TYPO3 Core

If it's just about documentation, I can might be able to contribute.

The other options (e.g. for a schema or formal description) are probably quite a bit more complicated. I mentioned it in case someone sees a solution there or is working on it. I opened it here for visibility and reference as core issue.

I am fine if we convert it into a documentation only issue in which case I would probably close here and work in GitHub TYPO3-Documenation.

so, is it about documentation or about changing the current implementation

I would handle it as documentation issue unless someone jumps in with an alternative solution or is working on one.

which parser are you referring to (and in relation to that, which type of "formal language", there are plenty)

Originally, I opened this issue because I did not find a full definition / description besides the source code.

The implementation in the Typolink*SoftReferenceParsers does not consider page links with t3://page?uid=current. But this is what is written automatically by the RTE post processing if an empty href exists. So this is (as far as I could see) not really documented and inconsistently implemented, see #100934.

if it's just about documentation, I could imagine having some aBNF for the t3://... scheme

I am aware of EBNF, not aBNF. Will look into it. Thanks.