rab OpenVMS usage:rab type: longword (unsigned) access: modify mechanism: by reference RAB control block whose contents are to be used as indirect arguments for the Truncate service call. The rab argument is the address of the RAB control block. err OpenVMS usage:ast_procedure type: procedure value access: call without stack unwinding mechanism: by reference AST-level error completion routine that the service invokes if the operation is unsuccessful. The err argument is the address of the entry mask of this user-written completion routine. suc OpenVMS usage:ast_procedure type: procedure value access: call without stack unwinding mechanism: by reference AST-level success completion routine that the service invokes if the operation is successful. The suc argument is the address of the entry mask of this user-written completion routine.