[tz] Japanese Summer time fallback transition in autumn 2020?

[Phake Nick]

I have found a bit more information on the topic.
In the webpage authored by National Astronomical Observatory of Japan
https://eco.mtk.nao.ac.jp/koyomi/wiki/BBFEB9EF2FB2C6BBFEB9EF.html , it
mentioned that using Showa 23 (year 1948) as example, 13pm of September 11
in summer time will equal to 0am of September 12 in standard time.
It cited a document issued by the Liaison Office which briefly existed
during the postwar period of Japan, where the detail on implementation of
the summer time is described in the document.
https://eco.mtk.nao.ac.jp/koyomi/wiki/BBFEB9EF2FB2C6BBFEB9EFB2C6BBFEB9EFA4CEBCC2BBDCA4CBA4C4A4A4A4C6.pdf

The text in the document do instruct a fall back to occur at September 11,
13pm in summer time, while ordinary citizens can change the clock before
they sleep.
* Note: despite the webpage being named as wiki, it is actually a
collection of information maintained by the Ephemeris Computation Office,
NAOJ, not something that can be edited by others.

2018-9-19 Wed 04:59, Paul Eggert <eggert at cs.ucla.edu> wrote:

> 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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