Just to higlight the confusion at CO, I now have 3 tickets on NW bought thru CO from the US to Asia that I bought and Upgraded with miles from my OnePass account at the time of purchase thru a call to the OnePass Platinum Line.
Ticket 1 EWR-BKK- Ticketed in "Z" class
Ticket 2 JFK-SIN- Ticketed in "C" class
Ticket 3 JFK-TPE- Ticketed in "D" class

All three were "low fare" tickets (BKK/TPE~$850RT, SIN $1,000 RT).