Touchstones for "Mapping"

Vint Cerf vint at
Thu Apr 2 21:12:39 CEST 2009

thanks Michel, I think you've captured both our concerns.


Vint Cerf
1818 Library Street, Suite 400
Reston, VA 20190
vint at

On Apr 2, 2009, at 12:47 PM, Michel SUIGNARD wrote:

> From Mark Davis
>> I think the issue is around what is meant by "storage". Look at a  
>> snippet of text:
>> href="http://εύβοια.el"
>> I just stored both of those URLs. Where? Well, in my GMail storage,
>> in the idna message archive, on my machine (in Gears), on any  
>> recipient's machine
>> (until deleted), eventually in the search engine caches, and the  
>> wayback machine.
> I think both Vint and you have a point.
> For all practical purpose, your text snippet is an IRI. IRI are so  
> far only presentation elements for underlying protocol elements  
> through a well defined mapping (see RFC 3987). Any application that  
> use IRI in storage are supposed to map domain names detected in an  
> IRI string (and that's not always easy) into a DNS complying name  
> before processing it for DNS purpose.
> The problem is that IRI is still stuck with IDNA-2003 definition.  
> Until this is fixed, we are in a grey area, and all apps that have  
> to convert IRI to URI have an issue. In that aspect A-labels are  
> safer, unless applications are careful at storing U-label that are  
> deemed to be identical with either IDN-2003 or IDNA-2003. Hopefully,  
> implementers will be careful, otherwise we could be in a world of  
> hurt.
> Michel
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