es.txt">
          sphere_q4_nodes.txt</a>, the node file;
        </li>
        <li>
          <a href = "../../data/polygonal_surface/sphere_q4_faces.txt">
          sphere_q4_faces.txt</a>, the face file;
        </li>
        <li>
          <a href = "../../data/polygonal_surface/sphere_q4.png">
          sphere_q4.png</a>,
          a <a href = "../../data/png/png.html">PNG</a> image of
          the shape as displayed by <b>POLYGONAL_SURFACE_DISPLAY</b>.
        </li>
      </ul>
    </p>

    <p>
   