Join Date: Feb 2000
Location: Oslo, Norway.
Programs: SK EBD, AX Cent, SPG Gold, HH Diamond, Club-A Plat, Avis' PC, CC Gold,Hertz PC, CX Diamond,BA Bronz
Posts: 683
I believe that Z-class is widely used amongst airlines for Business Class award/bonus flights.
The corresponding code for economy class is "X" class.