[tz] IANA timezone database - request to add Omaha, Nebraska

Paul Eggert eggert at cs.ucla.edu
Mon Aug 1 08:13:39 UTC 2022

On 8/1/22 01:06, Florian Weimer wrote:
> There is TzdbZoneRulesCompiler, which I think is used to compile the
> data which can be accessed through these interfaces:
> <https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/time/zone/package-summary.html>
> There I think ICU has something in this area, too, and the time zone
> library that was standardized into C++ has a backend based on .zi files,
> too (for systems which do not install the TZif files).
>> Distros like FreeBSD should consider installing tzdata.zi as that will
>> make it easier for applications to enumerate all supported Zone and
>> Link names, as well as do other things.
> But that file also lists the (abbreviated) rules, and you wrote above
> that those aren't for end-user consumption.

Good point. Although Rule names and contents weren't intended for 
end-user consumption, you've identified two places that use them anyway.

However, these places presumably use them reasonably carefully. For 
example, they don't care that tzdata.zi renames and abbreviates the rules.

Looking back at your original question "How does this system implement a 
programming interface that enumerates the TZ rules?" 
<https://mm.icann.org/pipermail/tz/2022-July/031702.html> I think the 
answer is that TZif files don't do that. That is, they don't give you 
access to the Rule lines, only to the effect of the Rule lines on 
transitions and/or TZ strings.

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