r_type</span> <span class="identifier">nadt_string</span><span class="special">;</span>
  <span class="keyword">static</span> <span class="keyword">const</span> <span class="identifier">char_type</span> <span class="identifier">neg_inf_string</span><span class="special">;</span>
  <span class="keyword">static</span> <span class="keyword">const</span> <span class="identifier">char_type</span> <span class="identifier">pos_inf_string</span><span class="special">;</span>
  <span class="keyword">static</span> <s