Do you remember or if it was part of a specific online community ?
A common choice for macOS users to handle varied compression formats. M M08216205.7z
In many ROM sets, files are named using shorthand codes or hash-like strings. The "M" could denote a "Main" set or a specific manufacturer. Do you remember or if it was part
If found on The Internet Archive, this is likely a piece of a larger collection (e.g., "M" for Magazines, Music, or MAME) compressed for easier distribution. "M" for Magazines