  <section id="activities">
      <h2><dfn id="activity">Activity</dfn></h2>

      <p>
        Activity objects are specializations of the base <a>Object</a>
        type that provide information about actions that have either
        already occurred, are in the process of occurring, or may occur
        in the future.
      </p>

      <p>
        In addition to common properties supported by all <a>Object</a>
        instances, <code>Activity</code> objects support the following
        additional prope