Wasabi,
Thanks for the guidance. The OWE thread with a sticky on this forum says

"Asia - No tickets to Vietnam or Cambodia permitted."

You motivated me to look in the starfile, which reads:
146N FOR TICKETS ISSUED ON/BEFORE 30JUN05, TRAVEL NOT
147N PERMITTED ON CX BETWEEN HONG KONG AND VIETNAM.

So i guess travel to vietname is permitted on OWE (yay).

But for surface sector, it reads:
153N 4. ORIGIN-DESTINATION SURFACE PERMITTED:
154N .
155N . * WITHIN THE COUNTRY OF ORIGIN
156N . * BETWEEN USA AND CANADA
157N . * BETWEEN HKG AND CHINA
158N . * WITHIN AFRICA
159N . * WITHIN SOUTH AMERICA
160N . * BETWEEN BANGLADESH AND BKK/SIN
161N . * BETWEEN MALAYSIA AND SIN


Which seems to rule out SGN-BKK, right?