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>
    <allimages gaicontinue="5A.jpg" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1874" ns="6" title="Fil:012-msp6-box.jpg" />
      <page pageid="1443" ns="6" title="Fil:1029.jpg" />
      <page pageid="2203" ns="6" title="Fil:1176 hintenlinks.jpg" />
      <page pageid="2204" ns="6" title="Fil:1176 innengross.jpg" />
      <page pageid="2205" ns="6" title="Fil:1176 obenhinten.jpg" />
      <page pageid="2206" ns="6" title="Fil:1176 obenvorne.jpg" />
      <page pageid="2207" ns="6" title="Fil:1176 vornebreit.jpg" />
      <page pageid="2414" ns="6" title="Fil:2 ledare skarm.jpg" />
      <page pageid="1708" ns="6" title="Fil:4001.jpg" />
      <page pageid="2547" ns="6" title="Fil:4 hogtalare.jpg" />
    </pages>
  </query>
</api>