cation of "verb" and "objectType" to "type"
        </li>
        <li>
          Removal of activity types and object types that weren't core to social
          use cases
        </li>
        <li>
          Introduction of the Link type for richly-described links
        </li>
        <li>
          Incorporation of audience targeting into the core spec
        </li>
        <li>
          The generalized "Undo" activity type, so all activities can be undone
        </li>
        <li>
          Consistent