      class template as a base class. Some operator templates support an <a
      href="#explicit_instantiation">alternate method</a>.</li>

      <li>The concept can be compound, <i>i.e.</i> it may represent a common
      combination of other, simpler concepts.</li>

      <li>Most operator templates require their target class to support
      operations related to the operators supplied by the template. In
      accordance with widely accepted <a href=
      "http://www.gotw.ca/gotw/004.htm">coding style