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>
    <allpages gapcontinue="Belongs_to" />
  </query-continue>
  <query>
    <pages>
      <page pageid="29881" ns="104" title="Attribut:2012 registration" />
      <page pageid="29882" ns="104" title="Attribut:2014 registration" />
      <page pageid="33131" ns="104" title="Attribut:2016 registration" />
      <page pageid="37055" ns="104" title="Attribut:2018 registration" />
      <page pageid="29868" ns="104" title="Attribut:A le type" />
      <page pageid="29869" ns="104" title="Attribut:A une valeur incorrecte pour" />
      <page pageid="29883" ns="104" title="Attribut:Arrives at" />
      <page pageid="29884" ns="104" title="Attribut:Arrives on" />
      <page pageid="29885" ns="104" title="Attribut:At party" />
      <page pageid="35464" ns="104" title="Attribut:Auteur" />
    </pages>
  </query>
</api>