Rules
Starting from 21.3, the Offer and Order messages will become backwards compatible for all future releases according to the rules defined by the Offer & Order and CMIG Working Groups. These messages will follow the below rules to ensure backwards compatible changes.
Scope
Backwards Compatibly will be enforced for all Offer & Order Messages within the Enhanced and Simplified Distribution messages. (Seller <-> Airline interactions).
Best efforts for backwards compatibility for Accounting and Delivery messages
Interline messages will not be backwards compatible.