Why does Yandex have most of the pages in xml format?

Question

Yandex

Very often I use some Yandex services and it constantly attracted my attention that most of the pages have an xml extension and the first line in the form
<?xml version="1.0" encoding="UTF-8"?>
For example: my.ya.ru/options_others_export.xml
But after the first line comes html. Why and why?
What is the meaning of such a construction of pages?

Answer 1

because there is xhtml - which is essentially xml.