Here's a quote from you post Terry, and I have inserted one more word, as you will notice. "These are the same principles I used in black-and-white and colour wet darkrooms for years and they are as important, and relevant today as back then". I believe that to be the case as well, but we also required the numbers back then for QC, now referred to as Colour Management, even though it "manages" a lot more than just colour.
Gary
Exactly, Gary. Thank you.