[ezio.melotti]
> I suggest something like:
> Matches the decimal digits ``[0-9]`` and all the characters that belong
> to the Unicode category Nd (Number, Decimal Digit).

Hmm.  I don't like this because it suggests (to me) that the characters 
[0-9] don't belong to category [Nd].  I agree the previous version was 
clunky, though.  I've shortened it some;  if anyone else wants to work on 
the wording please feel free.  It might be nice to annotate each of these 
character classes (\w, \s) with the Unicode character categories that they 
correspond to.

> Two more minor details: instead of '\d', I'd use '^\d$' and instead of
> self.assertEqual(re.match('\d', x), None)
> self.assertIsNone(re.match('\d', x)).

Thanks.  Changes applied.

Committed to py3k, r74237.   Leaving open for backport to trunk.