Squashed 'tz/' changes from 9ffa3f6e..fe890655

d2c79c4b Release 2021c
ec62c0db Adjust formatting of NEWS file
9b900f41 Fix 'zic -b fat' bug with Port Moresby 32-bit data
43dbb433 Port better to >64-bit platforms
7483e30b Revert most 2021b changes to 'backward'
6c15079a Add America/Virgin link in ‘backzone’
2a7c7c58 Fix Jan Mayen typo
79f5ac00 Distribute SECURITY in release tarballs

git-subtree-dir: tz
git-subtree-split: fe890655b72594ee42cf235f739220e71eef89f4

11 files changed, 154 insertions, 120 deletions

diff --git a/Makefile b/Makefile
index 33f3168..a222098 100644
--- a/Makefile
+++ b/Makefile
@@ -504,7 +504,7 @@ MANTXTS=	newctime.3.txt newstrftime.3.txt newtzset.3.txt \
 			tzfile.5.txt tzselect.8.txt zic.8.txt zdump.8.txt \
 			date.1.txt
 COMMON=		calendars CONTRIBUTING LICENSE Makefile \
-			NEWS README theory.html version
+			NEWS README SECURITY theory.html version
 WEB_PAGES=	tz-art.html tz-how-to.html tz-link.html
 CHECK_WEB_PAGES=check_theory.html check_tz-art.html \
 			check_tz-how-to.html check_tz-link.html
@@ -539,7 +539,7 @@ ENCHILADA = $(EIGHT_YARDS) $(TZS)
 # This list is not the same as the output of 'git ls-files', since
 # .gitignore is not distributed.
 VERSION_DEPS= \
-		calendars CONTRIBUTING LICENSE Makefile NEWS README \
+		calendars CONTRIBUTING LICENSE Makefile NEWS README SECURITY \
 		africa antarctica asctime.c asia australasia \
 		backward backzone \
 		checklinks.awk checktab.awk \
@@ -763,7 +763,7 @@ check_character_set: $(ENCHILADA)
 		sharp='#' && \
 		! grep -Env $(SAFE_LINE) $(MANS) date.1 $(MANTXTS) \
 			$(MISC) $(SOURCES) $(WEB_PAGES) \
-			CONTRIBUTING LICENSE README \
+			CONTRIBUTING LICENSE README SECURITY \
 			version tzdata.zi && \
 		! grep -Env $(SAFE_LINE)'|^UNUSUAL_OK_'$(OK_CHAR)'*$$' \
 			Makefile && \
diff --git a/NEWS b/NEWS
index d1ccf4e..f7362c8 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,41 @@
 News for the tz database
 
+Release 2021c - 2021-10-01 14:21:49 -0700
+
+  Briefly:
+    Revert most 2021b changes to 'backward'.
+    Fix 'zic -b fat' bug in pre-1970 32-bit data.
+    Fix two Link line typos.
+    Distribute SECURITY file.
+
+    This release is intended as a bugfix release, to fix compatibility
+    problems and typos reported since 2021b was released.
+
+  Changes to Link directives
+
+    Revert almost all of 2021b's changes to the 'backward' file,
+    by moving Link directives back to where they were in 2021a.
+    Although 'zic' doesn't care which source file contains a Link
+    directive, some downstream uses ran into trouble with the move.
+    (Problem reported by Stephen Colebourne for Joda-Time.)
+
+    Fix typo that linked Atlantic/Jan_Mayen to the wrong location
+    (problem reported by Chris Walton).
+
+    Fix 'backzone' typo that linked America/Virgin to the wrong
+    location (problem reported by Michael Deckers).
+
+  Changes to code
+
+    Fix a bug in 'zic -b fat' that caused old timestamps to be
+    mishandled in 32-bit-only readers (problem reported by Daniel
+    Fischer).
+
+  Changes to documentation
+
+    Distribute the SECURITY file (problem reported by Andreas Radke).
+
+
 Release 2021b - 2021-09-24 16:23:00 -0700
 
   Briefly:
@@ -18,13 +54,13 @@ Release 2021b - 2021-09-24 16:23:00 -0700
     tzfile.5 better matches a draft successor to RFC 8536.
     A new file SECURITY.
 
-  This release is prompted by recent announcements by Jordan and Samoa.
-  It incorporates many other changes that had accumulated since 2021a.
-  However, it omits most proposed changes that merged all Zones
-  agreeing since 1970, as concerns were raised about doing too many of
-  these changes at once.  It does keeps some of these changes in the
-  interest of making tzdb more equitable one step at a time; see
-  "Merge more location-based Zones" below.
+    This release is prompted by recent announcements by Jordan and Samoa.
+    It incorporates many other changes that had accumulated since 2021a.
+    However, it omits most proposed changes that merged all Zones
+    agreeing since 1970, as concerns were raised about doing too many of
+    these changes at once.  It does keeps some of these changes in the
+    interest of making tzdb more equitable one step at a time; see
+    "Merge more location-based Zones" below.
 
   Changes to future timestamps
 
diff --git a/africa b/africa
index c73f0df..48e9d79 100644
--- a/africa
+++ b/africa
@@ -150,6 +150,16 @@ Zone	Africa/Ndjamena	1:00:12 -	LMT	1912        # N'Djamena
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Abidjan	-0:16:08 -	LMT	1912
 			 0:00	-	GMT
+Link Africa/Abidjan Africa/Accra	# Ghana
+Link Africa/Abidjan Africa/Bamako	# Mali
+Link Africa/Abidjan Africa/Banjul	# The Gambia
+Link Africa/Abidjan Africa/Conakry	# Guinea
+Link Africa/Abidjan Africa/Dakar	# Senegal
+Link Africa/Abidjan Africa/Freetown	# Sierra Leone
+Link Africa/Abidjan Africa/Lome		# Togo
+Link Africa/Abidjan Africa/Nouakchott	# Mauritania
+Link Africa/Abidjan Africa/Ouagadougou	# Burkina Faso
+Link Africa/Abidjan Atlantic/St_Helena	# St Helena
 
 # Djibouti
 # See Africa/Nairobi.
@@ -436,6 +446,15 @@ Zone	Africa/Nairobi	2:27:16	-	LMT	1908 May
 			2:30	-	+0230	1936 Dec 31 24:00
 			2:45	-	+0245	1942 Jul 31 24:00
 			3:00	-	EAT
+Link Africa/Nairobi Africa/Addis_Ababa	 # Ethiopia
+Link Africa/Nairobi Africa/Asmara	 # Eritrea
+Link Africa/Nairobi Africa/Dar_es_Salaam # Tanzania
+Link Africa/Nairobi Africa/Djibouti
+Link Africa/Nairobi Africa/Kampala	 # Uganda
+Link Africa/Nairobi Africa/Mogadishu	 # Somalia
+Link Africa/Nairobi Indian/Antananarivo	 # Madagascar
+Link Africa/Nairobi Indian/Comoro
+Link Africa/Nairobi Indian/Mayotte
 
 # Lesotho
 # See Africa/Johannesburg.
@@ -1122,6 +1141,13 @@ Zone Africa/El_Aaiun	-0:52:48 -	LMT	1934 Jan # El Aaiún
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Maputo	2:10:20 -	LMT	1903 Mar
 			2:00	-	CAT
+Link Africa/Maputo Africa/Blantyre	# Malawi
+Link Africa/Maputo Africa/Bujumbura	# Burundi
+Link Africa/Maputo Africa/Gaborone	# Botswana
+Link Africa/Maputo Africa/Harare	# Zimbabwe
+Link Africa/Maputo Africa/Kigali	# Rwanda
+Link Africa/Maputo Africa/Lubumbashi	# E Dem. Rep. of Congo
+Link Africa/Maputo Africa/Lusaka	# Zambia
 
 
 # Namibia
@@ -1269,6 +1295,15 @@ Zone	Africa/Lagos	0:13:35 -	LMT	1905 Jul  1
 			0:13:35	-	LMT	1914 Jan  1
 			0:30	-	+0030	1919 Sep  1
 			1:00	-	WAT
+Link Africa/Lagos Africa/Bangui		# Central African Republic
+Link Africa/Lagos Africa/Brazzaville	# Rep. of the Congo
+Link Africa/Lagos Africa/Douala		# Cameroon
+Link Africa/Lagos Africa/Kinshasa	# Dem. Rep. of the Congo (west)
+Link Africa/Lagos Africa/Libreville	# Gabon
+Link Africa/Lagos Africa/Luanda		# Angola
+Link Africa/Lagos Africa/Malabo		# Equatorial Guinea
+Link Africa/Lagos Africa/Niamey		# Niger
+Link Africa/Lagos Africa/Porto-Novo	# Benin
 
 # Réunion
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
@@ -1366,6 +1401,8 @@ Rule	SA	1943	1944	-	Mar	Sun>=15	2:00	0	-
 Zone Africa/Johannesburg 1:52:00 -	LMT	1892 Feb 8
 			1:30	-	SAST	1903 Mar
 			2:00	SA	SAST
+Link Africa/Johannesburg Africa/Maseru	# Lesotho
+Link Africa/Johannesburg Africa/Mbabane	# Eswatini
 #
 # Marion and Prince Edward Is
 # scientific station since 1947
diff --git a/asia b/asia
index 73e0183..4e95797 100644
--- a/asia
+++ b/asia
@@ -1173,9 +1173,10 @@ Zone	Asia/Famagusta	2:15:48	-	LMT	1921 Nov 14
 			2:00	EUAsia	EE%sT	2016 Sep  8
 			3:00	-	+03	2017 Oct 29 1:00u
 			2:00	EUAsia	EE%sT
+
 # Classically, Cyprus belongs to Asia; e.g. see Herodotus, Histories, I.72.
 # However, for various reasons many users expect to find it under Europe.
-# See the 'backward' file for the Europe/Nicosia link.
+Link	Asia/Nicosia	Europe/Nicosia
 
 # Georgia
 # From Paul Eggert (1994-11-19):
@@ -3531,6 +3532,7 @@ Zone	Asia/Manila	-15:56:00 -	LMT	1844 Dec 31
 Zone	Asia/Qatar	3:26:08 -	LMT	1920     # Al Dawhah / Doha
 			4:00	-	+04	1972 Jun
 			3:00	-	+03
+Link Asia/Qatar Asia/Bahrain
 
 # Saudi Arabia
 #
@@ -3577,6 +3579,9 @@ Zone	Asia/Qatar	3:26:08 -	LMT	1920     # Al Dawhah / Doha
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Riyadh	3:06:52 -	LMT	1947 Mar 14
 			3:00	-	+03
+Link Asia/Riyadh Antarctica/Syowa
+Link Asia/Riyadh Asia/Aden	# Yemen
+Link Asia/Riyadh Asia/Kuwait
 
 # Singapore
 # taken from Mok Ly Yng (2003-10-30)
@@ -3833,6 +3838,8 @@ Zone	Asia/Dushanbe	4:35:12 -	LMT	1924 May  2
 Zone	Asia/Bangkok	6:42:04	-	LMT	1880
 			6:42:04	-	BMT	1920 Apr # Bangkok Mean Time
 			7:00	-	+07
+Link Asia/Bangkok Asia/Phnom_Penh	# Cambodia
+Link Asia/Bangkok Asia/Vientiane	# Laos
 
 # Turkmenistan
 # From Shanks & Pottenger.
@@ -3847,6 +3854,7 @@ Zone	Asia/Ashgabat	3:53:32 -	LMT	1924 May  2 # or Ashkhabad
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Dubai	3:41:12 -	LMT	1920
 			4:00	-	+04
+Link Asia/Dubai Asia/Muscat	# Oman
 
 # Uzbekistan
 # Byalokoz 1919 says Uzbekistan was 4:27:53.
diff --git a/australasia b/australasia
index 8e76c27..7348b87 100644
--- a/australasia
+++ b/australasia
@@ -458,6 +458,7 @@ Zone	Pacific/Guam	-14:21:00 -	LMT	1844 Dec 31
 			 9:00	-	+09	1944 Jul 31
 			10:00	Guam	G%sT	2000 Dec 23
 			10:00	-	ChST	# Chamorro Standard Time
+Link Pacific/Guam Pacific/Saipan # N Mariana Is
 
 # Kiribati
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
@@ -583,6 +584,8 @@ Zone Pacific/Chatham	12:13:48 -	LMT	1868 Nov  2
 			12:15	-	+1215	1946 Jan  1
 			12:45	Chatham	+1245/+1345
 
+Link Pacific/Auckland Antarctica/McMurdo
+
 # Auckland Is
 # uninhabited; Māori and Moriori, colonial settlers, pastoralists, sealers,
 # and scientific personnel have wintered
@@ -676,6 +679,7 @@ Zone Pacific/Palau	-15:02:04 -	LMT	1844 Dec 31	# Koror
 Zone Pacific/Port_Moresby 9:48:40 -	LMT	1880
 			9:48:32	-	PMMT	1895 # Port Moresby Mean Time
 			10:00	-	+10
+Link Pacific/Port_Moresby Antarctica/DumontDUrville
 #
 # From Paul Eggert (2014-10-13):
 # Base the Bougainville entry on the Arawa-Kieta region, which appears to have
@@ -711,6 +715,7 @@ Zone Pacific/Pitcairn	-8:40:20 -	LMT	1901        # Adamstown
 Zone Pacific/Pago_Pago	 12:37:12 -	LMT	1892 Jul  5
 			-11:22:48 -	LMT	1911
 			-11:00	-	SST	            # S=Samoa
+Link Pacific/Pago_Pago Pacific/Midway # in US minor outlying islands
 
 # Samoa (formerly and also known as Western Samoa)
 
diff --git a/backward b/backward
index 7c288e3..7685c74 100644
--- a/backward
+++ b/backward
@@ -4,120 +4,51 @@
 # 2009-05-17 by Arthur David Olson.
 
 # This file provides links from old or merged timezone names to current ones.
-# Many names changed in late 1993, and many merged names moved here
-# in the period from 2013 through 2021.  Several of these names are
+# Many names changed in late 1993.  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	Africa/Abidjan		Africa/Accra
-Link	Africa/Nairobi		Africa/Addis_Ababa
-Link	Africa/Nairobi		Africa/Asmara
 Link	Africa/Nairobi		Africa/Asmera
-Link	Africa/Abidjan		Africa/Bamako
-Link	Africa/Lagos		Africa/Bangui
-Link	Africa/Abidjan		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	Africa/Nairobi		Africa/Dar_es_Salaam
-Link	Africa/Nairobi		Africa/Djibouti
-Link	Africa/Lagos		Africa/Douala
-Link	Africa/Abidjan		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	Africa/Lagos		Africa/Luanda
-Link	Africa/Maputo		Africa/Lubumbashi
-Link	Africa/Maputo		Africa/Lusaka
-Link	Africa/Lagos		Africa/Malabo
-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	Africa/Lagos		Africa/Porto-Novo
 Link	Africa/Abidjan		Africa/Timbuktu
-Link	America/Puerto_Rico	America/Anguilla
-Link	America/Puerto_Rico	America/Antigua
 Link	America/Argentina/Catamarca	America/Argentina/ComodRivadavia
-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	America/Panama		America/Cayman
 Link	America/Panama		America/Coral_Harbour
 Link	America/Argentina/Cordoba	America/Cordoba
-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/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/Puerto_Rico	America/Kralendijk
 Link	America/Kentucky/Louisville	America/Louisville
-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/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/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	Pacific/Port_Moresby	Antarctica/DumontDUrville
-Link	Pacific/Auckland	Antarctica/McMurdo
 Link	Pacific/Auckland	Antarctica/South_Pole
-Link	Asia/Riyadh		Antarctica/Syowa
-Link	Europe/Oslo		Arctic/Longyearbyen
-Link	Asia/Riyadh		Asia/Aden
 Link	Asia/Ashgabat		Asia/Ashkhabad
-Link	Asia/Qatar		Asia/Bahrain
 Link	Asia/Kolkata		Asia/Calcutta
 Link	Asia/Shanghai		Asia/Chongqing
 Link	Asia/Shanghai		Asia/Chungking
 Link	Asia/Dhaka		Asia/Dacca
 Link	Asia/Shanghai		Asia/Harbin
-Link	Europe/Istanbul		Asia/Istanbul
 Link	Asia/Urumqi		Asia/Kashgar
 Link	Asia/Kathmandu		Asia/Katmandu
-Link	Asia/Riyadh		Asia/Kuwait
 Link	Asia/Macau		Asia/Macao
-Link	Asia/Dubai		Asia/Muscat
-Link	Asia/Bangkok		Asia/Phnom_Penh
 Link	Asia/Yangon		Asia/Rangoon
 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	Atlantic/Faroe		Atlantic/Faeroe
-Link	Europe/Berlin		Atlantic/Jan_Mayen
-Link	Africa/Abidjan		Atlantic/St_Helena
+Link	Europe/Oslo		Atlantic/Jan_Mayen
 Link	Australia/Sydney	Australia/ACT
 Link	Australia/Sydney	Australia/Canberra
 Link	Australia/Hobart	Australia/Currie
@@ -152,22 +83,7 @@ Link	Africa/Cairo		Egypt
 Link	Europe/Dublin		Eire
 Link	Etc/UTC			Etc/UCT
 Link	Europe/London		Europe/Belfast
-Link	Europe/Prague		Europe/Bratislava
-Link	Europe/Zurich		Europe/Busingen
-Link	Europe/London		Europe/Guernsey
-Link	Europe/London		Europe/Isle_of_Man
-Link	Europe/London		Europe/Jersey
-Link	Europe/Belgrade		Europe/Ljubljana
-Link	Europe/Helsinki		Europe/Mariehamn
-Link	Asia/Nicosia		Europe/Nicosia
-Link	Europe/Belgrade		Europe/Podgorica
-Link	Europe/Rome		Europe/San_Marino
-Link	Europe/Belgrade		Europe/Sarajevo
-Link	Europe/Belgrade		Europe/Skopje
 Link	Europe/Chisinau		Europe/Tiraspol
-Link	Europe/Zurich		Europe/Vaduz
-Link	Europe/Rome		Europe/Vatican
-Link	Europe/Belgrade		Europe/Zagreb
 Link	Europe/London		GB
 Link	Europe/London		GB-Eire
 Link	Etc/GMT			GMT+0
@@ -176,9 +92,6 @@ Link	Etc/GMT			GMT0
 Link	Etc/GMT			Greenwich
 Link	Asia/Hong_Kong		Hongkong
 Link	Atlantic/Reykjavik	Iceland
-Link	Africa/Nairobi		Indian/Antananarivo
-Link	Africa/Nairobi		Indian/Comoro
-Link	Africa/Nairobi		Indian/Mayotte
 Link	Asia/Tehran		Iran
 Link	Asia/Jerusalem		Israel
 Link	America/Jamaica		Jamaica
@@ -194,9 +107,7 @@ Link	America/Denver		Navajo
 Link	Asia/Shanghai		PRC
 Link	Pacific/Kanton		Pacific/Enderbury
 Link	Pacific/Honolulu	Pacific/Johnston
-Link	Pacific/Pago_Pago	Pacific/Midway
 Link	Pacific/Pohnpei		Pacific/Ponape
-Link	Pacific/Guam		Pacific/Saipan
 Link	Pacific/Pago_Pago	Pacific/Samoa
 Link	Pacific/Chuuk		Pacific/Truk
 Link	Pacific/Chuuk		Pacific/Yap
diff --git a/backzone b/backzone
index fc5e8bf..9b51273 100644
--- a/backzone
+++ b/backzone
@@ -780,6 +780,7 @@ Zone America/St_Lucia	-4:04:00 -	LMT	1890 # Castries
 # US Virgin Is
 Zone America/St_Thomas	-4:19:44 -	LMT	1911 Jul # Charlotte Amalie
 			-4:00	-	AST
+Link America/St_Thomas America/Virgin
 
 # St Vincent and the Grenadines
 Zone America/St_Vincent	-4:04:56 -	LMT	1890 # Kingstown
diff --git a/europe b/europe
index 1204c09..2adc308 100644
--- a/europe
+++ b/europe
@@ -505,6 +505,9 @@ Zone	Europe/London	-0:01:15 -	LMT	1847 Dec  1  0:00s
 			 1:00	-	BST	1971 Oct 31  2:00u
 			 0:00	GB-Eire	%s	1996
 			 0:00	EU	GMT/BST
+Link	Europe/London	Europe/Jersey
+Link	Europe/London	Europe/Guernsey
+Link	Europe/London	Europe/Isle_of_Man
 
 # From Paul Eggert (2018-02-15):
 # In January 2018 we discovered that the negative SAVE values in the
@@ -1303,8 +1306,9 @@ Zone	Europe/Helsinki	1:39:49 -	LMT	1878 May 31
 			1:39:49	-	HMT	1921 May    # Helsinki Mean Time
 			2:00	Finland	EE%sT	1983
 			2:00	EU	EE%sT
+
 # Åland Is
-# See Europe/Helsinki.
+Link	Europe/Helsinki	Europe/Mariehamn
 
 
 # France
@@ -1500,7 +1504,8 @@ Zone	Europe/Berlin	0:53:28 -	LMT	1893 Apr
 
 # From Arthur David Olson (2012-03-03):
 # Büsingen and Zurich have shared clocks since 1970.
-# See Europe/Zurich.
+
+Link	Europe/Zurich	Europe/Busingen
 
 # Georgia
 # Please see the "asia" file for Asia/Tbilisi.
@@ -1798,6 +1803,9 @@ Zone	Europe/Rome	0:49:56 -	LMT	1866 Dec 12
 # See Europe/Belgrade.
 
 
+Link	Europe/Rome	Europe/Vatican
+Link	Europe/Rome	Europe/San_Marino
+
 # Latvia
 
 # From Liene Kanepe (1998-09-17):
@@ -1890,7 +1898,7 @@ Zone	Europe/Riga	1:36:34	-	LMT	1880
 # I could confirm from the paper that Liechtenstein did in fact follow
 # the same DST in 1941 and 1942 as Switzerland did.
 
-# See Europe/Zurich.
+Link Europe/Zurich Europe/Vaduz
 
 
 # Lithuania
@@ -2247,7 +2255,8 @@ Zone	Europe/Oslo	0:43:00 -	LMT	1895 Jan  1
 # Haudegen did not surrender to the Allies until September 1945.
 #
 # All these events predate our cutoff date of 1970, so use Europe/Oslo
-# for these regions; see 'backward'.
+# for these regions.
+Link	Europe/Oslo	Arctic/Longyearbyen
 
 # Poland
 
@@ -3516,9 +3525,14 @@ Zone	Europe/Belgrade	1:22:00	-	LMT	1884
 # Shanks & Pottenger don't give as much detail, so go with Koželj.
 			1:00	-	CET	1982 Nov 27
 			1:00	EU	CE%sT
+Link Europe/Belgrade Europe/Ljubljana	# Slovenia
+Link Europe/Belgrade Europe/Podgorica	# Montenegro
+Link Europe/Belgrade Europe/Sarajevo	# Bosnia and Herzegovina
+Link Europe/Belgrade Europe/Skopje	# North Macedonia
+Link Europe/Belgrade Europe/Zagreb	# Croatia
 
 # Slovakia
-# See Europe/Prague.
+Link Europe/Prague Europe/Bratislava
 
 # Slovenia
 # See Europe/Belgrade.
@@ -3989,7 +4003,7 @@ Zone	Europe/Istanbul	1:55:52 -	LMT	1880
 			2:00	1:00	EEST	2015 Nov  8  1:00u
 			2:00	EU	EE%sT	2016 Sep  7
 			3:00	-	+03
-# See the 'backward' file for Asia/Istanbul.
+Link	Europe/Istanbul	Asia/Istanbul	# Istanbul is in both continents.
 
 # Ukraine
 #
diff --git a/northamerica b/northamerica
index a2f2b43..b1a306d 100644
--- a/northamerica
+++ b/northamerica
@@ -829,6 +829,8 @@ Zone America/Phoenix	-7:28:18 -	LMT	1883 Nov 18 11:31:42
 			-7:00	-	MST	1967
 			-7:00	US	M%sT	1968 Mar 21
 			-7:00	-	MST
+Link America/Phoenix America/Creston
+
 # From Arthur David Olson (1988-02-13):
 # A writer from the Inter Tribal Council of Arizona, Inc.,
 # notes in private correspondence dated 1987-12-28 that "Presently, only the
@@ -1766,6 +1768,7 @@ Zone America/Toronto	-5:17:32 -	LMT	1895
 			-5:00	Canada	E%sT	1946
 			-5:00	Toronto	E%sT	1974
 			-5:00	Canada	E%sT
+Link America/Toronto America/Nassau
 Zone America/Thunder_Bay -5:57:00 -	LMT	1895
 			-6:00	-	CST	1910
 			-5:00	-	EST	1942
@@ -2810,7 +2813,7 @@ Zone America/Tijuana	-7:48:04 -	LMT	1922 Jan  1  0:11:56
 # See America/Puerto_Rico.
 
 # The Bahamas
-# See America/Montreal.
+# See America/Toronto.
 
 
 # Barbados
@@ -3565,6 +3568,8 @@ Zone	America/Managua	-5:45:08 -	LMT	1890
 Zone	America/Panama	-5:18:08 -	LMT	1890
 			-5:19:36 -	CMT	1908 Apr 22 # Colón Mean Time
 			-5:00	-	EST
+Link America/Panama America/Atikokan
+Link America/Panama America/Cayman
 
 # Puerto Rico
 # There are too many San Juans elsewhere, so we'll use 'Puerto_Rico'.
@@ -3573,6 +3578,25 @@ Zone America/Puerto_Rico -4:24:25 -	LMT	1899 Mar 28 12:00 # San Juan
 			-4:00	-	AST	1942 May  3
 			-4:00	US	A%sT	1946
 			-4:00	-	AST
+Link America/Puerto_Rico America/Anguilla
+Link America/Puerto_Rico America/Antigua
+Link America/Puerto_Rico America/Aruba
+Link America/Puerto_Rico America/Curacao
+Link America/Puerto_Rico America/Blanc-Sablon	# Quebec (Lower North Shore)
+Link America/Puerto_Rico America/Dominica
+Link America/Puerto_Rico America/Grenada
+Link America/Puerto_Rico America/Guadeloupe
+Link America/Puerto_Rico America/Kralendijk	# Caribbean Netherlands
+Link America/Puerto_Rico America/Lower_Princes	# Sint Maarten
+Link America/Puerto_Rico America/Marigot	# St Martin (French part)
+Link America/Puerto_Rico America/Montserrat
+Link America/Puerto_Rico America/Port_of_Spain	# Trinidad & Tobago
+Link America/Puerto_Rico America/St_Barthelemy	# St Barthélemy
+Link America/Puerto_Rico America/St_Kitts	# St Kitts & Nevis
+Link America/Puerto_Rico America/St_Lucia
+Link America/Puerto_Rico America/St_Thomas	# Virgin Islands (US)
+Link America/Puerto_Rico America/St_Vincent
+Link America/Puerto_Rico America/Tortola	# Virgin Islands (UK)
 
 # St Kitts-Nevis
 # St Lucia
diff --git a/southamerica b/southamerica
index 9d8f460..7900af9 100644
--- a/southamerica
+++ b/southamerica
@@ -1375,8 +1375,8 @@ Zone	America/Bogota	-4:56:16 -	LMT	1884 Mar 13
 # 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"....
-# From Paul Eggert (2021-05-06):
-# These backward-compatibility links now are in the 'backward' file.
+# From Paul Eggert (2021-09-29):
+# These backward-compatibility links now are in the 'northamerica' file.
 
 # Ecuador
 #
diff --git a/zic.c b/zic.c
index c6feb8b..0101351 100644
--- a/zic.c
+++ b/zic.c
@@ -1990,7 +1990,7 @@ limitrange(struct timerange r, bool locut, zic_t lo, zic_t hi,
 
 
   /* Omit ordinary and leap second transitions greater than HI + 1.  */
-  if (hi < ZIC_MAX) {
+  if (hi < max_time) {
     while (0 < r.count && hi + 1 < ats[r.base + r.count - 1])
       r.count--;
     while (0 < r.leapcount && hi + 1 < trans[r.leapbase + r.leapcount - 1])
@@ -2003,7 +2003,7 @@ limitrange(struct timerange r, bool locut, zic_t lo, zic_t hi,
      This is needed when the output is truncated at the start, and is
      also useful when catering to buggy 32-bit clients that do not use
      time type 0 for timestamps before the first transition.  */
-  r.pretrans = locut && ! (r.count && ats[r.base] == lo);
+  r.pretrans = locut && r.base && ! (r.count && ats[r.base] == lo);
 
   /* Determine whether to append an expiration to the leap second table.  */
   r.leapexpiry = 0 <= leapexpires && leapexpires - 1 <= hi;
@@ -2120,7 +2120,7 @@ writezone(const char *const name, const char *const string, char version,
 	rangeall.pretrans = rangeall.leapexpiry = false;
 	range64 = limitrange(rangeall, min_time < lo_time,
 			     lo_time, hi_time, ats, types);
-	range32 = limitrange(range64, INT32_MIN < lo_time,
+	range32 = limitrange(range64, INT32_MIN < lo_time || want_bloat(),
 			     INT32_MIN, INT32_MAX, ats, types);
 
 	/* TZif version 4 is needed if a no-op transition is appended to
@@ -2205,12 +2205,12 @@ writezone(const char *const name, const char *const string, char version,
 		  error(_("too many transition times"));
 
 		thistimelim = thistimei + thistimecnt;
-		if (thistimecnt && hi_time < ZIC_MAX
+		if (thistimecnt && hi_time < max_time
 		    && ats[thistimelim - 1] == hi_time + 1)
 		  hicut = false;
 		memset(omittype, true, typecnt);
 		omittype[thisdefaulttype] = false;
-		for (i = thistimei; i < thistimelim; i++)
+		for (i = thistimei - pretrans; i < thistimelim; i++)
 		  omittype[types[i]] = false;
 
 		/* Reorder types to make THISDEFAULTTYPE type 0.
@@ -2232,7 +2232,7 @@ writezone(const char *const name, const char *const string, char version,
 			register int	mrudst, mrustd, hidst, histd, type;
 
 			hidst = histd = mrudst = mrustd = -1;
-			for (i = thistimei; i < thistimelim; ++i)
+			for (i = thistimei - pretrans; i < thistimelim; ++i)
 				if (isdsts[types[i]])
 					mrudst = types[i];
 				else	mrustd = types[i];
@@ -2348,9 +2348,7 @@ writezone(const char *const name, const char *const string, char version,
 		if (hicut)
 		  puttzcodepass(hi_time + 1, fp, pass);
 		currenttype = 0;
-		if (pretrans)
-		  putc(currenttype, fp);
-		for (i = thistimei; i < thistimelim; ++i) {
+		for (i = thistimei - pretrans; i < thistimelim; ++i) {
 		  currenttype = typemap[types[i]];
 		  putc(currenttype, fp);
 		}