On the git part: the text only mentions "git commit checksum", not "branches and tags" -- and it couldn't, since these are not immutable nor are they restricted

On the git part: the text only mentions "git commit checksum", not "branches and tags" -- and it couldn't, since these are not immutable nor are they restricted to hex characters. My point above is that the EBNF defines "GIT_COMMIT_REF" to be the letter "g" and a _single_ hex character. So "GIT_COMMIT_REF" may be "g0", "g1", ... "g9", "gA", ... "gF", "ga", ..., "gf". That's it. Which obviously contradicts the text and the intention.