I have been trying to find the origin of the term "b-money". What does the b refer to in Wei Dai's post http://www.weidai.com/bmoney.txt)? The term "b-money" appears first in the Appendix title. Does "b" denote the second method (with "a-money" referring to the first method)? Or was the term b-money already in use referring to digital money, b[it]-money?

Any info appreciated.