Acl
    Noacl

    Specifies whether to back up the root file access control list
    (ACL) for a database when you back up the database. The root file
    ACL controls users privileges to issue Oracle RMU commands.

    If you specify the Acl qualifier, the root file ACL will be
    backed up with the database.

    If you specify the Noacl qualifier, the root file ACL will not
    be backed up with the database. The Noacl qualifier can be
    useful if you plan to restore the database on a system where
    the identifiers in the current root file ACL will not be valid.

    The default is the Acl qualifier.