refactor-ability. not sure if thats a word. basically, a "modular" design that allows for changes in business logic that won't lead to redesigning the entire system.
now, using the word "modular" when it comes to data flow in MIIS seems a bit odd. but there are design considerations that would lead to a "flexible" system that allows for changes in business logic that won't lead to breaking everything.
SO. I think i'm going to quit at part 4.