[tz] Portuguese time zones - Africa/Luanda

Paul Eggert eggert at cs.ucla.edu
Mon Aug 11 07:32:24 UTC 2014


Stephen Colebourne wrote:
> I'd suggest that the data should be changed from 1911 May 26 to 1
> January 1912

Thanks, I pushed the attached change to the experimental version on github.
-------------- next part --------------
From 115b6002d8601dd4f110082ab52c7b0e726ce9b2 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert at cs.ucla.edu>
Date: Mon, 11 Aug 2014 00:28:13 -0700
Subject: [PATCH] Adjust pre-1912 Portuguese transitions in the light of the
 1911 decree.

(Thanks to Stephen Colebourne for a heads-up about the decree.)
* africa (Africa/Luanda, Africa/Bissau):
Change transition date to 1912-01-01.
(Atlantic/Cape_Verde, Africa/Maputo):
Add commentary about the switch.
* asia (Asia/Kolkata): Add commentary about Portuguese India.
* europe (Europe/Lisbon): Change Lisbon Mean Time from -0:36:32
to -0:36:45 (rounded from -0:36:44.68).
(Atlantic/Azores, Atlantic/Madeira):
Change transition date to 1912-01-01.
* NEWS: Document the above.
---
 NEWS   |  6 ++++++
 africa | 30 +++++++++++++++++++++++++++---
 asia   | 11 +++++++++--
 europe | 19 +++++++++++++------
 4 files changed, 55 insertions(+), 11 deletions(-)

diff --git a/NEWS b/NEWS
index 7db0a32..cdaf3dd 100644
--- a/NEWS
+++ b/NEWS
@@ -11,6 +11,12 @@ Unreleased, experimental changes
     Asia/Yekaterinburg the correction is a few minutes.  (Thanks to
     Vladimir Karpinsky.)
 
+    The Portuguese decree of 1911-05-25 took effect on 1912-01-01.
+    This affects 1911 time stamps in Africa/Bissau, Africa/Luanda,
+    Atlantic/Azores, and Atlantic/Madeira.  Also, Lisbon's pre-1912
+    GMT offset was -0:36:45 (rounded from -0:36:44.68), not -0:36:32.
+    (Thanks to Stephen Colebourne for pointing to the decree.)
+
     Asia/Dakha ended DST on 2009-12-31 at 24:00, not 23:59.
 
 
diff --git a/africa b/africa
index 438f2a7..c20a46d 100644
--- a/africa
+++ b/africa
@@ -105,16 +105,22 @@ Zone	Africa/Algiers	0:12:12 -	LMT	1891 Mar 15  0:01
 			1:00	-	CET
 
 # Angola
+#
+# Shanks gives 1911-05-26 for the transition to WAT,
+# evidently confusing the date of the Portuguese decree
+# http://dre.pt/pdf1sdip/1911/05/12500/23132313.pdf
+# with the date that it took effect, namely 1912-01-01.
+#
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Luanda	0:52:56	-	LMT	1892
-			0:52:04	-	AOT	1911 May 26 # Angola Time
+			0:52:04	-	AOT	1912 Jan  1 # Angola Time
 			1:00	-	WAT
 
 # Benin
 # Whitman says they switched to 1:00 in 1946, not 1934;
 # go with Shanks & Pottenger.
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
-Zone Africa/Porto-Novo	0:10:28	-	LMT	1912
+Zone Africa/Porto-Novo	0:10:28	-	LMT	1912 Jan  1
 			0:00	-	GMT	1934 Feb 26
 			1:00	-	WAT
 
@@ -144,6 +150,12 @@ Zone	Africa/Douala	0:38:48	-	LMT	1912
 			1:00	-	WAT
 
 # Cape Verde
+#
+# Shanks gives 1907 for the transition to CVT.
+# Perhaps the 1911-05-26 Portuguese decree
+# http://dre.pt/pdf1sdip/1911/05/12500/23132313.pdf
+# merely made it official?
+#
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
 Zone Atlantic/Cape_Verde -1:34:04 -	LMT	1907			# Praia
 			-2:00	-	CVT	1942 Sep
@@ -461,8 +473,14 @@ Zone	Africa/Accra	-0:00:52 -	LMT	1918
 # See Africa/Abidjan.
 
 # Guinea-Bissau
+#
+# Shanks gives 1911-05-26 for the transition to WAT,
+# evidently confusing the date of the Portuguese decree
+# http://dre.pt/pdf1sdip/1911/05/12500/23132313.pdf
+# with the date that it took effect, namely 1912-01-01.
+#
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
-Zone	Africa/Bissau	-1:02:20 -	LMT	1911 May 26
+Zone	Africa/Bissau	-1:02:20 -	LMT	1912 Jan  1
 			-1:00	-	WAT	1975
 			 0:00	-	GMT
 
@@ -964,6 +982,12 @@ Zone Africa/El_Aaiun	-0:52:48 -	LMT	1934 Jan # El Aaiún
 			 0:00	Morocco	WE%sT
 
 # Mozambique
+#
+# Shanks gives 1903-03-01 for the transition to CAT.
+# Perhaps the 1911-05-26 Portuguese decree
+# http://dre.pt/pdf1sdip/1911/05/12500/23132313.pdf
+# merely made it official?
+#
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Maputo	2:10:20 -	LMT	1903 Mar
 			2:00	-	CAT
diff --git a/asia b/asia
index bab1aa0..17813ce 100644
--- a/asia
+++ b/asia
@@ -765,7 +765,7 @@ Rule	Macau	1975	1977	-	Apr	Sun>=15	3:30	1:00	S
 Rule	Macau	1978	1980	-	Apr	Sun>=15	0:00	1:00	S
 Rule	Macau	1978	1980	-	Oct	Sun>=15	0:00	0	-
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
-Zone	Asia/Macau	7:34:20 -	LMT	1912
+Zone	Asia/Macau	7:34:20 -	LMT	1912 Jan  1
 			8:00	Macau	MO%sT	1999 Dec 20 # return to China
 			8:00	PRC	C%sT
 
@@ -870,7 +870,7 @@ Zone	Asia/Tbilisi	2:59:11 -	LMT	1880
 # midnight on Saturday, September 16.
 
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
-Zone	Asia/Dili	8:22:20 -	LMT	1912
+Zone	Asia/Dili	8:22:20 -	LMT	1912 Jan  1
 			8:00	-	TLT	1942 Feb 21 23:00 # E Timor Time
 			9:00	-	JST	1945 Sep 23
 			9:00	-	TLT	1976 May  3
@@ -878,6 +878,13 @@ Zone	Asia/Dili	8:22:20 -	LMT	1912
 			9:00	-	TLT
 
 # India
+
+# From Paul Eggert (2014-08-11), after a heads-up from Stephen Colebourne:
+# According to a Portuguese decree (1911-05-26)
+# http://dre.pt/pdf1sdip/1911/05/12500/23132313.pdf
+# Portuguese India switched to GMT+5 on 1912-01-01.
+# Ignore this as it predates our 1970 cutoff.
+
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Kolkata	5:53:28 -	LMT	1880	# Kolkata
 			5:53:20	-	HMT	1941 Oct    # Howrah Mean Time?
diff --git a/europe b/europe
index 010fa2e..001fb4d 100644
--- a/europe
+++ b/europe
@@ -1961,6 +1961,14 @@ Zone	Europe/Warsaw	1:24:00 -	LMT	1880
 
 # Portugal
 #
+# From Paul Eggert (2014-08-11), after a heads-up from Stephen Colebourne:
+# According to a Portuguese decree (1911-05-26)
+# http://dre.pt/pdf1sdip/1911/05/12500/23132313.pdf
+# Lisbon was at -0:36:44.68, but switched to GMT on 1912-01-01 at 00:00.
+# Round the old offset to -0:36:45.  This agrees with Willett but disagrees
+# with Shanks, who says the transition occurred on 1911-05-24 at 00:00 for
+# Europe/Lisbon, Atlantic/Azores, and Atlantic/Madeira.
+#
 # From Rui Pedro Salgueiro (1992-11-12):
 # Portugal has recently (September, 27) changed timezone
 # (from WET to MET or CET) to harmonize with EEC.
@@ -2040,11 +2048,10 @@ Rule	Port	1979	1982	-	Sep	lastSun	 1:00s	0	-
 Rule	Port	1980	only	-	Mar	lastSun	 0:00s	1:00	S
 Rule	Port	1981	1982	-	Mar	lastSun	 1:00s	1:00	S
 Rule	Port	1983	only	-	Mar	lastSun	 2:00s	1:00	S
+#
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
-# Shanks & Pottenger say the transition from LMT to WET occurred 1911-05-24;
-# Willett says 1912-01-01.  Go with Willett.
-Zone	Europe/Lisbon	-0:36:32 -	LMT	1884
-			-0:36:32 -	LMT	1912 Jan  1  # Lisbon Mean Time
+Zone	Europe/Lisbon	-0:36:45 -	LMT	1884
+			-0:36:45 -	LMT	1912 Jan  1  # Lisbon Mean Time
 			 0:00	Port	WE%sT	1966 Apr  3  2:00
 			 1:00	-	CET	1976 Sep 26  1:00
 			 0:00	Port	WE%sT	1983 Sep 25  1:00s
@@ -2052,14 +2059,14 @@ Zone	Europe/Lisbon	-0:36:32 -	LMT	1884
 			 1:00	EU	CE%sT	1996 Mar 31  1:00u
 			 0:00	EU	WE%sT
 Zone Atlantic/Azores	-1:42:40 -	LMT	1884		# Ponta Delgada
-			-1:54:32 -	HMT	1911 May 24  # Horta Mean Time
+			-1:54:32 -	HMT	1912 Jan  1  # Horta Mean Time
 			-2:00	Port	AZO%sT	1966 Apr  3  2:00 # Azores Time
 			-1:00	Port	AZO%sT	1983 Sep 25  1:00s
 			-1:00	W-Eur	AZO%sT	1992 Sep 27  1:00s
 			 0:00	EU	WE%sT	1993 Mar 28  1:00u
 			-1:00	EU	AZO%sT
 Zone Atlantic/Madeira	-1:07:36 -	LMT	1884		# Funchal
-			-1:07:36 -	FMT	1911 May 24  # Funchal Mean Time
+			-1:07:36 -	FMT	1912 Jan  1  # Funchal Mean Time
 			-1:00	Port	MAD%sT	1966 Apr  3  2:00 # Madeira Time
 			 0:00	Port	WE%sT	1983 Sep 25  1:00s
 			 0:00	EU	WE%sT
-- 
1.9.1


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