  </enum>
  </type>
  <type name="AssistDescription">
    <p>
      The description of a registered assist.
    </p>
    <object>
      <field name="id">
        <ref>String</ref>
        <p>
          The ID.
        </p>
      </field>
      <field name="message">
        <ref>String</ref>
        <p>
          The message that is presented to the user, to carry out this assist.
        </p>
      </field>
    </object>
  </type>
  <type name="ChangeContentOverlay">
    <p>
      A directive to modify an 