The Disconnect service breaks the connection between a RAB and a
    FAB, thereby terminating a record stream. All system resources,
    such as I/O buffers and data structure space, are deallocated.

                         RAB64 USERS (ALPHA ONLY)

       On Alpha systems, RAB64 can replace the RAB or RAB prefix
       wherever it is used with the Disconnect service on OpenVMS
       Alpha systems.

    Format

      SYS$DISCONNECT  rab [,[err] [,suc]]