Update to clarify combining characters

[John C Klensin]

--On Monday, 21 April, 2014 18:51 +0200 Patrik Fältström
<paf at frobbit.se> wrote:

> On 21 apr 2014, at 18:01, Peter Occil <poccil14 at gmail.com>
> wrote:
> 
>>  I'm not aware of any registries that allow labels that begin
>>  with those characters.
> 
> You can not know what I uses in my own zones... ;-)

More important (I think) there are norms/ requirements
established by the standard and a requirement (in 5891) that
individual registries (at all levels) establish their own,
presumably more restrictive, policies.  So what registries do or
do not do really doesn't help inform the standard.

   john