ss="keyword">const</span> <span class="identifier">string_type</span> <span class="special">&amp;</span> neg_inf_str<span class="special">,</span> 
                      <span class="keyword">const</span> <span class="identifier">string_type</span> <span class="special">&amp;</span> pos_inf_str<span class="special">,</span> 
                      <span class="keyword">const</span> <span class="identifier">string_type</span> <span class="special">&amp;</span> min_dt_str<span class="special">,</span> 
       