 field on articles published on
or after April 02, 2006, as the linked page will have richer content.
       </td>
       <td>
        optional
       </td>
       <td>
       </td>
      </tr>
      <tr>
       <td>
        2
       </td>
       <td>
        articleAbstract
       </td>
       <td>
        <code>
         string
        </code>
       </td>
       <td>
        This field is a summary of the article, possibly written by
an indexing service.
       </td>
       <td>
        optional
       <