Скорее всего, речь идет об этом:

In the simplest case, airline A would have to "endorse" the ticket to airline B. Doing so would authorize airline B to collect the value of that leg of the ticket from the ticket clearinghouse (all tickets go to a clearinghouse after they're used to sort out payments).

Airline A may choose not to endorse the ticket, and generally they are under no obligation to do so. If a flight is canceled on airline A, they may agree to endorse the ticket to airline B to keep the customer happy. Some consolidator fare tickets are marked "non-endorsable", meaning that airline A could not endorse the ticket to airline B even if they wanted to do so.

http://www.travelterminal.com/airportfaq.shtml


На самом деле все происходит совсем не так, как в действительности.