Fiddling with Travelocity fare listings in search of mistake fares and low longhaul pricing ex various EU points, I found this BA fare on PRG-CCS:

FARE CODE: LHRCEUR

INSTANT PURCHASE EXCURSION SPECIAL FARE FARE

BK CODE: L

FLT APPL: APPLIES TO ANY BA FLIGHT ON THE DEPARTURE OF EACH TRANSATLANTIC SECTOR.

AFAIK, BA has stopped service to CCS. So how would such an itin be ticketed?
The only fares that BA publish in the UK for flights to CCS are full fare (Y, W, D, J, C, F). The somewhat restricted Y2R stipulates the following under Flt Appl:
APPLY ONE OF THE FOLLOWING FLIGHT PROVISIONS ----------------------PROVISION 1------------------------ APPLIES TO ANY BA FLIGHT BETWEEN LON AND NYC/HOU AND APPLIES TO ANY CO/AA FLIGHT BETWEEN NYC/HOU AND CCS. ----------------------PROVISION 2------------------------ APPLIES TO ANY BA FLIGHT BETWEEN LON AND DFW/MIA AND APPLIES TO ANY AA/AV FLIGHT BETWEEN DFW/MIA AND CCS.

So the provisions are somewhat different to the PRG fare, and this certainly is much closer to a fully flexible IATA fare. After all, it costs 3 times as much as the L ex PRG.
Can any of the experts advise on how this has come about?
Also, don't you think it's a bit strange that BA don't codeshare with IB on the S.Am. destinations not served by themselves?
My question is purely encyclopaedic, I am not likely to purchase such a fare, but that doesn't stop me from being curious.