All right. Too technical? Maybe and maybe not. Go back and look at the graphs I posted from Haist. There is nothing technical about that. Just simple logic and looking at a graph. Much simpler than other posts here, and no disrespect to those people, i am merely saying that the posts may go over some people's heads, thats all. Grant Haist has shown it with no math or fiddling. Just a simple film curve with "zones" showing print reproduction.
And, btw, negative films are shown increasing in density from left to right, as are paper densities. Print densities are shown decreasing in density from left to right. This convention is used throughout the photographic industry including "gasp" digital.