Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (draft-liman-tld-names-05)
John C Klensin <john-ietf@jck.com> Tue, 19 July 2011 13:24 UTC
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Date: Tue, 19 Jul 2011 09:24:04 -0400
From: John C Klensin <john-ietf@jck.com>
To: Behnam Esfahbod <behnam@esfahbod.info>
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Subject: Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (draft-liman-tld-names-05)
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Behnam, I'm sorry I was not clear. Let me try again, first by reference to Patrik's comment: independent of how ICANN has formulated the variant investigation, the question remains "what is safe across all scripts" and not "what does a particular language need". The ASCII ("English") examples were not intended to justify the situation, only to point out that restrictions have been with us for a very long time and that one of those restrictions is that a string being a valid word in some language does not create an entitlement to use that string as a DNS label... and never has. In retrospect, the terms "domain name system", and the earlier "hostname" are misleading. Precision would have called for substituting something like "mneumonic" for "name". Second, while your detailed explanation is appreciated, we fully understand the importance of ZWNJ to writing Persian (and most non-Arabic language use of Arabic script) and, although the use is a little different, the importance of ZWNJ and ZWJ in writing most Indic scripts. CONTEXTJ was not included in IDNA2008 by some magical accident: we (including both Patrik and myself) fought to include it in the standard precisely to facilitate those uses. But, examples, explanations, and language requirements aside, the issue remains one of whether those characters are safe in the root. With the understanding that this is just my opinion, part of that safety evaluation is that the root zone almost certainly should have a clear and simple set of rules, rules that are easily checked and enforced by the various types of (language-independent) software that call on the DNS. While one could imagine a large collection of rules based on a model of "determine the script, guess at the language, and then interpret and render accordingly", it is almost certainly not feasible even if ICANN agrees to use self-discipline about single-script labels. First, the DNS and IDNA do not support explicit language information and heuristics to determine language that work well with moderate or large blocks of text are not reliable when strings are only a few characters long. Second, and equally important, we know that complex procedures based on layers of tables are rarely implemented correctly. So, again returning to one of the implications of Patrik's note: please assume that we understand the importance of this character to most of the languages that use Arabic script (and to most of the languages that use several of the Indic scripts) and that, in case knowing this is helpful, we understood it long before ICANN created the VIP program. We also understand its importance regardless of how (or whether) "variants" (whatever that means in the general case) are supported. The question is whether the use of characters that, among other things, become invisible if the wrong rendering engine is chosen, is safe in a root context or can be made safe by a plausible, understandable, and, if appropriate, enforceable set of rules. regards, john --On Monday, July 18, 2011 21:01 -0400 Behnam Esfahbod <behnam@esfahbod.info> wrote: > Hi John, > > I think it is time to stop general pronouncements that have > been repeated and repeated so many times over these past years > and get down to specifics. Here are two very concrete points > you should note: > > 1. ZWNJ is not a special quirk of Persian language, it is not > a mnemonic tool, nor is it an optional writing-style > device. ZWNJ is used in the writing of MOST languages >...
- [apps-discuss] CONTEXTJ in TLD DNS-Labels (draft-… Behnam Esfahbod
- Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (dr… John C Klensin
- Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (dr… Behnam Esfahbod
- Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (dr… Patrik Fältström
- Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (dr… John C Klensin
- Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (dr… Paul Hoffman
- Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (dr… John C Klensin
- Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (dr… Patrik Fältström
- Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (dr… Paul Hoffman
- Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (dr… Paul Hoffman
- Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (dr… Patrik Fältström
- Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (dr… Martin J. Dürst
- Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (dr… John C Klensin
- Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (dr… Paul Hoffman
- Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (dr… Paul Hoffman
- Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (dr… John C Klensin
- Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (dr… Behnam Esfahbod
- Re: [apps-discuss] CONTEXTJ in TLD DNS-Labels (dr… Martin J. Dürst