>struct</span> <span class="identifier">my_unit_tag</span> <span class="special">:</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">units</span><span class="special">::</span><span class="identifier">base_unit</span><span class="special">&lt;</span><span class="identifier">my_unit_tag</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">units</span><span class="special">::</span><s