There are two kinds of ticket change: change and transfer. Change of visa, also known as rescheduling, refers to the change made when the guest's itinerary remains unchanged and the carrier's airline remains unchanged. There are two kinds of changes: changes at the same level and upgrades. The change of the same cabin refers to the change of the airline and the same cabin; Upgrade refers to the change of the same airline, but the discount of the changed cabin is higher than that of the original booking cabin.