Syntax options:

       USING (tx-options)
       USING DEFAULTS

    Specifies the transaction options you want for the database
    referred to by the alias in the preceding ON clause. You can
    explicitly specify the transaction, wait mode, and isolation
    level option, or you can use the DEFAULTS keyword. Using DEFAULTS
    is equivalent to specifying READ WRITE WAIT. For more information
    on DEFAULTS, see the Oracle Rdb SQL Reference Manual.