n class="special">(</span><span class="keyword">const</span> <span class="identifier">char_type</span> <span class="special">*</span> format_str<span class="special">,</span> 
                    <a class="link" href="date_facet.html#boost.date_time.date_facet.period_formatter_type">period_formatter_type</a> per_formatter <span class="special">=</span> <a class="link" href="period_formatter.html" title="Class template period_formatter">period_formatter_type</a><span class="special">(</span><span class="spec