<svg xmlns:xlink="http://www.w3.org/1999/xlink" 
     xmlns:html="http://www.w3.org/1999/xhtml"
     xmlns="http://www.w3.org/2000/svg" 
     onload="setTimeout(boom, 30);"
     class="reftest-wait">

<html:style>
  .zind { z-index: 0; }
  .gencon:after { content: counter(chicken); }
</html:style>

<script>
function boom()
{
  document.getElementById("define").setAttribute("class", "gencon");
  document.getElementById("use").setAttribute("class", "zind");

  document.documentElement.removeAttribute("class");
}
</script>

<defs>
  <g id="define">
    <rect x="0" y="0" width="75" height="75" fill="green"/>
  </g>
</defs>

<use xlink:href="#define" x="0" y="20" id="use" />

</svg>