Re: An argument against multiple character sets

["Martin J. Duerst" <duerst@w3.org>]

At 12:12 00/01/25 +0100, Patrik F$BgM(Jtstr$B‹N(J wrote:

> I have not really seen this discussion agree on even the first layer here,
> i.e. requirements on multiple character sets and the issue with
> canonlization which is even more troublesome questions than handling of
> casing -- but the problems are similar.
> 
> 
> What I am nervous about is the previous discussions whether it is a
> requirement to define issues like case sensitivity, canonilization etc, and
> my answer is definitely yes.

Agreed. And we should have the main reasons for this, and the main
constrainst, and ideally even the way to go for some of the more
obvious cases (such as casing) in the req document.


> This because of the impact on registration
> issues, because domain names have to be "unique" in a zone at time of
> registration. Because of that, the rules for equality have to be known at
> the time of registration,

Not only the rules for equality, also the ways to deal with this
equality. If some equality is dealt with on the client side, then
registration has to make sure the right variant of the name is
registered.


> and IF the rules changes, it might have
> "interesting" impact on already registered domainnames (as we have seen in
> the previous examples of "ibM.com" equal or not to "IBM.com", extrapolated
> into equality of "$Bg(J with "a" followed by combining "M").
> 
> 
> Is there some consensus even on what the requirement is?

I think it's building up. I haven't seen Paul come back asking that
we require case distinctions after he was hit by lists of variants
that would have to be registered in that case.


On a higher level, I think we have to avoid that the system makes
distinctions purely due to variants in the encoding that are never
supposed to be visible to the user.

In the case of Unicode, this is on first approximation equivalent to
requiring that canonical equivalents are considered equivalent by
the overall system.

There are a few other things one may want (or may not want) to take
care about; I can dig out a list of these somewhere if you want.


Regards,   Martin.


#-#-#  Martin J. Du"rst, World Wide Web Consortium
#-#-#  mailto:duerst@w3.org   http://www.w3.org