How occurs RSS forming in the format of data export to Yandex News?

Along with standard RSS 2.0 elements, in order to export data into Yandex a special elemnt "yandex-fulltext" is needed, which should contain full contents of the publication:
    <yandex-fulltext>Full contents of the publication</yandex-fulltext>

To include the full content of publications, the feed must use the additional namespace:
HTML-formatted text should be wrapped by CDATA section.
Full text should not contain the name of the source and date/time of the publication, and contact information or any other information, which is repeated in every publication.