[tz] Fwd: DST changes in Hungary (full historical revision)

Paul Eggert eggert at cs.ucla.edu
Tue Jun 9 20:52:29 UTC 2020

On 6/9/20 11:53 AM, Michael H Deckers wrote:
>    In all the cases where I could check the exact time of day of a switch
>    to time zone time, this turned out to be the case -- except, of course,
>    for Dublin on 1916-10-01 where British law said that the time had to jump
>    from 03:00:00 to 02:25:21.1.

There are other such cases in tzdb. For example, the 1911-03-11 transition in
Paris is from 00:01 Paris Mean Time to 23:51:39 GMT the previous day. If the
comments are right this transition came from Ciro Disceopolo but we don't have
exact citations.

>    I guess I just wanted to say that the default jump produced by zic
>    is not necessarily a good guess of what really has happened (except
>    possibly for Britain).

Absolutely. It's a tension between making it clear in the source code that the
time (or in some cases even date) is not known, versus coming up with the
most-likely guess. There's no single right answer here.

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