arc:render

<table border="1">
  <tr>
  <td>
    <arc:render template="error.rst">
      <arc:catch code="*">
        <a name="caught">
        A problem was encountered with the template
        </a>
      </arc:catch>
    </arc:render>
    <!-- Ensure that tags are closed -->
  </td>
  </tr>
</table>

<arc:setc attr="a.t" value="this is [name]."/>
<arc:set attr="i.name" value="a test" />
<arc:set item="r" />
<arc:render templateData="[a.t]" in="i" to="r.text" />
[r.text]