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="Beresford_in_his_Conning_Tower.jpg|2708" />
  </query-continue>
  <query>
    <allfileusages>
      <f fromid="3756" ns="6" title="File:BBC StromnessMuseum MarkVIIIDumaresq 1.jpg" />
      <f fromid="3756" ns="6" title="File:BBC StromnessMuseum MarkVIIIDumaresq 2.jpg" />
      <f fromid="3756" ns="6" title="File:BBC StromnessMuseum MarkVIIIDumaresq 3.jpg" />
      <f fromid="3877" ns="6" title="File:BR1534 Plate4.jpg" />
      <f fromid="3142" ns="6" title="File:Backhouse, Oliver, Australia IWM Q 18757.jpg" />
      <f fromid="3406" ns="6" title="File:Backhouse in Lion, National Archives of Canada PA-6543.jpg" />
      <f fromid="2393" ns="6" title="File:Ballard, NPG Ax39039.jpg" />
      <f fromid="2740" ns="6" title="File:Barlow.jpg" />
      <f fromid="2705" ns="6" title="File:Beaumont, RCN.jpg" />
      <f fromid="2708" ns="6" title="File:Beresford.jpg" />
    </allfileusages>
  </query>
</api>