Final Sigma (was: RE: Esszett, Final Sigma, ZWJ and ZWNJ)

[John C Klensin]

--On Saturday, February 28, 2009 10:44 +1100 Mark Andrews
<Mark_Andrews at isc.org> wrote:

> 	You could get partial support the moment the type code was
> 	allocated.  Clients would query for the record.  Authoritative
> 	servers could use unknown type support to add the record.
> 	It would work for all names except those with CNAMEs.

Excuse me?  How can one expect clients to "query for the record"
before they, and the protocols they support, are updated?
Remember that, as one moves out toward the stub resolvers, there
are a lot of systems that haven't heard of RRSIG or even EDNS0
and that will probably be updated only when their hardware rusts
out.  You also said some things about the additional section --
I assume that any required changes there would require software
development and deployment.  Is that not correct?

> 	Support for CNAMEs requires servers and caches to be updated.

And, of course, a decision that adding this type of information
to CNAMEs is wise given that it is metadata and much closer to
an ordinary RR than RRSIG is.

Incidentally, no directionality indicator is needed: Bidi is
complicated, but largely takes care of itself unless you have
visions of right-to-left Latin strings.

     john