I-D Action: draft-klensin-idna-rfc5891bis-00.txt

[John C Klensin]

--On Saturday, March 11, 2017 19:47 +0000 Shawn Steele
<Shawn.Steele at microsoft.com> wrote:

> It makes sense to reinforce that registrars need to do their
> own narrowing of code points according to their needs.

That was the position that motivated the document.

> WRT the other issues that are avoided here, IMO the IETF
> should defer to Unicode as they are the ones that add new
> codepoints and they fully understand the security and other
> issues in the space.  Encoding characters is, after all, their
> expertise.

No one has questioned their ability to encode characters.  The
issues are things that have been issues since IDN work was
initiated (at least since the decision to use Unicode).   I
think Unicode is a great system for encoding running text and an
even better one for encoding text that is to be rendered and
printed or otherwise displayed.  There is no dispute about that.
However, for identifiers and identifier matching, there are
differences in philosophy, several of which have been
illustrated by issues that have shown up in the last few years.
As one example, the DNS, at least the way IDNs and IDNA were
conceived, does not have any "language" context, so Unicode
distinctions among code points or ways of composing characters
that are based strictly on language distinctions don't work well
within IDNA (we could have designed IDNA to incorporate language
information but we didn't for what seemed like good ideas at the
time --and still do to many of us-- but, if anyone has the
stomach to reopen that design question and start planning a
major incompatible change were the decision to go the other way,
go for it).   

best,
   john