VMS Help SET, FILE, /BI_JOURNAL, Description  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    The SET FILE/BI_JOURNAL command marks one or more RMS files
    for before-image journaling. You can also specify certain
    characteristics of the journal with this command, including its
    file specification, whether it is to be created, its initial
    size, and its default extension quantity. The SET FILE/NOBI_
    JOURNAL command unmarks a file for before-image journaling.

    After a data file is marked for before-image journaling with the
    SET FILE/BI_JOURNAL command, the following events occur whenever
    the data file is opened by RMS for write operations:

    o  The journal is opened.

    o  All subsequent modifications to the data file are recorded in
       the journal.

    By default, the journal has the same file specification as
    the data file that is to be journaled, but with the file type
    RMS$JOURNAL. That is, if you issue the following command, then,
    by default, the file specification for the before-image journal
    is FINANCE_DISK:PAYROLL.RMS$JOURNAL:

    $ SET FILE/BI_JOURNAL FINANCE_DISK:PAYROLL.DAT

    If erroneous or corrupt data is introduced into the data file,
    you can use the RMS Recovery Utility to "roll back" the data file
    that has been marked for before-image journaling. This will allow
    you to restore the data file to a previous state by removing data
    until a specified time (prior to the introduction of bad data).

    Use the SET FILE/NOBI_JOURNAL command to unmark a file for
    before-image journaling. After you use the SET FILE/NOBI_JOURNAL
    command for a file, modifications to that data file will no
    longer be written to the journal.

    You must use the SET FILE/NOBI_JOURNAL command before you can
    delete a file that has been marked for before-image journaling.