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"?>
    <allfileusages gafcontinue="Custom_report_search_form.png" />
      <page pageid="2802" ns="6" title="File:Bad robots.txt" />
      <page pageid="2882" ns="6" title="File:Bazaar-entry.jpg" />
      <page pageid="1936" ns="6" title="File:Browse by journal.png" />
      <page pageid="1937" ns="6" title="File:Browse by journal volume.png" />
      <page pageid="1933" ns="6" title="File:Browse by navbar.png" />
      <page pageid="2883" ns="6" title="File:Config-after.jpg" />
      <page pageid="2884" ns="6" title="File:Config.jpg" />
      <page pageid="2899" ns="6" title="File:Create user ss.png" />
      <page pageid="2900" ns="6" title="File:Create user stage 1 ss.png" />
      <page pageid="2901" ns="6" title="File:Create user stage 2 ss.png" />