ARINC Specification 620 defines the interfaces between the Datalink Service Provider (DSP) and the aircraft, other ground-based datalink services, and users. The datalink ground system standard definition supports traditional ACARS and AOA protocols, as well as Media Independent Aircraft Messaging (MIAM) as defined by ARINC Specification 841. MIAM messages can be much larger than ACARS messages (5 MB versus 3.3 kB per message). Supplement 10 improves Controller-Pilot Data Link Communications (CPDLC) by defining a “Deliver By (DB)” period that allows the DSP, that originated the message, to intercept and discard the message if it is not delivered by the specified time. Supplement 10 also adds a Media Advisory code for ACARS over IP (AoIP) indicating that an ACARS non Safety Services messages is being transferred over IP links. New Reason Codes are assigned for un-transmittable or undeliverable messages. ACARS Character set clarifications are also provided in Supplement 10.