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HTML is good for debugging, but is unsuitable for application use.
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To see the non HTML representation of the XML format, set format=xml.
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<?xml version="1.0"?>
<api>
<query-continue>
<allcategories accontinue="Epic" />
</query-continue>
<query>
<allcategories>
<c size="1" pages="1" files="0" subcats="0" xml:space="preserve">Article message templates</c>
<c size="2" pages="2" files="0" subcats="0" xml:space="preserve">Articles which use infobox templates with no data rows</c>
<c size="219" pages="219" files="0" subcats="0" xml:space="preserve">Block</c>
<c size="0" pages="0" files="0" subcats="0" xml:space="preserve">Blocks</c>
<c size="12" pages="12" files="0" subcats="0" xml:space="preserve">Bosses</c>
<c size="2" pages="2" files="0" subcats="0" xml:space="preserve">Crafting Station</c>
<c size="0" pages="0" files="0" subcats="0" xml:space="preserve">Documentation subpages without corresponding pages</c>
<c size="25" pages="25" files="0" subcats="0" xml:space="preserve">Documentation templates</c>
<c size="13" pages="13" files="0" subcats="0" xml:space="preserve">Dungeon</c>
<c size="57" pages="57" files="0" subcats="0" xml:space="preserve">Entities</c>
</allcategories>
</query>
</api>