MiSTer MRA files.
All MRA files support merged, nonmerged and split MAME rom sets.
The _Clones directory contains clones of the base game as per MAME's game database. Within each game specific _Clone directory there is also a _NotWorking directory. These clones could not be made to work with the Arcade core for various reasons.
In the case where the clone runs on different hardware, if there is a relevant core for that hardware the clone is configured to run on it if possible.