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="BI:Business_Inteligence:BIREL_FATURAS_POR_MES_1" />
  </query-continue>
  <query>
    <allpages>
      <p pageid="3493" ns="0" title="BI" />
      <p pageid="3491" ns="0" title="BI:Business Inteligence" />
      <p pageid="3541" ns="0" title="BI:Business Inteligence:BIREL CLIENTES POR CIDADE" />
      <p pageid="3543" ns="0" title="BI:Business Inteligence:BIREL CLIENTES POR DATA CADASTRO" />
      <p pageid="3544" ns="0" title="BI:Business Inteligence:BIREL CLIENTES POR DATA CADASTRO PLANO" />
      <p pageid="3542" ns="0" title="BI:Business Inteligence:BIREL CLIENTES POR DATA NASCIMENTO" />
      <p pageid="3546" ns="0" title="BI:Business Inteligence:BIREL CLIENTES POR PLANO" />
      <p pageid="3545" ns="0" title="BI:Business Inteligence:BIREL CLIENTES POR VENDEDOR" />
      <p pageid="3530" ns="0" title="BI:Business Inteligence:BIREL FATURAS POR ANO" />
      <p pageid="3495" ns="0" title="BI:Business Inteligence:BIREL FATURAS POR MES" />
    </allpages>
  </query>
</api>