RE: Lower casing
John C Klensin <klensin@jck.com> Sat, 29 January 2011 16:39 UTC
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Date: Sat, 29 Jan 2011 11:39:09 -0500
From: John C Klensin <klensin@jck.com>
To: Shawn Steele <Shawn.Steele@microsoft.com>, Mark Davis ☕ <mark@macchiato.com>
Subject: RE: Lower casing
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References: <8762u4o1ty.fsf@latte.josefsson.org> <AANLkTin5CYOt=h6FsMsAQXQnjC-V+LjCmkS1_Dk96PT-@mail.gmail.com> <87d3nkwqy4.fsf@latte.josefsson.org> <AANLkTi=6LLkiVRGG9S9VAC5_4EQst+HfvP7F67OnJnpt@mail.gmail.com> <87sjweppa0.fsf_-_@latte.josefsson.org> <AANLkTikU+p+AMWf3RzxfxTqZQnOK-tk397Mfs8E3wzdh@mail.gmail.com> <4F23BD940E50BCA3F707ADEA@PST.JCK.COM> <AANLkTimsK3HPp-3iy=NnC_-LLHJsxP2fFTGp2198Nnss@mail.gmail.com> <E14011F8737B524BB564B05FF748464A11C899E7@TK5EX14MBXC133.redmond.corp.microsoft.com>
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Cc: Simon Josefsson <simon@josefsson.org>, idna-update@alvestrand.no
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Shawn, The problem here is that there is no "transition" for those four characters. If browsers and other client systems provide the IDNA2003/ TR46 mapping there are only: -- IDNA2003 behavior forever -- Rolling flag day now -- Rolling flag day at some indefinite point in the future. By "rolling flag day" I mean that a client computer has one behavior or the other on a given day but that not all client systems will convert on the same day (or even in the same month or year). IMO, the reason why the WG was willing to make the change was because of significant input that the ability to distinguish between the characters that are, under UTS#46, source and targets of mappings was important on both input and output (remember that there is a display issue here too because an IDNA2008 A-label that encodes the four characters is essentially invalid under IDNA2003). For those groups for whom the distinction among one or more of those character pairs (including "ignore" as the pair for the Joiner set) actually is important, "register both" is not meaningful: "we are applying the UTS#46 rules, including those for 'deviation' characters" is equivalent to "you lose; we know what your language needs better than you do". It is telling that all of the registries who are focused on those strings and from whom we've received reports (other than the somewhat-conflicting reports about Greek) have basically said "ok, let's do it and get it over with". There is another element of this depending on when the mapping is applied: the "native UTF-8 in lookups outside the public DNS" situation that is addressed in draft-iab-idn-encoding is, in general, UTF-8 without even any normalization, much less encoding. By applying UTS#46 mappings, you compound the problem of having to support two lookup encodings by having strings that are fully-valid and accessible under IDNA2008 _and_ the internal databases/ directories but that are not accessible from your browser (at all for the public DNS and maybe not from the private databases if you guess wrong about when to apply the mapping. That is also another way to look at the "incompetible change" problem, which is that this is either about maintaining compatibility with the public DNS names that were registered or used assuming the IDNA2003 rules and restoring compatibility with the strings that are valid and sensible in those internal databases that you support and encourage. As long as you understand all of those tradeoffs, you should make whatever decisions make sense to you. I'm glad I don't have to make the decision. john --On Saturday, January 29, 2011 1:35 AM +0000 Shawn Steele <Shawn.Steele@microsoft.com> wrote: > (& I've been describing that behavior, including UTS#46 > transitional behavior and mappings, as IDNA2008 + UTS#46 to > make it clear). > > -Shawn > > From: Shawn Steele > Sent: Friday, January 28, 2011 5:34 PM > To: 'Mark Davis ☕'; John C Klensin > Cc: Simon Josefsson; idna-update@alvestrand.no > Subject: RE: Lower casing > > It is worth mentioning that our code will follow the > transitional guidelines, as we will otherwise break existing > IDNA2003 users. Presumably people who want both versions to > work will register both versions.
- IDNA2008 test vectors Simon Josefsson
- Re: IDNA2008 test vectors Mark Davis ☕
- Re: IDNA2008 test vectors Yoshiro YONEYA
- Re: IDNA2008 test vectors Simon Josefsson
- Re: IDNA2008 test vectors Patrik Fältström
- Re: IDNA2008 test vectors Mark Davis ☕
- Lower casing Simon Josefsson
- Re: Lower casing Mark Davis ☕
- Re: Lower casing John C Klensin
- Re: Lower casing Simon Josefsson
- Re: Lower casing Mark Davis ☕
- RE: Lower casing Shawn Steele
- RE: Lower casing Shawn Steele
- RE: Lower casing John C Klensin
- RE: Lower casing Shawn Steele
- RE: Lower casing John C Klensin
- RE: Lower casing Shawn Steele
- RE: Lower casing John C Klensin
- RE: Lower casing Shawn Steele
- RE: Lower casing John C Klensin
- RE: Lower casing J-F C. Morfin
- RE: Lower casing John C Klensin
- Re: IDNA2008 test vectors Simon Josefsson
- Re: IDNA2008 test vectors Simon Josefsson
- Re: IDNA2008 test vectors Mark Davis ☕
- Re: IDNA2008 test vectors Simon Josefsson