[tz] What data should TZDB offer?

Clive D.W. Feather clive at davros.org
Mon Jun 7 09:22:16 UTC 2021

Tom Lane via tz said:
> One other issue that I think deserves more attention than it has
> gotten lately is that tzdb has become a de facto standard and users
> rely on its stability.  I would like to see some sort of principle
> adopted that minimizes changes in historical data.
> and also
> the changes a few years ago that removed "made up" zone abbreviations.
> Whatever the justification for those abbreviations originally, some
> people had come to depend on them, and little was to be gained by
> removing them.

But I'd like another principle to be "truth". We should not be making up
data - that goes both for lying about LMT offsets and lying about the
abbreviations people use.

Remember that the basic principle was "what's used on the ground".

> The idea of having at least one zone per ISO-3166-1 country does
> seem like a good one, though.  Aside from possibly deflecting
> politically-based complaints,

And adding other ones.

> this seems basically like future
> proofing: even if two countries have shared clocks since 1970,
> they could diverge at any time.

So can a country and a dependent territory. Or even a non-dependent one: to
pick a fanciful example, as part of the upcoming EU changes, Italy could
decide to stick to UTC+2 but France to UTC+1, then Corsica decide to go to

> Being prepared with an appropriate
> zone name should minimize the pain to users.

Why not wait until it's needed? We're likely to get more notice than we get
for some countries' Ramadan changes.

Clive D.W. Feather          | If you lie to the compiler,
Email: clive at davros.org     | it will get its revenge.
Web: http://www.davros.org  |   - Henry Spencer
Mobile: +44 7973 377646

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