Re: [I18nrp] Last Call: <draft-faltstrom-unicode11-05.txt> (IDNA2008 and Unicode 11.0.0) to Informational RFC

["Paul Hoffman" <[e-mail]>]

On 3 Dec 2018, at 22:59, Patrik Fältström wrote:

> Good morning!
>
> I see there are a few comments on this draft, I will try to respond to 
> each one of them.
>
> On 4 Dec 2018, at 1:02, Paul Hoffman wrote:
>
>> Before I go to the [e-mail] mailing list with my concerns about 
>> this draft, I hope it is OK to bounce them off people here in case 
>> I'm wildly off track.
>>
>> =====
>>
>> In Section 1:
>>    Specifically, the Internet Architecture Board did issue a 
>> statement
>>    [IAB] which requested IETF to resolve the issues related to the 
>> code
>>    point ARABIC LETTER BEH WITH HAMZA ABOVE (U+08A1), introduced in
>>    Unicode 7.0.0 [Unicode-7.0.0].  This document resolves this issue 
>> and
>>    suggests IDNA2008 standard is to follow the Unicode Standard and 
>> not
>>    update RFC 5892 [RFC5892] or any other IDNA2008 RFCs.
>>
>> In Section 4.1:
>>    The discussion in the IETF concluded that although it is possible 
>> to
>>    create "the same" character in multiple ways, the issue with 
>> U+08A1
>>    is not unique.  In the case of U+08A1, it can be represented with 
>> the
>>    sequence ARABIC LETTER BEH (U+0628) and ARABIC HAMZA ABOVE 
>> (U+0654).
>>    Just like LATIN SMALL LETTER A WITH DIAERESIS (U+00E4) can be
>>    represented via the sequence LATIN SMALL LETTER A (U+0061), and
>>    COMBINING DIAERESIS (U+0308).  One difference between these 
>> sequences
>>    is how they are treated in the normalization forms specified by 
>> the
>>    Unicode Consortium.
>>
>> This sounds like the IETF is saying that if the Unicode Consortium 
>> changes how a character appears in a normalization form other than 
>> for case folding (Section 2.2 of RFC 5892), that change does not 
>> affect the tables for IDNA2008. Is that correct?
>
> First of all, this document evaluates the individual changes made up 
> until and including Unicode 11. Sure, one could say this has 
> implications on the IETF view of existence of normalization rules (or 
> not) but that is not the intention here. The result of this review 
> should neither be extrapolated to future versions of Unicode nor to 
> future evolutions of normalizations.

This is good to know. In that case, could you either remove the "One 
difference between these sequences..." sentences, or add a sentence in 
the Introduction section that says "The result of this review should 
neither be extrapolated to future versions of Unicode." Either action 
would clear up this confusion.

>> =====
>>
>> In Section 4.1:
>>    As U+08A1 is discussed in draft-freytag-troublesome-characters
>>    [I-D.freytag-troublesome-characters] and elsewhere.  Regardless of
>>    whether those discussions ends in recommending including the code
>>    point in the repertoire of characters permissable for registration 
>> or
>>    not, it is acceptable to allow the code point to have a derived
>>    property value of PVALID.
>>
>> This sounds like it is saying that even though 
>> draft-freytag-troublesome-characters is meant for standards track, 
>> because it is not yet finished, this document (which is 
>> informational) can ignore the other document and make changes to the 
>> IANA registry. If that's correct, it concerns me because it could 
>> make the IANA registry unstable for characters that we know about and 
>> are actively discussing. If I'm not correct, I'd like to hear why so 
>> that maybe this document can be reworded.
>
> First of all, this document is (as it seems to me now) to be Standards 
> Track. So that issue is taken care of.

Procedurally, it is not, I believe. A new draft needs to be issued, and 
the IETF Last Call has to start again. Fortunately, this IETF Last Call 
is only a few days old, so this should not delay anything much.

> Regarding the reference to the troublesome characters, I also have 
> referenced a document by Klensin. I do not mind referencing other 
> documents as well regarding U+08A1, but I do NOT want to explain 
> everything in this document (again), i.e. no repeat please.

Agreed.

> The klensin document unfortunately have expired but look at diff 
> between -04 and -05 and you see the reference. This is also why I in 
> this version wrote "and elsewhere".
>
> If you have better more references, send them in my direction.

This misses my concern. There is an active draft 
(draft-freytag-troublesome-characters) that seems to want to change the 
IANA registry. Your draft (draft-faltstrom-unicode11) also wants to 
change the registry, but in a different way. My question is whether we 
should be making the registry unstable in this way.

--Paul Hoffman