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HTML is good for debugging, but probably is not suitable for your application.
See complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query>
    <allcategories>
      <c size="1" pages="0" files="0" subcats="1" xml:space="preserve">Content</c>
      <c size="1" pages="1" files="0" subcats="0" xml:space="preserve">Content bundle</c>
      <c size="1" pages="1" files="0" subcats="0" xml:space="preserve">Cross-browser compatibility templates</c>
      <c size="1" pages="1" files="0" subcats="0" xml:space="preserve">DYK navigational boxes</c>
      <c size="1" pages="1" files="0" subcats="0" xml:space="preserve">Document</c>
      <c size="1" pages="1" files="0" subcats="0" xml:space="preserve">Foo</c>
      <c size="8" pages="8" files="0" subcats="0" xml:space="preserve">Form</c>
      <c size="2" pages="2" files="0" subcats="0" xml:space="preserve">Image insertion templates</c>
      <c size="1" pages="1" files="0" subcats="0" xml:space="preserve">Infobox templates</c>
      <c size="7" pages="0" files="0" subcats="7" xml:space="preserve">Media</c>
    </allcategories>
  </query>
  <query-continue>
    <allcategories acfrom="Navigational boxes without horizontal lists" />
  </query-continue>
</api>