Standardizing on IDNA 2003 in the URL Standard

Shawn Steele Shawn.Steele at microsoft.com
Fri Aug 23 21:25:40 CEST 2013


>   2. The TR46 deviation character
> support can be dropped in clients once the major registries
> that allow them provide a bundle or block approach to labels that 
> include them, so that new clients can be
> guaranteed that URLs won't go to a different location than
> they would under IDNA2003. The bundle/block needs to last
> while there are a significant number of IDNA2003    clients
> out in the world. Because newer browsers have automatic
> updates,    this can be far faster than it would have been a
> few years ago.

That's not necessarily true.  If someone's subdomain uses some IDNA2003 domain name that lands on a different machine, the client applications will get the bug reports that they broke the customer when a customer's URL stops working.  Blocking at the registry could have a similar issue (if the user wants to move from one to another).  Also we cannot enforce that the registrars bundle-or-block.

However if the registrars DO bundle the names with the IDNA2003 form (other variations could be blocked), and the client software continues to resolve using the transient rules for these 5 characters, the user will always land on the right machine, no matter which way they enter the name.  The "worst" problem could be that the address bar looks a little different than what the user entered.  Which could be considered a UI problem.  And if the clients really thought that UI issue was worth fixing, they could ensure that they didn't map the form the users entered for these few characters. 

-Shawn


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