[shadowwolf007]

Honestly with the schema thing I'd probably be fine with either/or!

A checksum would be crude and user-hostile, only being able to say "you did it wrong" but not really good at tell you what it means to do it right.

If I understand the concepts correctly then it seems like a shared ontology could potentially solve the problem in a non-hostile way.

Plus, it makes me happy because I feel like types are a real-world problem, so it is always nice if the type system could enforce that real-world-ness and all the messiness that comes along for the ride.