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>
<allcategories accontinue="Agriculture" />
</query-continue>
<query>
<allcategories>
<c size="0" pages="0" files="0" subcats="0" xml:space="preserve">19th Century History</c>
<c size="1" pages="1" files="0" subcats="0" xml:space="preserve">19th Century United States</c>
<c size="0" pages="0" files="0" subcats="0" xml:space="preserve">20th Century History</c>
<c size="1" pages="1" files="0" subcats="0" xml:space="preserve">A. G. Roeber</c>
<c size="1" pages="1" files="0" subcats="0" xml:space="preserve">Adam M. McKeown</c>
<c size="1" pages="1" files="0" subcats="0" xml:space="preserve">Adam Rome</c>
<c size="1" pages="1" files="0" subcats="0" xml:space="preserve">Advertising and Business</c>
<c size="1" pages="1" files="0" subcats="0" xml:space="preserve">African American</c>
<c size="1" pages="1" files="0" subcats="0" xml:space="preserve">African History</c>
<c size="1" pages="1" files="0" subcats="0" xml:space="preserve">Agrarian Societies</c>
</allcategories>
</query>
</api>