Originally Posted by ETStar
Then what happens when, say an agent looks up seat availability, charges the customer based on GDS X's inaccurate availability info and he/she goes on his merry way? Would the airline refuse ticketing?
Availability normally gets re-checked by the airline at the time the actual booking is made. It shouldn't happen often, but there is a potential possibility that the airline will not confirm the booking, even though the availability screen says there is availability. After the booking is confirmed by the airline, availability no longer matters.