[Archelaos]

> Maybe, but you're missing the other use case - that in the future you'll need an extension requiring geometries that are considered invalid by the current set of rules, forcing you to update all tools processing the file format to acommodate the new extension.

I think the way to go is to define several layers of correctness. A data set might then be partially valid. In such cases a tool might, for example, support transitions from a complete valid state A to a complete valid state C by an intermediate partially valid state B. (As databases with referential integrity may allow intermediate states in a transaction where referential integrity is broken.)

[TuringTest]

> I think the way to go is to define several layers of correctness. A data set might then be partially valid

Thanks, that summarizes what I was aiming for. An open platform will be more flexible and and allow for different use cases the fewer assumptions about how it should be used it includes.