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="Docu_Create_AddProperty.png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="119" ns="6" title="File:Docu Alert.png" />
      <page pageid="120" ns="6" title="File:Docu Create.png" />
      <page pageid="154" ns="6" title="File:Docu Create AddAttribute Expertise.png" />
      <page pageid="155" ns="6" title="File:Docu Create AddAttribute Owner.png" />
      <page pageid="156" ns="6" title="File:Docu Create AddAttribute Participants.png" />
      <page pageid="157" ns="6" title="File:Docu Create AddAttribute ProgressCalculation.png" />
      <page pageid="158" ns="6" title="File:Docu Create AddAttribute TimeFunnel.png" />
      <page pageid="159" ns="6" title="File:Docu Create AddAttribute Type HierachySample.png" />
      <page pageid="160" ns="6" title="File:Docu Create AddAttribute Type SelectType.png" />
      <page pageid="161" ns="6" title="File:Docu Create AddAttributes.png" />
    </pages>
  </query>
</api>