 context of the specification.
  </li>
  <li>
    The <b>Category</b> column groups assertions by function.
  </li>
  <li>
    The <b>Req</b> column is a Y/N value indicating
    whether the assertion is for a feature which is required.
    Note however that the feature may only be required if another feature is
    also used or in a particular context, as indicated in
    the <b>Context</b> column.
  </li>
  <li>
    The <b>Context</b> column indicates that the "required" status of this feature depends on 