The naming convention follows standard digital media archiving practices:
Refers to the specific sequence or version. In series with multiple endings, "1" denotes the first ending theme (ED 1), and "e" might signify a specific variant or edit (such as a TV-sized version vs. a Blu-ray edit). Clean Ending 1e.mkv
An open-standard container format known for holding multiple video, audio, and subtitle tracks in a single file without losing quality. Usage in Media and Archiving Clean Ending 1e.mkv