A much rarer form of test-promotional banknote, the BB series features different security features than the AA.
The AA series was the official PWPW promotional banknote for the 85th anniversary of the Works, whose security features were described in the issue folders. The image of a bell in the upper left corner, made with optically variable ink, was described, while on the BB series banknote it is imprinted with a dry seal.
The folder describing this version of the banknote we have not met.
The auction item is a banknote with a standard folder.
