Merge timezones that are alike since 1970

* NEWS: Describe the change and its motivation.
* Makefile (TZS_DEPS, check_tables): Depend on YDATA, not just
PRIMARY_YDATA, since etcetera matters here.
* africa (Africa/Abidjan, Ghana, Africa/Accra, Indian/Reunion)
(Indian/Mahe):
* antarctica (Indian/Kerguelen, Antarctica/DumontDUrville)
(Antarctica/Syowa, Antarctica/Vostok):
* asia (Asia/Brunei, Asia/Urumqi, NBorneo, Asia/Kuala_Lumpur)
(Asia/Kuching, Indian/Maldives, Asia/Riyadh, Asia/Bangkok)
(Asia/Dubai):
* australasia (Indian/Christmas, Indian/Cocos, Pacific/Gambier)
(Pacific/Tahiti, Pacific/Tarawa, Pacific/Majuro, Pacific/Chuuk)
(Pacific/Pohnpei, Pacific/Palau, Pacific/Port_Moresby)
(Pacific/Guadalcanal, Pacific/Funafuti, Pacific/Wake)
(Pacific/Wallis):
* europe (Denmark, Europe/Copenhagen, Iceland, Atlantic/Reykjavik)
(Lux, Europe/Luxembourg, Europe/Monaco, Neth, Europe/Amsterdam)
(Norway, Europe/Oslo, Europe/Stockholm):
* northamerica (America/Blanc-Sablon, America/Atikokan)
(America/Creston, Bahamas, America/Nassau):
* southamerica (America/La_Paz, America/Curacao, America/Cayenne)
(Atlantic/South_Georgia, America/Port_of_Spain):
Move these duplicate Zone entries to 'backzone', and add
backward-compatibility links in 'backward'.
* checktab.awk: Don’t worry about links to Etc/*.
* theory.html: Change examples to avoid merged-away zones.  Remove
references to SET, and to Amsterdam, Bangkok, Copenhagen and Port
Moresby Mean Times.
* zone.tab, zone1970.tab: Change 3rd column to avoid links in
'backward', which might not be present.
* zone1970.tab: Merge lines to match the above changes.

Makefile

@@ -529,7 +529,7 @@ TZS_YEAR=	2050
 TZS_CUTOFF_FLAG=	-c $(TZS_YEAR)
 TZS=		to$(TZS_YEAR).tzs
 TZS_NEW=	to$(TZS_YEAR)new.tzs
-TZS_DEPS=	$(PRIMARY_YDATA) asctime.c localtime.c \
+TZS_DEPS=	$(YDATA) asctime.c localtime.c \
 			private.h tzfile.h zdump.c zic.c
 # EIGHT_YARDS is just a yard short of the whole ENCHILADA.
 EIGHT_YARDS = $(COMMON) $(DOCS) $(SOURCES) $(DATA) $(MISC) tzdata.zi
@@ -802,9 +802,9 @@ check_links:	checklinks.awk $(TDATA_TO_CHECK) tzdata.zi
 		$(AWK) -f checklinks.awk tzdata.zi
 		touch $@
 
-check_tables:	checktab.awk $(PRIMARY_YDATA) $(ZONETABLES)
+check_tables:	checktab.awk $(YDATA) $(ZONETABLES)
 		for tab in $(ZONETABLES); do \
-		  $(AWK) -f checktab.awk -v zone_table=$$tab $(PRIMARY_YDATA) \
+		  $(AWK) -f checktab.awk -v zone_table=$$tab $(YDATA) \
 		    || exit; \
 		done
 		touch $@

NEWS

@@ -26,6 +26,23 @@ Unreleased, experimental changes
     (Thanks to P Chan, Michael Deckers, Alexander Krivenyshev and
     Alois Treindl.)
 
+    Merge timezones whose timestamps agree since 1970, since pre-1970
+    timestamps are out of scope.  This change does not affect
+    post-1970 timestamps, and timezone historians who build with 'make
+    PACKRATDATA=backzone' should see no changes to pre-1970 timestamps.
+    When merging, keep the most-populous location's data, and move
+    data for other locations to 'backzone' with a backward
+    compatibility link in 'backward'.  Also, merge timezones with
+    neither post-1970 clock changes nor alphabetic abbreviations into
+    their Etc counterparts.  For example, move the Europe/Oslo data to
+    'backzone' with a link in 'backward' from Europe/Berlin because
+    the two timezones' timestamps agree since 1970; this change
+    affects some pre-1966 timestamps in Europe/Oslo because Berlin and
+    Oslo disagreed before 1966.  For another example, move the
+    Asia/Aden data to 'backzone' with a link in 'backward' from
+    Etc/GMT-3.  Affected entries range from Africa/Abidjan to
+    Pacific/Yap.
+
   Changes to maintenance procedure
 
     The new file SECURITY covers how to report security-related bugs.

africa

@@ -105,7 +105,7 @@ Zone	Africa/Algiers	0:12:12 -	LMT	1891 Mar 16
 # See Africa/Maputo.
 
 # Burkina Faso
-# See Africa/Abidjan.
+# See Etc/GMT.
 
 # Burundi
 # See Africa/Maputo.
@@ -147,9 +147,7 @@ Zone	Africa/Ndjamena	1:00:12 -	LMT	1912        # N'Djamena
 # See Africa/Lagos.
 
 # Côte d'Ivoire / Ivory Coast
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Africa/Abidjan	-0:16:08 -	LMT	1912
-			 0:00	-	GMT
+# See Etc/GMT.
 
 # Djibouti
 # See Africa/Nairobi.
@@ -370,94 +368,9 @@ Zone	Africa/Cairo	2:05:09 -	LMT	1900 Oct
 # See Africa/Lagos.
 
 # The Gambia
-# See Africa/Abidjan.
-
 # Ghana
-
-# From P Chan (2020-11-20):
-# Interpretation Amendment Ordinance, 1915 (No.24 of 1915) [1915-11-02]
-# Ordinances of the Gold Coast, Ashanti, Northern Territories 1915, p 69-71
-# https://books.google.com/books?id=ErA-AQAAIAAJ&pg=PA70
-# This Ordinance added "'Time' shall mean Greenwich Mean Time" to the
-# Interpretation Ordinance, 1876.
-#
-# Determination of the Time Ordinance, 1919 (No. 18 of 1919) [1919-11-24]
-# Ordinances of the Gold Coast, Ashanti, Northern Territories 1919, p 75-76
-# https://books.google.com/books?id=MbA-AQAAIAAJ&pg=PA75
-# This Ordinance removed the previous definition of time and introduced DST.
-#
-# Time Determination Ordinance (Cap. 214)
-# The Laws of the Gold Coast (including Togoland Under British Mandate)
-# Vol. II (1937), p 2328
-# https://books.google.com/books?id=Z7M-AQAAIAAJ&pg=PA2328
-# Revised edition of the 1919 Ordinance.
-#
-# Time Determination (Amendment) Ordinance, 1940 (No. 9 of 1940) [1940-04-06]
-# Annual Volume of the Laws of the Gold Coast:
-# Containing All Legislation Enacted During Year 1940, p 22
-# https://books.google.com/books?id=1ao-AQAAIAAJ&pg=PA22
-# This Ordinance changed the forward transition from September to May.
-#
-# Defence (Time Determination Ordinance Amendment) Regulations, 1942
-# (Regulations No. 6 of 1942) [1942-01-31, commenced on 1942-02-08]
-# Annual Volume of the Laws of the Gold Coast:
-# Containing All Legislation Enacted During Year 1942, p 48
-# https://books.google.com/books?id=Das-AQAAIAAJ&pg=PA48
-# These regulations advanced the [standard] time by thirty minutes.
-#
-# Defence (Time Determination Ordinance Amendment (No.2)) Regulations,
-# 1942 (Regulations No. 28 of 1942) [1942-04-25]
-# Annual Volume of the Laws of the Gold Coast:
-# Containing All Legislation Enacted During Year 1942, p 87
-# https://books.google.com/books?id=Das-AQAAIAAJ&pg=PA87
-# These regulations abolished DST and changed the time to GMT+0:30.
-#
-# Defence (Revocation) (No.4) Regulations, 1945 (Regulations No. 45 of
-# 1945) [1945-10-24, commenced on 1946-01-06]
-# Annual Volume of the Laws of the Gold Coast:
-# Containing All Legislation Enacted During Year 1945, p 256
-# https://books.google.com/books?id=9as-AQAAIAAJ&pg=PA256
-# These regulations revoked the previous two sets of Regulations.
-#
-# Time Determination (Amendment) Ordinance, 1945 (No. 18 of 1945) [1946-01-06]
-# Annual Volume of the Laws of the Gold Coast:
-# Containing All Legislation Enacted During Year 1945, p 69
-# https://books.google.com/books?id=9as-AQAAIAAJ&pg=PA69
-# This Ordinance abolished DST.
-#
-# Time Determination (Amendment) Ordinance, 1950 (No. 26 of 1950) [1950-07-22]
-# Annual Volume of the Laws of the Gold Coast:
-# Containing All Legislation Enacted During Year 1950, p 35
-# https://books.google.com/books?id=e60-AQAAIAAJ&pg=PA35
-# This Ordinance restored DST but with thirty minutes offset.
-#
-# Time Determination Ordinance (Cap. 264)
-# The Laws of the Gold Coast, Vol. V (1954), p 380
-# https://books.google.com/books?id=Mqc-AQAAIAAJ&pg=PA380
-# Revised edition of the Time Determination Ordinance.
-#
-# Time Determination (Amendment) Ordinance, 1956 (No. 21 of 1956) [1956-08-29]
-# Annual Volume of the Ordinances of the Gold Coast Enacted During the
-# Year 1956, p 83
-# https://books.google.com/books?id=VLE-AQAAIAAJ&pg=PA83
-# This Ordinance abolished DST.
-
-# Rule	NAME	FROM	TO	-	IN	ON	AT	SAVE	LETTER/S
-Rule	Ghana	1919	only	-	Nov	24	0:00	0:20	+0020
-Rule	Ghana	1920	1942	-	Jan	 1	2:00	0	GMT
-Rule	Ghana	1920	1939	-	Sep	 1	2:00	0:20	+0020
-Rule	Ghana	1940	1941	-	May	 1	2:00	0:20	+0020
-Rule	Ghana	1950	1955	-	Sep	 1	2:00	0:30	+0030
-Rule	Ghana	1951	1956	-	Jan	 1	2:00	0	GMT
-
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Africa/Accra	-0:00:52 -	LMT	1915 Nov  2
-			 0:00	Ghana	%s	1942 Feb  8
-			 0:30	-	+0030	1946 Jan  6
-			 0:00	Ghana	%s
-
 # Guinea
-# See Africa/Abidjan.
+# See Etc/GMT.
 
 # Guinea-Bissau
 #
@@ -612,7 +525,7 @@ Zone	Africa/Tripoli	0:52:44 -	LMT	1920
 
 # Mali
 # Mauritania
-# See Africa/Abidjan.
+# See Etc/GMT.
 
 # Mauritius
 
@@ -711,7 +624,7 @@ Zone Indian/Mauritius	3:50:00 -	LMT	1907 # Port Louis
 # See Africa/Nairobi.
 
 # Morocco
-# See the 'europe' file for Spanish Morocco (Africa/Ceuta).
+# See Africa/Ceuta for Spanish Morocco.
 
 # From Alex Krivenyshev (2008-05-09):
 # Here is an article that Morocco plan to introduce Daylight Saving Time between
@@ -1356,29 +1269,15 @@ Zone	Africa/Lagos	0:13:35 -	LMT	1905 Jul  1
 			1:00	-	WAT
 
 # Réunion
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Indian/Reunion	3:41:52 -	LMT	1911 Jun # Saint-Denis
-			4:00	-	+04
+# See Etc/GMT-4.
 #
 # Crozet Islands also observes Réunion time; see the 'antarctica' file.
-#
-# Scattered Islands (Îles Éparses) administered from Réunion are as follows.
-# The following information about them is taken from
-# Îles Éparses (<http://www.outre-mer.gouv.fr/domtom/ile.htm>, 1997-07-22,
-# in French; no longer available as of 1999-08-17).
-# We have no info about their time zone histories.
-#
-# Bassas da India - uninhabited
-# Europa Island - inhabited from 1905 to 1910 by two families
-# Glorioso Is - inhabited until at least 1958
-# Juan de Nova - uninhabited
-# Tromelin - inhabited until at least 1958
 
 # Rwanda
 # See Africa/Maputo.
 
 # St Helena
-# See Africa/Abidjan.
+# See Etc/GMT.
 # The other parts of the St Helena territory are similar:
 #	Tristan da Cunha: on GMT, say Whitman and the CIA
 #	Ascension: on GMT, say the USNO (1995-12-21) and the CIA
@@ -1413,34 +1312,13 @@ Zone	Africa/Sao_Tome	 0:26:56 -	LMT	1884
 			 0:00	-	GMT
 
 # Senegal
-# See Africa/Abidjan.
+# See Etc/GMT.
 
 # Seychelles
-
-# From P Chan (2020-11-27):
-# Standard Time was adopted on 1907-01-01.
-#
-# Standard Time Ordinance (Chapter 237)
-# The Laws of Seychelles in Force on the 31st December, 1971, Vol. 6, p 571
-# https://books.google.com/books?id=efE-AQAAIAAJ&pg=PA571
-#
-# From Tim Parenti (2020-12-05):
-# A footnote on https://books.google.com/books?id=DYdDAQAAMAAJ&pg=PA1689
-# confirms that Ordinance No. 9 of 1906 "was brought into force on the 1st
-# January, 1907."
-
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Indian/Mahe	3:41:48 -	LMT	1907 Jan  1 # Victoria
-			4:00	-	+04
-# From Paul Eggert (2001-05-30):
-# Aldabra, Farquhar, and Desroches, originally dependencies of the
-# Seychelles, were transferred to the British Indian Ocean Territory
-# in 1965 and returned to Seychelles control in 1976.  We don't know
-# whether this affected their time zone, so omit this for now.
-# Possibly the islands were uninhabited.
+# See Etc/GMT-4.
 
 # Sierra Leone
-# See Africa/Abidjan.
+# See Etc/GMT.
 
 # Somalia
 # See Africa/Nairobi.
@@ -1505,7 +1383,7 @@ Zone	Africa/Juba	2:06:28 -	LMT	1931
 # See Africa/Nairobi.
 
 # Togo
-# See Africa/Abidjan.
+# See Etc/GMT.
 
 # Tunisia
 
@@ -1599,7 +1477,7 @@ Rule	Tunisia	2005	only	-	Sep	30	 1:00s	0	-
 Rule	Tunisia	2006	2008	-	Mar	lastSun	 2:00s	1:00	S
 Rule	Tunisia	2006	2008	-	Oct	lastSun	 2:00s	0	-
 
-# See Europe/Paris for PMT-related transitions.
+# See Europe/Paris commentary for PMT-related transitions.
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Tunis	0:40:44 -	LMT	1881 May 12
 			0:09:21	-	PMT	1911 Mar 11 # Paris Mean Time

antarctica

@@ -148,7 +148,7 @@ Zone Antarctica/Mawson	0	-	-00	1954 Feb 13
 #
 # Alfred Faure, Possession Island, Crozet Islands, -462551+0515152, since 1964;
 #	sealing & whaling stations operated variously 1802/1911+;
-#	see Indian/Reunion.
+#	see Etc/GMT-4.
 #
 # Martin-de-Viviès, Amsterdam Island, -374105+0773155, since 1950
 # Port-aux-Français, Kerguelen Islands, -492110+0701303, since 1951;
@@ -157,22 +157,10 @@ Zone Antarctica/Mawson	0	-	-00	1954 Feb 13
 # St Paul Island - near Amsterdam, uninhabited
 #	fishing stations operated variously 1819/1931
 #
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Indian/Kerguelen	0	-	-00	1950 # Port-aux-Français
-			5:00	-	+05
+# Kerguelen - see Etc/GMT-5.
 #
 # year-round base in the main continent
-# Dumont d'Urville, Île des Pétrels, -6640+14001, since 1956-11
-# <https://en.wikipedia.org/wiki/Dumont_d'Urville_Station> (2005-12-05)
-#
-# Another base at Port-Martin, 50km east, began operation in 1947.
-# It was destroyed by fire on 1952-01-14.
-#
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Antarctica/DumontDUrville 0 -	-00	1947
-			10:00	-	+10	1952 Jan 14
-			0	-	-00	1956 Nov
-			10:00	-	+10
+# Dumont d'Urville - see Etc/GMT-10.
 
 # France & Italy - year-round base
 # Concordia, -750600+1232000, since 2005
@@ -188,20 +176,7 @@ Zone Antarctica/DumontDUrville 0 -	-00	1947
 # Zuchelli, Terra Nova Bay, -744140+1640647, since 1986
 
 # Japan - year-round bases
-# Syowa (also known as Showa), -690022+0393524, since 1957
-#
-# From Hideyuki Suzuki (1999-02-06):
-# In all Japanese stations, +0300 is used as the standard time.
-#
-# Syowa station, which is the first antarctic station of Japan,
-# was established on 1957-01-29.  Since Syowa station is still the main
-# station of Japan, it's appropriate for the principal location.
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Antarctica/Syowa	0	-	-00	1957 Jan 29
-			3:00	-	+03
-# See:
-# NIPR Antarctic Research Activities (1999-08-17)
-# http://www.nipr.ac.jp/english/ara01.html
+# See Etc/GMT-3.
 
 # S Korea - year-round base
 # Jang Bogo, Terra Nova Bay, -743700+1641205 since 2014
@@ -265,31 +240,7 @@ Zone Antarctica/Troll	0	-	-00	2005 Feb 12
 #	year-round from 1960/61 to 1992
 
 # Vostok, since 1957-12-16, temporarily closed 1994-02/1994-11
-# From Craig Mundell (1994-12-15):
-# http://quest.arc.nasa.gov/antarctica/QA/computers/Directions,Time,ZIP
-# Vostok, which is one of the Russian stations, is set on the same
-# time as Moscow, Russia.
-#
-# From Lee Hotz (2001-03-08):
-# I queried the folks at Columbia who spent the summer at Vostok and this is
-# what they had to say about time there:
-# "in the US Camp (East Camp) we have been on New Zealand (McMurdo)
-# time, which is 12 hours ahead of GMT. The Russian Station Vostok was
-# 6 hours behind that (although only 2 miles away, i.e. 6 hours ahead
-# of GMT). This is a time zone I think two hours east of Moscow. The
-# natural time zone is in between the two: 8 hours ahead of GMT."
-#
-# From Paul Eggert (2001-05-04):
-# This seems to be hopelessly confusing, so I asked Lee Hotz about it
-# in person.  He said that some Antarctic locations set their local
-# time so that noon is the warmest part of the day, and that this
-# changes during the year and does not necessarily correspond to mean
-# solar noon.  So the Vostok time might have been whatever the clocks
-# happened to be during their visit.  So we still don't really know what time
-# it is at Vostok.  But we'll guess +06.
-#
-Zone Antarctica/Vostok	0	-	-00	1957 Dec 16
-			6:00	-	+06
+# See Etc/GMT-6.
 
 # S Africa - year-round bases
 # Marion Island, -4653+03752

asia

@@ -255,10 +255,7 @@ Zone	Indian/Chagos	4:49:40	-	LMT	1907
 			6:00	-	+06
 
 # Brunei
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Asia/Brunei	7:39:40 -	LMT	1926 Mar # Bandar Seri Begawan
-			7:30	-	+0730	1933
-			8:00	-	+08
+# See Etc/GMT-8.
 
 # Burma / Myanmar
 
@@ -278,7 +275,7 @@ Zone	Asia/Yangon	6:24:47 -	LMT	1880        # or Rangoon
 			6:30	-	+0630
 
 # Cambodia
-# See Asia/Bangkok.
+# See Etc/GMT-7.
 
 
 # China
@@ -534,7 +531,7 @@ Rule	PRC	1987	1991	-	Apr	Sun>=11	 2:00	1:00	D
 # In earlier versions of this file, China had many separate Zone entries, but
 # this was based on what were apparently incorrect data in Shanks & Pottenger.
 # This has now been simplified to the two entries Asia/Shanghai and
-# Asia/Urumqi, with the others being links for backward compatibility.
+# Etc/GMT-6, with the others being links for backward compatibility.
 # Proposed in 1918 and theoretically in effect until 1949 (although in practice
 # mainly observed in coastal areas), the five zones were:
 #
@@ -556,7 +553,7 @@ Rule	PRC	1987	1991	-	Apr	Sun>=11	 2:00	1:00	D
 # Yangchun, Yangjiang, Yu'nan, and Yunfu.
 #
 # Xin-zang Time ("Xinjiang-Tibet Time") UT +06
-# This region is now part of either Asia/Urumqi or Asia/Shanghai with
+# This region is now part of either Etc/GMT-6 or Asia/Shanghai with
 # current boundaries uncertain; times before 1970 for areas that
 # disagree with Ürümqi or Shanghai are not recorded here.
 # The Gansu counties Aksay, Anxi, Dunhuang, Subei; west Qinghai;
@@ -609,68 +606,14 @@ Rule	PRC	1987	1991	-	Apr	Sun>=11	 2:00	1:00	D
 # 2. Kashi...
 # 3. Urumqi...
 # 4. Kashgar...
-# ...
-# 5. It seems that Uyghurs in Ürümqi has been using Xinjiang since at least the
-# 1960's. I know of one Han, now over 50, who grew up in the surrounding
-# countryside and used Xinjiang time as a child.
-#
-# 6. Likewise for Kashgar and the rest of south Xinjiang I don't know of any
-# start date for Xinjiang time.
-#
-# Without having access to local historical records, nor the ability to legally
-# publish them, I would go with October 1, 1949, when Xinjiang became the Uyghur
-# Autonomous Region under the PRC. (Before that Uyghurs, of course, would also
-# not be using Beijing time, but some local time.)
-
-# From David Cochrane (2014-03-26):
-# Just a confirmation that Ürümqi time was implemented in Ürümqi on 1 Feb 1986:
-# https://content.time.com/time/magazine/article/0,9171,960684,00.html
-
-# From Luther Ma (2014-04-22):
-# I have interviewed numerous people of various nationalities and from
-# different localities in Xinjiang and can confirm the information in Guo's
-# report regarding Xinjiang, as well as the Time article reference by David
-# Cochrane.  Whether officially recognized or not (and both are officially
-# recognized), two separate times have been in use in Xinjiang since at least
-# the Cultural Revolution: Xinjiang Time (XJT), aka Ürümqi Time or local time;
-# and Beijing Time.  There is no confusion in Xinjiang as to which name refers
-# to which time. Both are widely used in the province, although in some
-# population groups might be use one to the exclusion of the other.  The only
-# problem is that computers and smart phones list Ürümqi (or Kashgar) as
-# having the same time as Beijing.
-
-# From Paul Eggert (2014-06-30):
-# In the early days of the PRC, Tibet was given its own time zone (UT +06)
-# but this was withdrawn in 1959 and never reinstated; see Tubten Khétsun,
-# Memories of life in Lhasa under Chinese Rule, Columbia U Press, ISBN
-# 978-0231142861 (2008), translator's introduction by Matthew Akester, p x.
-# As this is before our 1970 cutoff, Tibet doesn't need a separate zone.
-#
-# Xinjiang Time is well-documented as being officially recognized.  E.g., see
-# "The Working-Calendar for The Xinjiang Uygur Autonomous Region Government"
-# <http://www.sinkiang.gov.cn/service/ourworking/> (2014-04-22).
-# Unfortunately, we have no good records of time in Xinjiang before 1986.
-# During the 20th century parts of Xinjiang were ruled by the Qing dynasty,
-# the Republic of China, various warlords, the First and Second East Turkestan
-# Republics, the Soviet Union, the Kuomintang, and the People's Republic of
-# China, and tracking down all these organizations' timekeeping rules would be
-# quite a trick.  Approximate this lost history by a transition from LMT to
-# UT +06 at the start of 1928, the year of accession of the warlord Jin Shuren,
-# which happens to be the date given by Shanks & Pottenger (no doubt as a
-# guess) as the transition from LMT.  Ignore the usage of +08 before
-# 1986-02-01 under the theory that the transition date to +08 is unknown and
-# that the sort of users who prefer Asia/Urumqi now typically ignored the
-# +08 mandate back then.
 
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 # Beijing time, used throughout China; represented by Shanghai.
 Zone	Asia/Shanghai	8:05:43	-	LMT	1901
 			8:00	Shang	C%sT	1949 May 28
 			8:00	PRC	C%sT
-# Xinjiang time, used by many in western China; represented by Ürümqi / Ürümchi
-# / Wulumuqi.  (Please use Asia/Shanghai if you prefer Beijing time.)
-Zone	Asia/Urumqi	5:50:20	-	LMT	1928
-			6:00	-	+06
+# See Etc/GMT-6 for Xinjiang time, used by many in western China.
+# (Please use Asia/Shanghai if you prefer Beijing time.)
 
 
 # Hong Kong
@@ -2693,10 +2636,10 @@ Zone	Asia/Pyongyang	8:23:00 -	LMT	1908 Apr  1
 ###############################################################################
 
 # Kuwait
-# See Asia/Riyadh.
+# See Etc/GMT-3.
 
 # Laos
-# See Asia/Bangkok.
+# See Etc/GMT-7.
 
 
 # Lebanon
@@ -2730,39 +2673,12 @@ Zone	Asia/Beirut	2:22:00 -	LMT	1880
 			2:00	Lebanon	EE%sT
 
 # Malaysia
-# Rule	NAME	FROM	TO	-	IN	ON	AT	SAVE	LETTER/S
-Rule	NBorneo	1935	1941	-	Sep	14	0:00	0:20	-
-Rule	NBorneo	1935	1941	-	Dec	14	0:00	0	-
-#
-# peninsular Malaysia
-# taken from Mok Ly Yng (2003-10-30)
-# http://www.math.nus.edu.sg/aslaksen/teaching/timezone.html
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Asia/Kuala_Lumpur	6:46:46 -	LMT	1901 Jan  1
-			6:55:25	-	SMT	1905 Jun  1 # Singapore M.T.
-			7:00	-	+07	1933 Jan  1
-			7:00	0:20	+0720	1936 Jan  1
-			7:20	-	+0720	1941 Sep  1
-			7:30	-	+0730	1942 Feb 16
-			9:00	-	+09	1945 Sep 12
-			7:30	-	+0730	1982 Jan  1
-			8:00	-	+08
-# Sabah & Sarawak
-# From Paul Eggert (2014-08-12):
-# The data entries here are mostly from Shanks & Pottenger, but the 1942, 1945
-# and 1982 transition dates are from Mok Ly Yng.
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Asia/Kuching	7:21:20	-	LMT	1926 Mar
-			7:30	-	+0730	1933
-			8:00 NBorneo  +08/+0820	1942 Feb 16
-			9:00	-	+09	1945 Sep 12
-			8:00	-	+08
+# For peninsular Malaysia see Asia/Singapore.
+# For Sabah & Sarawak see Etc/GMT-8.
 
 # Maldives
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Indian/Maldives	4:54:00 -	LMT	1880 # Malé
-			4:54:00	-	MMT	1960 # Malé Mean Time
-			5:00	-	+05
+# See Etc/GMT-5.
+
 
 # Mongolia
 
@@ -2926,7 +2842,7 @@ Zone	Asia/Kathmandu	5:41:16 -	LMT	1920
 			5:45	-	+0545
 
 # Oman
-# See Asia/Dubai.
+# See Etc/GMT-4.
 
 # Pakistan
 
@@ -3523,54 +3439,11 @@ Zone	Asia/Qatar	3:26:08 -	LMT	1920     # Al Dawhah / Doha
 			3:00	-	+03
 
 # Saudi Arabia
-#
-# From Paul Eggert (2018-08-29):
-# Time in Saudi Arabia and other countries in the Arabian peninsula was not
-# standardized until 1968 or so; we don't know exactly when, and possibly it
-# has never been made official.  Richard P Hunt, in "Islam city yielding to
-# modern times", New York Times (1961-04-09), p 20, wrote that only airlines
-# observed standard time, and that people in Jeddah mostly observed quasi-solar
-# time, doing so by setting their watches at sunrise to 6 o'clock (or to 12
-# o'clock for "Arab" time).
-#
-# Timekeeping differed depending on who you were and which part of Saudi
-# Arabia you were in.  In 1969, Elias Antar wrote that although a common
-# practice had been to set one's watch to 12:00 (i.e., midnight) at sunset -
-# which meant that the time on one side of a mountain could differ greatly from
-# the time on the other side - many foreigners set their watches to 6pm
-# instead, while airlines instead used UTC +03 (except in Dhahran, where they
-# used UTC +04), Aramco used UTC +03 with DST, and the Trans-Arabian Pipe Line
-# Company used Aramco time in eastern Saudi Arabia and airline time in western.
-# (The American Military Aid Advisory Group used plain UTC.)  Antar writes,
-# "A man named Higgins, so the story goes, used to run a local power
-# station. One day, the whole thing became too much for Higgins and he
-# assembled his staff and laid down the law. 'I've had enough of this,' he
-# shrieked. 'It is now 12 o'clock Higgins Time, and from now on this station is
-# going to run on Higgins Time.' And so, until last year, it did."  See:
-# Antar E. Dinner at When? Saudi Aramco World, 1969 March/April. 2-3.
-# http://archive.aramcoworld.com/issue/196902/dinner.at.when.htm
-# Also see: Antar EN. Arabian flying is confusing.
-# Port Angeles (WA) Evening News. 1965-03-10. page 3.
-#
-# The TZ database cannot represent quasi-solar time; airline time is the best
-# we can do.  The 1946 foreign air news digest of the U.S. Civil Aeronautics
-# Board (OCLC 42299995) reported that the "... Arabian Government, inaugurated
-# a weekly Dhahran-Cairo service, via the Saudi Arabian cities of Riyadh and
-# Jidda, on March 14, 1947".  Shanks & Pottenger guessed 1950; go with the
-# earlier date.
-#
-# Shanks & Pottenger also state that until 1968-05-01 Saudi Arabia had two
-# time zones; the other zone, at UT +04, was in the far eastern part of
-# the country.  Presumably this is documenting airline time.  Ignore this,
-# as it's before our 1970 cutoff.
-#
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Asia/Riyadh	3:06:52 -	LMT	1947 Mar 14
-			3:00	-	+03
+# See Etc/GMT-3.
 
 # Singapore
 # taken from Mok Ly Yng (2003-10-30)
-# http://www.math.nus.edu.sg/aslaksen/teaching/timezone.html
+# https://web.archive.org/web/20190822231045/http://www.math.nus.edu.sg/~mathelmr/teaching/timezone.html
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Singapore	6:55:25 -	LMT	1901 Jan  1
 			6:55:25	-	SMT	1905 Jun  1 # Singapore M.T.
@@ -3819,10 +3692,7 @@ Zone	Asia/Dushanbe	4:35:12 -	LMT	1924 May  2
 			5:00	-	+05
 
 # Thailand
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Asia/Bangkok	6:42:04	-	LMT	1880
-			6:42:04	-	BMT	1920 Apr # Bangkok Mean Time
-			7:00	-	+07
+# See Etc/GMT-7.
 
 # Turkmenistan
 # From Shanks & Pottenger.
@@ -3834,9 +3704,7 @@ Zone	Asia/Ashgabat	3:53:32 -	LMT	1924 May  2 # or Ashkhabad
 			5:00	-	+05
 
 # United Arab Emirates
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Asia/Dubai	3:41:12 -	LMT	1920
-			4:00	-	+04
+# See Etc/GMT-4.
 
 # Uzbekistan
 # Byalokoz 1919 says Uzbekistan was 4:27:53.
@@ -3926,9 +3794,9 @@ Zone Asia/Ho_Chi_Minh	7:06:40 -	LMT	1906 Jul  1
 # details are unknown and would likely be too voluminous for this database.
 #
 # For timestamps in north Vietnam back to 1970 (the tzdb cutoff),
-# use Asia/Bangkok; see the VN entries in the file zone1970.tab.
+# use Etc/GMT-7; see the VN entries in the file zone1970.tab.
 # For timestamps before 1970, see Asia/Hanoi in the file 'backzone'.
 
 
 # Yemen
-# See Asia/Riyadh.
+# See Etc/GMT-3.

australasia

@@ -252,16 +252,10 @@ Zone Antarctica/Macquarie 0	-	-00	1899 Nov
 			10:00	AT	AE%sT
 
 # Christmas
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Indian/Christmas	7:02:52 -	LMT	1895 Feb
-			7:00	-	+07
+# See Etc/GMT-7.
 
 # Cocos (Keeling) Is
-# These islands were ruled by the Ross family from about 1830 to 1978.
-# We don't know when standard time was introduced; for now, we guess 1900.
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Indian/Cocos	6:27:40	-	LMT	1900
-			6:30	-	+0630
+# See Asia/Yangon.
 
 
 # Fiji
@@ -409,12 +403,9 @@ Zone	Pacific/Fiji	11:55:44 -	LMT	1915 Oct 26 # Suva
 
 # French Polynesia
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Pacific/Gambier	 -8:59:48 -	LMT	1912 Oct # Rikitea
-			 -9:00	-	-09
 Zone	Pacific/Marquesas -9:18:00 -	LMT	1912 Oct
 			 -9:30	-	-0930
-Zone	Pacific/Tahiti	 -9:58:16 -	LMT	1912 Oct # Papeete
-			-10:00	-	-10
+# See Etc/GMT+9 for the Gambier Islands and Etc/GMT+10 for the Society Islands.
 # Clipperton (near North America) is administered from French Polynesia;
 # it is uninhabited.
 
@@ -460,9 +451,8 @@ Zone	Pacific/Guam	-14:21:00 -	LMT	1844 Dec 31
 			10:00	-	ChST	# Chamorro Standard Time
 
 # Kiribati
+# See Etc/GMT-12 for the Gilbert Islands.
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Pacific/Tarawa	 11:32:04 -	LMT	1901 # Bairiki
-			 12:00	-	+12
 Zone Pacific/Enderbury	-11:24:20 -	LMT	1901
 			-12:00	-	-12	1979 Oct
 			-11:00	-	-11	1994 Dec 31
@@ -476,15 +466,8 @@ Zone Pacific/Kiritimati	-10:29:20 -	LMT	1901
 # See Pacific/Guam.
 
 # Marshall Is
+# See Etc/GMT-12 for most locations.
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Pacific/Majuro	 11:24:48 -	LMT	1901
-			 11:00	-	+11	1914 Oct
-			  9:00	-	+09	1919 Feb  1
-			 11:00	-	+11	1937
-			 10:00	-	+10	1941 Apr  1
-			  9:00	-	+09	1944 Jan 30
-			 11:00	-	+11	1969 Oct
-			 12:00	-	+12
 Zone Pacific/Kwajalein	 11:09:20 -	LMT	1901
 			 11:00	-	+11	1937
 			 10:00	-	+10	1941 Apr  1
@@ -494,22 +477,9 @@ Zone Pacific/Kwajalein	 11:09:20 -	LMT	1901
 			 12:00	-	+12
 
 # Micronesia
+# For Chuuk and Yap see Etc/GMT-10.
+# For Pohnpei see Etc/GMT-11.
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Pacific/Chuuk	-13:52:52 -	LMT	1844 Dec 31
-			 10:07:08 -	LMT	1901
-			 10:00	-	+10	1914 Oct
-			  9:00	-	+09	1919 Feb  1
-			 10:00	-	+10	1941 Apr  1
-			  9:00	-	+09	1945 Aug
-			 10:00	-	+10
-Zone Pacific/Pohnpei	-13:27:08 -	LMT	1844 Dec 31	# Kolonia
-			 10:32:52 -	LMT	1901
-			 11:00	-	+11	1914 Oct
-			  9:00	-	+09	1919 Feb  1
-			 11:00	-	+11	1937
-			 10:00	-	+10	1941 Apr  1
-			  9:00	-	+09	1945 Aug
-			 11:00	-	+11
 Zone Pacific/Kosrae	-13:08:04 -	LMT	1844 Dec 31
 			 10:51:56 -	LMT	1901
 			 11:00	-	+11	1914 Oct
@@ -658,16 +628,10 @@ Zone	Pacific/Norfolk	11:11:52 -	LMT	1901 # Kingston
 			11:00	AN	+11/+12
 
 # Palau (Belau)
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Pacific/Palau	-15:02:04 -	LMT	1844 Dec 31	# Koror
-			  8:57:56 -	LMT	1901
-			  9:00	-	+09
+# See Etc/GMT-9.
 
 # Papua New Guinea
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Pacific/Port_Moresby 9:48:40 -	LMT	1880
-			9:48:32	-	PMMT	1895 # Port Moresby Mean Time
-			10:00	-	+10
+# See Etc/GMT-10 for most locations.
 #
 # From Paul Eggert (2014-10-13):
 # Base the Bougainville entry on the Arawa-Kieta region, which appears to have
@@ -787,9 +751,8 @@ Zone Pacific/Apia	 12:33:04 -	LMT	1892 Jul  5
 
 # Solomon Is
 # excludes Bougainville, for which see Papua New Guinea
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Pacific/Guadalcanal 10:39:48 -	LMT	1912 Oct # Honiara
-			11:00	-	+11
+# See Etc/GMT-11.
+
 
 # Tokelau
 #
@@ -830,9 +793,7 @@ Zone Pacific/Tongatapu	12:19:12 -	LMT	1945 Sep 10
 			13:00	Tonga	+13/+14
 
 # Tuvalu
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Pacific/Funafuti	11:56:52 -	LMT	1901
-			12:00	-	+12
+# See Etc/GMT-12.
 
 
 # US minor outlying islands
@@ -891,9 +852,7 @@ Zone Pacific/Funafuti	11:56:52 -	LMT	1901
 # uninhabited since World War II; was probably like Pacific/Kiritimati
 
 # Wake
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Pacific/Wake	11:06:28 -	LMT	1901
-			12:00	-	+12
+# See Etc/GMT-12.
 
 
 # Vanuatu
@@ -932,9 +891,7 @@ Zone	Pacific/Efate	11:13:16 -	LMT	1912 Jan 13 # Vila
 			11:00	Vanuatu	+11/+12
 
 # Wallis and Futuna
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Pacific/Wallis	12:15:20 -	LMT	1901
-			12:00	-	+12
+# See Etc/GMT-12.
 
 ###############################################################################
 
@@ -1834,13 +1791,6 @@ Zone	Pacific/Wallis	12:15:20 -	LMT	1901
 # Like the Ladrones (see Guam commentary), assume the Spanish East Indies
 # kept American time until the Philippines switched at the end of 1844.
 
-# Alan Eugene Davis writes (1996-03-16),
-# "I am certain, having lived there for the past decade, that 'Truk'
-# (now properly known as Chuuk) ... is in the time zone GMT+10."
-#
-# Shanks & Pottenger write that Truk switched from UT +10 to +11
-# on 1978-10-01; ignore this for now.
-
 # From Paul Eggert (1999-10-29):
 # The Federated States of Micronesia Visitors Board writes in
 # The Federated States of Micronesia - Visitor Information (1999-01-26)
@@ -2001,9 +1951,6 @@ Zone	Pacific/Wallis	12:15:20 -	LMT	1901
 # From Michael Deckers (2019-08-14):
 # https://www.legislation.gov.au/Details/F2019C00010
 
-# Palau
-# See commentary for Micronesia.
-
 # Pitcairn
 
 # From Rives McDow (1999-11-08):
@@ -2173,26 +2120,6 @@ Zone	Pacific/Wallis	12:15:20 -	LMT	1901
 # For now, guess that DST is discontinued.  That's what the IATA is guessing.
 
 
-# Wake
-
-# From Vernice Anderson, Personal Secretary to Philip Jessup,
-# US Ambassador At Large (oral history interview, 1971-02-02):
-#
-# Saturday, the 14th [of October, 1950] - ...  The time was all the
-# more confusing at that point, because we had crossed the
-# International Date Line, thus getting two Sundays.  Furthermore, we
-# discovered that Wake Island had two hours of daylight saving time
-# making calculation of time in Washington difficult if not almost
-# impossible.
-#
-# https://www.trumanlibrary.org/oralhist/andrsonv.htm
-
-# From Paul Eggert (2003-03-23):
-# We have no other report of DST in Wake Island, so omit this info for now.
-
-# See also the commentary for Micronesia.
-
-
 ###############################################################################
 
 # The International Date Line

backward

@@ -5,30 +5,35 @@
 
 # This file provides links between current names for timezones
 # and their old names.  Many names changed in late 1993.
+# Many others were moved here in 2021.  Several of these names are
+# also present in the file 'backzone', which has data important only
+# for pre-1970 timestamps and so is out of scope for tzdb proper.
 
 # Link	TARGET			LINK-NAME
+Link	Etc/GMT			Africa/Abidjan
+Link	Etc/GMT			Africa/Accra
 Link	Africa/Nairobi		Africa/Addis_Ababa
 Link	Africa/Nairobi		Africa/Asmara
 Link	Africa/Nairobi		Africa/Asmera
-Link	Africa/Abidjan		Africa/Bamako
+Link	Etc/GMT			Africa/Bamako
 Link	Africa/Lagos		Africa/Bangui
-Link	Africa/Abidjan		Africa/Banjul
+Link	Etc/GMT			Africa/Banjul
 Link	Africa/Maputo		Africa/Blantyre
 Link	Africa/Lagos		Africa/Brazzaville
 Link	Africa/Maputo		Africa/Bujumbura
-Link	Africa/Abidjan		Africa/Conakry
-Link	Africa/Abidjan		Africa/Dakar
+Link	Etc/GMT			Africa/Conakry
+Link	Etc/GMT			Africa/Dakar
 Link	Africa/Nairobi		Africa/Dar_es_Salaam
 Link	Africa/Nairobi		Africa/Djibouti
 Link	Africa/Lagos		Africa/Douala
-Link	Africa/Abidjan		Africa/Freetown
+Link	Etc/GMT			Africa/Freetown
 Link	Africa/Maputo		Africa/Gaborone
 Link	Africa/Maputo		Africa/Harare
 Link	Africa/Nairobi		Africa/Kampala
 Link	Africa/Maputo		Africa/Kigali
 Link	Africa/Lagos		Africa/Kinshasa
 Link	Africa/Lagos		Africa/Libreville
-Link	Africa/Abidjan		Africa/Lome
+Link	Etc/GMT			Africa/Lome
 Link	Africa/Lagos		Africa/Luanda
 Link	Africa/Maputo		Africa/Lubumbashi
 Link	Africa/Maputo		Africa/Lusaka
@@ -37,75 +42,95 @@ Link	Africa/Johannesburg	Africa/Maseru
 Link	Africa/Johannesburg	Africa/Mbabane
 Link	Africa/Nairobi		Africa/Mogadishu
 Link	Africa/Lagos		Africa/Niamey
-Link	Africa/Abidjan		Africa/Nouakchott
-Link	Africa/Abidjan		Africa/Ouagadougou
+Link	Etc/GMT			Africa/Nouakchott
+Link	Etc/GMT			Africa/Ouagadougou
 Link	Africa/Lagos		Africa/Porto-Novo
-Link	Africa/Abidjan		Africa/Timbuktu
-Link	America/Port_of_Spain	America/Anguilla
-Link	America/Port_of_Spain	America/Antigua
+Link	Etc/GMT			Africa/Timbuktu
+Link	America/Puerto_Rico	America/Anguilla
+Link	America/Puerto_Rico	America/Antigua
 Link	America/Argentina/Catamarca	America/Argentina/ComodRivadavia
-Link	America/Curacao		America/Aruba
+Link	America/Puerto_Rico	America/Aruba
+Link	America/Panama		America/Atikokan
 Link	America/Adak		America/Atka
+Link	America/Puerto_Rico	America/Blanc-Sablon
 Link	America/Argentina/Buenos_Aires	America/Buenos_Aires
 Link	America/Argentina/Catamarca	America/Catamarca
+Link	Etc/GMT+3		America/Cayenne
 Link	America/Panama		America/Cayman
-Link	America/Atikokan	America/Coral_Harbour
+Link	America/Panama		America/Coral_Harbour
 Link	America/Argentina/Cordoba	America/Cordoba
-Link	America/Port_of_Spain	America/Dominica
+Link	America/Phoenix		America/Creston
+Link	America/Puerto_Rico	America/Curacao
+Link	America/Puerto_Rico	America/Dominica
 Link	America/Tijuana		America/Ensenada
 Link	America/Indiana/Indianapolis	America/Fort_Wayne
 Link	America/Nuuk		America/Godthab
-Link	America/Port_of_Spain	America/Grenada
-Link	America/Port_of_Spain	America/Guadeloupe
+Link	America/Puerto_Rico	America/Grenada
+Link	America/Puerto_Rico	America/Guadeloupe
 Link	America/Indiana/Indianapolis	America/Indianapolis
 Link	America/Argentina/Jujuy	America/Jujuy
 Link	America/Indiana/Knox	America/Knox_IN
-Link	America/Curacao		America/Kralendijk
+Link	America/Puerto_Rico	America/Kralendijk
+Link	Etc/GMT+4		America/La_Paz
 Link	America/Kentucky/Louisville	America/Louisville
-Link	America/Curacao		America/Lower_Princes
-Link	America/Port_of_Spain	America/Marigot
+Link	America/Puerto_Rico	America/Lower_Princes
+Link	America/Puerto_Rico	America/Marigot
 Link	America/Argentina/Mendoza	America/Mendoza
 Link	America/Toronto		America/Montreal
-Link	America/Port_of_Spain	America/Montserrat
+Link	America/Puerto_Rico	America/Montserrat
+Link	America/Toronto		America/Nassau
+Link	America/Puerto_Rico	America/Port_of_Spain
 Link	America/Rio_Branco	America/Porto_Acre
 Link	America/Argentina/Cordoba	America/Rosario
 Link	America/Tijuana		America/Santa_Isabel
 Link	America/Denver		America/Shiprock
-Link	America/Port_of_Spain	America/St_Barthelemy
-Link	America/Port_of_Spain	America/St_Kitts
-Link	America/Port_of_Spain	America/St_Lucia
-Link	America/Port_of_Spain	America/St_Thomas
-Link	America/Port_of_Spain	America/St_Vincent
-Link	America/Port_of_Spain	America/Tortola
-Link	America/Port_of_Spain	America/Virgin
+Link	America/Puerto_Rico	America/St_Barthelemy
+Link	America/Puerto_Rico	America/St_Kitts
+Link	America/Puerto_Rico	America/St_Lucia
+Link	America/Puerto_Rico	America/St_Thomas
+Link	America/Puerto_Rico	America/St_Vincent
+Link	America/Puerto_Rico	America/Tortola
+Link	America/Puerto_Rico	America/Virgin
+Link	Etc/GMT-10		Antarctica/DumontDUrville
 Link	Pacific/Auckland	Antarctica/McMurdo
 Link	Pacific/Auckland	Antarctica/South_Pole
-Link	Europe/Oslo		Arctic/Longyearbyen
-Link	Asia/Riyadh		Asia/Aden
+Link	Etc/GMT-3		Antarctica/Syowa
+Link	Etc/GMT-6		Antarctica/Vostok
+Link	Europe/Berlin		Arctic/Longyearbyen
+Link	Etc/GMT-3		Asia/Aden
 Link	Asia/Ashgabat		Asia/Ashkhabad
 Link	Asia/Qatar		Asia/Bahrain
+Link	Etc/GMT-7		Asia/Bangkok
+Link	Etc/GMT-8		Asia/Brunei
 Link	Asia/Kolkata		Asia/Calcutta
 Link	Asia/Shanghai		Asia/Chongqing
 Link	Asia/Shanghai		Asia/Chungking
 Link	Asia/Dhaka		Asia/Dacca
+Link	Etc/GMT-4		Asia/Dubai
 Link	Asia/Shanghai		Asia/Harbin
 Link	Europe/Istanbul		Asia/Istanbul
-Link	Asia/Urumqi		Asia/Kashgar
+Link	Etc/GMT-6		Asia/Kashgar
 Link	Asia/Kathmandu		Asia/Katmandu
-Link	Asia/Riyadh		Asia/Kuwait
+Link	Asia/Singapore		Asia/Kuala_Lumpur
+Link	Etc/GMT-8		Asia/Kuching
+Link	Etc/GMT-3		Asia/Kuwait
 Link	Asia/Macau		Asia/Macao
-Link	Asia/Dubai		Asia/Muscat
-Link	Asia/Bangkok		Asia/Phnom_Penh
+Link	Etc/GMT-4		Asia/Muscat
+Link	Etc/GMT-7		Asia/Phnom_Penh
 Link	Asia/Yangon		Asia/Rangoon
+Link	Etc/GMT-3		Asia/Riyadh
 Link	Asia/Ho_Chi_Minh	Asia/Saigon
 Link	Asia/Jerusalem		Asia/Tel_Aviv
 Link	Asia/Thimphu		Asia/Thimbu
 Link	Asia/Makassar		Asia/Ujung_Pandang
 Link	Asia/Ulaanbaatar	Asia/Ulan_Bator
-Link	Asia/Bangkok		Asia/Vientiane
+Link	Etc/GMT-6		Asia/Urumqi
+Link	Etc/GMT-7		Asia/Vientiane
 Link	Atlantic/Faroe		Atlantic/Faeroe
-Link	Europe/Oslo		Atlantic/Jan_Mayen
-Link	Africa/Abidjan		Atlantic/St_Helena
+Link	Europe/Berlin		Atlantic/Jan_Mayen
+Link	Etc/GMT			Atlantic/Reykjavik
+Link	Etc/GMT+2		Atlantic/South_Georgia
+Link	Etc/GMT			Atlantic/St_Helena
 Link	Australia/Sydney	Australia/ACT
 Link	Australia/Sydney	Australia/Canberra
 Link	Australia/Hobart	Australia/Currie
@@ -139,19 +164,25 @@ Link	America/Havana		Cuba
 Link	Africa/Cairo		Egypt
 Link	Europe/Dublin		Eire
 Link	Etc/UTC			Etc/UCT
+Link	Europe/Brussels		Europe/Amsterdam
 Link	Europe/London		Europe/Belfast
 Link	Europe/Prague		Europe/Bratislava
 Link	Europe/Zurich		Europe/Busingen
+Link	Europe/Berlin		Europe/Copenhagen
 Link	Europe/London		Europe/Guernsey
 Link	Europe/London		Europe/Isle_of_Man
 Link	Europe/London		Europe/Jersey
 Link	Europe/Belgrade		Europe/Ljubljana
+Link	Europe/Brussels		Europe/Luxembourg
 Link	Europe/Helsinki		Europe/Mariehamn
+Link	Europe/Paris		Europe/Monaco
 Link	Asia/Nicosia		Europe/Nicosia
+Link	Europe/Berlin		Europe/Oslo
 Link	Europe/Belgrade		Europe/Podgorica
 Link	Europe/Rome		Europe/San_Marino
 Link	Europe/Belgrade		Europe/Sarajevo
 Link	Europe/Belgrade		Europe/Skopje
+Link	Europe/Berlin		Europe/Stockholm
 Link	Europe/Chisinau		Europe/Tiraspol
 Link	Europe/Zurich		Europe/Vaduz
 Link	Europe/Rome		Europe/Vatican
@@ -163,10 +194,16 @@ Link	Etc/GMT			GMT-0
 Link	Etc/GMT			GMT0
 Link	Etc/GMT			Greenwich
 Link	Asia/Hong_Kong		Hongkong
-Link	Atlantic/Reykjavik	Iceland
+Link	Etc/GMT			Iceland
 Link	Africa/Nairobi		Indian/Antananarivo
+Link	Etc/GMT-7		Indian/Christmas
+Link	Asia/Yangon		Indian/Cocos
 Link	Africa/Nairobi		Indian/Comoro
+Link	Etc/GMT-5		Indian/Kerguelen
+Link	Etc/GMT-4		Indian/Mahe
+Link	Etc/GMT-5		Indian/Maldives
 Link	Africa/Nairobi		Indian/Mayotte
+Link	Etc/GMT-4		Indian/Reunion
 Link	Asia/Tehran		Iran
 Link	Asia/Jerusalem		Israel
 Link	America/Jamaica		Jamaica
@@ -180,13 +217,25 @@ Link	Pacific/Auckland	NZ
 Link	Pacific/Chatham		NZ-CHAT
 Link	America/Denver		Navajo
 Link	Asia/Shanghai		PRC
+Link	Etc/GMT-10		Pacific/Chuuk
+Link	Etc/GMT-12		Pacific/Funafuti
+Link	Etc/GMT+9		Pacific/Gambier
+Link	Etc/GMT-11		Pacific/Guadalcanal
 Link	Pacific/Honolulu	Pacific/Johnston
+Link	Etc/GMT-12		Pacific/Majuro
 Link	Pacific/Pago_Pago	Pacific/Midway
-Link	Pacific/Pohnpei		Pacific/Ponape
+Link	Etc/GMT-9		Pacific/Palau
+Link	Etc/GMT-11		Pacific/Pohnpei
+Link	Etc/GMT-11		Pacific/Ponape
+Link	Etc/GMT-10		Pacific/Port_Moresby
 Link	Pacific/Guam		Pacific/Saipan
 Link	Pacific/Pago_Pago	Pacific/Samoa
-Link	Pacific/Chuuk		Pacific/Truk
-Link	Pacific/Chuuk		Pacific/Yap
+Link	Etc/GMT+10		Pacific/Tahiti
+Link	Etc/GMT-12		Pacific/Tarawa
+Link	Etc/GMT-10		Pacific/Truk
+Link	Etc/GMT-12		Pacific/Wake
+Link	Etc/GMT-12		Pacific/Wallis
+Link	Etc/GMT-10		Pacific/Yap
 Link	Europe/Warsaw		Poland
 Link	Europe/Lisbon		Portugal
 Link	Asia/Taipei		ROC

checktab.awk

@@ -147,7 +147,7 @@ $1 ~ /^#/ { next }
 		ruleUsed[$2] = 1
 		if ($3 ~ /%/) rulePercentUsed[$2] = 1
 	}
-	if (tz && tz ~ /\//) {
+	if (tz && tz ~ /\// && tz !~ /^Etc\//) {
 		if (!tztab[tz]) {
 			printf "%s: no data for '%s'\n", zone_table, tz \
 				>>"/dev/stderr"
@@ -171,7 +171,7 @@ END {
 		}
 	}
 	for (tz in tztab) {
-		if (!zoneSeen[tz]) {
+		if (!zoneSeen[tz] && tz !~ /^Etc\//) {
 			printf "%s:%d: no Zone table for '%s'\n", \
 				zone_table, tz2NR[tz], tz >>"/dev/stderr"
 			status = 1

etcetera

@@ -12,6 +12,8 @@
 # Starting with POSIX 1003.1-2001, the entries below are all
 # unnecessary as settings for the TZ environment variable.  E.g.,
 # instead of TZ='Etc/GMT+4' one can use the POSIX setting TZ='<-04>+4'.
+# However, some entries are needed if 'backward' is used:
+# for example, the 'backward' file links Etc/GMT to Africa/Abidjan.
 #
 # Do not use a POSIX TZ setting like TZ='GMT+4', which is four hours
 # behind GMT but uses the completely misleading abbreviation "GMT".

europe

@@ -68,7 +68,6 @@
 #        0:00       GMT  BST  BDST  Greenwich, British Summer
 #        0:00       GMT  IST        Greenwich, Irish Summer
 #        0:00       WET  WEST WEMT  Western Europe
-#        0:19:32.13 AMT* NST*       Amsterdam, Netherlands Summer (1835-1937)
 #        1:00       BST             British Standard (1968-1971)
 #        1:00       IST  GMT        Irish Standard (1968-) with winter DST
 #        1:00       CET  CEST CEMT  Central Europe
@@ -1024,59 +1023,8 @@ Zone	Europe/Prague	0:57:44 -	LMT	1850
 # Use Europe/Prague also for Slovakia.
 
 # Denmark, Faroe Islands, and Greenland
+# For Denmark see Europe/Berlin.
 
-# From Jesper Nørgaard Welen (2005-04-26):
-# the law [introducing standard time] was in effect from 1894-01-01....
-# The page https://www.retsinformation.dk/eli/lta/1893/83
-# confirms this, and states that the law was put forth 1893-03-29.
-#
-# The EU [actually, EEC and Euratom] treaty with effect from 1973:
-# https://www.retsinformation.dk/eli/lta/1972/21100
-#
-# This provoked a new law from 1974 to make possible summer time changes
-# in subsequent decrees with the law
-# https://www.retsinformation.dk/eli/lta/1974/223
-#
-# It seems however that no decree was set forward until 1980.  I have
-# not found any decree, but in another related law, the effecting DST
-# changes are stated explicitly to be from 1980-04-06 at 02:00 to
-# 1980-09-28 at 02:00.  If this is true, this differs slightly from
-# the EU rule in that DST runs to 02:00, not 03:00.  We don't know
-# when Denmark began using the EU rule correctly, but we have only
-# confirmation of the 1980-time, so I presume it was correct in 1981:
-# The law is about the management of the extra hour, concerning
-# working hours reported and effect on obligatory-rest rules (which
-# was suspended on that night):
-# https://web.archive.org/web/20140104053304/https://www.retsinformation.dk/Forms/R0710.aspx?id=60267
-
-# From Jesper Nørgaard Welen (2005-06-11):
-# The Herning Folkeblad (1980-09-26) reported that the night between
-# Saturday and Sunday the clock is set back from three to two.
-
-# From Paul Eggert (2005-06-11):
-# Hence the "02:00" of the 1980 law refers to standard time, not
-# wall-clock time, and so the EU rules were in effect in 1980.
-
-# Rule	NAME	FROM	TO	-	IN	ON	AT	SAVE	LETTER/S
-Rule	Denmark	1916	only	-	May	14	23:00	1:00	S
-Rule	Denmark	1916	only	-	Sep	30	23:00	0	-
-Rule	Denmark	1940	only	-	May	15	 0:00	1:00	S
-Rule	Denmark	1945	only	-	Apr	 2	 2:00s	1:00	S
-Rule	Denmark	1945	only	-	Aug	15	 2:00s	0	-
-Rule	Denmark	1946	only	-	May	 1	 2:00s	1:00	S
-Rule	Denmark	1946	only	-	Sep	 1	 2:00s	0	-
-Rule	Denmark	1947	only	-	May	 4	 2:00s	1:00	S
-Rule	Denmark	1947	only	-	Aug	10	 2:00s	0	-
-Rule	Denmark	1948	only	-	May	 9	 2:00s	1:00	S
-Rule	Denmark	1948	only	-	Aug	 8	 2:00s	0	-
-#
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Europe/Copenhagen	 0:50:20 -	LMT	1890
-			 0:50:20 -	CMT	1894 Jan  1 # Copenhagen MT
-			 1:00	Denmark	CE%sT	1942 Nov  2  2:00s
-			 1:00	C-Eur	CE%sT	1945 Apr  2  2:00
-			 1:00	Denmark	CE%sT	1980
-			 1:00	EU	CE%sT
 Zone Atlantic/Faroe	-0:27:04 -	LMT	1908 Jan 11 # Tórshavn
 			 0:00	-	WET	1981
 			 0:00	EU	WE%sT
@@ -1621,62 +1569,7 @@ Zone	Europe/Budapest	1:16:20 -	LMT	1890 Nov  1
 			1:00	EU	CE%sT
 
 # Iceland
-#
-# From Adam David (1993-11-06):
-# The name of the timezone in Iceland for system / mail / news purposes is GMT.
-#
-# (1993-12-05):
-# This material is paraphrased from the 1988 edition of the University of
-# Iceland Almanak.
-#
-# From January 1st, 1908 the whole of Iceland was standardised at 1 hour
-# behind GMT. Previously, local mean solar time was used in different parts
-# of Iceland, the almanak had been based on Reykjavík mean solar time which
-# was 1 hour and 28 minutes behind GMT.
-#
-# "first day of winter" referred to [below] means the first day of the 26 weeks
-# of winter, according to the old icelandic calendar that dates back to the
-# time the norsemen first settled Iceland.  The first day of winter is always
-# Saturday, but is not dependent on the Julian or Gregorian calendars.
-#
-# (1993-12-10):
-# I have a reference from the Oxford Icelandic-English dictionary for the
-# beginning of winter, which ties it to the ecclesiastical calendar (and thus
-# to the julian/gregorian calendar) over the period in question.
-#	the winter begins on the Saturday next before St. Luke's day
-#	(old style), or on St. Luke's day, if a Saturday.
-# St. Luke's day ought to be traceable from ecclesiastical sources. "old style"
-# might be a reference to the Julian calendar as opposed to Gregorian, or it
-# might mean something else (???).
-#
-# From Paul Eggert (2014-11-22):
-# The information below is taken from the 1988 Almanak; see
-# http://www.almanak.hi.is/klukkan.html
-#
-# Rule	NAME	FROM	TO	-	IN	ON	AT	SAVE	LETTER/S
-Rule	Iceland	1917	1919	-	Feb	19	23:00	1:00	-
-Rule	Iceland	1917	only	-	Oct	21	 1:00	0	-
-Rule	Iceland	1918	1919	-	Nov	16	 1:00	0	-
-Rule	Iceland	1921	only	-	Mar	19	23:00	1:00	-
-Rule	Iceland	1921	only	-	Jun	23	 1:00	0	-
-Rule	Iceland	1939	only	-	Apr	29	23:00	1:00	-
-Rule	Iceland	1939	only	-	Oct	29	 2:00	0	-
-Rule	Iceland	1940	only	-	Feb	25	 2:00	1:00	-
-Rule	Iceland	1940	1941	-	Nov	Sun>=2	 1:00s	0	-
-Rule	Iceland	1941	1942	-	Mar	Sun>=2	 1:00s	1:00	-
-# 1943-1946 - first Sunday in March until first Sunday in winter
-Rule	Iceland	1943	1946	-	Mar	Sun>=1	 1:00s	1:00	-
-Rule	Iceland	1942	1948	-	Oct	Sun>=22	 1:00s	0	-
-# 1947-1967 - first Sunday in April until first Sunday in winter
-Rule	Iceland	1947	1967	-	Apr	Sun>=1	 1:00s	1:00	-
-# 1949 and 1967 Oct transitions delayed by 1 week
-Rule	Iceland	1949	only	-	Oct	30	 1:00s	0	-
-Rule	Iceland	1950	1966	-	Oct	Sun>=22	 1:00s	0	-
-Rule	Iceland	1967	only	-	Oct	29	 1:00s	0	-
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Atlantic/Reykjavik	-1:28	-	LMT	1908
-			-1:00	Iceland	-01/+00	1968 Apr  7  1:00s
-			 0:00	-	GMT
+# See Etc/GMT.
 
 # Italy
 #
@@ -1947,40 +1840,7 @@ Zone	Europe/Vilnius	1:41:16	-	LMT	1880
 			2:00	EU	EE%sT
 
 # Luxembourg
-# Whitman disagrees with most of these dates in minor ways;
-# go with Shanks & Pottenger.
-# Rule	NAME	FROM	TO	-	IN	ON	AT	SAVE	LETTER/S
-Rule	Lux	1916	only	-	May	14	23:00	1:00	S
-Rule	Lux	1916	only	-	Oct	 1	 1:00	0	-
-Rule	Lux	1917	only	-	Apr	28	23:00	1:00	S
-Rule	Lux	1917	only	-	Sep	17	 1:00	0	-
-Rule	Lux	1918	only	-	Apr	Mon>=15	 2:00s	1:00	S
-Rule	Lux	1918	only	-	Sep	Mon>=15	 2:00s	0	-
-Rule	Lux	1919	only	-	Mar	 1	23:00	1:00	S
-Rule	Lux	1919	only	-	Oct	 5	 3:00	0	-
-Rule	Lux	1920	only	-	Feb	14	23:00	1:00	S
-Rule	Lux	1920	only	-	Oct	24	 2:00	0	-
-Rule	Lux	1921	only	-	Mar	14	23:00	1:00	S
-Rule	Lux	1921	only	-	Oct	26	 2:00	0	-
-Rule	Lux	1922	only	-	Mar	25	23:00	1:00	S
-Rule	Lux	1922	only	-	Oct	Sun>=2	 1:00	0	-
-Rule	Lux	1923	only	-	Apr	21	23:00	1:00	S
-Rule	Lux	1923	only	-	Oct	Sun>=2	 2:00	0	-
-Rule	Lux	1924	only	-	Mar	29	23:00	1:00	S
-Rule	Lux	1924	1928	-	Oct	Sun>=2	 1:00	0	-
-Rule	Lux	1925	only	-	Apr	 5	23:00	1:00	S
-Rule	Lux	1926	only	-	Apr	17	23:00	1:00	S
-Rule	Lux	1927	only	-	Apr	 9	23:00	1:00	S
-Rule	Lux	1928	only	-	Apr	14	23:00	1:00	S
-Rule	Lux	1929	only	-	Apr	20	23:00	1:00	S
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Europe/Luxembourg	0:24:36 -	LMT	1904 Jun
-			1:00	Lux	CE%sT	1918 Nov 25
-			0:00	Lux	WE%sT	1929 Oct  6  2:00s
-			0:00	Belgium	WE%sT	1940 May 14  3:00
-			1:00	C-Eur	WE%sT	1944 Sep 18  3:00
-			1:00	Belgium	CE%sT	1977
-			1:00	EU	CE%sT
+# See Europe/Brussels.
 
 # North Macedonia
 # See Europe/Belgrade.
@@ -2081,122 +1941,16 @@ Zone	Europe/Chisinau	1:55:20 -	LMT	1880
 			2:00	Moldova	EE%sT
 
 # Monaco
-#
-# From Michael Deckers (2020-06-12):
-# In the "Journal de Monaco" of 1892-05-24, online at
-# https://journaldemonaco.gouv.mc/var/jdm/storage/original/application/b1c67c12c5af11b41ea888fb048e4fe8.pdf
-# we read: ...
-#  [In virtue of a Sovereign Ordinance of the May 13 of the current [year],
-#   legal time in the Principality will be set to, from the date of June 1,
-#   1892 onwards, to the meridian of Paris, as in France.]
-# In the "Journal de Monaco" of 1911-03-28, online at
-# https://journaldemonaco.gouv.mc/var/jdm/storage/original/application/de74ffb7db53d4f599059fe8f0ed482a.pdf
-# we read an ordinance of 1911-03-16: ...
-#  [Legal time in the Principality will be set, from the date of promulgation
-#   of the present ordinance, to legal time in France....  Consequently, legal
-#   time will be retarded by 9 minutes and 21 seconds.]
-#
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Europe/Monaco	0:29:32 -	LMT	1892 Jun  1
-			0:09:21	-	PMT	1911 Mar 29 # Paris Mean Time
-			0:00	France	WE%sT	1945 Sep 16  3:00
-			1:00	France	CE%sT	1977
-			1:00	EU	CE%sT
+# See Europe/Paris.
 
 # Montenegro
 # See Europe/Belgrade.
 
 # Netherlands
-
-# Howse writes that the Netherlands' railways used GMT between 1892 and 1940,
-# but for other purposes the Netherlands used Amsterdam mean time.
-
-# However, Robert H. van Gent writes (2001-04-01):
-# Howse's statement is only correct up to 1909. From 1909-05-01 (00:00:00
-# Amsterdam mean time) onwards, the whole of the Netherlands (including
-# the Dutch railways) was required by law to observe Amsterdam mean time
-# (19 minutes 32.13 seconds ahead of GMT). This had already been the
-# common practice (except for the railways) for many decades but it was
-# not until 1909 when the Dutch government finally defined this by law.
-# On 1937-07-01 this was changed to 20 minutes (exactly) ahead of GMT and
-# was generally known as Dutch Time ("Nederlandse Tijd").
-#
-# (2001-04-08):
-# 1892-05-01 was the date when the Dutch railways were by law required to
-# observe GMT while the remainder of the Netherlands adhered to the common
-# practice of following Amsterdam mean time.
-#
-# (2001-04-09):
-# In 1835 the authorities of the province of North Holland requested the
-# municipal authorities of the towns and cities in the province to observe
-# Amsterdam mean time but I do not know in how many cases this request was
-# actually followed.
-#
-# From 1852 onwards the Dutch telegraph offices were by law required to
-# observe Amsterdam mean time. As the time signals from the observatory of
-# Leiden were also distributed by the telegraph system, I assume that most
-# places linked up with the telegraph (and railway) system automatically
-# adopted Amsterdam mean time.
-#
-# Although the early Dutch railway companies initially observed a variety
-# of times, most of them had adopted Amsterdam mean time by 1858 but it
-# was not until 1866 when they were all required by law to observe
-# Amsterdam mean time.
-
-# The data entries before 1945 are taken from
-# https://www.staff.science.uu.nl/~gent0113/wettijd/wettijd.htm
-
-# Rule	NAME	FROM	TO	-	IN	ON	AT	SAVE	LETTER/S
-Rule	Neth	1916	only	-	May	 1	0:00	1:00	NST	# Netherlands Summer Time
-Rule	Neth	1916	only	-	Oct	 1	0:00	0	AMT	# Amsterdam Mean Time
-Rule	Neth	1917	only	-	Apr	16	2:00s	1:00	NST
-Rule	Neth	1917	only	-	Sep	17	2:00s	0	AMT
-Rule	Neth	1918	1921	-	Apr	Mon>=1	2:00s	1:00	NST
-Rule	Neth	1918	1921	-	Sep	lastMon	2:00s	0	AMT
-Rule	Neth	1922	only	-	Mar	lastSun	2:00s	1:00	NST
-Rule	Neth	1922	1936	-	Oct	Sun>=2	2:00s	0	AMT
-Rule	Neth	1923	only	-	Jun	Fri>=1	2:00s	1:00	NST
-Rule	Neth	1924	only	-	Mar	lastSun	2:00s	1:00	NST
-Rule	Neth	1925	only	-	Jun	Fri>=1	2:00s	1:00	NST
-# From 1926 through 1939 DST began 05-15, except that it was delayed by a week
-# in years when 05-15 fell in the Pentecost weekend.
-Rule	Neth	1926	1931	-	May	15	2:00s	1:00	NST
-Rule	Neth	1932	only	-	May	22	2:00s	1:00	NST
-Rule	Neth	1933	1936	-	May	15	2:00s	1:00	NST
-Rule	Neth	1937	only	-	May	22	2:00s	1:00	NST
-Rule	Neth	1937	only	-	Jul	 1	0:00	1:00	S
-Rule	Neth	1937	1939	-	Oct	Sun>=2	2:00s	0	-
-Rule	Neth	1938	1939	-	May	15	2:00s	1:00	S
-Rule	Neth	1945	only	-	Apr	 2	2:00s	1:00	S
-Rule	Neth	1945	only	-	Sep	16	2:00s	0	-
-#
-# Amsterdam Mean Time was +00:19:32.13, but the .13 is omitted
-# below because the current format requires STDOFF to be an integer.
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Europe/Amsterdam	0:19:32 -	LMT	1835
-			0:19:32	Neth	%s	1937 Jul  1
-			0:20	Neth +0020/+0120 1940 May 16  0:00
-			1:00	C-Eur	CE%sT	1945 Apr  2  2:00
-			1:00	Neth	CE%sT	1977
-			1:00	EU	CE%sT
+# See Europe/Brussels.
 
 # Norway
-# http://met.no/met/met_lex/q_u/sommertid.html (2004-01) agrees with Shanks &
-# Pottenger.
-# Rule	NAME	FROM	TO	-	IN	ON	AT	SAVE	LETTER/S
-Rule	Norway	1916	only	-	May	22	1:00	1:00	S
-Rule	Norway	1916	only	-	Sep	30	0:00	0	-
-Rule	Norway	1945	only	-	Apr	 2	2:00s	1:00	S
-Rule	Norway	1945	only	-	Oct	 1	2:00s	0	-
-Rule	Norway	1959	1964	-	Mar	Sun>=15	2:00s	1:00	S
-Rule	Norway	1959	1965	-	Sep	Sun>=15	2:00s	0	-
-Rule	Norway	1965	only	-	Apr	25	2:00s	1:00	S
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Europe/Oslo	0:43:00 -	LMT	1895 Jan  1
-			1:00	Norway	CE%sT	1940 Aug 10 23:00
-			1:00	C-Eur	CE%sT	1945 Apr  2  2:00
-			1:00	Norway	CE%sT	1980
-			1:00	EU	CE%sT
+# See Europe/Berlin.
 
 # Svalbard & Jan Mayen
 
@@ -2243,7 +1997,7 @@ Zone	Europe/Oslo	0:43:00 -	LMT	1895 Jan  1
 # the German armed forces at the Svalbard weather station code-named
 # Haudegen did not surrender to the Allies until September 1945.
 #
-# All these events predate our cutoff date of 1970, so use Europe/Oslo
+# All these events predate our cutoff date of 1970, so use Europe/Berlin
 # for these regions.
 
 
@@ -3627,58 +3381,7 @@ Zone	Atlantic/Canary	-1:01:36 -	LMT	1922 Mar # Las Palmas de Gran C.
 # Ignore this for now, as the Canaries are part of the EU.
 
 # Sweden
-
-# From Ivan Nilsson (2001-04-13), superseding Shanks & Pottenger:
-#
-# The law "Svensk författningssamling 1878, no 14" about standard time in 1879:
-# From the beginning of 1879 (that is 01-01 00:00) the time for all
-# places in the country is "the mean solar time for the meridian at
-# three degrees, or twelve minutes of time, to the west of the
-# meridian of the Observatory of Stockholm".  The law is dated 1878-05-31.
-#
-# The observatory at that time had the meridian 18° 03' 30"
-# eastern longitude = 01:12:14 in time.  Less 12 minutes gives the
-# national standard time as 01:00:14 ahead of GMT....
-#
-# About the beginning of CET in Sweden. The lawtext ("Svensk
-# författningssamling 1899, no 44") states, that "from the beginning
-# of 1900... ... the same as the mean solar time for the meridian at
-# the distance of one hour of time from the meridian of the English
-# observatory at Greenwich, or at 12 minutes 14 seconds to the west
-# from the meridian of the Observatory of Stockholm". The law is dated
-# 1899-06-16.  In short: At 1900-01-01 00:00:00 the new standard time
-# in Sweden is 01:00:00 ahead of GMT.
-#
-# 1916: The lawtext ("Svensk författningssamling 1916, no 124") states
-# that "1916-05-15 is considered to begin one hour earlier". It is
-# pretty obvious that at 05-14 23:00 the clocks are set to 05-15 00:00....
-# Further the law says, that "1916-09-30 is considered to end one hour later".
-#
-# The laws regulating [DST] are available on the site of the Swedish
-# Parliament beginning with 1985 - the laws regulating 1980/1984 are
-# not available on the site (to my knowledge they are only available
-# in Swedish): <http://www.riksdagen.se/english/work/sfst.asp> (type
-# "sommartid" without the quotes in the field "Fritext" and then click
-# the Sök-button).
-#
-# (2001-05-13):
-#
-# I have now found a newspaper stating that at 1916-10-01 01:00
-# summertime the church-clocks etc were set back one hour to show
-# 1916-10-01 00:00 standard time.  The article also reports that some
-# people thought the switch to standard time would take place already
-# at 1916-10-01 00:00 summer time, but they had to wait for another
-# hour before the event took place.
-#
-# Source: The newspaper "Dagens Nyheter", 1916-10-01, page 7 upper left.
-
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Europe/Stockholm	1:12:12 -	LMT	1879 Jan  1
-			1:00:14	-	SET	1900 Jan  1 # Swedish Time
-			1:00	-	CET	1916 May 14 23:00
-			1:00	1:00	CEST	1916 Oct  1  1:00
-			1:00	-	CET	1980
-			1:00	EU	CE%sT
+# See Europe/Berlin.
 
 # Switzerland
 # From Howse:

northamerica

@@ -1593,24 +1593,7 @@ Zone America/Moncton	-4:19:08 -	LMT	1883 Dec  9
 # From Paul Eggert (2020-01-10):
 # See America/Toronto for most of Quebec, including Montreal.
 # See America/Halifax for the Îles de la Madeleine and the Listuguj reserve.
-#
-# Matthews and Vincent (1998) also write that Quebec east of the -63
-# meridian is supposed to observe AST, but residents as far east as
-# Natashquan use EST/EDT, and residents east of Natashquan use AST.
-# The Quebec department of justice writes in
-# "The situation in Minganie and Basse-Côte-Nord"
-# https://www.justice.gouv.qc.ca/en/department/ministre/functions-and-responsabilities/legal-time-in-quebec/the-situation-in-minganie-and-basse-cote-nord/
-# that the coastal strip from just east of Natashquan to Blanc-Sablon
-# observes Atlantic standard time all year round.
-# This common practice was codified into law as of 2007; see Legal Time Act,
-# CQLR c T-5.1 <http://legisquebec.gouv.qc.ca/en/ShowDoc/cs/T-5.1>.
-# For lack of better info, guess this practice began around 1970, contra to
-# Shanks & Pottenger who have this region observing AST/ADT.
-
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone America/Blanc-Sablon -3:48:28 -	LMT	1884
-			-4:00	Canada	A%sT	1970
-			-4:00	-	AST
+# See America/Puerto_Rico for east of Natashquan.
 
 # Ontario
 
@@ -1649,54 +1632,6 @@ Zone America/Blanc-Sablon -3:48:28 -	LMT	1884
 # time became a comic failure in Orillia. Toronto Star 2017-07-08.
 # https://www.thestar.com/news/insight/2017/07/08/bold-attempt-at-daylight-saving-time-became-a-comic-failure-in-orillia.html
 
-# From Paul Eggert (1997-10-17):
-# Mark Brader writes that an article in the 1997-10-14 Toronto Star
-# says that Atikokan, Ontario currently does not observe DST,
-# but will vote on 11-10 whether to use EST/EDT.
-# He also writes that the Ontario Time Act (1990, Chapter T.9)
-# http://www.gov.on.ca/MBS/english/publications/statregs/conttext.html
-# says that Ontario east of 90W uses EST/EDT, and west of 90W uses CST/CDT.
-# Officially Atikokan is therefore on CST/CDT, and most likely this report
-# concerns a non-official time observed as a matter of local practice.
-#
-# From Paul Eggert (2000-10-02):
-# Matthews and Vincent (1998) write that Atikokan, Pickle Lake, and
-# New Osnaburgh observe CST all year, that Big Trout Lake observes
-# CST/CDT, and that Upsala and Shebandowan observe EST/EDT, all in
-# violation of the official Ontario rules.
-#
-# From Paul Eggert (2006-07-09):
-# Chris Walton (2006-07-06) mentioned an article by Stephanie MacLellan in the
-# 2005-07-21 Chronicle-Journal, which said:
-#
-#	The clocks in Atikokan stay set on standard time year-round.
-#	This means they spend about half the time on central time and
-#	the other half on eastern time.
-#
-#	For the most part, the system works, Mayor Dennis Brown said.
-#
-#	"The majority of businesses in Atikokan deal more with Eastern
-#	Canada, but there are some that deal with Western Canada," he
-#	said.  "I don't see any changes happening here."
-#
-# Walton also writes "Supposedly Pickle Lake and Mishkeegogamang
-# [New Osnaburgh] follow the same practice."
-
-# From Garry McKinnon (2006-07-14) via Chris Walton:
-# I chatted with a member of my board who has an outstanding memory
-# and a long history in Atikokan (and in the telecom industry) and he
-# can say for certain that Atikokan has been practicing the current
-# time keeping since 1952, at least.
-
-# From Paul Eggert (2006-07-17):
-# Shanks & Pottenger say that Atikokan has agreed with Rainy River
-# ever since standard time was introduced, but the information from
-# McKinnon sounds more authoritative.  For now, assume that Atikokan
-# switched to EST immediately after WWII era daylight saving time
-# ended.  This matches the old (less-populous) America/Coral_Harbour
-# entry since our cutoff date of 1970, so we can move
-# America/Coral_Harbour to the 'backward' file.
-
 # From Mark Brader (2010-03-06):
 #
 # Currently the database has:
@@ -1842,11 +1777,7 @@ Zone America/Rainy_River -6:18:16 -	LMT	1895
 			-6:00	Canada	C%sT	1940 Sep 29
 			-6:00	1:00	CDT	1942 Feb  9  2:00s
 			-6:00	Canada	C%sT
-Zone America/Atikokan	-6:06:28 -	LMT	1895
-			-6:00	Canada	C%sT	1940 Sep 29
-			-6:00	1:00	CDT	1942 Feb  9  2:00s
-			-6:00	Canada	C%sT	1945 Sep 30  2:00
-			-5:00	-	EST
+# For Atikokan see America/Panama.
 
 
 # Manitoba
@@ -2037,60 +1968,6 @@ Zone America/Edmonton	-7:33:52 -	LMT	1906 Sep
 # Shanks & Pottenger write that since 1970 most of this region has
 # been like Vancouver.
 # Dawson Creek uses MST.  Much of east BC is like Edmonton.
-# Matthews and Vincent (1998) write that Creston is like Dawson Creek.
-
-# It seems though that (re: Creston) is not entirely correct:
-
-# From Chris Walton (2011-12-01):
-# There are two areas within the Canadian province of British Columbia
-# that do not currently observe daylight saving:
-# a) The Creston Valley (includes the town of Creston and surrounding area)
-# b) The eastern half of the Peace River Regional District
-# (includes the cities of Dawson Creek and Fort St. John)
-
-# Earlier this year I stumbled across a detailed article about the time
-# keeping history of Creston; it was written by Tammy Hardwick who is the
-# manager of the Creston & District Museum. The article was written in May 2009.
-# http://www.ilovecreston.com/?p=articles&t=spec&ar=260
-# According to the article, Creston has not changed its clocks since June 1918.
-# i.e. Creston has been stuck on UT-7 for 93 years.
-# Dawson Creek, on the other hand, changed its clocks as recently as April 1972.
-
-# Unfortunately the exact date for the time change in June 1918 remains
-# unknown and will be difficult to ascertain.  I e-mailed Tammy a few months
-# ago to ask if Sunday June 2 was a reasonable guess.  She said it was just
-# as plausible as any other date (in June).  She also said that after writing
-# the article she had discovered another time change in 1916; this is the
-# subject of another article which she wrote in October 2010.
-# http://www.creston.museum.bc.ca/index.php?module=comments&uop=view_comment&cm+id=56
-
-# Here is a summary of the three clock change events in Creston's history:
-# 1. 1884 or 1885: adoption of Mountain Standard Time (GMT-7)
-# Exact date unknown
-# 2. Oct 1916: switch to Pacific Standard Time (GMT-8)
-# Exact date in October unknown; Sunday October 1 is a reasonable guess.
-# 3. June 1918: switch to Pacific Daylight Time (GMT-7)
-# Exact date in June unknown; Sunday June 2 is a reasonable guess.
-# note 1:
-# On Oct 27/1918 when daylight saving ended in the rest of Canada,
-# Creston did not change its clocks.
-# note 2:
-# During WWII when the Federal Government legislated a mandatory clock change,
-# Creston did not oblige.
-# note 3:
-# There is no guarantee that Creston will remain on Mountain Standard Time
-# (UTC-7) forever.
-# The subject was debated at least once this year by the town Council.
-# http://www.bclocalnews.com/kootenay_rockies/crestonvalleyadvance/news/116760809.html
-
-# During a period WWII, summer time (Daylight saying) was mandatory in Canada.
-# In Creston, that was handled by shifting the area to PST (-8:00) then applying
-# summer time to cause the offset to be -7:00, the same as it had been before
-# the change.  It can be argued that the timezone abbreviation during this
-# period should be PDT rather than MST, but that doesn't seem important enough
-# (to anyone) to further complicate the rules.
-
-# The transition dates (and times) are guesses.
 
 # From Matt Johnson (2015-09-21):
 # Fort Nelson, BC, Canada will cancel DST this year.  So while previously they
@@ -2144,10 +2021,7 @@ Zone America/Fort_Nelson	-8:10:47 -	LMT	1884
 			-8:00	Vanc	P%sT	1987
 			-8:00	Canada	P%sT	2015 Mar  8  2:00
 			-7:00	-	MST
-Zone America/Creston	-7:46:04 -	LMT	1884
-			-7:00	-	MST	1916 Oct 1
-			-8:00	-	PST	1918 Jun 2
-			-7:00	-	MST
+# For Creston see America/Phoenix.
 
 # Northwest Territories, Nunavut, Yukon
 
@@ -2929,50 +2803,11 @@ Zone America/Tijuana	-7:48:04 -	LMT	1922 Jan  1  0:11:56
 
 # Anguilla
 # Antigua and Barbuda
-# See America/Port_of_Spain.
+# See America/Puerto_Rico.
 
 # The Bahamas
-#
-# For 1899 Milne gives -5:09:29.5; round that.
-#
-# From P Chan (2020-11-27, corrected on 2020-12-02):
-# There were two periods of DST observed in 1942-1945: 1942-05-01
-# midnight to 1944-12-31 midnight and 1945-02-01 to 1945-10-17 midnight.
-# "midnight" should mean 24:00 from the context.
-#
-# War Time Order 1942 [1942-05-01] and War Time (No. 2) Order 1942  [1942-09-29]
-# Appendix to the Statutes of 7 George VI. and the Year 1942. p 34, 43
-# https://books.google.com/books?id=5rlNAQAAIAAJ&pg=RA3-PA34
-# https://books.google.com/books?id=5rlNAQAAIAAJ&pg=RA3-PA43
-#
-# War Time Order 1943 [1943-03-31] and War Time Order 1944 [1943-12-29]
-# Appendix to the Statutes of 8 George VI. and the Year 1943. p 9-10, 28-29
-# https://books.google.com/books?id=5rlNAQAAIAAJ&pg=RA4-PA9
-# https://books.google.com/books?id=5rlNAQAAIAAJ&pg=RA4-PA28
-#
-# War Time Order 1945 [1945-01-31] and the Order which revoke War Time Order
-# 1945 [1945-10-16] Appendix to the Statutes of 9 George VI. and the Year
-# 1945. p 160, 247-248
-# https://books.google.com/books?id=5rlNAQAAIAAJ&pg=RA6-PA160
-# https://books.google.com/books?id=5rlNAQAAIAAJ&pg=RA6-PA247
-#
-# From Sue Williams (2006-12-07):
-# The Bahamas announced about a month ago that they plan to change their DST
-# rules to sync with the U.S. starting in 2007....
-# http://www.jonesbahamas.com/?c=45&a=10412
+# See America/Montreal.
 
-# Rule	NAME	FROM	TO	-	IN	ON	AT	SAVE	LETTER/S
-Rule	Bahamas	1942	only	-	May	 1	24:00	1:00	W
-Rule	Bahamas	1944	only	-	Dec	31	24:00	0	S
-Rule	Bahamas	1945	only	-	Feb	 1	0:00	1:00	W
-Rule	Bahamas	1945	only	-	Aug	14	23:00u	1:00	P # Peace
-Rule	Bahamas	1945	only	-	Oct	17	24:00	0	S
-Rule	Bahamas	1964	1975	-	Oct	lastSun	2:00	0	S
-Rule	Bahamas	1964	1975	-	Apr	lastSun	2:00	1:00	D
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	America/Nassau	-5:09:30 -	LMT	1912 Mar 2
-			-5:00	Bahamas	E%sT	1976
-			-5:00	US	E%sT
 
 # Barbados
 
@@ -3185,7 +3020,7 @@ Zone Atlantic/Bermuda	-4:19:18 -	LMT	1890	# Hamilton
 			-4:00	US	A%sT
 
 # Caribbean Netherlands
-# See America/Curacao.
+# See America/Puerto_Rico.
 
 # Cayman Is
 # See America/Panama.
@@ -3415,7 +3250,7 @@ Zone	America/Havana	-5:29:28 -	LMT	1890
 			-5:00	Cuba	C%sT
 
 # Dominica
-# See America/Port_of_Spain.
+# See America/Puerto_Rico.
 
 # Dominican Republic
 
@@ -3467,7 +3302,7 @@ Zone America/El_Salvador -5:56:48 -	LMT	1921 # San Salvador
 # Guadeloupe
 # St Barthélemy
 # St Martin (French part)
-# See America/Port_of_Spain.
+# See America/Puerto_Rico.
 
 # Guatemala
 #
@@ -3654,7 +3489,7 @@ Zone America/Martinique	-4:04:20 -      LMT	1890        # Fort-de-France
 			-4:00	-	AST
 
 # Montserrat
-# See America/Port_of_Spain.
+# See America/Puerto_Rico.
 
 # Nicaragua
 #
@@ -3737,7 +3572,7 @@ Zone America/Puerto_Rico -4:24:25 -	LMT	1899 Mar 28 12:00 # San Juan
 
 # St Kitts-Nevis
 # St Lucia
-# See America/Port_of_Spain.
+# See America/Puerto_Rico.
 
 # St Pierre and Miquelon
 # There are too many St Pierres elsewhere, so we'll use 'Miquelon'.
@@ -3748,10 +3583,10 @@ Zone America/Miquelon	-3:44:40 -	LMT	1911 May 15 # St Pierre
 			-3:00	Canada	-03/-02
 
 # St Vincent and the Grenadines
-# See America/Port_of_Spain.
+# See America/Puerto_Rico.
 
 # Sint Maarten
-# See America/Curacao.
+# See America/Puerto_Rico.
 
 # Turks and Caicos
 #
@@ -3823,7 +3658,7 @@ Zone America/Grand_Turk	-4:44:32 -	LMT	1890
 
 # British Virgin Is
 # US Virgin Is
-# See America/Port_of_Spain.
+# See America/Puerto_Rico.
 
 
 # Local Variables:

southamerica

@@ -574,14 +574,11 @@ Zone America/Argentina/Ushuaia -4:33:12 - LMT	1894 Oct 31
 			-3:00	-	-03
 
 # Aruba
-# See America/Curacao.
+# See America/Puerto_Rico.
 
 # Bolivia
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	America/La_Paz	-4:32:36 -	LMT	1890
-			-4:32:36 -	CMT	1931 Oct 15 # Calamarca MT
-			-4:32:36 1:00	BST	1932 Mar 21 # Bolivia ST
-			-4:00	-	-04
+# See Etc/GMT+4.
+
 
 # Brazil
 
@@ -1369,33 +1366,12 @@ Zone	America/Bogota	-4:56:16 -	LMT	1884 Mar 13
 # no information; probably like America/Bogota
 
 # Curaçao
-
-# Milne gives 4:35:46.9 for Curaçao mean time; round to nearest.
+# See America/Puerto_Rico.
 #
-# From Paul Eggert (2006-03-22):
-# Shanks & Pottenger say that The Bottom and Philipsburg have been at
-# -4:00 since standard time was introduced on 1912-03-02; and that
-# Kralendijk and Rincon used Kralendijk Mean Time (-4:33:08) from
-# 1912-02-02 to 1965-01-01.  The former is dubious, since S&P also say
-# Saba Island has been like Curaçao.
-# This all predates our 1970 cutoff, though.
-#
-# By July 2007 Curaçao and St Maarten are planned to become
-# associated states within the Netherlands, much like Aruba;
-# Bonaire, Saba and St Eustatius would become directly part of the
-# Netherlands as Kingdom Islands.  This won't affect their time zones
-# though, as far as we know.
-#
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	America/Curacao	-4:35:47 -	LMT	1912 Feb 12 # Willemstad
-			-4:30	-	-0430	1965
-			-4:00	-	AST
-
 # From Arthur David Olson (2011-06-15):
 # use links for places with new iso3166 codes.
 # The name "Lower Prince's Quarter" is both longer than fourteen characters
-# and contains an apostrophe; use "Lower_Princes" below.
-
+# and contains an apostrophe; use "Lower_Princes"....
 # From Paul Eggert (2021-05-06):
 # These backward-compatibility links now are in the 'backward' file.
 
@@ -1534,10 +1510,8 @@ Zone Atlantic/Stanley	-3:51:24 -	LMT	1890
 			-3:00	-	-03
 
 # French Guiana
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone America/Cayenne	-3:29:20 -	LMT	1911 Jul
-			-4:00	-	-04	1967 Oct
-			-3:00	-	-03
+# See Etc/GMT+3.
+
 
 # Guyana
 
@@ -1698,9 +1672,7 @@ Zone	America/Lima	-5:08:12 -	LMT	1890
 			-5:00	Peru	-05/-04
 
 # South Georgia
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Atlantic/South_Georgia -2:26:08 -	LMT	1890 # Grytviken
-			-2:00	-	-02
+# See Etc/GMT+2.
 
 # South Sandwich Is
 # uninhabited; scientific personnel have wintered
@@ -1714,9 +1686,7 @@ Zone America/Paramaribo	-3:40:40 -	LMT	1911
 			-3:00	-	-03
 
 # Trinidad and Tobago
-# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone America/Port_of_Spain -4:06:04 -	LMT	1912 Mar 2
-			-4:00	-	AST
+# See America/Puerto_Rico.
 
 # Uruguay
 # From Paul Eggert (1993-11-18):

theory.html

@@ -192,8 +192,8 @@ in decreasing order of importance:
     <code>TZ</code> strings</a>.
     A file name component must not exceed 14 characters or start with
     '<code>-</code>'.
-    E.g., prefer <code>Asia/Brunei</code> to
-    <code>Asia/Bandar_Seri_Begawan</code>.
+    E.g., prefer <code>America/Noronha</code> to
+    <code>America/Fernando_de_Noronha</code>.
     Exceptions: see the discussion of legacy names below.
   </li>
   <li>
@@ -475,10 +475,10 @@ in decreasing order of importance:
 
     <p>
     <small>These abbreviations are:
-      AMT Amsterdam, Asunción, Athens;
-      BMT Baghdad, Bangkok, Batavia, Bermuda, Bern, Bogotá, Bridgetown,
+      AMT Asunción, Athens;
+      BMT Baghdad, Batavia, Bermuda, Bern, Bogotá, Bridgetown,
         Brussels, Bucharest;
-      CMT Calamarca, Caracas, Chisinau, Colón, Copenhagen, Córdoba;
+      CMT Calamarca, Caracas, Chisinau, Colón, Córdoba;
       DMT Dublin/Dunsink;
       EMT Easter;
       FFMT Fort-de-France;
@@ -493,7 +493,6 @@ in decreasing order of importance:
 	Moratuwa, Moscow;
       PLMT Phù Liễn;
       PMT Paramaribo, Paris, Perm, Pontianak, Prague;
-      PMMT Port Moresby;
       QMT Quito;
       RMT Rangoon, Riga, Rome;
       SDMT Santo Domingo;
@@ -516,9 +515,7 @@ in decreasing order of importance:
 	1880&ndash;1916,
       MMT/MST/MDST for Moscow 1880&ndash;1919, and
       RMT/LST for Riga Mean Time and Latvian Summer time 1880&ndash;1926.
-    An extra-special case is SET for Swedish Time (<em>svensk
-    normaltid</em>) 1879&ndash;1899, 3&deg; west of the Stockholm
-    Observatory.</small>
+    </small>
     </p>
   </li>
   <li>
@@ -705,11 +702,9 @@ href="https://www.dissentmagazine.org/blog/booked-a-global-history-of-time-vanes
   <li>
     Sometimes historical timekeeping was specified more precisely
     than what the <code><abbr>tz</abbr></code> code can handle.
-    For example, from 1909 to 1937 <a
-    href="https://www.staff.science.uu.nl/~gent0113/wettijd/wettijd.htm"
-    hreflang="nl">Netherlands clocks</a> were legally Amsterdam Mean
+    For example, from 1880 to 1916 clocks in Ireland observed Dublin Mean
     Time (estimated to be <abbr>UT</abbr>
-    +00:19:32.13), but the <code><abbr>tz</abbr></code>
+    &minus;00:25:21.1), but the <code><abbr>tz</abbr></code>
     code cannot represent the fractional second.
     In practice these old specifications were rarely if ever
     implemented to subsecond precision.
@@ -759,7 +754,7 @@ href="https://www.dissentmagazine.org/blog/booked-a-global-history-of-time-vanes
     such as that required by POSIX.
     If <abbr>DST</abbr> is not used a different time zone
     can often do the trick; for example, in Kenya a <code>TZ</code> setting
-    like <code>&lt;-03&gt;3</code> or <code>America/Cayenne</code> starts
+    like <code>&lt;-03&gt;3</code> starts
     the day six hours later than <code>Africa/Nairobi</code> does.
   </li>
   <li>
@@ -1240,11 +1235,11 @@ based on guesswork and these guesses may be corrected or improved.
 
 <p>
 Timezone boundaries are not part of the stable interface.
-For example, even though the <samp>Asia/Bangkok</samp> timezone
-currently includes Chang Mai, Hanoi, and Phnom Penh, this is not part
+For example, even though the <samp>Asia/Singapore</samp> timezone
+currently includes peninsular Malaysia as well as Singapore, this is not part
 of the stable interface and the timezone can split at any time.
 If a calendar application records a future event in some location other
-than Bangkok by putting "<samp>Asia/Bangkok</samp>" in the event's record,
+than Singapore by putting "<samp>Asia/Singapore</samp>" in the event's record,
 the application should be robust in the presence of timezone splits
 between now and the future time.
 </p>

zone.tab

@@ -27,23 +27,23 @@
 #country-
 #code	coordinates	TZ			comments
 AD	+4230+00131	Europe/Andorra
-AE	+2518+05518	Asia/Dubai
+AE	+2518+05518	Etc/GMT-4
 AF	+3431+06912	Asia/Kabul
-AG	+1703-06148	America/Port_of_Spain
-AI	+1812-06304	America/Port_of_Spain
+AG	+1703-06148	America/Puerto_Rico
+AI	+1812-06304	America/Puerto_Rico
 AL	+4120+01950	Europe/Tirane
 AM	+4011+04430	Asia/Yerevan
 AO	-0848+01314	Africa/Lagos
 AQ	-7750+16636	Pacific/Auckland	New Zealand time - McMurdo, South Pole
 AQ	-6617+11031	Antarctica/Casey	Casey
 AQ	-6835+07758	Antarctica/Davis	Davis
-AQ	-6640+14001	Antarctica/DumontDUrville	Dumont-d'Urville
+AQ	-6640+14001	Etc/GMT-10	Dumont-d'Urville
 AQ	-6736+06253	Antarctica/Mawson	Mawson
 AQ	-6448-06406	Antarctica/Palmer	Palmer
 AQ	-6734-06808	Antarctica/Rothera	Rothera
-AQ	-690022+0393524	Antarctica/Syowa	Syowa
+AQ	-690022+0393524	Etc/GMT-3	Syowa
 AQ	-720041+0023206	Antarctica/Troll	Troll
-AQ	-7824+10654	Antarctica/Vostok	Vostok
+AQ	-7824+10654	Etc/GMT-6	Vostok
 AR	-3436-05827	America/Argentina/Buenos_Aires	Buenos Aires (BA, CF)
 AR	-3124-06411	America/Argentina/Cordoba	Argentina (most areas: CB, CC, CN, ER, FM, MN, SE, SF)
 AR	-2447-06525	America/Argentina/Salta	Salta (SA, LP, NQ, RN)
@@ -70,23 +70,23 @@ AU	-3455+13835	Australia/Adelaide	South Australia
 AU	-1228+13050	Australia/Darwin	Northern Territory
 AU	-3157+11551	Australia/Perth	Western Australia (most areas)
 AU	-3143+12852	Australia/Eucla	Western Australia (Eucla)
-AW	+1230-06958	America/Curacao
+AW	+1230-06958	America/Puerto_Rico
 AX	+6006+01957	Europe/Helsinki
 AZ	+4023+04951	Asia/Baku
 BA	+4352+01825	Europe/Belgrade
 BB	+1306-05937	America/Barbados
 BD	+2343+09025	Asia/Dhaka
 BE	+5050+00420	Europe/Brussels
-BF	+1222-00131	Africa/Abidjan
+BF	+1222-00131	Etc/GMT
 BG	+4241+02319	Europe/Sofia
 BH	+2623+05035	Asia/Qatar
 BI	-0323+02922	Africa/Maputo
 BJ	+0629+00237	Africa/Lagos
-BL	+1753-06251	America/Port_of_Spain
+BL	+1753-06251	America/Puerto_Rico
 BM	+3217-06446	Atlantic/Bermuda
-BN	+0456+11455	Asia/Brunei
-BO	-1630-06809	America/La_Paz
-BQ	+120903-0681636	America/Curacao
+BN	+0456+11455	Etc/GMT-8
+BO	-1630-06809	Etc/GMT+4
+BQ	+120903-0681636	America/Puerto_Rico
 BR	-0351-03225	America/Noronha	Atlantic islands
 BR	-0127-04829	America/Belem	Para (east); Amapa
 BR	-0343-03830	America/Fortaleza	Brazil (northeast: MA, PI, CE, RN, PB)
@@ -103,7 +103,7 @@ BR	+0249-06040	America/Boa_Vista	Roraima
 BR	-0308-06001	America/Manaus	Amazonas (east)
 BR	-0640-06952	America/Eirunepe	Amazonas (west)
 BR	-0958-06748	America/Rio_Branco	Acre
-BS	+2505-07721	America/Nassau
+BS	+2505-07721	America/Toronto
 BT	+2728+08939	Asia/Thimphu
 BW	-2439+02555	Africa/Maputo
 BY	+5354+02734	Europe/Minsk
@@ -113,13 +113,13 @@ CA	+4439-06336	America/Halifax	Atlantic - NS (most areas); PE
 CA	+4612-05957	America/Glace_Bay	Atlantic - NS (Cape Breton)
 CA	+4606-06447	America/Moncton	Atlantic - New Brunswick
 CA	+5320-06025	America/Goose_Bay	Atlantic - Labrador (most areas)
-CA	+5125-05707	America/Blanc-Sablon	AST - QC (Lower North Shore)
+CA	+5125-05707	America/Puerto_Rico	AST - QC (Lower North Shore)
 CA	+4339-07923	America/Toronto	Eastern - ON, QC (most areas)
 CA	+4901-08816	America/Nipigon	Eastern - ON, QC (no DST 1967-73)
 CA	+4823-08915	America/Thunder_Bay	Eastern - ON (Thunder Bay)
 CA	+6344-06828	America/Iqaluit	Eastern - NU (most east areas)
 CA	+6608-06544	America/Pangnirtung	Eastern - NU (Pangnirtung)
-CA	+484531-0913718	America/Atikokan	EST - ON (Atikokan); NU (Coral H)
+CA	+484531-0913718	America/Panama	EST - ON (Atikokan); NU (Coral H)
 CA	+4953-09709	America/Winnipeg	Central - ON (west); Manitoba
 CA	+4843-09434	America/Rainy_River	Central - ON (Rainy R, Ft Frances)
 CA	+744144-0944945	America/Resolute	Central - NU (Resolute)
@@ -130,40 +130,40 @@ CA	+5333-11328	America/Edmonton	Mountain - AB; BC (E); SK (W)
 CA	+690650-1050310	America/Cambridge_Bay	Mountain - NU (west)
 CA	+6227-11421	America/Yellowknife	Mountain - NT (central)
 CA	+682059-1334300	America/Inuvik	Mountain - NT (west)
-CA	+4906-11631	America/Creston	MST - BC (Creston)
+CA	+4906-11631	America/Phoenix	MST - BC (Creston)
 CA	+5946-12014	America/Dawson_Creek	MST - BC (Dawson Cr, Ft St John)
 CA	+5848-12242	America/Fort_Nelson	MST - BC (Ft Nelson)
 CA	+6043-13503	America/Whitehorse	MST - Yukon (east)
 CA	+6404-13925	America/Dawson	MST - Yukon (west)
 CA	+4916-12307	America/Vancouver	Pacific - BC (most areas)
-CC	-1210+09655	Indian/Cocos
+CC	-1210+09655	Asia/Yangon
 CD	-0418+01518	Africa/Lagos	Dem. Rep. of Congo (west)
 CD	-1140+02728	Africa/Maputo	Dem. Rep. of Congo (east)
 CF	+0422+01835	Africa/Lagos
 CG	-0416+01517	Africa/Lagos
 CH	+4723+00832	Europe/Zurich
-CI	+0519-00402	Africa/Abidjan
+CI	+0519-00402	Etc/GMT
 CK	-2114-15946	Pacific/Rarotonga
 CL	-3327-07040	America/Santiago	Chile (most areas)
 CL	-5309-07055	America/Punta_Arenas	Region of Magallanes
 CL	-2709-10926	Pacific/Easter	Easter Island
 CM	+0403+00942	Africa/Lagos
 CN	+3114+12128	Asia/Shanghai	Beijing Time
-CN	+4348+08735	Asia/Urumqi	Xinjiang Time
+CN	+4348+08735	Etc/GMT-6	Xinjiang Time
 CO	+0436-07405	America/Bogota
 CR	+0956-08405	America/Costa_Rica
 CU	+2308-08222	America/Havana
 CV	+1455-02331	Atlantic/Cape_Verde
-CW	+1211-06900	America/Curacao
-CX	-1025+10543	Indian/Christmas
+CW	+1211-06900	America/Puerto_Rico
+CX	-1025+10543	Etc/GMT-7
 CY	+3510+03322	Asia/Nicosia	Cyprus (most areas)
 CY	+3507+03357	Asia/Famagusta	Northern Cyprus
 CZ	+5005+01426	Europe/Prague
 DE	+5230+01322	Europe/Berlin	Germany (most areas)
 DE	+4742+00841	Europe/Zurich	Swiss time
 DJ	+1136+04309	Africa/Nairobi
-DK	+5540+01235	Europe/Copenhagen
-DM	+1518-06124	America/Port_of_Spain
+DK	+5540+01235	Europe/Berlin
+DM	+1518-06124	America/Puerto_Rico
 DO	+1828-06954	America/Santo_Domingo
 DZ	+3647+00303	Africa/Algiers
 EC	-0210-07950	America/Guayaquil	Ecuador (mainland)
@@ -179,29 +179,29 @@ ET	+0902+03842	Africa/Nairobi
 FI	+6010+02458	Europe/Helsinki
 FJ	-1808+17825	Pacific/Fiji
 FK	-5142-05751	Atlantic/Stanley
-FM	+0725+15147	Pacific/Chuuk	Chuuk/Truk, Yap
-FM	+0658+15813	Pacific/Pohnpei	Pohnpei/Ponape
+FM	+0725+15147	Etc/GMT-10	Chuuk/Truk, Yap
+FM	+0658+15813	Etc/GMT-11	Pohnpei/Ponape
 FM	+0519+16259	Pacific/Kosrae	Kosrae
 FO	+6201-00646	Atlantic/Faroe
 FR	+4852+00220	Europe/Paris
 GA	+0023+00927	Africa/Lagos
 GB	+513030-0000731	Europe/London
-GD	+1203-06145	America/Port_of_Spain
+GD	+1203-06145	America/Puerto_Rico
 GE	+4143+04449	Asia/Tbilisi
-GF	+0456-05220	America/Cayenne
+GF	+0456-05220	Etc/GMT+3
 GG	+492717-0023210	Europe/London
-GH	+0533-00013	Africa/Accra
+GH	+0533-00013	Etc/GMT
 GI	+3608-00521	Europe/Gibraltar
 GL	+6411-05144	America/Nuuk	Greenland (most areas)
 GL	+7646-01840	America/Danmarkshavn	National Park (east coast)
 GL	+7029-02158	America/Scoresbysund	Scoresbysund/Ittoqqortoormiit
 GL	+7634-06847	America/Thule	Thule/Pituffik
-GM	+1328-01639	Africa/Abidjan
-GN	+0931-01343	Africa/Abidjan
-GP	+1614-06132	America/Port_of_Spain
+GM	+1328-01639	Etc/GMT
+GN	+0931-01343	Etc/GMT
+GP	+1614-06132	America/Puerto_Rico
 GQ	+0345+00847	Africa/Lagos
 GR	+3758+02343	Europe/Athens
-GS	-5416-03632	Atlantic/South_Georgia
+GS	-5416-03632	Etc/GMT+2
 GT	+1438-09031	America/Guatemala
 GU	+1328+14445	Pacific/Guam
 GW	+1151-01535	Africa/Bissau
@@ -222,7 +222,7 @@ IN	+2232+08822	Asia/Kolkata
 IO	-0720+07225	Indian/Chagos
 IQ	+3321+04425	Asia/Baghdad
 IR	+3540+05126	Asia/Tehran
-IS	+6409-02151	Atlantic/Reykjavik
+IS	+6409-02151	Etc/GMT
 IT	+4154+01229	Europe/Rome
 JE	+491101-0020624	Europe/London
 JM	+175805-0764736	America/Jamaica
@@ -230,15 +230,15 @@ JO	+3157+03556	Asia/Amman
 JP	+353916+1394441	Asia/Tokyo
 KE	-0117+03649	Africa/Nairobi
 KG	+4254+07436	Asia/Bishkek
-KH	+1133+10455	Asia/Bangkok
-KI	+0125+17300	Pacific/Tarawa	Gilbert Islands
+KH	+1133+10455	Etc/GMT-7
+KI	+0125+17300	Etc/GMT-12	Gilbert Islands
 KI	-0308-17105	Pacific/Enderbury	Phoenix Islands
 KI	+0152-15720	Pacific/Kiritimati	Line Islands
 KM	-1141+04316	Africa/Nairobi
-KN	+1718-06243	America/Port_of_Spain
+KN	+1718-06243	America/Puerto_Rico
 KP	+3901+12545	Asia/Pyongyang
 KR	+3733+12658	Asia/Seoul
-KW	+2920+04759	Asia/Riyadh
+KW	+2920+04759	Etc/GMT-3
 KY	+1918-08123	America/Panama
 KZ	+4315+07657	Asia/Almaty	Kazakhstan (most areas)
 KZ	+4448+06528	Asia/Qyzylorda	Qyzylorda/Kyzylorda/Kzyl-Orda
@@ -247,27 +247,27 @@ KZ	+5017+05710	Asia/Aqtobe	Aqtobe/Aktobe
 KZ	+4431+05016	Asia/Aqtau	Mangghystau/Mankistau
 KZ	+4707+05156	Asia/Atyrau	Atyrau/Atirau/Gur'yev
 KZ	+5113+05121	Asia/Oral	West Kazakhstan
-LA	+1758+10236	Asia/Bangkok
+LA	+1758+10236	Etc/GMT-7
 LB	+3353+03530	Asia/Beirut
-LC	+1401-06100	America/Port_of_Spain
+LC	+1401-06100	America/Puerto_Rico
 LI	+4709+00931	Europe/Zurich
 LK	+0656+07951	Asia/Colombo
 LR	+0618-01047	Africa/Monrovia
 LS	-2928+02730	Africa/Johannesburg
 LT	+5441+02519	Europe/Vilnius
-LU	+4936+00609	Europe/Luxembourg
+LU	+4936+00609	Europe/Brussels
 LV	+5657+02406	Europe/Riga
 LY	+3254+01311	Africa/Tripoli
 MA	+3339-00735	Africa/Casablanca
-MC	+4342+00723	Europe/Monaco
+MC	+4342+00723	Europe/Paris
 MD	+4700+02850	Europe/Chisinau
 ME	+4226+01916	Europe/Belgrade
-MF	+1804-06305	America/Port_of_Spain
+MF	+1804-06305	America/Puerto_Rico
 MG	-1855+04731	Africa/Nairobi
-MH	+0709+17112	Pacific/Majuro	Marshall Islands (most areas)
+MH	+0709+17112	Etc/GMT-12	Marshall Islands (most areas)
 MH	+0905+16720	Pacific/Kwajalein	Kwajalein
 MK	+4159+02126	Europe/Belgrade
-ML	+1239-00800	Africa/Abidjan
+ML	+1239-00800	Etc/GMT
 MM	+1647+09610	Asia/Yangon
 MN	+4755+10653	Asia/Ulaanbaatar	Mongolia (most areas)
 MN	+4801+09139	Asia/Hovd	Bayan-Olgiy, Govi-Altai, Hovd, Uvs, Zavkhan
@@ -275,11 +275,11 @@ MN	+4804+11430	Asia/Choibalsan	Dornod, Sukhbaatar
 MO	+221150+1133230	Asia/Macau
 MP	+1512+14545	Pacific/Guam
 MQ	+1436-06105	America/Martinique
-MR	+1806-01557	Africa/Abidjan
-MS	+1643-06213	America/Port_of_Spain
+MR	+1806-01557	Etc/GMT
+MS	+1643-06213	America/Puerto_Rico
 MT	+3554+01431	Europe/Malta
 MU	-2010+05730	Indian/Mauritius
-MV	+0410+07330	Indian/Maldives
+MV	+0410+07330	Etc/GMT-5
 MW	-1547+03500	Africa/Maputo
 MX	+1924-09909	America/Mexico_City	Central Time
 MX	+2105-08646	America/Cancun	Eastern Standard Time - Quintana Roo
@@ -292,8 +292,8 @@ MX	+2934-10425	America/Ojinaga	Mountain Time US - Chihuahua (US border)
 MX	+2904-11058	America/Hermosillo	Mountain Standard Time - Sonora
 MX	+3232-11701	America/Tijuana	Pacific Time US - Baja California
 MX	+2048-10515	America/Bahia_Banderas	Central Time - Bahia de Banderas
-MY	+0310+10142	Asia/Kuala_Lumpur	Malaysia (peninsula)
-MY	+0133+11020	Asia/Kuching	Sabah, Sarawak
+MY	+0310+10142	Asia/Singapore	Malaysia (peninsula)
+MY	+0133+11020	Etc/GMT-8	Sabah, Sarawak
 MZ	-2558+03235	Africa/Maputo
 NA	-2234+01706	Africa/Windhoek
 NC	-2216+16627	Pacific/Noumea
@@ -301,20 +301,20 @@ NE	+1331+00207	Africa/Lagos
 NF	-2903+16758	Pacific/Norfolk
 NG	+0627+00324	Africa/Lagos
 NI	+1209-08617	America/Managua
-NL	+5222+00454	Europe/Amsterdam
-NO	+5955+01045	Europe/Oslo
+NL	+5222+00454	Europe/Brussels
+NO	+5955+01045	Europe/Berlin
 NP	+2743+08519	Asia/Kathmandu
 NR	-0031+16655	Pacific/Nauru
 NU	-1901-16955	Pacific/Niue
 NZ	-3652+17446	Pacific/Auckland	New Zealand (most areas)
 NZ	-4357-17633	Pacific/Chatham	Chatham Islands
-OM	+2336+05835	Asia/Dubai
+OM	+2336+05835	Etc/GMT-4
 PA	+0858-07932	America/Panama
 PE	-1203-07703	America/Lima
-PF	-1732-14934	Pacific/Tahiti	Society Islands
+PF	-1732-14934	Etc/GMT+10	Society Islands
 PF	-0900-13930	Pacific/Marquesas	Marquesas Islands
-PF	-2308-13457	Pacific/Gambier	Gambier Islands
-PG	-0930+14710	Pacific/Port_Moresby	Papua New Guinea (most areas)
+PF	-2308-13457	Etc/GMT+9	Gambier Islands
+PG	-0930+14710	Etc/GMT-10	Papua New Guinea (most areas)
 PG	-0613+15534	Pacific/Bougainville	Bougainville
 PH	+1435+12100	Asia/Manila
 PK	+2452+06703	Asia/Karachi
@@ -327,10 +327,10 @@ PS	+313200+0350542	Asia/Hebron	West Bank
 PT	+3843-00908	Europe/Lisbon	Portugal (mainland)
 PT	+3238-01654	Atlantic/Madeira	Madeira Islands
 PT	+3744-02540	Atlantic/Azores	Azores
-PW	+0720+13429	Pacific/Palau
+PW	+0720+13429	Etc/GMT-9
 PY	-2516-05740	America/Asuncion
 QA	+2517+05132	Asia/Qatar
-RE	-2052+05528	Indian/Reunion
+RE	-2052+05528	Etc/GMT-4
 RO	+4426+02606	Europe/Bucharest
 RS	+4450+02030	Europe/Belgrade
 RU	+5443+02030	Europe/Kaliningrad	MSK-01 - Kaliningrad
@@ -364,32 +364,32 @@ RU	+6728+15343	Asia/Srednekolymsk	MSK+08 - Sakha (E); North Kuril Is
 RU	+5301+15839	Asia/Kamchatka	MSK+09 - Kamchatka
 RU	+6445+17729	Asia/Anadyr	MSK+09 - Bering Sea
 RW	-0157+03004	Africa/Maputo
-SA	+2438+04643	Asia/Riyadh
-SB	-0932+16012	Pacific/Guadalcanal
-SC	-0440+05528	Indian/Mahe
+SA	+2438+04643	Etc/GMT-3
+SB	-0932+16012	Etc/GMT-11
+SC	-0440+05528	Etc/GMT-4
 SD	+1536+03232	Africa/Khartoum
-SE	+5920+01803	Europe/Stockholm
+SE	+5920+01803	Europe/Berlin
 SG	+0117+10351	Asia/Singapore
-SH	-1555-00542	Africa/Abidjan
+SH	-1555-00542	Etc/GMT
 SI	+4603+01431	Europe/Belgrade
-SJ	+7800+01600	Europe/Oslo
+SJ	+7800+01600	Europe/Berlin
 SK	+4809+01707	Europe/Prague
-SL	+0830-01315	Africa/Abidjan
+SL	+0830-01315	Etc/GMT
 SM	+4355+01228	Europe/Rome
-SN	+1440-01726	Africa/Abidjan
+SN	+1440-01726	Etc/GMT
 SO	+0204+04522	Africa/Nairobi
 SR	+0550-05510	America/Paramaribo
 SS	+0451+03137	Africa/Juba
 ST	+0020+00644	Africa/Sao_Tome
 SV	+1342-08912	America/El_Salvador
-SX	+180305-0630250	America/Curacao
+SX	+180305-0630250	America/Puerto_Rico
 SY	+3330+03618	Asia/Damascus
 SZ	-2618+03106	Africa/Johannesburg
 TC	+2128-07108	America/Grand_Turk
 TD	+1207+01503	Africa/Ndjamena
-TF	-492110+0701303	Indian/Kerguelen
-TG	+0608+00113	Africa/Abidjan
-TH	+1345+10031	Asia/Bangkok
+TF	-492110+0701303	Etc/GMT-5
+TG	+0608+00113	Etc/GMT
+TH	+1345+10031	Etc/GMT-7
 TJ	+3835+06848	Asia/Dushanbe
 TK	-0922-17114	Pacific/Fakaofo
 TL	-0833+12535	Asia/Dili
@@ -397,8 +397,8 @@ TM	+3757+05823	Asia/Ashgabat
 TN	+3648+01011	Africa/Tunis
 TO	-210800-1751200	Pacific/Tongatapu
 TR	+4101+02858	Europe/Istanbul
-TT	+1039-06131	America/Port_of_Spain
-TV	-0831+17913	Pacific/Funafuti
+TT	+1039-06131	America/Puerto_Rico
+TV	-0831+17913	Etc/GMT-12
 TW	+2503+12130	Asia/Taipei
 TZ	-0648+03917	Africa/Nairobi
 UA	+5026+03031	Europe/Kiev	Ukraine (most areas)
@@ -406,7 +406,7 @@ UA	+4837+02218	Europe/Uzhgorod	Transcarpathia
 UA	+4750+03510	Europe/Zaporozhye	Zaporozhye and east Lugansk
 UG	+0019+03225	Africa/Nairobi
 UM	+2813-17722	Pacific/Pago_Pago	Midway Islands
-UM	+1917+16637	Pacific/Wake	Wake Island
+UM	+1917+16637	Etc/GMT-12	Wake Island
 US	+404251-0740023	America/New_York	Eastern (most areas)
 US	+421953-0830245	America/Detroit	Eastern - MI (most areas)
 US	+381515-0854534	America/Kentucky/Louisville	Eastern - KY (Louisville area)
@@ -440,16 +440,16 @@ UY	-345433-0561245	America/Montevideo
 UZ	+3940+06648	Asia/Samarkand	Uzbekistan (west)
 UZ	+4120+06918	Asia/Tashkent	Uzbekistan (east)
 VA	+415408+0122711	Europe/Rome
-VC	+1309-06114	America/Port_of_Spain
+VC	+1309-06114	America/Puerto_Rico
 VE	+1030-06656	America/Caracas
-VG	+1827-06437	America/Port_of_Spain
-VI	+1821-06456	America/Port_of_Spain
-VN	+2102+10551	Asia/Bangkok	Vietnam (north)
+VG	+1827-06437	America/Puerto_Rico
+VI	+1821-06456	America/Puerto_Rico
+VN	+2102+10551	Etc/GMT-7	Vietnam (north)
 VN	+1045+10640	Asia/Ho_Chi_Minh	Vietnam (south)
 VU	-1740+16825	Pacific/Efate
-WF	-1318-17610	Pacific/Wallis
+WF	-1318-17610	Etc/GMT-12
 WS	-1350-17144	Pacific/Apia
-YE	+1245+04512	Asia/Riyadh
+YE	+1245+04512	Etc/GMT-3
 YT	-1247+04514	Africa/Nairobi
 ZA	-2615+02800	Africa/Johannesburg
 ZM	-1525+02817	Africa/Maputo

zone1970.tab

@@ -34,19 +34,18 @@
 #country-
 #codes	coordinates	TZ	comments
 AD	+4230+00131	Europe/Andorra
-AE,OM	+2518+05518	Asia/Dubai
+AE,OM,RE,SC,TF	+2518+05518	Etc/GMT-4	UAE, Oman, Réunion, Seychelles, Crozet, Scattered Is
 AF	+3431+06912	Asia/Kabul
 AL	+4120+01950	Europe/Tirane
 AM	+4011+04430	Asia/Yerevan
 AQ	-6617+11031	Antarctica/Casey	Casey
 AQ	-6835+07758	Antarctica/Davis	Davis
-AQ	-6640+14001	Antarctica/DumontDUrville	Dumont-d'Urville
 AQ	-6736+06253	Antarctica/Mawson	Mawson
 AQ	-6448-06406	Antarctica/Palmer	Palmer
 AQ	-6734-06808	Antarctica/Rothera	Rothera
-AQ	-690022+0393524	Antarctica/Syowa	Syowa
 AQ	-720041+0023206	Antarctica/Troll	Troll
-AQ	-7824+10654	Antarctica/Vostok	Vostok
+AQ,KW,SA,YE	+2438+04643	Etc/GMT-3	Arabia, Syowa
+AQ,FM,PG	-0930+14710	Etc/GMT-10	Papua New Guinea (most areas), Chuuk, Yap, Dumont d'Urville
 AR	-3436-05827	America/Argentina/Buenos_Aires	Buenos Aires (BA, CF)
 AR	-3124-06411	America/Argentina/Cordoba	Argentina (most areas: CB, CC, CN, ER, FM, MN, SE, SF)
 AR	-2447-06525	America/Argentina/Salta	Salta (SA, LP, NQ, RN)
@@ -76,11 +75,12 @@ AU	-3143+12852	Australia/Eucla	Western Australia (Eucla)
 AZ	+4023+04951	Asia/Baku
 BB	+1306-05937	America/Barbados
 BD	+2343+09025	Asia/Dhaka
-BE	+5050+00420	Europe/Brussels
+BE,LU,NL	+5050+00420	Europe/Brussels
+BF,CI,GH,GM,GN,IS,ML,MR,SH,SL,SN,TG	+0519-00402	Etc/GMT
 BG	+4241+02319	Europe/Sofia
 BM	+3217-06446	Atlantic/Bermuda
-BN	+0456+11455	Asia/Brunei
-BO	-1630-06809	America/La_Paz
+BN,MY	+0133+11020	Etc/GMT-8	Sabah, Sarawak, Brunei
+BO	-1630-06809	Etc/GMT+4
 BR	-0351-03225	America/Noronha	Atlantic islands
 BR	-0127-04829	America/Belem	Pará (east); Amapá
 BR	-0343-03830	America/Fortaleza	Brazil (northeast: MA, PI, CE, RN, PB)
@@ -97,7 +97,6 @@ BR	+0249-06040	America/Boa_Vista	Roraima
 BR	-0308-06001	America/Manaus	Amazonas (east)
 BR	-0640-06952	America/Eirunepe	Amazonas (west)
 BR	-0958-06748	America/Rio_Branco	Acre
-BS	+2505-07721	America/Nassau
 BT	+2728+08939	Asia/Thimphu
 BY	+5354+02734	Europe/Minsk
 BZ	+1730-08812	America/Belize
@@ -106,13 +105,11 @@ CA	+4439-06336	America/Halifax	Atlantic - NS (most areas); PE
 CA	+4612-05957	America/Glace_Bay	Atlantic - NS (Cape Breton)
 CA	+4606-06447	America/Moncton	Atlantic - New Brunswick
 CA	+5320-06025	America/Goose_Bay	Atlantic - Labrador (most areas)
-CA	+5125-05707	America/Blanc-Sablon	AST - QC (Lower North Shore)
-CA	+4339-07923	America/Toronto	Eastern - ON, QC (most areas)
+CA,BS	+4339-07923	America/Toronto	Eastern - ON, QC (most areas), Bahamas
 CA	+4901-08816	America/Nipigon	Eastern - ON, QC (no DST 1967-73)
 CA	+4823-08915	America/Thunder_Bay	Eastern - ON (Thunder Bay)
 CA	+6344-06828	America/Iqaluit	Eastern - NU (most east areas)
 CA	+6608-06544	America/Pangnirtung	Eastern - NU (Pangnirtung)
-CA	+484531-0913718	America/Atikokan	EST - ON (Atikokan); NU (Coral H)
 CA	+4953-09709	America/Winnipeg	Central - ON (west); Manitoba
 CA	+4843-09434	America/Rainy_River	Central - ON (Rainy R, Ft Frances)
 CA	+744144-0944945	America/Resolute	Central - NU (Resolute)
@@ -123,32 +120,27 @@ CA	+5333-11328	America/Edmonton	Mountain - AB; BC (E); SK (W)
 CA	+690650-1050310	America/Cambridge_Bay	Mountain - NU (west)
 CA	+6227-11421	America/Yellowknife	Mountain - NT (central)
 CA	+682059-1334300	America/Inuvik	Mountain - NT (west)
-CA	+4906-11631	America/Creston	MST - BC (Creston)
 CA	+5946-12014	America/Dawson_Creek	MST - BC (Dawson Cr, Ft St John)
 CA	+5848-12242	America/Fort_Nelson	MST - BC (Ft Nelson)
 CA	+6043-13503	America/Whitehorse	MST - Yukon (east)
 CA	+6404-13925	America/Dawson	MST - Yukon (west)
 CA	+4916-12307	America/Vancouver	Pacific - BC (most areas)
-CC	-1210+09655	Indian/Cocos
 CH,DE,LI	+4723+00832	Europe/Zurich	Swiss time
-CI,BF,GM,GN,ML,MR,SH,SL,SN,TG	+0519-00402	Africa/Abidjan
 CK	-2114-15946	Pacific/Rarotonga
 CL	-3327-07040	America/Santiago	Chile (most areas)
 CL	-5309-07055	America/Punta_Arenas	Region of Magallanes
 CL	-2709-10926	Pacific/Easter	Easter Island
 CN	+3114+12128	Asia/Shanghai	Beijing Time
-CN	+4348+08735	Asia/Urumqi	Xinjiang Time
+CN,AQ	+4348+08735	Etc/GMT-6	Xinjiang Time, Vostok
 CO	+0436-07405	America/Bogota
 CR	+0956-08405	America/Costa_Rica
 CU	+2308-08222	America/Havana
 CV	+1455-02331	Atlantic/Cape_Verde
-CW,AW,BQ,SX	+1211-06900	America/Curacao
-CX	-1025+10543	Indian/Christmas
+CX,KH,LA,TH,VN	+1345+10031	Etc/GMT-7	Indochina (most areas)
 CY	+3510+03322	Asia/Nicosia	Cyprus (most areas)
 CY	+3507+03357	Asia/Famagusta	Northern Cyprus
 CZ,SK	+5005+01426	Europe/Prague
-DE	+5230+01322	Europe/Berlin	Germany (most areas)
-DK	+5540+01235	Europe/Copenhagen
+DE,DK,NO,SE,SJ	+5230+01322	Europe/Berlin	Germany (most areas), Scandinavia
 DO	+1828-06954	America/Santo_Domingo
 DZ	+3647+00303	Africa/Algiers
 EC	-0210-07950	America/Guayaquil	Ecuador (mainland)
@@ -162,22 +154,19 @@ ES	+2806-01524	Atlantic/Canary	Canary Islands
 FI,AX	+6010+02458	Europe/Helsinki
 FJ	-1808+17825	Pacific/Fiji
 FK	-5142-05751	Atlantic/Stanley
-FM	+0725+15147	Pacific/Chuuk	Chuuk/Truk, Yap
-FM	+0658+15813	Pacific/Pohnpei	Pohnpei/Ponape
 FM	+0519+16259	Pacific/Kosrae	Kosrae
 FO	+6201-00646	Atlantic/Faroe
-FR	+4852+00220	Europe/Paris
+FR,MC	+4852+00220	Europe/Paris
 GB,GG,IM,JE	+513030-0000731	Europe/London
 GE	+4143+04449	Asia/Tbilisi
-GF	+0456-05220	America/Cayenne
-GH	+0533-00013	Africa/Accra
+GF	+0456-05220	Etc/GMT+3
 GI	+3608-00521	Europe/Gibraltar
 GL	+6411-05144	America/Nuuk	Greenland (most areas)
 GL	+7646-01840	America/Danmarkshavn	National Park (east coast)
 GL	+7029-02158	America/Scoresbysund	Scoresbysund/Ittoqqortoormiit
 GL	+7634-06847	America/Thule	Thule/Pituffik
 GR	+3758+02343	Europe/Athens
-GS	-5416-03632	Atlantic/South_Georgia
+GS	-5416-03632	Etc/GMT+2
 GT	+1438-09031	America/Guatemala
 GU,MP	+1328+14445	Pacific/Guam
 GW	+1151-01535	Africa/Bissau
@@ -196,16 +185,15 @@ IN	+2232+08822	Asia/Kolkata
 IO	-0720+07225	Indian/Chagos
 IQ	+3321+04425	Asia/Baghdad
 IR	+3540+05126	Asia/Tehran
-IS	+6409-02151	Atlantic/Reykjavik
 IT,SM,VA	+4154+01229	Europe/Rome
 JM	+175805-0764736	America/Jamaica
 JO	+3157+03556	Asia/Amman
 JP	+353916+1394441	Asia/Tokyo
 KE,DJ,ER,ET,KM,MG,SO,TZ,UG,YT	-0117+03649	Africa/Nairobi
 KG	+4254+07436	Asia/Bishkek
-KI	+0125+17300	Pacific/Tarawa	Gilbert Islands
 KI	-0308-17105	Pacific/Enderbury	Phoenix Islands
 KI	+0152-15720	Pacific/Kiritimati	Line Islands
+KI,MH,TV,UM,WF	+0125+17300	Etc/GMT-12	Gilberts, Marshalls, Tuvalu, Wallis & Futuna, Wake
 KP	+3901+12545	Asia/Pyongyang
 KR	+3733+12658	Asia/Seoul
 KZ	+4315+07657	Asia/Almaty	Kazakhstan (most areas)
@@ -219,15 +207,12 @@ LB	+3353+03530	Asia/Beirut
 LK	+0656+07951	Asia/Colombo
 LR	+0618-01047	Africa/Monrovia
 LT	+5441+02519	Europe/Vilnius
-LU	+4936+00609	Europe/Luxembourg
 LV	+5657+02406	Europe/Riga
 LY	+3254+01311	Africa/Tripoli
 MA	+3339-00735	Africa/Casablanca
-MC	+4342+00723	Europe/Monaco
 MD	+4700+02850	Europe/Chisinau
-MH	+0709+17112	Pacific/Majuro	Marshall Islands (most areas)
 MH	+0905+16720	Pacific/Kwajalein	Kwajalein
-MM	+1647+09610	Asia/Yangon
+MM,CC	+1647+09610	Asia/Yangon
 MN	+4755+10653	Asia/Ulaanbaatar	Mongolia (most areas)
 MN	+4801+09139	Asia/Hovd	Bayan-Ölgii, Govi-Altai, Hovd, Uvs, Zavkhan
 MN	+4804+11430	Asia/Choibalsan	Dornod, Sükhbaatar
@@ -235,7 +220,7 @@ MO	+221150+1133230	Asia/Macau
 MQ	+1436-06105	America/Martinique
 MT	+3554+01431	Europe/Malta
 MU	-2010+05730	Indian/Mauritius
-MV	+0410+07330	Indian/Maldives
+MV,TF	+0410+07330	Etc/GMT-5	Maldives, Kerguelen, St Paul I, Amsterdam I
 MX	+1924-09909	America/Mexico_City	Central Time
 MX	+2105-08646	America/Cancun	Eastern Standard Time - Quintana Roo
 MX	+2058-08937	America/Merida	Central Time - Campeche, Yucatán
@@ -247,43 +232,37 @@ MX	+2934-10425	America/Ojinaga	Mountain Time US - Chihuahua (US border)
 MX	+2904-11058	America/Hermosillo	Mountain Standard Time - Sonora
 MX	+3232-11701	America/Tijuana	Pacific Time US - Baja California
 MX	+2048-10515	America/Bahia_Banderas	Central Time - Bahía de Banderas
-MY	+0310+10142	Asia/Kuala_Lumpur	Malaysia (peninsula)
-MY	+0133+11020	Asia/Kuching	Sabah, Sarawak
 MZ,BI,BW,CD,MW,RW,ZM,ZW	-2558+03235	Africa/Maputo	Central Africa Time
 NA	-2234+01706	Africa/Windhoek
 NC	-2216+16627	Pacific/Noumea
 NF	-2903+16758	Pacific/Norfolk
 NG,AO,BJ,CD,CF,CG,CM,GA,GQ,NE	+0627+00324	Africa/Lagos	West Africa Time
 NI	+1209-08617	America/Managua
-NL	+5222+00454	Europe/Amsterdam
-NO,SJ	+5955+01045	Europe/Oslo
 NP	+2743+08519	Asia/Kathmandu
 NR	-0031+16655	Pacific/Nauru
 NU	-1901-16955	Pacific/Niue
 NZ,AQ	-3652+17446	Pacific/Auckland	New Zealand time
 NZ	-4357-17633	Pacific/Chatham	Chatham Islands
-PA,KY	+0858-07932	America/Panama
+PA,CA,KY	+0858-07932	America/Panama	EST - Panama, Cayman, ON (Atikokan), NU (Coral H)
 PE	-1203-07703	America/Lima
-PF	-1732-14934	Pacific/Tahiti	Society Islands
+PF	-1732-14934	Etc/GMT+10	Society Islands
 PF	-0900-13930	Pacific/Marquesas	Marquesas Islands
-PF	-2308-13457	Pacific/Gambier	Gambier Islands
-PG	-0930+14710	Pacific/Port_Moresby	Papua New Guinea (most areas)
+PF	-2308-13457	Etc/GMT+9	Gambier Islands
 PG	-0613+15534	Pacific/Bougainville	Bougainville
 PH	+1435+12100	Asia/Manila
 PK	+2452+06703	Asia/Karachi
 PL	+5215+02100	Europe/Warsaw
 PM	+4703-05620	America/Miquelon
 PN	-2504-13005	Pacific/Pitcairn
-PR	+182806-0660622	America/Puerto_Rico
+PR,AG,CA,AI,AW,BL,BQ,CW,DM,GD,GP,KN,LC,MF,MS,SX,TT,VC,VG,VI	+182806-0660622	America/Puerto_Rico	AST
 PS	+3130+03428	Asia/Gaza	Gaza Strip
 PS	+313200+0350542	Asia/Hebron	West Bank
 PT	+3843-00908	Europe/Lisbon	Portugal (mainland)
 PT	+3238-01654	Atlantic/Madeira	Madeira Islands
 PT	+3744-02540	Atlantic/Azores	Azores
-PW	+0720+13429	Pacific/Palau
+PW	+0720+13429	Etc/GMT-9
 PY	-2516-05740	America/Asuncion
 QA,BH	+2517+05132	Asia/Qatar
-RE,TF	-2052+05528	Indian/Reunion	Réunion, Crozet, Scattered Islands
 RO	+4426+02606	Europe/Bucharest
 RS,BA,HR,ME,MK,SI	+4450+02030	Europe/Belgrade
 RU	+5443+02030	Europe/Kaliningrad	MSK-01 - Kaliningrad
@@ -314,12 +293,9 @@ RU	+4658+14242	Asia/Sakhalin	MSK+08 - Sakhalin Island
 RU	+6728+15343	Asia/Srednekolymsk	MSK+08 - Sakha (E); North Kuril Is
 RU	+5301+15839	Asia/Kamchatka	MSK+09 - Kamchatka
 RU	+6445+17729	Asia/Anadyr	MSK+09 - Bering Sea
-SA,KW,YE	+2438+04643	Asia/Riyadh
-SB	-0932+16012	Pacific/Guadalcanal
-SC	-0440+05528	Indian/Mahe
+SB,FM	-0932+16012	Etc/GMT-11	Solomons, Pohnpei
 SD	+1536+03232	Africa/Khartoum
-SE	+5920+01803	Europe/Stockholm
-SG	+0117+10351	Asia/Singapore
+SG,MY	+0117+10351	Asia/Singapore	Singapore, peninsular Malaysia
 SR	+0550-05510	America/Paramaribo
 SS	+0451+03137	Africa/Juba
 ST	+0020+00644	Africa/Sao_Tome
@@ -327,8 +303,6 @@ SV	+1342-08912	America/El_Salvador
 SY	+3330+03618	Asia/Damascus
 TC	+2128-07108	America/Grand_Turk
 TD	+1207+01503	Africa/Ndjamena
-TF	-492110+0701303	Indian/Kerguelen	Kerguelen, St Paul Island, Amsterdam Island
-TH,KH,LA,VN	+1345+10031	Asia/Bangkok	Indochina (most areas)
 TJ	+3835+06848	Asia/Dushanbe
 TK	-0922-17114	Pacific/Fakaofo
 TL	-0833+12535	Asia/Dili
@@ -336,13 +310,10 @@ TM	+3757+05823	Asia/Ashgabat
 TN	+3648+01011	Africa/Tunis
 TO	-210800-1751200	Pacific/Tongatapu
 TR	+4101+02858	Europe/Istanbul
-TT,AG,AI,BL,DM,GD,GP,KN,LC,MF,MS,VC,VG,VI	+1039-06131	America/Port_of_Spain
-TV	-0831+17913	Pacific/Funafuti
 TW	+2503+12130	Asia/Taipei
 UA	+5026+03031	Europe/Kiev	Ukraine (most areas)
 UA	+4837+02218	Europe/Uzhgorod	Transcarpathia
 UA	+4750+03510	Europe/Zaporozhye	Zaporozhye and east Lugansk
-UM	+1917+16637	Pacific/Wake	Wake Island
 US	+404251-0740023	America/New_York	Eastern (most areas)
 US	+421953-0830245	America/Detroit	Eastern - MI (most areas)
 US	+381515-0854534	America/Kentucky/Louisville	Eastern - KY (Louisville area)
@@ -362,7 +333,7 @@ US	+465042-1012439	America/North_Dakota/New_Salem	Central - ND (Morton rural)
 US	+471551-1014640	America/North_Dakota/Beulah	Central - ND (Mercer)
 US	+394421-1045903	America/Denver	Mountain (most areas)
 US	+433649-1161209	America/Boise	Mountain - ID (south); OR (east)
-US	+332654-1120424	America/Phoenix	MST - Arizona (except Navajo)
+US,CA	+332654-1120424	America/Phoenix	MST - Arizona (except Navajo), Creston BC
 US	+340308-1181434	America/Los_Angeles	Pacific
 US	+611305-1495401	America/Anchorage	Alaska (most areas)
 US	+581807-1342511	America/Juneau	Alaska - Juneau area
@@ -378,6 +349,5 @@ UZ	+4120+06918	Asia/Tashkent	Uzbekistan (east)
 VE	+1030-06656	America/Caracas
 VN	+1045+10640	Asia/Ho_Chi_Minh	Vietnam (south)
 VU	-1740+16825	Pacific/Efate
-WF	-1318-17610	Pacific/Wallis
 WS	-1350-17144	Pacific/Apia
 ZA,LS,SZ	-2615+02800	Africa/Johannesburg