Nice to see your program coming to the aid of a forum discussion!
PeterB, The reason our curves end abruptly on the right, is that "we" try to catch the toe in our tests and haven't done studies of gross overexposure... All it would take to see how far out the straight line extends... would be to remove a ND filter from the well of the sensitometer, pop a test, and develop and measure it. I believe there is a great long straight line ahead.
Thanks Bill. I'm curious as to why films are rated with so much latitude for over exposure but virtually none for under exposure ?