It must be one of the following characters (not case-sensitive):
O - OSVS COBOL dialect V - VS COBOL II dialect, default level 1 - VS COBOL II dialect, level 1 2 - VS COBOL II dialect, level 2 3 - VS COBOL II dialect, level 3 4 - VS COBOL II dialect, level 4 D - DOSVS COBOL dialect 0 - not specified