Greek Casefolding sigma

Jelte Jansen jelte at
Sat Mar 29 12:49:59 CET 2008

Hash: SHA1

Patrik Fältström wrote:
> The way IDNA2003 is designed is that the key does _NOT_ allow final
> sigma, and this because of design of Unicode. Regardless of if "the user
> typed" sigma or final sigma, the same key should match. Without changing
> the matching algorithm (that is out), the key have to be calculated on
> the client side. This key that is sent in is sigma, never final sigma.

i think that's what Mark was arguing too; let final sigma stay
DISALLOWED, let applications that do lookups map final sigmas to sigmas,
and let applications that want to display DNS data as unicode characters
(be it apps that interpret PTR records, 'wysywig'-editors for zone
files, anything that might want to convert xn-- labels back) be smart
and notice whether a sigma is on the end of a word, and display it as a
final sigma.

In other words, keep the mapping out of the DNS itself, and let the
presentation layer handle it.

I'm not proficient enough in Greek to know whether there are any
exceptions to the final sigma rules. Also, abbreviations might be
displayed wrong to (σσσ would be displayed as σσς), so I'm not sure
whether this is an acceptable solution.

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