Originally Posted by pdb
It was always my understanding (and experience) that a non-refundable domestic ticket could only be used toward another non-refundable domestic ticket, and that a non-refundable international ticket could only be used toward another non-refundable international ticket. Perhaps the old rule has been relaxed?
I was able to apply a non-refundable international ticket towards a non-refundable (YUP) domestic ticket, so the rule you descrbe apparently no longer exists. (Note that as I mentioned before, you can't apply a non-refundable international ticket towards a refundable ticket of any sort.)