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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>
    <blocks>
      <block id="1" user="69.4.231.200" by="TMakerAdmin" timestamp="2011-04-06T15:14:51Z" expiry="infinity" reason="" anononly="" nocreate="" />
    </blocks>
  </query>
</api>