Thank you for the current WIKI (Decoding ABC soup...). Please confirm/clarify:
1. Can one upgrade from Econ>Bz? Or only Econ > Prem Plus? If "yes" then can one only upgrade to BZ/First from a PremPlus fare?
2. PZ: can a Premiere Gold upgrade from Econ > Bz/First with this inventory code? Is this inventory limited to specific fare types, if so what are they?
3. Will PZ inventory apply to a Refundable Econ Fare?
Appears UA has severely decreased upgrade inventory, yes?