I've prepared the attached patches to address and further document this divergence. 0001 reverts the data change portion of the errant commit 6d6a21f592c421dcebf39b07a6271d68187cfa15 published on Saturday 2022-03-12. 0002 significantly expands our commentary on Chilean transitions in 1946 and 1947 and also adjusts LMT/SMT to match Chilean law. In particular, even recent Chilean law still refers to time reckoned as "the meridian of the Astronomical Observatory of Lo Espejo, advanced by 42 minutes and 45 seconds" https://www.diariooficial.interior.gob.cl/publicaciones/2018/11/23/42212/01/... While preparing these patches, I also noticed this in our commentary: # From Paul Eggert (2019-09-01): # The above says the Magallanes exception expires 2022-04-02 at 24:00, # so in theory, they will revert to -04/-03 after that. # For now, assume that they will not revert, # since they have extended the expiration date once already. So there's a decent chance we'll be hearing from Chile soon anyway. In any case, the attached patches (along with a couple small clerical patches) are now installed in the development repository. -- Tim Parenti On Mon, 14 Mar 2022 at 23:27, Tim Parenti <tim@timtimeonline.com> wrote:

On Fri, 11 Mar 2022 at 12:39, Alois Treindl via tz <tz@iana.org> wrote:

...

I wonder on which basis the 1946/47 DST was left out for Puntas_Arenas? Is that documented somewhere?

Although it doesn't appear to have been documented in our extended commentary, there's indeed a clue in the short line-comment that reads "central Chile".

It can sometimes get confusing looking at UNTIL lines, but the only place the UT offsets of the two zones actually deviate in our 2021e data is the roughly six-week period from through 1946-07-15 through 1946-08-31, inclusive. Compare the extract from America/Punta_Arenas: -5:00 - -05 1942 Aug 1 -4:00 - -04 1947 Apr 1 and America/Santiago: -5:00 - -05 1942 Aug 1 -4:00 - -04 1946 Jul 15 -4:00 1:00 -03 1946 Sep 1 # central Chile -4:00 - -04 1947 Apr 1

So what happened on 1946-07-15? Well, sure enough, an emergency decree which only applied to the central part of the country:

https://www.diariooficial.interior.gob.cl/versiones-anteriores/do-h/19460715... Núm. 3,891. Adelanta la hora oficial en el territorio nacional comprendido entre las provincias de Coquimbo y Concepción, inclusives, por el plazo de 30 días No. 3,891. Advancing the official time in the national territory between the provinces of Coquimbo and Concepción, inclusive, for a period of 30 days

Specifically (my Google-assisted translation): "In the national territory between the provinces of Coquimbo and Concepción, inclusive, the Official Time will be advanced by sixty minutes, for a period of 30 days, starting from 24:00 on July 14 [of the current yaer]."

That would include Santiago, which advanced to -03, but did not reach so far south as Magallanes, which would have stayed on -04.

The decree contemplated "[t]hat this advancement of the Official Time, even though it has been proposed for the cities of Santiago and Valparaíso only, must be agreed with that of other cities, due to the connection of various activities that require it, such as, for example, the operation of rail services".

As the 30 days reached their expiry, the time change was extended:

https://www.diariooficial.interior.gob.cl/versiones-anteriores/do-h/19460814... Núm. 4,506. Prorroga hasta el 31 del mes en curso la vigencia del cambio de hora oficial en el territoria nacional comprendido entre las provincias de Coquimbo y Concepción, inclusives No. 4,506. Extending until the 31st of the current month [August] the validity of the official time change in the national territory between the provinces of Coquimbo and Concepción, inclusive

Later in August, a bill reunified the country's clocks:

https://www.diariooficial.interior.gob.cl/versiones-anteriores/do-h/19460828... (translated excerpt) "The official time for the entire Republic will be from 1 September to 31 March of each year, the meridian of the Astronomical Observatory of Lo Espejo, advanced by 42 minutes and 45 seconds, which corresponds to the 20th time zone, four hours west of Greenwich, and will be called Summer Time. From 1 April to 31 August, it will be that of the Lo Espejo Observatory Meridian delayed by 17 minutes and 15 seconds, which corresponds to the 19th time zone, five hours west of Greenwich, and will be called Winter Time."

Technically, this bill came into force "from the date of its publication", but given that that was sufficiently close to the 1946-08-31 expiry of the extended emergency act anyway, and the rest of the country would have already been on -04, it seems just as likely that clocks changed in the center of the country on 1946-08-31 24:00, as previously scheduled. Under this law, the 1946/1947 observance of Summer Time at -04 lasted for all six of its months, but our data show the observance of Winter Time at -05 was cut short after about seven weeks on 1947-05-21 when -04 was adopted as the new Standard Time.

This differs somewhat from our horaoficial.cl source

https://web.archive.org/web/20120306042032/http://www.horaoficial.cl/ing/hor... which implies the divergence *began* on 1946-09-01 rather than *ended* on it, but the legal texts seem clear to me: Our 2021e data is right.

On Sat, 12 Mar 2022 at 14:44, Paul Eggert via tz <tz@iana.org> wrote:

...

Thanks for pointing out what appears to be a transcription error when I created America/Punta_Arenas in 2016. I installed the attached proposed patch into the development version.

Unfortunately, I believe this means that the data change here should at least be reverted. We can also better specify the transition dates and expand commentary as necessary.

And while it's before our 1970 cutoff for zone creation, those tracking expanded pre-1970 data should be keen to only put the correct areas on -03 for these few weeks in 1946. It really was only the middle bit on -03, not the south, and not the north.

-- Tim Parenti

On 3/18/22 09:09, Michael H Deckers wrote:

   On 2022-03-16 03:24, Tim Parenti via tz wrote:

...

https://www.diariooficial.interior.gob.cl/publicaciones/2018/11/23/42212/01/...

   • Law Number 8,522 was promulgated on 1946-08-28, not the day before.

Although the above URL indeed reprints the 1946-08-28 publication in Diario Oficial, I don't see a promulgation date there. <https://www.bcn.cl/leychile/navegar?i=285254> says law 8,522 was promulgated the day before. That being said, the law says it takes effect when it's published so the promulgation date doesn't matter to us.

   • That law contains an "artícolo transitorio" which specifies:

           Artícolo transitorio. Al tiempo de entrar en vigor la presente            ley, se fijará la hora oficial para toda la República con            arreglo al horário de Verano señalado en el artículo 1.o.

           (Transitional article. At the time when this law takes effect,            the official time for the whole Republic will be set according            to summer time as indicated in the 1st article.) [my translation]

     That article would be superfluous if the switch to summer time had      happened on 1946-09-01 (as tzdb currently says) because that      would have been the switching date already indicated in article 1.      Thus, the switch to summer time happened earlier than 1946-09-01      (as wrongly stated by Shanks).

Yes, and we already have Santiago switching to -03 daylight saving time (I wouldn't call it "summer time" :-) on 1946-07-15.

   Hence, both tzdb timezones should be amended:

       Zone America/Santiago  ...       -     -4:00   1:00    -03     1946 Sep  1 # central Chile       -     -4:00   -       -04     1947 Apr  1       +     -4:00   1:00    -03     1946 Aug 29 # central Chile       +     -5:00   1:00    -04     1947 Apr  1

       Zone America/Punta_Arenas ...       -     -4:00   -       -04     1947 Apr  1       +     -4:00   -       -04     1946 Aug 29       +     -5:00   1:00    -04     1947 Apr  1

   It would take further evidence (such as newspaper clips) in    order to ascertain the precise hour of the switch in both    cases.

It would indeed be good to have further evidence. Strictly interpreted, the Chilean law published August 28, 1946 required citizens in Punta Arenas to move their clocks back an hour immediately, and then forward an hour on August 31. I very much doubt whether that's what was intended or what citizens did; surely they just kept their clocks on -04. Although the TZDB change you're proposing does that, it sets tm_isdst on August 29 even though neither the law nor the previous practice said DST was being observed August 29. I expect it's better to set the DST flag when the new law said DST started. (I doubt whether newspapers will help us resolve the tm_isdst issue, as there would be no practical reasons to tell the citizens to do anything to their clocks.) Similarly, the law required citizens in Santiago to move their clocks back *two* hours on August 28 (from -03 to -05), and then forward an hour on August 31. This is also implausible. Surely they just picked a time to move back an hour from -03 to -04. Here, I think it more likely that it was done at the end of August 31, since that would have given more time to notify the citizens of the change. I was just talking to my father about this, and he jokingly suggested that I fly down to Santiago and check printed newspaper archives there. Unfortunately that would take more time than I can spare.... Proposed patch attached and installed into the development database.