</tr>
</tbody>
</table></div>
<h6>
<a name="spirit.advanced.customize.is_string.h7"></a>
          <span class="phrase"><a name="spirit.advanced.customize.is_string.when_to_implement"></a></span><a class="link" href="is_string.html#spirit.advanced.customize.is_string.when_to_implement">When to
          implement</a>
        </h6>
<p>
          This customization point needs to be implemented to use user-defined string
          classes that do not correspond to std::string syntax and semantics.
        </p