[tnzk]

Curious, which part in RFC 6749 do you refer to or other ones?

[swid]

I could have sworn I have seen this in the past, but I am not sure exactly where. Thinking about it; it probably would have been part of OIDC and not directly addressed by OAuth... maybe someone can find it for me, or maybe I misspoke when I said it was part of the spec.

[hirsin]

I could believe that being in 2.1 as a BCP,but if it's not it's a good idea to add it.