Contextual rule for MODIFIER LETTER PRIME?

[Kenneth Whistler]

Patrik,

Michael's point:

> "Romanized Cyrillic" is Latin. Not Cyrillic. The modifier letter prime  
> is not used with Cyrillic.

and Mark Davis' point:

> > On 5 nov 2008, at 03.15, Mark Davis wrote:
> >
> >> For example those
> >> for MODIFIER LETTER PRIME (used in romanized Cyrillic as well as  
> >> Greek) which can be a final characters in words, ...

is that U+02B9 is not used just as the normalized equivalent of
the U+0374 GREEN NUMERAL SIGN. It occurs commonly in Latin transliteration
of Slavic languages -- including Old Church Slavonic, but even Russian,
too. So it is used with the Latin script (but not with the Cyrillic).

> > Is what you say that the existing rules:
> >
> >> Appendix A.6.  MODIFIER LETTER PRIME
> >>   Code point:
> >>      U+02B9
> >>   Overview:
> >>      Permitted only in contexts in which GREEK LOWER NUMERAL SIGN,
> >>      U+0375, is permitted.  GREEK NUMERAL SIGN, U+0374, and the Lower
> >>      Numeral Sign (U+0375) are indicators for numeric use of  
> >> letters in
> >>      older Greek writing systems.  U+02B9 is relevant because
> >>      normalization maps U+0374 into it.
> >>   Lookup:
> >>      False
> >>   Rule Set:
> >>      True;
> >>      For All Characters:
> >>         If Script(cp) .ne.  Greek Then False;
> >>      End For;
> >
> > ...should be changed so that script cyrillic, or '-' as adjacent  
> > character makes this ok?

Neither.

> >
> > Can you please provide a new rule that works?

Once again, this attribution of CONTEXTO to U+02B9 is accomplishing
nothing but adding unnecessary complication to the rules.

U+02B9 should simply be PVALID -- which will happen
automatically if it is removed from the exception list in 2.6.
And then Appendix A.6 should simply be removed instead of
trying to define a complex rule that would make any sense
for it as CONTEXTO.

I realize that people think that the Greek numeral signs
are "dangerous" for IDN because they look kind of like
syntax characters. But this is no more true than any number
of other modifier letters which are quietly PVALID in the
table. If the Greeks think that the two numeral signs
make sense for IDNs, then we should just make 0375
PVALID in 2.6, leave 02B9 PVALID by rule, and be done with
it. No context rules needed. Simpler and cleaner.

--Ken