Re: U-labels and draft-obispo-epp-idn-00
Andrew Sullivan <[email protected]>
| Newsgroups | gmane.ietf.provreg |
|---|---|
| Message-ID | <[email protected]> |
On Wed, Feb 22, 2012 at 03:27:19PM +0100, Klaus Malorny wrote: > So you suggest that upper case domain names should be better > rejected, consequentially? And for both non-IDNs and IDN A-labels? > While it makes life easier for the registries, I have the feeling > that a few registrars would get some trouble with this. For LDH-labels, of course, it doesn't matter. I think for users it would be nice if we trained people to expect only lower case in domain names (more on why below), but I wasn't intending to advocate that. For U-labels, though, of course, an upper case character is DISALLOWED. This extends even to ASCII-range code points that would be accepted in LDH: "CaféCrème" is not a U-label, even though "CafeCreme" is a perfectly good LDH-label. Those need to be lower case for sure. In the case of A-labels, I _thought_ we issued a clarification about Appendix A in RFC 3492. That appendix has some remarks about mixed case, and the issue is that, since no U-label may have mixed case, therefore Punycode can't either. But I can't find the clarification right now. It nevertheless seems a consequence, and therefore I think A-labels should always be in lower case. Because U-labels can't ever have upper case, RFC 5895 and some other documents (prominently UTS 46) suggest always mapping upper to lower case. I think that's a good idea, but any time there's a mapping step in between user input and what the application actually uses I get nervous. Therefore, I think it would be better for everyone if we gradually trained people to use lower case for DNS labels everywhere. Yes, I'm aware that that will suck in places where CamelCase has helped clarify what ExpertsExchange is really about. But "the application knows your intention" has not been, I suggest, a universal success. This goal is probably tilting at windmills, however, since many registries I know of often spell their domain names in capital letters in running text. Best, A -- Andrew Sullivan [email protected] _______________________________________________ provreg mailing list [email protected] https://www.ietf.org/mailman/listinfo/provreg