The OrderChangeNotif message allows partners to be informed when changes are made to the NDC order, initiated by the airline. The change can be voluntary, upon the passenger request, or involuntary based on operational constraints. An acknowledgement message is then returned by the Seller/Aggregator to the airline. Only Light OrderChangeNotif implementation is currently supported: only a "reason for change" categorizing the change is transmitted to the Seller/Aggregator. Partners are expected to retrieve the order to determine the changes, as specific details will not be sent in OrderChangeNotif.