/sys$common/syshlp/helplib.hlb BACKUP Command, Qualifiers, /EXCLUDE  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /EXCLUDE=(file-spec[,...])

    Input File-Selection Qualifier

    Excludes files that otherwise meet the selection criteria for
    a save or copy operation. If you specify more than one file,
    separate the file specifications with commas and enclose the list
    in parentheses.

    Do not use a device specification when defining the files to be
    excluded. You can use most standard wildcard characters, but you
    cannot use wildcard characters denoting latest versions of files
    (;) or relative versions of files (;-n).

    If you specify directory files (files with the file type .DIR),
    your command is processed but the directory files are not
    excluded (they are processed).

    You cannot use the /EXCLUDE qualifier in image restore
    operations.