           These need to be defined in a way so that they will be found using
                argument dependent lookup (ADL).
              </li>
<li class="listitem">
                a valid specialization of the type <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">numeric_limits</span><span class="special">&lt;</span><span class="identifier">Num</span><span class="special">&gt;</span></code> allowing for numeric property
            