[tz] Chile TZ rule 1942 June superfluous? PS

[Paul Eggert]

Alois Treindl wrote:
> PS: on second thought, could it be that the lines for 1942 are generally in error:
>
> Rule    Chile   1942    only    -       Jun      1      4:00u   0       -
> Rule    Chile   1942    only    -       Aug      1      5:00u   1:00    S
> Rule    Chile   1946    only    -       Jul     15      4:00u   1:00    S
> Rule    Chile   1946    only    -       Sep      1      3:00u   0:00    -
>
> They make no sense, because according to this,
> - Jun 1942 line is superfluous

No, because according to the database Chile was on daylight-saving time (UTC-4) 
from 1932-09-01 05:00 UTC until 1942-06-01 04:00 UTC, so that line is needed for 
Chile to exit DST.

> - Aug 1942 sets DST in force until next cancellation of DST in Sep 1946,
> - JUL 1946 line would be superfluous, as well.

Yes, that's right.  The line mentioning "Jul 15" can be removed without changing 
the meaning of the data.  I don't know why that line is there, but I suppose we 
can remove it.

> when I look at the reference, http://www.horaoficial.cl/historia_hora.html
> it does not contain anything about DST in 1942.

This entry was contributed by Jesper Nørgaard Welen in 2006; please see:

http://mm.icann.org/pipermail/tz/2006-October/013906.html
http://mm.icann.org/pipermail/tz/2006-October/013908.html
http://mm.icann.org/pipermail/tz/2006-October/013909.html
http://mm.icann.org/pipermail/tz/2006-October/013936.html

I'll CC: this message to him to see if he can provide insight, though we haven't 
heard from Jesper for a while so we may not get a response here.  I did not 
check horaoficial.cl myself.  Possibly it has changed since 2006, possibly there 
were transcription errors.  Either way, we should fix it.