About 30% of the games marked as "working" in 2003 have since been proven to have wrong colors, missing sound channels, or incorrect protection emulation. Star Wars (vector) has shaky aiming. NBA Jam runs slightly too fast. Purists will twitch.
A complete reference set typically includes three distinct types of data: MAME 2003 Reference Set - MAME 0.078 ROMs- CHDs...