Which is great if the issuing airline has ticketing facilities at the airport where you're trying to check in. At HKG, for example, there are no AA ticketing facilities so I'd have to make a special trip to their GSA (which may be what I end up doing to avoid the stress at the airport). But this should all be unnecessary. A ticket is a ticket. It has all the information on it that the airline needs - Booking Class (A), Validity dates, and the endorsement "Valid on OneWorld airlines" (or a list of the airlines), and the ticket number. That's all it should need to be a valid ticket.