> As mentioned in the doc in [3], COALESCE and all the others are actually not
functions (those are specific keywords handled in the parser):
Thanks. Yeah, I noticed that comment, but NULLIF which is also documented on that page isn't mentioned in that comment, but it's still shown in upper-case. It's maybe worth adding NULLIF to that comment.
I'm also not sure I'd consider real/not real distinction as something that's very relevant to the user, to the extent that it warrants a case difference... But that doesn't matter much.