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>
      <b>TETRA_T6</b> is a tetrahedron, tiled with 6-node triangles.
      <ul>
        <li>
          <a href = "../../data/polygonal_surface/tetra_t6_nodes.txt">
          tetra_t6_nodes.txt</a>, the node file;
        </li>
        <li>
          <a href = "../../data/polygonal_surface/tetra_t6_faces.txt">
          tetra_t6