I was searching for a first class 1-stop route where there's such class on the first leg which is operated by me, the other leg only has business class but the joint ticket was available as an option in the ORS anyway. It seems this kind of interlining is allowed in AS? How are this type of F + C (or F + Y, C + Y) tickets rated?
First of all, at least one of the legs must be booked in F class for it to be F-class booking eligible.
And I guess the ORS rating would be calculated the same way as it is done for any particular connecting flight.
Individual first ORS ratings of flights x trip duration factor.