A friend has paper vouchers I might buy – I can't reach her at the moment. What I do know is they say Travel Voucher, type B, eligible for United and United Express flights. Its a booklet of $150s with a serial number. She was a voluntary bump from a US flight back to Canada. There's no other specific mention of route restrictions.

The thing I am most curious about - UA website doesn't show which routes UA and UX are, and I wonder what restrictions this may entail (e.g. international routes, United Flights operated by Luftansa etc.).

I find out soon enough with paper in hand a phone call, but any educated guesses in the meantime?