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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>
    <images imcontinue="13|Legensteinhütte_mit_Lightmeter_2017-02_12_IMAG0106.jpg" />
  </query-continue>
  <query>
    <pages>
      <page pageid="13" ns="0" title="Main Page">
        <images>
          <im ns="6" title="File:551086 OÖ Umweltanwalt Urteil des LVWG zu Effektbeleuchtung in Natura-2000-Gebiet.pdf" />
          <im ns="6" title="File:Aurora 2015-03-18 TLS.png" />
          <im ns="6" title="File:Dürrenstein Verteilung-2019-2020.png" />
          <im ns="6" title="File:Fireball at Tautenburg March2015 2015-03-15.png" />
          <im ns="6" title="File:Format SkysensorKepler-Sternwarte at LINZ 1 - Jän. - Jul. 2013 dist night.png" />
          <im ns="6" title="File:Hohe Warte Lightmeter 20200429 122628 1024.png" />
          <im ns="6" title="File:IMAG0576.jpg" />
          <im ns="6" title="File:IMG 20170622 084252.jpg" />
          <im ns="6" title="File:IMG 20190823 172828.jpg" />
          <im ns="6" title="File:JP Setagaya 1 Jun-Dec 2012 distribution.png" />
        </images>
      </page>
    </pages>
  </query>
</api>