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="Gp.jpg|1153" />
  </query-continue>
  <query>
    <pages>
      <page pageid="59" ns="0" title="Border" />
      <page pageid="60" ns="0" title="Bridge Crossing" />
      <page pageid="61" ns="0" title="Bridge SE" />
      <page pageid="62" ns="0" title="Dusk" />
      <page pageid="72" ns="0" title="FLS Assault" />
      <page pageid="1052" ns="0" title="Collapsed Tunnel" />
      <page pageid="1137" ns="0" title="M141 Bunker Defeat Munition (BDM)" />
      <page pageid="1145" ns="0" title="M84 Stun Grenade" />
      <page pageid="1147" ns="0" title="AGP-DB14 Door Breaching Charge" />
    </pages>
  </query>
</api>