Comments on draft-ietf-idnabis-defs-10

John C Klensin klensin at
Thu Sep 3 22:48:18 CEST 2009

--On Thursday, September 03, 2009 15:22 -0400 Vint Cerf
<vint at> wrote:

> patch it in.

Done in Protocol-16.  I'm not going to post that to the list yet
because the WG has seen the exact text being substituted in the
notes earlier and below.


> On Sep 3, 2009, at 2:15 PM, John C Klensin wrote:
>> --On Thursday, September 03, 2009 06:56 -0700 Paul Hoffman
>> <phoffman at> wrote:
>>> At 9:23 PM -0400 9/2/09, Vint Cerf wrote:
>>>> as far as I am aware, we have not modified punycode
>>>> algorithm in any way.
>>> At 9:24 PM -0400 9/2/09, John C Klensin wrote:
>>>> I believe that it doesn't.  It restricts the input to
>>>> Punycode but, so, albeit differently, do ToASCII and
>>>> ToUnicode.  Do you see it doing anything else?
>>> Section 4.4 says:
>>>   This document updates RFC 3492
>>>   only to the extent of replacing the reference to the
>>> discussion of    the ACE prefix.  The ACE prefix is now
>>> specified in this document    rather than as part of RFC 3490
>>> or Nameprep [RFC3491] but is the same    in both sets of
>>> documents.
>>> That's why I put the smiley: it does modify it, explicitly,
>>> but not in a noticable way.
>> Well, 3492 doesn't specify the prefix.  It just refers to one,
>> by reference and usually in oblique ways.  The first paragraph
>> of the introduction describes an ACE but describes the ACE as
>> consisting of a prefix followed by the Punycode-encoded
>> string. That makes it fairly clear to me that "Punycode"
>> doesn't include the prefix itself.  The references to 3490
>> and 3491 are at the end of that paragraph and just says "For
>> the details of the prefix and constraints, see [IDNA] and
>> [NAMEPREP].", a sentence that, in context, cannot possibly be
>> interpreted as normative (and, indeed, those two RFCs are
>> listed as informative, not normative, references).
>> The text that follows is similarly careful and oblique about
>> the prefix.
>> However, if anyone really wants to engage in nit-picking about
>> this (and I don't think you, Paul, do), the paragraph quoted
>> could be changed to:
>> 	This document does not update or alter the Punycode
>> 	algorithm specified in [RFC3492] in any way.  That
>> 	document does make a non-normative reference to the
>> 	information about the value and construction of the ACE
>> 	prefix that appears "in RFC 3490 or Nameprep [RFC3491]".
>> 	For consistency and reader convenience, IDNA2008
>> 	effectively updates that reference to point to this
>> 	document. That change does not alter the prefix itself.
>> 	The prefix, "xn--", is the same in both sets of
>> 	documents.
>> If anyone thinks that would be even a slight improvement, it
>> would only take me a few seconds to patch it in.
>>    john

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