The folks behind the Oil shell have suggested some vocabulary around reducing the number of integrations among M kinds of inputs and N kinds of outputs from M times N to M plus N: You create an intermediate conventional interface called a narrow waist. The Perlis-Thompson Principle expresses the scaling benefits of minimizing distinct concpts. Read more. Having done this narrow waist maneuver a few times and spotted it in the wild here and there, I’m glad to have some language for it.