From e8681e760f644c6c04d1bfef98123d1b47156e54 Mon Sep 17 00:00:00 2001
From: Tim Parenti <tim@timtimeonline.com>
Date: Tue, 15 Mar 2022 23:03:01 -0400
Subject: Adjust Chile LMT; expand 1946/1947 commentary

* southamerica (America/Santiago, America/Punta_Arenas):
Move LMT and SMT 1 s east; expand commentary on 1946/1947 transitions.
* NEWS: Mention this.
---
 NEWS         |  8 ++++++++
 southamerica | 45 ++++++++++++++++++++++++++++++++++++---------
 2 files changed, 44 insertions(+), 9 deletions(-)

diff --git a/NEWS b/NEWS
index 335bc48..79f5a0c 100644
--- a/NEWS
+++ b/NEWS
@@ -18,6 +18,14 @@ Unreleased, experimental changes
     From 1992 through spring 1996, Ukraine's DST transitions were at
     02:00 standard time, not at 01:00 UTC.  (Thanks to Alois Treindl.)
 
+    Chile's Santiago Mean Time and its LMT precursor have been adjusted
+    eastward by 1 second to align with past and present law.
+
+  Changes to commentary
+
+    Add several references for Chile's 1946/1947 transitions, some of
+    which only affected portions of the country.
+
   Changes to code
 
     Fix bug when mktime gets confused by truncated TZif files with
diff --git a/southamerica b/southamerica
index b86c027..c6249cd 100644
--- a/southamerica
+++ b/southamerica
@@ -1086,7 +1086,7 @@ Zone America/Rio_Branco	-4:31:12 -	LMT	1914
 
 # Chile
 
-# From Paul Eggert (2022-03-12):
+# From Paul Eggert (2022-03-15):
 # Shanks & Pottenger says America/Santiago introduced standard time in
 # 1890 and rounds its UT offset to 70W40; guess that in practice this
 # was the same offset as in 1916-1919.  It also says Pacific/Easter
@@ -1118,7 +1118,8 @@ Zone America/Rio_Branco	-4:31:12 -	LMT	1914
 #  - [1] says SMT was -4:42:45, [2] says Chile's official time from
 #    1916 to 1919 was -4:42:46.3, the meridian of Chile's National
 #    Astronomical Observatory (OAN), then located in what is now
-#    Quinta Normal in Santiago.  Go with [2], rounding it to -4:42:46.
+#    Quinta Normal in Santiago.  Go with [1], as this matches the meridian
+#    referred to by the relevant Chilean laws to this day.
 #
 #  - [1] says the 1918 transition was Sep 1, [2] says Sep 10 and cites
 #    Boletín No. 22, Aviso No. 129/1918 (1918-08-23).  Go with [2].
@@ -1140,6 +1141,32 @@ Zone America/Rio_Branco	-4:31:12 -	LMT	1914
 # this is known to work for DST transitions starting in 2008 and
 # may well be true for earlier transitions.
 
+# From Tim Parenti (2022-03-15):
+# For a brief period of roughly six weeks in 1946, DST was only observed on an
+# emergency basis in specific regions of central Chile; namely, "the national
+# territory between the provinces of Coquimbo and Concepción, inclusive".
+# This was enacted by Decree 3,891, dated 1946-07-13, and took effect
+# 1946-07-14 24:00, advancing these central regions to -03.
+# https://www.diariooficial.interior.gob.cl/versiones-anteriores/do-h/19460715/#page/1
+# 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".  It was originally set to expire after 30 days but was extended
+# through 1946-08-31 by Decree 4,506, dated 1946-08-13.
+# https://www.diariooficial.interior.gob.cl/versiones-anteriores/do-h/19460814/#page/1
+#
+# Law Number 8,522, promulgated 1946-08-27, reunified Chilean clocks at their
+# new "Summer Time" of -04, reckoned as that of "the meridian of the
+# Astronomical Observatory of Lo Espejo, advanced by 42 minutes and 45
+# seconds".
+# https://www.diariooficial.interior.gob.cl/versiones-anteriores/do-h/19460828/#page/1
+# After a brief "Winter Time" stint at -05 beginning 1947-04-01, Law Number
+# 8,777, promulgated 1947-05-17, established year-round -04 "from 23:00 on the
+# second day after it is published in the 'Diario Oficial'."  It was published
+# on Monday 1947-05-19 and so took effect from Wednesday 1947-05-21 23:00.
+# https://www.diariooficial.interior.gob.cl/versiones-anteriores/do-h/19470519/#page/1
+
 # From Eduardo Krell (1995-10-19):
 # The law says to switch to DST at midnight [24:00] on the second SATURDAY
 # of October....  The law is the same for March and October.
@@ -1298,12 +1325,12 @@ Rule	Chile	2019	max	-	Sep	Sun>=2	4:00u	1:00	-
 # IATA SSIM anomalies: (1992-02) says 1992-03-14;
 # (1996-09) says 1998-03-08.  Ignore these.
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone America/Santiago	-4:42:46 -	LMT	1890
-			-4:42:46 -	SMT	1910 Jan 10 # Santiago Mean Time
+Zone America/Santiago	-4:42:45 -	LMT	1890
+			-4:42:45 -	SMT	1910 Jan 10 # Santiago Mean Time
 			-5:00	-	-05	1916 Jul  1
-			-4:42:46 -	SMT	1918 Sep 10
+			-4:42:45 -	SMT	1918 Sep 10
 			-4:00	-	-04	1919 Jul  1
-			-4:42:46 -	SMT	1927 Sep  1
+			-4:42:45 -	SMT	1927 Sep  1
 			-5:00	Chile	-05/-04	1932 Sep  1
 			-4:00	-	-04	1942 Jun  1
 			-5:00	-	-05	1942 Aug  1
@@ -1313,11 +1340,11 @@ Zone America/Santiago	-4:42:46 -	LMT	1890
 			-5:00	-	-05	1947 May 21 23:00
 			-4:00	Chile	-04/-03
 Zone America/Punta_Arenas -4:43:40 -	LMT	1890
-			-4:42:46 -	SMT	1910 Jan 10
+			-4:42:45 -	SMT	1910 Jan 10
 			-5:00	-	-05	1916 Jul  1
-			-4:42:46 -	SMT	1918 Sep 10
+			-4:42:45 -	SMT	1918 Sep 10
 			-4:00	-	-04	1919 Jul  1
-			-4:42:46 -	SMT	1927 Sep  1
+			-4:42:45 -	SMT	1927 Sep  1
 			-5:00	Chile	-05/-04	1932 Sep  1
 			-4:00	-	-04	1942 Jun  1
 			-5:00	-	-05	1942 Aug  1
-- 
2.15.1

