Follow-up to Monday's discussion of digits

[Martin Duerst]

John - I understand that we want to avoid combinatorial explosion.
But your mail below doesn't explain why the restrictions can't
simply be made by registries.

I do see nothing in the current documents (nor in IDNA2003, for
that matter) that would forbid registries to have a policy to
restrict registrations in a single label to any one series
of digits, or to some desirable (and hopefully non-confusable
and therefore non-exploding) combination of series of digits.

Given that I do not see anything prohibiting or making impossible
such a restriction, I do not understand why we would have to
take an "enabling" (as you mention below) steps.

Regards,     Martin.

P.S.: According to a document I have received years ago, the
      Iranian registry, for the 


At 06:23 08/11/19, John C Klensin wrote:
>
>
>--On Tuesday, 18 November, 2008 07:53 -0600 Andrew Sullivan
><ajs at shinkuro.com> wrote:
>
>> On Tue, Nov 18, 2008 at 06:45:47AM -0600, Eric
>> Brunner-Williams wrote:
>> 
>>> Outside of the protocol, registries are free to implement a 
>>> registry-local policy, which may restrict code points in a
>>> label to one  range only, or one of two ranges, where one is
>>> in the U+0030..U+0039  range, but not both of the ranges
>>> U+0660..U+0669 and U+06F0..U+06F9.
>> 
>> Something that wasn't clear to me from the discussion
>> yesterday is why this ought not just to be a registry policy
>> issue, in the way we have said other possibly-confusing things
>> ought to be.  Is the argument from potential for harm?
>
>The key problem, as discussed during the meeting is to _enable_
>registry policy by preventing combinatorial explosion.   In
>other words, for most of the plausible cases in which there
>might be IME problems and/or more than one set of digits are
>used, the probably-best registry policy is to register all of
>the numeral-containing digit forms used with Arabic script.
>
>With this rule, that will typically require registering only two
>labels for each proposed label that contains digits (European
>digits and Arabic-Indic Digits  or European Digits and Extended
>Arabic-Indic Digits) or three labels (European Digits and both
>forms of Arabic-Indic Digits).  Without such a rule, one gets a
>combinatorial explosion because one has to register all of the
>possible combinations of digit forms for labels containing more
>than one numeral.
>
>Note that explanation is intended to clarify today's meeting
>discussion for the mailing list.    Until Eric and I re-consult
>our various authorities and then each other and report back to
>the group, there is uncertainty about what the rule should be,
>but the principle of avoiding a combinatorial explosion is
>likely to remain.
>
>     john
>
>
>
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#-#-#  Martin J. Du"rst, Assoc. Professor, Aoyama Gakuin University
#-#-#  http://www.sw.it.aoyama.ac.jp       mailto:duerst at it.aoyama.ac.jp