A PC routine can receive control in either 24-bit addressing mode or 31-bit addressing mode. If you specify the ROUTINE parameter on the ETDEF macro, you can specify RAMODE on ETDEF to indicate the PC routine's addressing mode. If you specify the PROGRAM parameter on ETDEF, then the system locates the PC routine and determines its addressing mode. The default is to pass control to the PC routine in 31-bit addressing mode.