<i18n dev> TZ database 2021b changes

Yoshito Umaoka y.umaoka at gmail.com
Tue Sep 28 15:34:56 UTC 2021

Hello OpenJDK i18n dev team,

As you may already know, TZ database 2021b was released last week, and 
it contains some drastic changes for pre-1970 rules. Multiple zones 
sharing post 1970 rules were merged into one, and they were moved to 
backward file. Pre-1970 rules used for these merged zones in 2021a were 
in backzone file, but it's not a part of standard package.

In the tz mailing list, many TZ database consumers are worrying about 
this move. It looks not a small number of people are against this 
change, and some are considering to maintain database separately to 
maintain rules for pre-1970 dates.

I'm curious about what Java i18n team will do for this. Do you plan to 
accept the changes done in TZ database 2021b as-is? Or do you plan to 
preserve rules in backzone?

We discussed this topic in Unicode ICU team meeting last week. We don't 
have long term strategy yet. However, DST change in Samoa is already in 
effect, we're going to ship a quick patch including 2021b zone rule 
updates applied on top of 2021a for now (today or tomorrow).


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