LDH-label terminology Iwas: Re: Comments on idnabis-rationale-01)

Vint Cerf vint at google.com
Sat Jul 26 21:35:33 CEST 2008


at the risk of making things more complicated, do any of the definitions
manage to proscribe the presence of "-" "-" in the 3rd and 4th  
position from the left in L2R LDH-conforming strings?
One assumes that despite the possibility of R2L U-labels, the correct  
associated A-Label expression is still L2R (?).

vint

On Jul 25, 2008, at 6:27 PM, John C Klensin wrote:

> This is a very good summary, even though Eric's taxonomy covers
> more of the landscape in a little more detail.  Comments below.
>
> --On Friday, 25 July, 2008 00:48 +0200 Frank Ellermann
> <hmdmhdfmhdjmzdtjmzdtzktdkztdjz at gmail.com> wrote:
>
>> Tina Dam wrote:
>>
>>> I would be ok with a different term as well, but I don't
>>> have any good ideas.
>>
>> The funny thing is that we all like LDH-label as intuitively
>> clear, and then don't agree on the same definition.  Here's
>> some simplified ASCII art:
>>
>> +--------------------------------+
>> | DNS labels (octets)            |
>> |                                |
>> | +------------------------------+
>> | | LDH labels (LDH)             |
>> | |                              |
>> | | +----------------------------+     +----------+
>> | | | A-labels (IDNAbis valid)   | <=> | U-labels |
>> | | +----------------------------+     +----------+
>> | |                              |
>> | +------------------------------+
>> |                                |
>> +--------------------------------+
>>
>> What I see is "A-labels are a proper subset of LDH-labels,
>> as specified in IDNAbis.  LDH-labels are a proper subset
>> of DNS labels, as specified in RFC 1123" (or similar).
>>
>> What John sees is "A-labels are one thing, and LDH-labels
>> are the DNS labels consisting of LDH which are no A-labels,
>> as specified in IDNAbis".
>
>> IOW John has no name for the union of A-label and LDH-label
>> in his terminology (the middle box in the ASCII art).
>
> I have periodically referred to them as LDH-conforming ASCII
> strings, or similar terms.  But, per Eric's note and my prior
> one, that box really consists of (my) LDH-labels, A-labels, plus
> some stuff that consists of other strings of ASCII characters.
>
>> I've no term for those LDH-labels which are no A-labels in
>> my terminology (the middle box excluding the innermost box).
>
> And neither of us have a term for things that fit in the DNS
> label box but that are not LDH-conformant.
>
>     john
>
> p.s. I sent a note off earlier today whose purpose is to dump
> much of this terminology stuff (and the 1123 clarification and
> related issues) onto the DNS experts and/or WG(s) or at least
> get them to work with us on it.  Don't know if that will be
> successful, but I'm  going to feel better for having tried.
>
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