You are looking at the HTML representation of the mFormat?> format.
HTML is good for debugging, but probably is not suitable for your application.
Please see "format" parameter documentation at the API help for more information. 
<?xml version="1.0" encoding="utf-8"?>
<api>
  <query>
    <pages>
      <page pageid="1" ns="0" title="Main Page">
        <revisions>
          <rev revid="13211" pageid="1" oldid="13062" user="Gregory.Szorc" minor="" timestamp="2006-09-09T19:27:34Z" comment="link to project listing" />
          <rev revid="12672" pageid="1" oldid="12526" user="Gregory.Szorc" minor="" timestamp="2006-08-31T05:56:15Z" comment="note on who can view content" />
          <rev revid="10330" pageid="1" oldid="10193" user="Gregory.Szorc" minor="" timestamp="2006-06-18T17:33:52Z" comment="rephrased intro paragraph" />
          <rev revid="10266" pageid="1" oldid="10129" user="Gregory.Szorc" minor="" timestamp="2006-06-02T16:55:59Z" comment="removed monthly featured article until someone comes up with a new one (can you blame me for enjoying California)" />
          <rev revid="9026" pageid="1" oldid="8906" user="Gregory.Szorc" minor="" timestamp="2006-04-01T05:13:49Z" comment="no" />
        </revisions>
      </page>
    </pages>
  </query>
  <query-continue>
    <revisions rvstartid="9019" />
  </query-continue>
</api>