Main S.Y.S.T.E.M program. - Designed for internal use.
End-User program. - Designed for Users and user-focused programs.
(Most should be labeled as 'S.U.B-S.Y.S.T.E.M' unless system is large.)
Reserved. - Designed for programs that should do one simple task, and remain focused on it.
(If program does only one task, this label should be applied.)