The RMU /SET command "DATABASE /TRANSACTION_MODE=(...)" allows
    altering of the database-allowed transaction modes without
    marking the database as modified. This command is intended to be
    used to set the transaction modes allowed on a standby database.
    This command requires exclusive database access (the database
    cannot be open or be accessed by other users).

    Because only read-only transactions are allowed on a standby
    database, you may wish to use the TRANSACTION_MODE=READ_ONLY
    qualifier setting on a standby database. This setting prevents
    modifications to the standby database at all times, even when
    replication operations are not active.

    The RMU /SET DATABASE command requires a database specification.
    Valid keywords for the RMU /SET DATABASE /TRANSACTION_MODE=(...)
    qualifier are:

    o  ALL - Enables all transaction modes

    o  CURRENT - Enables all transaction modes that are set in the
       database

    o  NONE - Disables all transaction modes

    o  [NO]BATCH_UPDATE

    o  [NO]READ_ONLY

    o  [NO]EXCLUSIVE

    o  [NO]EXCLUSIVE_READ

    o  [NO]EXCLUSIVE_WRITE

    o  [NO]PROTECTED

    o  [NO]PROTECTED_READ

    o  [NO]PROTECTED_WRITE

    o  [NO]READ_WRITE

    o  [NO]SHARED

    o  [NO]SHARED_READ

    o  [NO]SHARED_WRITE

    If you specify more than one transaction mode in the mode-list,
    enclose the list in parenthesis and separate the transaction
    modes from one another with a comma. Note the following:

    o  When you specify a negated transaction mode, it indicates
       that a mode is not an allowable access mode. For example, if
       you specify the Noexclusive_Write access mode, it indicates
       that exclusive write is not an allowable access mode for the
       restored database.

    o  If you specify the Shared, Exclusive, or Protected transaction
       mode, Oracle RMU assumes you are referring to both reading and
       writing in that transaction mode.

    o  No mode is enabled unless you add that mode to the list or you
       use the All option to enable all transaction modes.

    o  You can list one transaction mode that enables or disables a
       particular mode followed by another that does the opposite.

       For example, /TRANSACTION_MODE=(NOSHARED_WRITE, SHARED) is
       ambiguous because the first value disables Shared_Write access
       and the second value enables Shared_Write access. Oracle
       RMU resolves the ambiguity by first enabling the modes as
       specified in the modes-list and then disabling the modes as
       specified in the modes-list. The order of items in the list is
       irrelevant. In the example presented previously, Shared_Read
       is enabled and Shared_Write is disabled.