ASM.compatible for a diskgroup created in ASM 12c
Oracle® Automatic Storage Management
Administrator's Guide 12c Release 1 (12.1) E17612-19
COMPATIBLE.ASM
The value for the disk group COMPATIBLE.ASM attribute determines the minimum software version for an Oracle ASM instance that can use the disk group. This setting also affects the format of the data structures for the Oracle ASM metadata on the disk. The format of other file contents is determined by Oracle ASM Dynamic Volume Manager (Oracle ADVM) and the database instance.