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="B17jp.jpg" />
  </query-continue>
  <query>
    <pages>
      <page pageid="104665" ns="6" title="File:B-17G Nose in Detail.jpg" />
      <page pageid="104666" ns="6" title="File:B-17G formation on bomb run.jpg" />
      <page pageid="104667" ns="6" title="File:B-17 Damage Cologne.jpg" />
      <page pageid="104664" ns="6" title="File:B-17 at Mighty 8th Air Force Museum, Pooler, GA, US.jpg" />
      <page pageid="104660" ns="6" title="File:B-17 on bomb run.jpg" />
      <page pageid="104662" ns="6" title="File:B-17dorsalview.jpg" />
      <page pageid="104917" ns="6" title="File:B-38 cannon for MK-5.jpg" />
      <page pageid="101043" ns="6" title="File:B.B.T.Br.Panc-003.jpg" />
      <page pageid="9233" ns="6" title="File:B1-cap.png" />
      <page pageid="104663" ns="6" title="File:B17 - Chino Airshow 2014 (framed).jpg" />
    </pages>
  </query>
</api>