                 </p>
                </td>
</tr>
<tr>
<td>
                  <p>
                    no_bk_refs
                  </p>
                </td>
<td>
                  <p>
                    No
                  </p>
                </td>
<td>
                  <p>
                    When set then backreferences are disabled. This bit is on by
                    default for POSIX-Extended regular expressions, but can be unset
                    to support for backreferences on.
            