class="identifier">date_type</span><span class="special">::</span><span class="identifier">duration_type</span>                  <a name="boost.date_time.special_values_parser.duration_type"></a><span class="identifier">duration_type</span><span class="special">;</span>  
  <span class="keyword">typedef</span> <a class="link" href="string_parse_tree.html" title="Struct template string_parse_tree">string_parse_tree</a><span class="special">&lt;</span> <span class="identifier">charT</span> <span class="specia