 class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
  <span class="comment">// types</span>
  <span class="keyword">typedef</span> <span class="identifier">time_duration_type_</span> <a name="boost.date_time.null_dst_rules.time_duration_type"></a><span class="identifier">time_duration_type</span><span class="special">;</span>
  <span class="keyword">typedef</span> <span class="identifier">date_type_</span>          <a name="boost.date_time.null_dst_rules.date_type"></