Towards SHACL 1.2

Hi everyone,

with RDF 1.2 on the horizon, there has been renewed interest in working towards a new official SHACL release.
In particular, SHACL should be extended to support new RDF features such as the ability to define constraints
on reified or quoted triples. But this would also be an opportunity to make some other uncontroversial fixes or extensions.

In this spirit, some of us met this week for an ad hoc brain storming meeting, which is recorded here:

https://drive.google.com/file/d/1m8A9tg5PSUxxac6f_DHbYQFed9uTqiNP/view

The video has introductions in the beginning and outlined a plan moving forward.
To summarize, we propose to:

- Aim at a very focused process towards a Charter for an official W3C WG that could finish around the same time as RDF 1.2

- To inform the Charter, this CG would prepare drafts that come very close to the final documents

- To improve maintainability, we propose to split the current SHACL spec into two documents, for which I have prepared
  two very rough and totally unfinished drafts:

  a) SHACL 1.2 Core
       https://w3c.github.io/shacl/shacl-core/

  b) SHACL 1.2 SPARQL Extensions (or SHACL-SPARQL in short)
       https://w3c.github.io/shacl/shacl-sparql/

- (I hope we can find additional editors for these two documents.)

- These documents currently contain exactly the same content as the official standard. This means we can now
  make incremental changes through Pull Requests and have a full track record of what actually has changed.

- Once we are happy enough with these drafts, we could request an official WG to be formed, with a very
  narrow and focused scope to get it out of the door. I don't think anyone is keen to open can of worms that
  could lead to another multi-year effort. I would personally hope to be done with a decent draft by May 1st 2024.

- We still need volunteers to chair such a WG and otherwise drive the process forward. I'd be happy to again
  help with editing (if that's OK with everyone) but it would be ideal to have people with W3C process experience
  and a user perspective as chairs.

- We will use this mailing list and the issue tracker of the GitHub repo to coordinate work:
   https://github.com/w3c/shacl (don't use the old data-shapes repo please, which was for the closed WG).
  I have recently gone through the current issues and closed some outdated ones to get a clean slate.

- Anyone is invited to suggest what they would like to see in a SHACL 1.2 version as GitHub issues. But please
  keep in mind that we should only make small non-breaking changes that do not delay the process too much.

- Moving forward, there is also interest in setting up a lighter-weight process aka "Living Standard" that would
  maintain future SHACL releases.

- This process would then also better support additional documents including
  - SHACL Compact Syntax
  - SHACL Inferencing
  - SHACL Best Practices / Primer
  - SHACL UI
  - ...

Thanks, I hope we can pull this through together!
Holger

PS: Why SHACL 1.2 given that SHACL 1.1 was never released? That's just a proposal, but it would make sense
       to align with the RDF 1.2 versioning system. Also, I consider the intermediate documents like SHACL-AF
       to be a de-facto SHACL 1.1.