Originally Posted by stephem

For whatever reason, the OTA businessclass.com seems to be one of the better ones in terms of the "permissibility" of its validation logic and checks. What I mean by flexibility, is that it seems to have a list of all valid codeshares, and it just seems to be asking "is there an IB or AY coded flight on this segment?" and "do the flight restrictions in the fare rules allow that codeshare to be used in the underlying pricing unit?" and "do the sales restrictions in the fare allow me to plate the ticket on this carrier?". Many other tools, including I believe even ITA, tend to have some other level of check, so for instance they are unlikely to plate on a carrier due only to the use of longhaul codeshares, especially if the codeshare carrier doesnt have its own fare on the route in question. So if you look, AY and IB dont file fares for JNB-LAX, but BA fares do allow ticketing on AY/IB stock if other requirements are met. Businessclass.com seems to have been written to the max in terms of permissibility. But if you want AA or BA codes for upgrade purposes, the $2k to $2.1k seems like a good deal still and you can book those everywhere.

Reminder, Travelport still has some useful information Plating Carrier Logic and even some stuff about the S1 records (YQ-YR) now that ATPCO has taken then document down