Should additionalProperties be false

[kd-ods]

The metaschema patches currently set additionalProperties to false (overriding the default JSON Schema behaviour). I'm not sure this is desirable. It goes against the Permissive schema pattern.

[duncandewhurst]

In the metaschema patch, setting additionalProperties to false prevents schemas that reference the metaschema from using any keywords beyond those defined in JSON Schema and the patch. It does not restrict additional fields in the data described by those schemas. Does that make sense?

[kd-ods]

Yes, that makes sense. Is it desirable not to allow additional keywords though? If a schema designer is patching JSON schema, they presumably may want to make their own decision about more keyword additions.

I'm happy for it to be left as-is. I just wanted to check the logic.

[duncandewhurst]

Good point :-) the idea is to enable validation of the schema itself to catch errors like mispelling of a keyword, for example, and to ensure that additional keywords are documented in a metaschema patch.

If a schema designer wants to add more keywords, they should document them in a patch - either this patch, if the keyword might be useful in other contexts, or in a context-specific patch which could be applied 'on top' of this one.

This is probably good content to include in the docs site!