@jsch61KA said in #2:
> ==> Lichess seems to be compliant to the latest FEN definition.
> ==> What is unclear to me: Which consortium/committee has the right to decide and to publish changes in FEN data format !?!
This is an interesting question. I don't know the answer, but I suspect the right to update the spec died with Steven Edwards in 2016. That's probably why X-FEN has its own name.
It looks like Edwards "published" FEN on Usenet in the mid 90s, and that's the version that spread around the internet. He was working on the en passant change in 2002 -- this may or may not have been released. If it was, it seems to have rotted off the internet. I guess we should still be publishing important documents in dead-tree form.
> b) In Wikipedia there is a reference to the FEN spec (
github.com/fsmosca/PGN-Standard/blob/master/PGN-Standard.txt, revised Revised: 2023-03-22)
I don't know how these maintainers derive authority to modify FEN... they probably don't. I suppose someone's got to do it. But I wouldn't be surprised if there were multiple independent efforts to do this. FIDE should step in and be another one (ha, ha!).