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="Iota_tutorial_12_05182018.png" />
  </query-continue>
  <query>
    <allfileusages>
      <f ns="6" title="File:Cppxfel dials after threshold.png" />
      <f ns="6" title="File:Cppxfel dials spot finding parameters.png" />
      <f ns="6" title="File:Cppxfel dials threshold before.png" />
      <f ns="6" title="File:Cspadmetrology.png" />
      <f ns="6" title="File:Iota analysis screen 08022019.png" />
      <f ns="6" title="File:Iota main screen 08022019.png" />
      <f ns="6" title="File:Iota proc settings screen 08022019.png" />
      <f ns="6" title="File:Iota run screen 08022019.png" />
      <f ns="6" title="File:Iota tutorial 10 08022019.png" />
      <f ns="6" title="File:Iota tutorial 11 08022019.png" />
    </allfileusages>
  </query>
</api>