Mapping other Digits to 0-9

[Shawn Steele]

> andrew is correct as i recall with regard to protocol - the premise
> behind IDNA2008 is that mapping is not part of the specification.

That's fine, but then I'm confused about what the discussion of the Arabic digits is?  Is it just to disallow Arabic digits?  (Disallowing them implies to me that someone would map them.)  In either case this isn't just Arabic digits, we allow mapping of digits for other scripts as well.

- Shawn