Changing the xn-- prefix

Mark Davis mark.davis at
Fri Mar 21 02:34:18 CET 2008

I agree; I think changing the prefix would be a horrible mess. I'd rather
not see that as a possibility in the charter.


On Thu, Mar 20, 2008 at 11:18 AM, Shawn Steele <Shawn.Steele at>

> I think that changing the prefix would be a really bad idea:
> * Changing the domain name would break existing comparisons that rely on
> the punycode.  (domain name xn--A wouldn't necessarily equal domain name
> xx--A)
> * names wouldn't match in the registry either.  The browser would have to
> try the new prefix name, then if that failed, it'd have to try the xn-- name
> for back compat.
> * What happens when the xn-- and the new prefix names for the same
> machine/Unicode name point to different servers?  This could happen either
> because the registrars messed up or they are on a subnet that didn't know
> better?
> * Developers would have to consider 2 versions for even simple
> applications.
> I think that these are much more serious that changing behavior for
> anything that is considered "bad" (for security) today.  If a "bad" domain
> stops working we probably want it to stop working.
> Our intent is to replace the IDN resolution mechanism for IE/Windows/.Net
> with updated tables when they become available.  We would oppose anything
> that causes us to have multiple revisions or complex code paths for edge
> cases.
> - Shawn
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