You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allfileusages gafcontinue="Cups3colorb.png|200" />
  </query-continue>
  <query>
    <pages>
      <page pageid="17" ns="0" title="Bridges" />
      <page pageid="23" ns="0" title="Manual da Bridge" />
      <page pageid="32" ns="0" title="REUNI 2010" />
      <page pageid="200" ns="0" title="Instalacao" />
      <page pageid="273" ns="0" title="Manual de Instalação L203 e N229" />
      <page pageid="290" ns="0" title="Manual de instalação M1,N1,M2,ADM3" />
      <page pageid="333" ns="0" title="Manual de Instalação L203" />
    </pages>
  </query>
</api>