[tz] What data should TZDB offer?

Fred Gleason fredg at paravelsystems.com
Sun Jun 6 16:44:11 UTC 2021

On Jun 6, 2021, at 11:02, Tom Lane via tz <tz at iana.org> wrote:

> 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.  In particular,
> I think it's past time to prohibit data changes adopted for
> essentially-administrative reasons (as opposed to new findings of
> historical fact).  I'd put the recent reorganization under the
> heading of things that would be forbidden by this principle, 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.
> […]
> 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, this seems basically like future
> proofing: even if two countries have shared clocks since 1970,
> they could diverge at any time.  Being prepared with an appropriate
> zone name should minimize the pain to users.  Also notice that
> splitting an existing zone creates no compatibility problems, since
> no one is obligated to switch to the new zone name immediately.

These two points in particular are synergistic; stability of historical data is just a Good Thing, but no one here wants to see the TZDB maintainer receiving ‘vitriolic’ e-mail, nor getting sued [again]. Hence, politically ‘future-proofing' the DB seems a prudent move.


| Frederick F. Gleason, Jr. |             Chief Developer             |
|                           |             Paravel Systems             |
|         A room without books is like a body without a soul.         |
|                                                                     |
|                                                         -- Cicero   |

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