Schema for the data model

[darobin]

Would it be possible to develop a schema for the data model at some point? It does not need to be very constraining, but if it could list what can be relied upon versus what's optional in the data model, it would be helpful.

The case came up with https://api-test.w3.org/groups/76983 which was added to group-hug. It breaks the interface because there is very little information, notably it is missing some things that I assumed would be available on all groups (like type).

I guess it is possible for data consumers to assume that if the type has a given value then the rest of the structure is likely to be predictable? If so, not having type specified is probably a bug?