From: Mark Davis ☕ (firstname.lastname@example.org)
Date: Mon Jul 26 2010 - 14:13:22 CDT
I agree that having it stated at point of use is useful - and we do that in
other cases covered by stability clauses; but we can only state it IF we
have the corresponding stability policy.
*— Il meglio è l’inimico del bene —*
On Mon, Jul 26, 2010 at 11:06, Asmus Freytag <email@example.com> wrote:
> On 7/26/2010 6:55 AM, John Burger wrote:
>> Mark Davis ☕ wrote:
>> From just a quick scan, it appears that they are currently all contiguous
>>> within their respective groups. If we were to impose a stability policy, it
>>> would be a constraint on the general_category: we would not assign
>>> general_category=decimal_number to any character unless it was part of a
>>> contiguous range of 10 such characters with ascending values from 0..9.
>> While that is true for the properties, it's not true for the encoding of
> character that are *used* as decimal digits. Martin gave the most widely
> used counterexample.
>> Whether such a policy makes sense, I'm not clear on why it would be called
>> a "stability" policy - the analogy to the existing such policies seems
>> strained at best.
>> There are two parts to this.
> One, and I think this is the more important part, is to have an encoding
> policy of not splitting up runs of decimal digits - which would include
> reserving a spot for a zero, in case, *over the lifetime of Unicode*, some
> script changes their use from numbers 1-9 to decimal digits.
> The other is a guarantee of what it means for a character to have the
> decimal digit property.
> My suggestion for handling this, differ a bit from what has been discussed
> so far.
> The first I would address by suitable language in the WG2 Principles and
> Procedures document. This is where policies on encoding are maintained.
> True, these policies do allow exceptions, but exceptions (note Han !) do
> exist, and if a similar case of mixed-use character came along, then they
> would have to be dealt with accordingly. What the P&P would do is remove the
> wrong notion that it is OK to scatter runs of known decimal digits when
> encoding new scripts.
> The second I would address not by a stability policy, but by clarity of
> definition of the property. Language such as:
> "A character is given the decimal digit property, if and only if, it is
> used in a decimal place-value notation and all 10 digits are encoded
> in a single unbroken run starting with the digit of value 0, in
> order of magnitude".
> or equivalent would be quite sufficient. That language happens to be a much
> clearer statement of the *implicit* definition used in assigning this
> property than the language found in UAX#44 or Unicode Section 4.6.
> Having that language where the property is documented is much more useful
> and visible than in a stability policy.
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