Adjust Explicit Typing Guidance regarding `typ`

[OR13]

Per the comment here: https://github.com/w3c/vc-jose-cose/pull/183/files#r1405326097

This would still have the core data model taking a dependency on multiple suffixes, but it would make it so that there was no specific typ for W3C JSON-LD SD JWT VCs, which would counter the guidance from the IETF OAuth WG and the JWT BCP.

If we can't get consensus on the use of typ at W3C, we can remove references to it, such that profiles can lock down the behavior / comply with the JWT BCP... I am leaning towards that approach.

[OR13]

@TallTed wrote:

As noted many other places, just as there is no such thing as application/jpg+zip, the application/vp+ld+json+sd-jwt media type should not exist; this media type should be simply application/sd-jwt. The described reasoning behind wanting media types like application/vp+ld+json+sd-jwt would be well satisfied and better conform to RFC history by specifying profiles for the application/sd-jwtmedia type.

• https://github.com/w3c/vc-jose-cose/pull/183#pullrequestreview-1749264253

[OR13]

I sent a few messages to both the OAuth and Media Types lists at IETF:

• https://mailarchive.ietf.org/arch/msg/oauth/wG-ciZWCTatf_F5iLuPERZq6p0M/
• https://mailarchive.ietf.org/arch/msg/oauth/utKyjvovcqguwkAUTYVW-C6Yw-w/
• https://mailarchive.ietf.org/arch/msg/oauth/BkMuRmt6zExtr1TdsxX37pZtyfY/

Tracking the potential impact to application/vc+... in https://github.com/w3c/vc-data-model/issues/1363

[OR13]

Related: https://github.com/w3c/vc-jose-cose/issues/179

[OR13]

PR is up here: https://github.com/w3c/vc-jose-cose/pull/186

[selfissued]

Categorizing as post-CR, per decision on 20-Dec-23 working group call.

[TallTed]

Please use ISO 8601 date format, or at least 4-digit years. Ambiguous date formats cause endless trouble.

20-Dec-23 ==> 2023-12-20 or 20-Dec-2023

[selfissued]

We are using "typ" in the spec at this point. Therefore, I believe this can be closed, unless I'm missing something.