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="Catamaran-reaching.png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1728" ns="6" title="File:Battery1.jpg" />
      <page pageid="1729" ns="6" title="File:Battery2.jpg" />
      <page pageid="1732" ns="6" title="File:Battery switch.jpg" />
      <page pageid="1475" ns="6" title="File:BilgepumpCircuit.gif" />
      <page pageid="1721" ns="6" title="File:BlueWaterCrewTest.doc" />
      <page pageid="1815" ns="6" title="File:Bluewater-dinghy registration-2011 2013 aug.pdf" />
      <page pageid="1820" ns="6" title="File:Candc 43 drawing.jpg" />
      <page pageid="1887" ns="6" title="File:CatCrew1 May14.jpg" />
      <page pageid="1888" ns="6" title="File:CatCrew2 May14.jpg" />
      <page pageid="1752" ns="6" title="File:Catamaran-close-hauled.png" />
    </pages>
  </query>
</api>