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>
    <alltransclusions gatcontinue="LG_battery_notes" />
  </query-continue>
  <query>
    <pages>
      <page ns="10" title="Template:ContainerClasses" missing="" />
      <page pageid="40" ns="10" title="Template:Battery pinout abbreviations" />
      <page pageid="6101" ns="10" title="Template:BlacBerry battery seealso" />
      <page pageid="5647" ns="10" title="Template:BlackBerry battery notes" />
      <page pageid="6103" ns="10" title="Template:BlackBerry battery pinout seealso" />
      <page pageid="5648" ns="10" title="Template:BlackBerry battery seealso" />
      <page pageid="5528" ns="10" title="Template:Ericsson battery notes" />
      <page pageid="5531" ns="10" title="Template:Ericsson battery seealso" />
      <page pageid="5644" ns="10" title="Template:HTC battery notes" />
      <page pageid="5645" ns="10" title="Template:HTC battery seealso" />
    </pages>
  </query>
</api>