That is a valid question. Generally, you should always use the latest version of the FBNeo core.

: One of the primary reasons users seek specific FBNeo sets is the emulator's native support for RetroAchievements , a feature that MAME generally does not support. The "Exclusive" Appeal

FBNeo follows a rolling release model, but major milestones are marked by version numbers. The standard public releases hover around versions 1.0.0.2, 1.0.0.3, etc. So where does come from?