Originally Posted by
paperwastage
EF shows that SQ and 3K are valid airlines for SIN-<east-asia>. matrix pulls up 3K for SIN-SGN, cannot get SQ to stick though
The fare can be routed on SQ, but there's no delegated booking class. (Click the "C" button in ExpertFlyer and enter "SQ"). There are a list of countries and/or cities where SQ can be used; Vietnam isn't one of them.