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"?>
    <allcategories accontinue="БПЛА" />
      <c size="2" pages="2" files="0" subcats="0" xml:space="preserve">Авианесущие корабли</c>
      <c size="2" pages="2" files="0" subcats="0" xml:space="preserve">Авиапресса</c>
      <c size="119" pages="104" files="0" subcats="15" xml:space="preserve">Авиатехника</c>
      <c size="10" pages="9" files="0" subcats="1" xml:space="preserve">Авиационное вооружение</c>
      <c size="12" pages="11" files="0" subcats="1" xml:space="preserve">Авиационное оборудование</c>
      <c size="26" pages="25" files="0" subcats="1" xml:space="preserve">Авиационные двигатели</c>
      <c size="48" pages="48" files="0" subcats="0" xml:space="preserve">Авиационные конструкторы</c>
      <c size="14" pages="14" files="0" subcats="0" xml:space="preserve">Авиация ВМФ</c>
      <c size="5" pages="5" files="0" subcats="0" xml:space="preserve">Авиация ПВО</c>
      <c size="38" pages="38" files="0" subcats="0" xml:space="preserve">Аэродромы</c>