Some addl info. The rate at which rule 120'd tickets, are setteled at, is actually something that flucuates. As is the rate for INVOL rerouting of tickets. These rates can range from 50% of full Y, to 150% of full Y. How those percentages are picked I have no confirmation of, although I assume it is based on load factor trends. Most of these tickets are audited by the airline, and sent to IATA clearing houses where they are tallied for billing against other carriers. My understanding is that a lot of the time these are basically "paper" bills, that cancel eachother out at the end of the month. (ie what UA owes AA vs what AA owes UA) Some tickets believe it or not, are actually baled up and weighed, and the issuing airline is charged a price per pound as opposed to what the face value of said tickets were. (I've seen this with my own eyes)
As for another carrier forcing an endorsement on a full fare tkt, I too have had this happen to me numerous times Agent. The carrier forcing the issue is losing money on that ticket, as the price will then be fared out at a percentage of the face value instead of the whole thing. (assuming full Y)
Let's not even get into intl endorsements, as it seems very few agents at ANY US airline are trained on, or even informed of, Rule 735D which is the intl equivelent of a domestic rule 120. I've had passengers sent back headed to LHR, with the other airline (AA in this case) demanding a rule 120 on their BOS-LHR segment, because they had never heard of 735D. Putting a 120 on that segment meant AA got not a nickel for carrying that pax for us. (Barring some backroom diplomacy) By rights that tkt becomes invalid once I put that on there. Oh well, my passenger got taken care of, but just goes to show how confusing endorsements can sometimes be.

[This message has been edited by GGpillow (edited 04-18-2002).]