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HTML is good for debugging, but probably is not suitable for your application.
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<?xml version="1.0"?>
<api>
  <query>
    <blocks>
      <block id="1" user="MikeAjerson" by="Admin" timestamp="2011-06-23T16:57:46Z" expiry="infinity" reason="" nocreate="" autoblock="" />
    </blocks>
  </query>
</api>