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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>
    <pageswithprop gpwpcontinue="83" />
  </query-continue>
  <query>
    <pages>
      <page pageid="2" ns="0" title="Página principal" contentmodel="wikitext" pagelanguage="es" touched="2016-02-20T11:14:06Z" lastrevid="548" counter="477649" length="3962" />
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      <page pageid="4" ns="0" title="Evaluación de riesgos" contentmodel="wikitext" pagelanguage="es" touched="2015-11-19T23:52:30Z" lastrevid="432" counter="9758" length="2790" />
      <page pageid="9" ns="0" title="Servicio de Prevención" contentmodel="wikitext" pagelanguage="es" touched="2016-01-04T11:29:04Z" lastrevid="507" counter="4634" length="3915" />
      <page pageid="25" ns="0" title="R.D. 1627/1997 Obras de Construcción" contentmodel="wikitext" pagelanguage="es" touched="2016-08-04T09:54:10Z" lastrevid="698" counter="3294" length="3117" />
      <page pageid="30" ns="0" title="Proyectista" contentmodel="wikitext" pagelanguage="es" touched="2016-09-22T07:35:10Z" lastrevid="1174" counter="2598" length="924" />
      <page pageid="49" ns="0" title="R.D. 1215/1997 Equipos de trabajo" contentmodel="wikitext" pagelanguage="es" touched="2016-07-25T18:37:26Z" lastrevid="645" counter="3088" length="1606" />
      <page pageid="50" ns="0" title="R.D. 487/1997 Manipulación manual de cargas" contentmodel="wikitext" pagelanguage="es" touched="2016-08-03T07:04:25Z" lastrevid="694" counter="4195" length="3481" />
      <page pageid="51" ns="0" title="Manipulación manual de cargas" contentmodel="wikitext" pagelanguage="es" touched="2015-12-31T09:19:24Z" lastrevid="467" counter="5213" length="6549" />
      <page pageid="53" ns="0" title="R.D. 488/1997 Pantallas de visualización de datos" contentmodel="wikitext" pagelanguage="es" touched="2016-08-03T07:44:39Z" lastrevid="695" counter="2264" length="3606" />
    </pages>
  </query>
</api>