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"?>
    <alltransclusions gatcontinue="Enlace_roto" />
      <page ns="10" title="Plantilla:Editar/uso" missing="" />
      <page pageid="88" ns="10" title="Plantilla:Ca" />
      <page pageid="184" ns="10" title="Plantilla:Cita requerida" />
      <page pageid="386" ns="10" title="Plantilla:Clear" />
      <page pageid="378" ns="10" title="Plantilla:Column-count" />
      <page pageid="376" ns="10" title="Plantilla:Div col" />
      <page pageid="377" ns="10" title="Plantilla:Div end" />
      <page pageid="22" ns="10" title="Plantilla:Editar" />
      <page pageid="98" ns="10" title="Plantilla:En" />
      <page pageid="18" ns="10" title="Plantilla:En desarrollo" />