The Space service lets you space (skip) a tape file forward or
    backward a specified number of blocks.

                         RAB64 USERS (ALPHA ONLY)

       On Alpha systems, RAB64 can replace the RAB or RAB prefix
       wherever it is used with the Space service on OpenVMS Alpha
       systems.

    Format

      SYS$SPACE  rab [,[err] [,suc]]

1  –  Returns

    OpenVMS usage:cond_value
    type:         longword
    access:       write only
    mechanism:    by value

    The value is returned in symbolic offset RAB$L_STS. Symbolic
    offset RAB$L_STV may contain additional status information.

2  –  Arguments

 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 Space 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.

3  –  Condition Values Returned

 The following condition values can be returned. Use the Help Message
 utility to access online message descriptions.