sevo
Fokutorendaburando
It was my understanding that everything comes off master rolls. Sheet film, roll film, etc. It is what is done after that which makes it different. Slitting, perforation, and packaging.
Nope, there is quite a variety of master rolls for different purposes. For example, 35mm (and below) generally aren't back coated, while all larger or thinner film has to be, to prevent bulging. Besides, film holders and film paths were designed for the particular strength of the matching system film - variations beyond fairly narrow limits will interfere with focus and transport.