yep UML and such don't have what we think of as sensible semantics.

> if you really do it right, the high-level design might enable you to specify type-like properties that constrain the low-level implementation in a broadly helpful way

so this is exactly what we do. we have a general way to specify boxes and wires and if you give me some sort of type system and a functor and voila, we can produce some well behaved code. nothing is hand-wavy about it, or "complex", like specialized flags or properties of boxes, just some simple mappings