<shapes>
  <polygon kind="square">
    <a>10</a>  
    <b>10</b>
    <c>10</c>
    <d>10</d>
  </polygon>
  <polygon kind="rectangle">
    <a>10</a>  
    <b>8</b>
    <c>10</c>
    <d>8</d>
  </polygon>
  <polygon kind="triangle">
    <a>5</a>  
    <b>10</b>
    <c>15</c>
  </polygon>
</shapes>