From
this thread and thanks to
sftrvlr
S*PMO/UG is the main profile. It then lists the other upgrade profiles.
The Y/B is under S*PMO/UG-YB COMPLIMENTARY. The applicable fare basis codes for complimentary upgrade are:
-----BOOKING CODES/FARE BASIS CODES-----
PERMITTED FROM BOOKING CODE BOOK UPGRADE IN
---------------- -------------- -----------------
ECONOMY Y/B - SEE BELOW NC OR NF
FARE BASIS CODES: Y YUA YUAS BUA BUAS B1UA YUAX BUAX
BUANR YUANR B0CRREF B0NB B2 BE120C
BHE120C BHE90C BHO BHW0CR BHWR BA3
BHX0CR BHXR BLE120C BLE90C BLO BA3S
BLW0CR BLWR BLX0CR BLXR BPE90C
BRHOLNR BSFFL Y2 YHO YHWR YHXR
YLO YLWR YLXR