Cf?

[Kenneth Whistler]

Paul Hoffman asked:

> At 11:42 PM -0400 3/15/08, Patrik Fältström wrote:
> >Please propose something that I can use for -06.
> 
> We can only do that if we know which characters from {Cf}, if any, 
> are needed in domain names. Some of the character experts needs to 
> chime in here.

The character experts have been saying for months now that
only the following are needed:

U+200C ZWNJ
U+200D ZWJ

and no other gc=Cf characters.

> I see three sequential decisions here:
> - Does anything in {Cf} need saving?

Yes.

> - If so, what is the full list?

U+200C ZWNJ
U+200D ZWJ

i.e., just the joiners. But if the joiners are handled by
a separate rule, namely Rule H, based on the property
Join_Control=True, then no other context handling of
gc=Cf format control characters needs specification.
Just make the rest all Disallowed.

> - What is the context for each item in the list?

http://www.unicode.org/reports/tr31/tr31-8.html#Layout_and_Format_Control_Charac
ters

--Ken