[Atp] Draft "at" URI Scheme Document (legacy not-actually-URI version)

[Bryan Newbold <[e-mail]>]

Hi folks,

I uploaded a new I-D about the "at" URI scheme:
https://datatracker.ietf.org/doc/draft-newbold-atp-aturi/

As noted in the text, and discussed back in Vienna, the currently deployed
"at://did:plc:abc123" syntax does not meet the generic URI rules (RFC-3986),
because it includes multiple colons in the authority section.

Regardless of how we end up resolving that dilemma, we do need to document
the current string syntax and semantics, and this document does cover that.
I believe this document is relevant to the WG and should get linked to it
in the datatracker (apologies if I messed up the metadata on my end).

This current draft has two small divergences from what is currently
deployed:

1) the repository sync draft and this draft text both say that NSIDs "MUST"
have the domain authority part be lower-case (eg "com.EXAMPLE.record" is
invalid). I think this is an improvement, especially in references to
records, and I expect virtually all data in production to follow this norm
already, but is a slight change
2) this draft text does not support "URIs" with a single path segment (just
collection, no record key). I've honestly always been confused why that was
supported in the existing spec, and don't think it is used anywhere in the
deployed network

--bryan