VMS Help BACKUP Command, Qualifiers, /EXACT_ORDER  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Output Save-Set Qualifier

    Depending on the other qualifiers you specify on the command
    line, the /EXACT_ORDER qualifier allows you to perform the
    following actions: The /EXACT_ORDER qualifier allows you to
    perform the following actions:

    o  Specify the exact order of tape volume labels that you
       want to use in a BACKUP operation. You must use the
       /LABEL=(label1,label2,...) qualifier to specify the order
       of the labels. BACKUP continues the operation as long as the
       label of the tape in the drive matches the corresponding label
       on the command line. If you do not specify enough labels on
       the command line to complete the operation, BACKUP prompts you
       to enter a label for the tape in the drive.

    o  Preserve the existing volume label on a tape. If you do not
       use the /LABEL qualifier on the command line and the tape has
       an ANSI label, BACKUP uses the existing label.

    o  Prevent previous volumes of a multivolume save operation from
       being overwritten. BACKUP keeps track of the volume labels you
       have already used in the operation. If you accidently mount
       one of the previous volumes, BACKUP displays the following
       error message:

       %BACKUP-W-MOUNTERR, volume 1 on MKB100: was not mounted because
        its label does not match the one requested
        Volume with label TAPE1 was already used in this save operation
        specify option (QUIT or NEW tape)
       BACKUP>

    Note the following restrictions when you use the /EXACT_ORDER
    output qualifier:

    o  If you use the /EXACT_ORDER qualifier, you cannot specify a
       label longer than six characters on the command line. If you
       specify a label longer than six characters, BACKUP displays
       the following error message:

       %BACKUP-F-INVQUAVAL, value 'label_name' invalid for /LABEL qualifier

    o  You cannot use the /IGNORE=LABEL_PROCESSING qualifier with the
       /EXACT_ORDER qualifier.

    o  If you use the /LABEL qualifier with the /EXACT_ORDER
       qualifier, you cannot specify duplicate labels.

    The default is /NOEXACT_ORDER.