According to the
"Miles & More Website for SWISS" it's the "[2] Booking Class" that is shown on the boarding pass. While I know they usually just indicate travel class on the BP, the term "booking class" always meant "fare class" to me - and not "travel class".
I would do the same as
shuigao and call Swiss to confirm the booking...erm sorry, "fare class" again using your ticket number...