Allowing the flight crew to print messages, if an onboard printer is available.
Allowing the flight crew to load specific uplink messages into the Flight Management System (FMS), reducing input errors.
Allowing the crew to downlink a complex route clearance request, which the controller can automatically include in the uplink clearance, if approved, without having to type a long string of coordinates.
Specific uplink messages arm the FMS to automatically downlink a report when an event, such as crossing a waypoint, occurs. This automation assists with workload management for the flight crew and the controller.
Specific downlink messages, and the response to some uplink messages will automatically update the Flight Data Record in some ground systems.