Internationalization: Support for IANA time zones

Norbert Lindenberg ecmascript at lindenbergsoftware.com
Sat Mar 2 10:50:40 PST 2013


On Mar 2, 2013, at 8:46 , Mark Davis ☕ wrote:

> The TZDB has the equivalence class {Asia/Calcutta Asia/Kolkata}. They used to have the former as the canonical name (in Zone), but then changed it to the latter. Here is the current TZDB data:
> 
> zone.tab
> 
> IN	+2232+08822	Asia/Kolkata
> 
> asia
> 
> Zone	Asia/Kolkata	5:53:28 -	LMT	1880	# Kolkata
> ...
> 
> backward
> Link	Asia/Kolkata		Asia/Calcutta
> 
> Because of the Link, both are valid and equivalent.
> 
> 
> CLDR, because we need stability, retains the former TZID as the canonical name. That is the meaning of the first alias in http://unicode.org/repos/cldr/tags/release-22-1/common/bcp47/timezone.xml such as in:
> 
> <type name="inccu" alias="Asia/Calcutta Asia/Kolkata" description="Kolkata, India"/>
> 
> The short name (name="...") is only used for BCP47 subtags (because of the ASCII/8-char limit), not for communicating with TZDB implementations. Nor is it used in CLDR for the canonical ID. 
> 
> Instead Asia/Calcutta is used as the canonical ID.

That breaks if/when the tz database removes Asia/Calcutta from its Link list and other systems using IANA names stop supporting (or never start supporting) that name.

I still think the stability issue should be addressed in the IANA time zone database itself, not by adopting a IANA-derived alternate registry. Has that been tried?

Norbert



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