Below is a matrix fare breakout that shows 2625NOK as BA YQ. None of the flights OSL-HEL-JFK-LAX are BA operated, but BA marketed. What is the basis for this component (easily the largest non fare portion)?
TIA
OSL to LAX kr 12 879,00
Passenger type ADT, round trip fare, booking code R, J
Covers OSL-HEL (Business), HEL-JFK (Business), JFK-LAX (Business)

Fare 2: Carrier IB INN4C7S4 LAX to OSL kr 9 228,00
Passenger type ADT, round trip fare, booking code I
Covers LAX-HEL (Business), HEL-OSL (Business)

Finland Air Transport Supervision Charge (XU) kr 18,00
United States APHIS Passenger Fee Passengers (XA) kr 34,00
United States Customs User Fee (YC) kr 53,00
United States Immigration User Fee (XY) kr 61,00
US International Arrival Tax (US) kr 332,00
Finland Passenger Fee International Transfer (WL) kr 94,00
Norway Passenger Charge (ZN) kr 112,00
BA YQ surcharge (YQ) kr 2 625,00
Norway Air Passenger Tax (G2) kr 204,00
United States Passenger Civil Aviation Security Service Fee (AY) kr 98,00
US Passenger Facility Charge (XF) kr 39,00

Subtotal per passenger kr 25 778,00
Number of passengers x1

Total airfare & taxes kr 25 778,00

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Fare construction (can be useful to travel agents)

OSL BA X/HEL BA X/E/NYC BA LAX Q15.06 M 1483.22RNN4C3S2 IB X/HEL AY OSL Q15.06 M 1058.60INN4C7S4 NUC 2571.94 END ROE 8.595772 XT 204G2 112ZN 94WL 18XU 53YC 61XY 34XA 332US 98AY 2625YQ 39XF LAX4.5