proposed patch for Nicaragua, Iran, etc.

Paul Eggert eggert at CS.UCLA.EDU
Tue Apr 12 08:21:09 UTC 2005


Thanks for mentioning that; it's higher priority to fix this, as
current timestamps are wrong in Nicaragua.  Here are proposed changes
to the TZ database that take this into account, along with other
less-important changes that have been saved up.

* Nicaragua is observing DST, as of this weekend.  Thanks to
  Steffen Thorsen for this.

* A fix for transitions in 2025 in Iran.  Thanks to Oscar van Vlijmen
  for this info, and to Roozbeh Pournader and Ed Reingold for
  clarifications about the Iranian calendar.

* A comment typo fixed for Mexico, and a table typo (that did not
  affect any transitions) for Libya.  Thanks to Jesper Norgaard Welen
  for these fixes.

===================================================================
RCS file: RCS/northamerica,v
retrieving revision 2005.5
retrieving revision 2005.5.0.1
diff -pu -r2005.5 -r2005.5.0.1
--- northamerica	2005/02/07 21:19:42	2005.5
+++ northamerica	2005/04/12 08:11:31	2005.5.0.1
@@ -1427,7 +1427,7 @@ Zone America/Dawson	-9:17:40 -	LMT	1900 
 # Shanks reports that Baja was at -8:00 in 1922/1923.
 # Shanks says the 1930 transition in Baja was 1930-11-16.
 # Shanks reports no DST during summer 1931.
-# Shanks reports a transition at 1032-03-30 23:00, not 1932-04-01.
+# Shanks reports a transition at 1932-03-30 23:00, not 1932-04-01.
 # Shanks does not report transitions for Baja in 1945 or 1948.
 # Shanks reports southern Mexico transitions on 1981-12-01, not 12-23.
 # Shanks says Quintana Roo switched to -6:00 on 1982-12-02, and to -5:00
@@ -1931,11 +1931,28 @@ Zone America/Montserrat	-4:08:52 -	LMT	1
 # Nicaragua seems to be back at -6:00 but I have not been able to find when
 # they changed from -5:00.
 #
+# From Steffen Thorsen (2005-04-12):
+# I've got reports from 8 different people that Nicaragua just started
+# DST on Sunday 2005-04-10, in order to save energy because of
+# expensive petroleum.  The exact end date for DST is not yet
+# announced, only "September" but some sites also say "mid-September".
+# Some background information is available on the President's official site:
+# http://www.presidencia.gob.ni/Presidencia/Files_index/Secretaria/Notas%20de%20Prensa/Presidente/2005/ABRIL/Gobierno-de-nicaragua-adelanta-hora-oficial-06abril.htm
+# The Decree, no 23-2005 is available here:
+# http://www.presidencia.gob.ni/buscador_gaceta/BD/DECRETOS/2005/Decreto%2023-2005%20Se%20adelanta%20en%20una%20hora%20en%20todo%20el%20territorio%20nacional%20apartir%20de%20las%2024horas%20del%2009%20de%20Abril.pdf
+#
+# From Paul Eggert (2005-04-12):
+# The decree doesn't say anything about daylight saving, but for now let's
+# assume that it is daylight saving and that they'll switch back on the
+# 2nd Sunday in September.
+#
 # Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
 Rule	Nic	1979	1980	-	Mar	Sun>=16	0:00	1:00	D
 Rule	Nic	1979	1980	-	Jun	Mon>=23	0:00	0	S
 Rule	Nic	1992	only	-	Jan	1	4:00	1:00	D
 Rule	Nic	1992	only	-	Sep	24	0:00	0	S
+Rule	Nic	2005	only	-	Apr	10	0:00	1:00	D
+Rule	Nic	2005	only	-	Sep	11	0:00	0	S
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
 Zone	America/Managua	-5:45:08 -	LMT	1890
 			-5:45:12 -	MMT	1934 Jun 23 # Managua Mean Time?
@@ -1943,7 +1960,7 @@ Zone	America/Managua	-5:45:08 -	LMT	1890
 			-5:00	-	EST	1975 Feb 16
 			-6:00	Nic	C%sT	1993 Jan 1 4:00
 			-5:00	-	EST	1998 Dec
-			-6:00	-	CST
+			-6:00	Nic	C%sT
 
 # Panama
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
===================================================================
RCS file: RCS/africa,v
retrieving revision 2001.4
retrieving revision 2001.4.0.1
diff -pu -r2001.4 -r2001.4.0.1
--- africa	2001/10/09 17:31:30	2001.4
+++ africa	2005/04/12 08:11:31	2001.4.0.1
@@ -317,7 +317,7 @@ Rule	Libya	1985	only	-	Apr	 6	0:00	1:00	
 Rule	Libya	1986	only	-	Apr	 4	0:00	1:00	S
 Rule	Libya	1986	only	-	Oct	 3	0:00	0	-
 Rule	Libya	1987	1989	-	Apr	 1	0:00	1:00	S
-Rule	Libya	1987	1990	-	Oct	 1	0:00	0	-
+Rule	Libya	1987	1989	-	Oct	 1	0:00	0	-
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Tripoli	0:52:44 -	LMT	1920
 			1:00	Libya	CE%sT	1959
===================================================================
RCS file: RCS/asia,v
retrieving revision 2005.8
retrieving revision 2005.8.0.1
diff -pu -r2005.8 -r2005.8.0.1
--- asia	2005/04/04 15:24:32	2005.8
+++ asia	2005/04/12 08:11:31	2005.8.0.1
@@ -476,12 +476,33 @@ Zone Asia/Jayapura	9:22:48 -	LMT	1932 No
 # Thursday night of Shahrivar, but I can't give exact dates....
 # I have also changed the abbreviations to what is considered correct
 # here in Iran, IRST for regular time and IRDT for daylight saving time.
-
-# From Paul Eggert (2003-03-15)
+#
+# From Roozbeh Pournader (2005-04-05):
+# The text of the Iranian law, in effect since 1925, clearly mentions
+# that the true solar year is the measure, and there is no arithmetic
+# leap year calculation involved.  There has never been any serious
+# plan to change that law....
+#
+# From Paul Eggert (2005-04-05):
 # Go with Shanks before September 1991, and with Pournader thereafter.
-# I used Ed Reingold's cal-persia in GNU Emacs 21.2 to check Persian dates.
-# The Persian calendar is based on the sun, and dates after around 2050
-# are approximate; stop after 2037 when 32-bit time_t's overflow.
+# I used Ed Reingold's cal-persia in GNU Emacs 21.2 to check Persian dates,
+# stopping after 2037 when 32-bit time_t's overflow.
+# That cal-persia used Birashk's approximation, which disagrees with the solar
+# calendar predictions for the year 2025, so I corrected those dates by hand.
+#
+# From Oscar van Vlijmen (2005-03-30), writing about future
+# discrepancies between cal-persia and the Iranian calendar:
+# For 2091 solar-longitude-after yields 2091-03-20 08:40:07.7 UT for
+# the vernal equinox and that gets so close to 12:00 some local
+# Iranian time that the definition of the correct location needs to be
+# known exactly, amongst other factors.  2157 is even closer:
+# 2157-03-20 08:37:15.5 UT.  But the Gregorian year 2025 should give
+# no interpretation problem whatsoever.  By the way, another instant
+# in the near future where there will be a discrepancy between
+# arithmetical and astronomical Iranian calendars will be in 2058:
+# vernal equinox on 2058-03-20 09:03:05.9 UT.  The Java version of
+# Reingold's/Dershowitz' calculator gives correctly the Gregorian date
+# 2058-03-21 for 1 Farvardin 1437 (astronomical).
 #
 # Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
 Rule	Iran	1978	1980	-	Mar	21	0:00	1:00	D
@@ -519,10 +540,10 @@ Rule	Iran	2020	only	-	Mar	21	0:00	1:00	D
 Rule	Iran	2020	only	-	Sep	21	0:00	0	S
 Rule	Iran	2021	2023	-	Mar	22	0:00	1:00	D
 Rule	Iran	2021	2023	-	Sep	22	0:00	0	S
-Rule	Iran	2024	2025	-	Mar	21	0:00	1:00	D
-Rule	Iran	2024	2025	-	Sep	21	0:00	0	S
-Rule	Iran	2026	2027	-	Mar	22	0:00	1:00	D
-Rule	Iran	2026	2027	-	Sep	22	0:00	0	S
+Rule	Iran	2024	only	-	Mar	21	0:00	1:00	D
+Rule	Iran	2024	only	-	Sep	21	0:00	0	S
+Rule	Iran	2025	2027	-	Mar	22	0:00	1:00	D
+Rule	Iran	2025	2027	-	Sep	22	0:00	0	S
 Rule	Iran	2028	2029	-	Mar	21	0:00	1:00	D
 Rule	Iran	2028	2029	-	Sep	21	0:00	0	S
 Rule	Iran	2030	2031	-	Mar	22	0:00	1:00	D



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