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 afcontinue="Del_centr_f1.png" />
  </query-continue>
  <query>
    <allfileusages>
      <f ns="6" title="File:Band4 phase diff.png" />
      <f ns="6" title="File:Baseline solved-v-fghz.png" />
      <f ns="6" title="File:Baseline solved.png" />
      <f ns="6" title="File:Bz figure.png" />
      <f ns="6" title="File:Bz figure corrected.png" />
      <f ns="6" title="File:Cal src vis.png" />
      <f ns="6" title="File:Calib 20160116.png" />
      <f ns="6" title="File:Clean.png" />
      <f ns="6" title="File:Color.png" />
      <f ns="6" title="File:Coords Antenna position wiki fig1.gif" />
    </allfileusages>
  </query>
</api>