I-D Action:draft-faltstrom-5892bis-02.txt

Mark Davis ☕ mark at macchiato.com
Mon Feb 21 23:04:29 CET 2011

> Others, including me, have some discomfort with preserving these previous
(mis)classifications without exception.

That has not proved to be a problem with Unicode identifiers. None of the
characters listed in under Other_ID_*, are problematic for Unicode
identifiers, for example. Nor would they be problematic for IDNA2008 if it
had been instituted back in 2002, with such an automatic rule for adding to
Section G.

However, I can appreciate your position, which I think would be:

   - Maintain stability of labels (i.e., once valid, always valid) unless
   there is a compelling reason not to.

It is different than what is the position taken
in draft-faltstrom-5892bis-02.txt, however.


*— Il meglio è l’inimico del bene —*

2011/2/21 Vint Cerf <vint at google.com>

> there is a user side to this - and it isn't simple either. In one view,
> user expectations about the fitness of a character for use in domain names
> is sometimes tied to its linguistic function (e.g. is it a "letter" in the
> Unicode sense as opposed to, say, a "symbol"?
> Unicode workers have misclassified characters in the past, leading to valid
> registrations which might later be considered invalid because the character
> has been reclassified in a later version of Unicode. Or we have the cases of
> the sharp-S where the addition of a character makes the earlier mapped
> practice a surprise because of the (new) introduction of, in this case, a
> lower case version of sharp-S.
> I am not trying to revisit old debates as much as I am trying to highlight
> the continuing difficulty of dealing with reclassifications. Additions of
> new characters is the easier case but changes are really troubling. If they
> are allowed and registrations permitted and then there are changes in
> Unicode giving them properties invalidating their validity for use in domain
> names, we have to decide whether to promulgate the previous condition
> (allowing what is now under the Unicode properties an invalid character) or
> to alter the derived table (from the IDNA2008 rules) and thus make invalid
> an earlier registration. If user intuition favors the invalidation (ie it
> would not be expected that this would be a valid character for domain names)
> then promulgating the previous classification is counter-intuitive. On the
> other hand, previously allowed registrations that are invalidated lead to
> other kinds of confusion. In the end, the IETF or at least the working group
> has treated these cases idiosyncratically because of the ambiguity in
> deciding what will be least confusing in some sense.
> We could adopt the view that once decided, even if Unicode versions change
> properties, we will keep persistent all earlier classifications - that is
> how I interpret Mark's position. Others, including me, have some discomfort
> with preserving these previous (mis)classifications without exception.
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