ass="keyword">typename</span> <span class="identifier">SeverityDescriptorT</span><span class="special">::</span><span class="identifier">value_type</span><span class="special">,</span> <span class="identifier">fallback_to_none</span><span class="special">,</span> <span class="identifier">fallback_to_none</span><span class="special">,</span> <span class="identifier">ChannelOrderT</span><span class="special">,</span> <span class="identifier">SeverityCompareT</span><span class="special">,</span> <span class="i