All software. GEMS. AVTS. AVOS. Card Manager. You name it.
A - marketing number. bump when something is rewritten (seems to happen a lot with some projects) or when Barry feels like we can charge more for a bigger number.
B - major release number. changes that affect system compatibility.
C - minor release number. changes that don't affect system compatibility.
i - internal pre-releases created during testing and development before a public release
Outside a numbering system, major release branches are declared stable or development. Only bugfix changes are made to stable release branches. That is, no new features are added to a stable release, whether it would affect compatibility or not. By their nature, only stable releases should be sent for certification. Right now, GEMS 1.11 and 1.17 are stable.