A file specification for the backup file produced by a previous
    RMU Backup command. The default file extension is .rbf.

    Note that you cannot perform a remote restore operation on an
    .rbf file that has been backed up to tape and then copied to
    disk. When copying .rbf files to disk from tape, be sure to copy
    them onto the system on which you will be restoring them.

    Depending on whether you are performing a restore operation
    from magnetic tape, disk, or multiple disks, the backup file
    specification should be specified as follows:

    o  Restoring from magnetic tape

       If you used multiple tape drives to create the backup file,
       the backup-file-spec parameter must be provided with (and only
       with) the first tape drive name. Additional tape drive names
       must be separated from the first and subsequent tape drive
       names with commas, as shown in the following example:

       $ RMU/RESTORE /REWIND $111$MUA0:PERS_FULL_NOV30.RBF,$112$MUA1:

    o  Restoring from multiple or single disk files

       If you used multiple disk files to create the backup file,
       the backup-file-spec parameter must be provided with (and only
       with) the first disk device name. Additional disk device names
       must be separated from the first and subsequent disk device
       names with commas. You must include the Disk_file qualifier.
       For example:

       RMU/RESTORE/ONLY_ROOT/DISK_FILE DISK1:[DIR1]MFP.RBF,DISK2:[DIR2],
       DISK3:[DIR3]

       As an alternative to listing the disk device names on the
       command line (which can exceed the line-limit lenght for a
       command line if you use several devices), you can specify an
       options file in place of the backup-file-spec. For example:

       $ RMU/RESTORE/ONLY-ROOT/DISK_FILE" @DEVICES.OPT"

       The contents of devices.opt might appear as follows:

       DISK1:[DIR1]MFP.RBF
       DISK2:[DIR2]
       DIS3:[DIR3]

       The backup files referenced from sjuch an options file are:

       DISK1:[DIR1]MFP.RBF
       DISK2:[DIR2]MFP01.RBF
       DISK3:[DIR3]MFP02.RBF