These fares book into the "A" bucket, netting 1.5 miles/Q-points. They are not offered, as far as I know, on any 3 class flights as booking in A on those flights would take you directly from the Y cabin to the P cabin. As noted above, when the Hawaii fares first came out, this little error was not caught and several people were able to book YUP fares from the east coast and get a P cabin seat to LAX / SFO since it booked in A. That loophole was quickly closed, however.