</span><span class="identifier">tag</span><span class="special">&lt;</span><span class="identifier">polygon_type</span><span class="special">&gt;::</span><span class="identifier">type</span> <span class="identifier">tag</span><span class="special">;</span>
    <span class="keyword">typedef</span> <span class="identifier">geo</span><span class="special">::</span><span class="identifier">tag_cast</span><span class="special">&lt;</span><span class="identifier">tag</span><span class="special">,</span> <span cla