Eszett (Sharp-S) again (was: Re: AW: Oustanding issues tracking)

Mark Andrews Mark_Andrews at
Wed May 28 08:53:20 CEST 2008

> > (2) If we treat Eszett as a separate character, we create a
> > fairly nasty incompatibility between IDNA2003, where it maps to
> > "ss" and disappears and IDNA2008, where it is separate.
> > Preventing that incompatibility from being a nasty problem would
> > require some very careful action by the relevant registries (as
> > usual, in the "zone administrator" sense, not just TLD
> > registries).  Possibly a well-designed variant strategy would be
> > sufficient, possibly not.   We haven't heard from the most
> > obvious registries yet as to whether they would be willing to
> > deal with this.
> If eszett were to be added to the IDNA2008 tables as protocol-valid, DENIC 
> probably would, after the standard is passed, allow eszett registration 
> under the DE TLD. Since that codepoint was not allowed for registration 
> until now (i.e. no mapping eszett->ss occurred within the registry), there 
> is no "nasty problem" here from our point of view. When typing eszett in a 
> domain name while browsing, some users (IDNA2003) would certainly end up 
> at the ss-mapped-name, some other users (IDNA2008) would end up at the 
> eszett-name. Still from our point of view (which is not up for debate 
> here), usage of variants at the registry would not be an appropriate 
> technique for dealing with this issue. On the contrary, it would be my 
> recommendation for all ss-mapped-name-registrants to apply for 
> registration of the corresponding eszett-name, where applicable. Maybe 
> registrars could automatically do this for their customers, I actually 
> don't mind. And if the eszett-name would already have been registered by a 
> different registrant, chances are very high that the corresponding 
> ss-mapped-name-registrant would win a dispute on the eszett-name.

	Or just add a DNAME to map from IDNA2003 -> IDNA2008 versions
	of the name.  The reverse mapping could be done also if
	needed though it would be better to map from old to new
> Best regards,
> Marcos
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> Idna-update at
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at

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