Fascinating stuff, thanks a lot.
So now a quick summary, if I understood it all correctly. Let’s do it on an example, e.g. Star Wars.

It has scenes of 3 types :

I) scenes consisting only of live action shots
II) scenes containing some simple visual effects like fade-ins, fade-outs, dissolves etc.
III) scenes containing composite shots created using live action shots and visual effects

If I was the Star Wars editor, I would do …

I) these scenes would be done by cutting and joining the original camera negative
II) these scenes would be created using negative A and B rolls
III) these scenes would be a combination of edited negatives and various optical elements joined together using an optical printer

So we would have properly edited scenes of 3 types, and they would still be negatives - correct? Then we would join these scenes together, and interpositives would be made? Then from these interpositives new internegatives would be printed, and these IN would be the source for theatrical prints?

Correct or complete bull…?