Seems they should allow them on int'l itins just because int'l costs more. If I apply a $250 e-cert to a domestic flight, there's a good chance that UA isn't getting more than $50 out of pocket from me. If I apply $400 in TC's to an int'l flight, I'm often ponying up another $500 to go with it!

There's a reason that some of the most prolific FT mileage runners run almost 100% domestic!