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 apcontinue="Comment_insérer_une_pièce_jointe_dans_votre_message" />
  </query-continue>
  <query>
    <allpages>
      <p pageid="96" ns="0" title="Bull express 5800/LH120-Outil collaboratif" />
      <p pageid="97" ns="0" title="Bull express 5800/LH120-Test" />
      <p pageid="148" ns="0" title="CODES HORAIRES" />
      <p pageid="2135" ns="0" title="Calendrier zimbra" />
      <p pageid="420" ns="0" title="Carambole" />
      <p pageid="8" ns="0" title="Cocktail:Accueil" />
      <p pageid="2007" ns="0" title="Code NINE" />
      <p pageid="2005" ns="0" title="Code RNE" />
      <p pageid="2006" ns="0" title="Code SISE" />
      <p pageid="2008" ns="0" title="Code des UE et des EC" />
    </allpages>
  </query>
</api>