Comment by mort96
I don't know all the details of `unicode.IsPrint` function, but one major issue is: it's Go-specific. If you're defining a protocol, you probably don't want the spec to include text such as, "the username field must only contain Unicode code points which are conidered printable by the Go programming language's 'unicode.IsPrint' function". You would rather want to write, "the username field must not contain Unicode code points which are considered problematic by RFC 9839".
interesting. so Go seem to be using unicode categories, which is part of unicode spec/standard. so it is fairly language agnostic.
> IsPrint == .. categories L, M, N, P, S and the ASCII space character.
how does that compare to this standard (RFC 9839)? (don't mind that this is Go. just consider same unicode categories).