From: karl williamson (public@khwilliamson.com)
Date: Thu Jul 29 2010 - 18:13:26 CDT
Asmus Freytag wrote:
> Having Nd be limited to characters that
>
> a) are used in decimal radix numbers
> b) are part of a complete, ordered sequence 0..9
>
> would make this property regular enough to serve
> implementers. You could script the creation of
> relevant data for your implementation based on that
> property.
>
> *Exceptions* exist and need to be documented.
> Having exceptions machine readable is not as
> important, but having implementers understand
> them is.
>
> Therefore, the best thing is for these to become
> something other than Nd, but to retain their numeric
> type of digit.
>
> Together with a detailed explanation of each in
> the appropriate script chapter, AND a complete
> summary of all exceptional cases in a central
> place (section 4.6 comes to mind) would provide
> implementers with the information they need.
>
> The exceptional cases that I'm aware of are
>
> a) Arabic using two complete series of digits
> b) New Thai Lue using an extra digit 1
> c) Han digits being scattered and used in two
> different types of numeric expressions
> d) ASCII digits being used for some scripts
> as preferred decimal-radix digits, because
> their native number system is not, or not
> exclusively decimal-radix
>
> The above information belongs in section 4.6
> in summary form, or simply as table of pointers
> to each script chapter that contains a description
> of unusual numeric behavior for decimal-radix
> digits.
>
> (A separate table pulling together all the descriptions
> of non-decimal radix number systems that are
> discussed in the Standard would equally be useful
> for the readers).
> A./
>
This sounds good to me.
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