Discussing ROM packs requires addressing the legal reality. The legality of downloading ROMs is a complex, grey area, but here are the general principles:
Anyone else packing lean sets for their arcade cabinet or Batocera build? What’s your go‑to filter list? pack rom mame
MAME is an open-source project under constant development. As developers improve the emulation accuracy of specific hardware, they sometimes discover that the previous way they "read" the ROM files was incorrect. Consequently, they change the filename requirements or the internal checksums required for a game to work. Discussing ROM packs requires addressing the legal reality
When you download a "ROM Pack" for MAME, you are downloading a ZIP folder containing all these individual files, named precisely how MAME expects them to be named. pack rom mame