You are looking at the HTML representation of the XML format.
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>
    <userinfo id="0" name="10.30.226.43" anon="" blockedby="" blockreason="Your IP address is listed as an open proxy in the DNSBL used by Ext4.">
      <groups>
        <g>*</g>
        <g>autoconfirmed</g>
      </groups>
      <rights>
        <r>read</r>
        <r>createpage</r>
        <r>createtalk</r>
        <r>writeapi</r>
      </rights>
    </userinfo>
  </query>
</api>