From 7f860c0fea05d9da354bf761e003ecd403851f9d Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Fri, 30 Sep 2022 11:11:57 -0700
Subject: [PATCH 1/2] Circa-1922 Mexico fixes

* northamerica (America/Cancun, America/Merida, America/Matamoros)
(America/Monterrey, America/Mexico_City, America/Ojinaga)
(America/Chihuahua, America/Hermosillo, America/Mazatlan)
(America/Bahia_Banderas, America/Tijuana): Do the 1922-01-01
transition using UT, not local time.  This simplifies maintenance
and fixes an off-by-one-hour bug for Tijuana.
(America/Matamoros): Fix LMT offset (thanks to Michael Deckers).
---
 NEWS         |  4 ++++
 northamerica | 22 +++++++++++-----------
 2 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/NEWS b/NEWS
index bcdad417..c7f3a897 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,10 @@ News for the tz database
 
 Unreleased, experimental changes
 
+  Changes to past timestamps
+
+    On 1922-01-01 Tijuana adopted standard time at 00:00, not 01:00.
+
   Changes to past time zone abbreviations and DST flags
 
     The temporary advancement of clocks in central Mexico in summer
diff --git a/northamerica b/northamerica
index f848228a..ea1b2c0e 100644
--- a/northamerica
+++ b/northamerica
@@ -2635,13 +2635,13 @@ Rule	Mexico	2002	max	-	Apr	Sun>=1	2:00	1:00	D
 Rule	Mexico	2002	max	-	Oct	lastSun	2:00	0	S
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 # Quintana Roo; represented by Cancún
-Zone America/Cancun	-5:47:04 -	LMT	1922 Jan  1  0:12:56
+Zone America/Cancun	-5:47:04 -	LMT	1922 Jan  1  6:00u
 			-6:00	-	CST	1981 Dec 23
 			-5:00	Mexico	E%sT	1998 Aug  2  2:00
 			-6:00	Mexico	C%sT	2015 Feb  1  2:00
 			-5:00	-	EST
 # Campeche, Yucatán; represented by Mérida
-Zone America/Merida	-5:58:28 -	LMT	1922 Jan  1  0:01:32
+Zone America/Merida	-5:58:28 -	LMT	1922 Jan  1  6:00u
 			-6:00	-	CST	1981 Dec 23
 			-5:00	-	EST	1982 Dec  2
 			-6:00	Mexico	C%sT
@@ -2655,18 +2655,18 @@ Zone America/Merida	-5:58:28 -	LMT	1922 Jan  1  0:01:32
 # See: Inicia mañana Horario de Verano en zona fronteriza, El Universal,
 # 2016-03-12
 # http://www.eluniversal.com.mx/articulo/estados/2016/03/12/inicia-manana-horario-de-verano-en-zona-fronteriza
-Zone America/Matamoros	-6:40:00 -	LMT	1921 Dec 31 23:20:00
+Zone America/Matamoros	-6:30:00 -	LMT	1922 Jan  1  6:00u
 			-6:00	-	CST	1988
 			-6:00	US	C%sT	1989
 			-6:00	Mexico	C%sT	2010
 			-6:00	US	C%sT
 # Durango; Coahuila, Nuevo León, Tamaulipas (away from US border)
-Zone America/Monterrey	-6:41:16 -	LMT	1921 Dec 31 23:18:44
+Zone America/Monterrey	-6:41:16 -	LMT	1922 Jan  1  6:00u
 			-6:00	-	CST	1988
 			-6:00	US	C%sT	1989
 			-6:00	Mexico	C%sT
 # Central Mexico
-Zone America/Mexico_City -6:36:36 -	LMT	1922 Jan  1  0:23:24
+Zone America/Mexico_City -6:36:36 -	LMT	1922 Jan  1  7:00u
 			-7:00	-	MST	1927 Jun 10 23:00
 			-6:00	-	CST	1930 Nov 15
 			-7:00	Mexico	M%sT	1932 Apr  1
@@ -2677,7 +2677,7 @@ Zone America/Mexico_City -6:36:36 -	LMT	1922 Jan  1  0:23:24
 # This includes the municipalities of Janos, Ascensión, Juárez, Guadalupe,
 # Práxedis G Guerrero, Coyame del Sotol, Ojinaga, and Manuel Benavides.
 # (See the 2016-03-12 El Universal source mentioned above.)
-Zone America/Ojinaga	-6:57:40 -	LMT	1922 Jan  1  0:02:20
+Zone America/Ojinaga	-6:57:40 -	LMT	1922 Jan  1  7:00u
 			-7:00	-	MST	1927 Jun 10 23:00
 			-6:00	-	CST	1930 Nov 15
 			-7:00	Mexico	M%sT	1932 Apr  1
@@ -2687,7 +2687,7 @@ Zone America/Ojinaga	-6:57:40 -	LMT	1922 Jan  1  0:02:20
 			-7:00	Mexico	M%sT	2010
 			-7:00	US	M%sT
 # Chihuahua (away from US border)
-Zone America/Chihuahua	-7:04:20 -	LMT	1921 Dec 31 23:55:40
+Zone America/Chihuahua	-7:04:20 -	LMT	1922 Jan  1  7:00u
 			-7:00	-	MST	1927 Jun 10 23:00
 			-6:00	-	CST	1930 Nov 15
 			-7:00	Mexico	M%sT	1932 Apr  1
@@ -2696,7 +2696,7 @@ Zone America/Chihuahua	-7:04:20 -	LMT	1921 Dec 31 23:55:40
 			-6:00	-	CST	1998 Apr Sun>=1  3:00
 			-7:00	Mexico	M%sT
 # Sonora
-Zone America/Hermosillo	-7:23:52 -	LMT	1921 Dec 31 23:36:08
+Zone America/Hermosillo	-7:23:52 -	LMT	1922 Jan  1  7:00u
 			-7:00	-	MST	1927 Jun 10 23:00
 			-6:00	-	CST	1930 Nov 15
 			-7:00	Mexico	M%sT	1932 Apr  1
@@ -2734,7 +2734,7 @@ Zone America/Hermosillo	-7:23:52 -	LMT	1921 Dec 31 23:36:08
 # Use "Bahia_Banderas" to keep the name to fourteen characters.
 
 # Mazatlán
-Zone America/Mazatlan	-7:05:40 -	LMT	1921 Dec 31 23:54:20
+Zone America/Mazatlan	-7:05:40 -	LMT	1922 Jan  1  7:00u
 			-7:00	-	MST	1927 Jun 10 23:00
 			-6:00	-	CST	1930 Nov 15
 			-7:00	Mexico	M%sT	1932 Apr  1
@@ -2744,7 +2744,7 @@ Zone America/Mazatlan	-7:05:40 -	LMT	1921 Dec 31 23:54:20
 			-7:00	Mexico	M%sT
 
 # Bahía de Banderas
-Zone America/Bahia_Banderas	-7:01:00 -	LMT	1921 Dec 31 23:59:00
+Zone America/Bahia_Banderas -7:01:00 -	LMT	1922 Jan  1  7:00u
 			-7:00	-	MST	1927 Jun 10 23:00
 			-6:00	-	CST	1930 Nov 15
 			-7:00	Mexico	M%sT	1932 Apr  1
@@ -2755,7 +2755,7 @@ Zone America/Bahia_Banderas	-7:01:00 -	LMT	1921 Dec 31 23:59:00
 			-6:00	Mexico	C%sT
 
 # Baja California
-Zone America/Tijuana	-7:48:04 -	LMT	1922 Jan  1  0:11:56
+Zone America/Tijuana	-7:48:04 -	LMT	1922 Jan  1  7:00u
 			-7:00	-	MST	1924
 			-8:00	-	PST	1927 Jun 10 23:00
 			-7:00	-	MST	1930 Nov 15
-- 
2.34.1

