Yangwoo Ko newcat at
Tue Dec 11 09:49:59 CET 2007

Quoted from an email sent by John Klensin.

> Put differently, there is no way
> to interoperably conform to both that provision of RFC 3490 and
> conform to RFC 1034/ 1035.

I am convinced by the above argument. Like it or not (personally, I did 
NOT like it), IDN WG decided to go for ACE, which seems to be the best 
way to live with old DNS servers. By having that provision of 3490, if 
we lose the interoperability with old servers, we are losing one of the 
most important values we wanted to achieve.

More comments are embedded below.

fujiwara at wrote:
>> From: John C Klensin <klensin at>
>>> The dot-mapping is already implemented in many applications.
>>> Removing it causes many problems.
>> Removing it _from those applications_ would be a bad idea, IMO.
> If the dot-mapping is removed from the standards, the implementors
> will remove it.

I don't think so but, even though implementers are so diligent (*-P) to 
remove it, then users will learn how to avoid lookup errors. Critical 
point is that how consistently lookups will fail. By having partially 
successful list of dots, we will end up with inconsistent failures (and 
some successes too). And this will make users confused and hard to learn.

>>> I'm afraid that another languages may have the same problem
>>> and the characters which need to be treated as a dot may
>>> increase.
>> Yes. And the risk of more dot-characters being added is one of
>> the reasons for removing dot-mapping from the protocol.  
>> Let me try again to explain:
>> In your applications, both legacy and new, you should certainly
>> map the dots that make sense to you to map.   For your case,
>> that means you should almost certainly map Japanese-related
>> dots, but should not make an attempt to map any character
>> (worldwide and in any script) that looks to you like a dot.   If
>> you start mapping anything that looks like a dot to you or your
>> users, you might end up, e.g., treating the numeral 5 as a dot.
> Representative implementations (firefox, IE, Safari) are
> internationalized. Language specific implementation is rare.

This is what localization is for while admitting the fact that there are 
cases where locale is missing or vague. For completely context free 
situations, any mapping will be harmful. But, you should be aware of the 
fact that human beings are intelligent enough to overcome such a 
difficulty if they are involved in the process. Without human in the 
process, consistent failures will be the right thing.

> (snip)

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