looking up domain names with unassigned code points

Shawn Steele Shawn.Steele at microsoft.com
Mon May 12 21:34:07 CEST 2008

> > I expected some disagreement with my assertion that some
> > protocols/users will require the Unicode form, so therefore
> > the benefit of looking up punyicode is limited to some
> > specific scenarios, probably leading to inconsistent
> > experiences with "new" names.

> I'm not sure I understand this.  Applications that have not been
> upgraded to understand IDNA are going to look those punycode
> forms up because they don't know any better _and_ because those
> forms are perfectly good LDH labels.  That was a major part if
> the IDNA design and some other alternatives were sacrificed to
> get it.  And, of course, some protocols and users will "require
> the Unicode form".

That is a technical part of IDN.  As a practical matter I expect the Unicode form, not the A form, on a business card.  Specifically, imagine that I go to the library and they have the latest updates.  I click on a link (which happens to be in a-form) and find a web site useful to a project I'm working on at work.  I then write the "URL" from the address bar down on a scrap of paper and take it to work.  I try to email this to my coworkers but discover the URL I wrote down doesn't work because my work environment hasn't received the latest updates yet.

As the owner of such a domain name I need users to have reliable access to the name.  If I can't use the Unicode form on a business card or a display ad because the adoption rate is too low, then the A form is useless to me in a link since I can't even get the core scenarios to work.

So I'm suggesting that the A-form is interesting for back-compat (all those xn-- domains registered before IDN, which the IDN RFCs effectively made illegal anyway), but not for forward-compat.

- Shawn

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