[tz] Recommendations to governments about time zone update notice period and format

Neil Fuller nfuller at google.com
Mon Mar 6 11:41:52 UTC 2023

The latest short-notice time zone change from Egypt, so soon after the
Mexico changes, made me wonder...

Would it be useful to have a canonical thread or set of links in the TZDB
docs to point to for user-facing "Why hasn't my device updated?" or
government-facing "Why didn't our legislation change reach citizen's
devices in time?" -type questions?

For example, here are recommendations/policy I know of for a couple of
widely-used operating systems / platforms:

(this is relatively new)


Maybe these could be collated and extended for other consumers of TZDB.


I vaguely remembered there being something in the TZDB docs that says
something along these lines [*] but I couldn't find it and might be getting
confused with threads on the mailing list.

I don't honestly expect having it written down to make a lot of difference,
but the regular lack of notice and confusion about what *exactly* governments
have changed makes me think there *could* be a set of recommendations.
Then, governments that *want* to do the right thing could then know what to
provide / expect and plan accordingly, and ones that don't try can be
easily informed why things didn't work out like they may have expected.



[*] e.g. maybe something like "Many downstream users of the TZDB wait for
an official TZDB release before they will produce an update to time zone
behavior in consumer devices and software products. After TZDB has been
updated, various parties have to perform their own integration, testing,
and rollout of an update before users will see changes. These updates can
be expensive, e.g. for the QA process itself and the network costs for
updates to each TZDB copy. Updates may be batched with other updates and
take substantial time to reach users after the TZDB release. Updates will
require that affected products have a suitable update mechanism in place
and are still supported."

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