A matroska file extension is related to the MPG and MKV Player software.
MATROSKA file extension - MPG and MKV Player data
What is matroska file? How to open matroska files?
File type specification:
The matroska file extension is associated with the MPG and MKV Player, a software for Microsoft Windows operating system that allows users playback multimedia data.
The matroska file stores some kind of information about *.mkv files.
This matroska file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.