Likely a shorthand for the release group's name or a specific audio/video codec configuration used for that file.

A man named Paul, revealed as the disciple of the missing "Shining Star" Valkyrie, uses his Ether Gear to remove the crew's collars and hands Homura a B-Cube containing the truth about Valkyrie's fate. Understanding the Filename

The terms in your filename typically provide technical context used by fansubbing or encoding groups: Refers to the episode number.

A common multimedia container format (Matroska) that supports multiple audio tracks and subtitle streams.

This episode concludes a major portion of the with the following key events:

Despite defeating the creature to bring their "prisoner counters" to zero, Madame Kurenai reveals the counters were a lie and resets them to 100,000, intending to keep them enslaved.