Original text:
Preserving this information is referred to as identity chaining. This document defines a mechanism for preserving identity chaining information across trust domains using a combination of OAuth 2.0 <del> Token Exchange RFC8693 and Assertion Framework for OAuth 2.0 Client Authentication and Authorization Grants RFC7521. </del>  1.1.

Reviewer comments:
and minor other little fixes to fix issues , , an editor's draft preview of these changes here: URL
says this: However, if the authorization grant is a JWT (which it always should be, but see for details), then defines the grant type of the request to be: The other implication of this is that the only way to distinguish the type of JWT assertion is in the JWT itself, which can be done using the field in the JWT header.
Per is an "identifier [...] for the representation of the issued security token" and I think it's admittedly a bit odd but perfectly reasonable to use the URN of the grant type that the token is intended for as the value conveying the representation that token.
With that said however, I do kinda think that'd it be better to limit to JWT authz grant only (a la ) and not tie the issuedtokentype to the grant type.
My point was more about the grant type of the request as described by RFC7523. access token request as defined in of the OAuth Assertion Framework ] with the following specific parameter values and encodings. So if the request contains a JWT, then the grant type value has to be . Which means according to Section 2.4.3 of this spec the issuedtokentype "SHOULD" be , which is silly. So my proposal is to remove the "and SHOULD be passed into the assertion request" part, so that issuedtokentype can be a value that makes sense, and use as the grant type. As I said in the original comment, the implication is then that the JWT header itself would need to include something that indicates the type of JWT it is, otherwise all token exchange requests look the same.
I might argue that it's not actually silly but I won't b/c it'll be moot as PR addresses this with the removal of the "issuedtokentype parameter in the response indicates the type and SHOULD be passed into the assertion request" URL
issuedtokentype (a required parameter of a token exchange response URL) is missing from the example response at URL
NAME can you prepare a PR with an updated example?
example would be fixed by PR
Feedback from Brian Campbell Conceptually having "flexibility for authorization servers to change format and content" sounds nice but I can't help but wonder if that flexibility is actually useful and if this document wouldn't be better served and more straightforward using just JWT authz grants from 7523 (rather than being abstract about using 7521 and the very brief mention of SAML w/out a 7522 ref).
I agree that limiting the authorization grant format to JWT is useful. In fact you've almost already done that by adding the validation to the processing rules here: URL
As discussed in the meeting with the editors and Aaron, we will make the use of JWT explicit.
PR would limit the authorization grant format to RFC7523 JWT

Revised text:
Preserving this information is referred to as identity chaining. This document defines a mechanism for preserving identity chaining information across trust domains using a combination of OAuth 2.0  <ins> Token Exchange RFC8693 and JSON Web Token (JWT) Profile for OAuth 2.0 Client Authentication and Authorization Grants RFC7523. </ins> 1.1.