Originally Posted by Sykes

That's partially true. That booking class table tells you what booking class you are allowed to book into if you book that carrier's flight number directly, not what the codeshares map to. While they are usually the same, there are some exceptions so you shouldn't rely on that as gospel. For example, I've run into situations in the past where, on a TATL W fare, the booking class table specifies W for Lufthansa, but when the same flight was booked as a UA codeshare operated by Lufthansa, it booked into V. (Fortunately, it was a discrepancy in my favor.)