Overwrite
    Nooverwrite

    The Overwrite qualifier specifies that .aij files can be
    overwritten without first being backed up. The Nooverwrite
    qualifier specifies that only an .aij file that has been backed
    up can be overwritten. You can specify the Nooverwrite qualifier
    only when users are detached from the database. If you do
    not specify either the Overwrite qualifier or the Nooverwrite
    qualifier, the Overwrite characteristic remains unchanged.

    This qualifier is ignored if only one .aij file is available.
    When you specify the Overwrite qualifier, it is only activated
    when two or more .aij files are, or become, available.

    Note that if you use the Overwrite qualifier, you will be unable
    to perform a rollforward from a restored backup file. Most users
    will not want to use the Overwrite qualifier; it is provided for
    layered applications that might want to take advantage of some
    performance features provided by Oracle Rdb that require after-
    image journaling, but where the use of after-image journaling is
    not required for the application to run reliably.