Originally Posted by justageek
I tried to apply an unused (international) non-full-fare coach (can't remember the booking class) ticket towards a Y (domestic) ticket a few months ago and was told that unused non-refundable tickets can only be applied towards other non-refundable tickets, not towards full-fare tickets.
This is correct. I run into this frequently exchanging tickets into STL-LAX itineraries, as they match WN's $299 refundable prices. They're not even Y fares, but they're refundable -- I can never exchange a NR ticket into these itineraries.