time.date_facet.period_type"></a><span class="identifier">period_type</span><span class="special">;</span>                  
  <span class="keyword">typedef</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">basic_string</span><span class="