Originally Posted by
rustykettel
I don't think you can buy it as a standalone flight, only with an AS flight, either on the same leg or as a multi city itinerary.
FWIW, Alaska lists 10 other partners as codeshare partners: AF, CX, EK, KE, etc...
The majority of the codeshare partnerships are one-way, though--AS puts its code on some domestic AA flights and vice-versa, but they're not selling EK SEA-DXB with an Alaska number on it.
As a data point, I was able to buy PWM-DCA-PDX last year with the first segment on AA, and this was before the codeshare expansion, so it didn't even have an AS number on it.