What about SQ?
I think I’m pretty sure it refers to Singapore Airlines flights…but does it also refer to some airport security or improvement fee, on an AC ticket receipt?
Or is the latter rarely mentioned, and SQ is almost always intended to refer to the airline? I got confused with it on all the banter that was going on during last month's 18 days of craziness (especially on all those mini-RTWs booked on J/F rewards, using the fewer-required Y points).