list of examples of documents includes:

        <ul>
          <li>
            A document representing an actor
          </li>
          <li>
            A document representing an object
          </li>
          <li>
            A document representing an activity
          </li>
          <li>
            A document representing a collection of the activities done by an
            actor
          </li>
          <li>
            A document representing a collection of the activities done to an
      