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 atcontinue="Editor_Settings" />
  </query-continue>
  <query>
    <alltransclusions>
      <t ns="10" title="Template:Back" />
      <t ns="10" title="Template:Commands for switching pages" />
      <t ns="10" title="Template:Component card" />
      <t ns="10" title="Template:Connection to iRidium Gate via the Internet" />
      <t ns="10" title="Template:Creation of Graphic Interfaces" />
      <t ns="10" title="Template:Creation of New Projects" />
      <t ns="10" title="Template:Creation of graphic interfaces" />
      <t ns="10" title="Template:Definition" />
      <t ns="10" title="Template:Download a project" />
      <t ns="10" title="Template:Download the project" />
    </alltransclusions>
  </query>
</api>