[tz] Japanese Summer time fallback transition in autumn 2020?
eggert at cs.ucla.edu
Tue Sep 18 20:59:06 UTC 2018
On 9/18/18 1:43 PM, Paul Ganssle wrote:
> The law says that the last day of DST had 25 hours instead of 24. The
> question is whether in practice what happened was that starting 0:00 on
> Saturday, did people wait 25 hours (until 01:00 on Sunday) and THEN set
> their clocks back 1 hour, or did they wait 24 hours (until 00:00 on
> Sunday), and then set the clock back to 23:00?
Yes, that's the nub of the question. If people in Japan generally did
the former, we should change tzdb to model the transition as one from
01:00 to 00:00 Sunday; this is not exact but is the best we can do. If
people generally did the latter we're OK as-is. Possibly some people did
one thing while others did the other, as the American occupiers did not
always see eye-to-eye with the Japanese populace and I doubt whether
it's entirely a coincidence that Japan stopped observing DST three days
after US occupation ended.
As we've already mentioned, old Japanese-language newspapers could help
resolve this issue.
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