Shawn Steele Shawn.Steele at
Wed Aug 13 20:07:18 CEST 2014

IDNA2003 provided mapping rules that mapped eszett to ss.  IDNA2008 decided that didn’t allow full support for a language, and decided to remove the mapping (so it’d get it’s own punycode).  However most browsers use the UTS#46 transitional rules because that would allow a link that previously went to one server to end up going to a new server if IDNA2008 rules were applied.

IMO I’d really like to see a “display” record so that if someone wanted their display name (that equivalent to the IDNA canonical form) look a certain way, then they could for presentation.


From: idna-update-bounces at [mailto:idna-update-bounces at] On Behalf Of Cary Karp
Sent: Wednesday, August 13, 2014 10:56 AM
To: idna-update at
Subject: Re: Eszett

Quoting Shawn:
> Exactly, but a there's a somewhat popular<> site.  Users probably expect the sharp-s version to take them there.

> Which it does when I try it. If others get a different result this whole thing is really screwed.

Well, that’s likely because the browser developers are afraid of what the IDNA2008 change would do to that scenario and have implemented the transitional part of UTR#46.  If you followed pure IDNA2008, you could end up somewhere else.


The zone file contains the A-label not the U-label, which unsurprisingly also works when called directly. It's also what the registrant believes they entered into the zone. A browser developer is free to decide which form to display but implementing "could end up somewhere else" functionality does not strike me as being inthe best interests of either the registrant or user communities.

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