Re: [idn] The layers and character handling in DNS

[John C Klensin <klensin@jck.com>]

--On Sunday, 18 February, 2001 08:30 -0800 Patrik Fältström
<paf@cisco.com> wrote:

>> Agreed.  But that implies, as above, that we make _zero_ of our
>> own rules.  If the Nameprep document is more complex than "take
>> the UTC rules and apply them" (perhaps in some specific order
>> relative to other things that need doing), I think we are out
>> of this space and into applying our own judgement... we I
>> think we agree we should not do.
> > I agree with this in principle, BUT, we need still some extra
> text.
> > This because we might want to
> > - prohibit some code points as part of a label (compare with
> the problems with having no definition of what is a hostname
> compared with definition in DNS protocol to be able to handle
> decimal values of 0-255 (inclusive) as part of a label).

I think this takes us well out on a slippery slope.  And much
further out if the rules/ prohibitions are not _extremely_ short
and simple.

> - specify what should happen with non-assigned characters
> (which solves the versioning problem).

Solves the versioning problem iff you believe that we will get it
exactly right, for all currently-assigned characters, the first
time.   Watching the Nameprep discussions over the last few
months does not lead me to be optimistic about this.

> - specify in what order case folding, normalization etc should
> happen.

Yes, this I agree with.  But this one can be done as a few simple
rules or not at all.  And we had better be able to enumerate
"etc" and not need to add anything to that list in the future, or
we will have another versioning problem.

    john