IANA 2019b

29 files changed, 1361 insertions, 784 deletions

diff --git a/tz/.gitignore b/tz/.gitignore
index 1e62d11..cf3b825 100644
--- a/tz/.gitignore
+++ b/tz/.gitignore
@@ -2,14 +2,20 @@
 # This file is in the public domain.
 *.a
 *.asc
+*.diff
+*.i
 *.o
+*.orig
 *.patch
+*.rej
+*.tar
 *.tar.*
 *.txt
 *.tzs
 *.zi
 *~
 ChangeLog
+check_*
 date
 leapseconds
 tzselect
diff --git a/tz/Makefile b/tz/Makefile
index 25f1d35..fec0a4f 100644
--- a/tz/Makefile
+++ b/tz/Makefile
@@ -35,11 +35,13 @@ DATAFORM=		main
 
 LOCALTIME=	GMT
 
-# If you want something other than Eastern United States time as a template
-# for handling ruleless POSIX-style timezone environment variables,
+# The POSIXRULES macro controls interpretation of nonstandard and obsolete
+# POSIX-like TZ settings like TZ='EET-2EEST' that lack DST transition rules.
+# In the reference implementation, if you want something other than Eastern
+# United States time as a template for handling these settings, you can
 # change the line below (after finding the timezone you want in the
 # one of the $(TDATA) source files, or adding it to a source file).
-# A ruleless environment setting like TZ='CST6CDT' uses the rules in the
+# A setting like TZ='EET-2EEST' is supposed to use the rules in the
 # template file to determine "spring forward" and "fall back" days and
 # times; the environment variable itself specifies UT offsets of standard and
 # daylight saving time.
@@ -49,6 +51,17 @@ LOCALTIME=	GMT
 # Use the command
 #	make zonenames
 # to get a list of the values you can use for POSIXRULES.
+#
+# If POSIXRULES is empty, no template is installed; this is the intended
+# future default for POSIXRULES.
+#
+# Nonempty POSIXRULES is obsolete and should not be relied on, because:
+# * It does not work correctly in popular implementations such as GNU/Linux.
+# * It does not work in the tzdb implementation for timestamps after 2037.
+# * It is incompatible with 'zic -b slim' if POSIXRULES specifies transitions
+#   at standard time or UT rather than at local time.
+# In short, software should avoid ruleless settings like TZ='EET-2EEST'
+# and so should not depend on the value of POSIXRULES.
 
 POSIXRULES=	America/New_York
 
@@ -231,6 +244,13 @@ LDLIBS=
 #	other than simply getting garbage data
 #  -DUSE_LTZ=0 to build zdump with the system time zone library
 #	Also set TZDOBJS=zdump.o and CHECK_TIME_T_ALTERNATIVES= below.
+#  -DZIC_BLOAT_DEFAULT=\"slim\" to default zic's -b option to "slim", and
+#	similarly for "fat".  Fat TZif files work around incompatibilities
+#	and bugs in some TZif readers, notably readers that mishandle 64-bit
+#	data in TZif files.  Slim TZif files are more efficient and do not
+#	work around these incompatibilities and bugs.  If not given, the
+#	current default is "fat" but this is intended to change as readers
+#	requiring fat files often mishandle timestamps after 2037 anyway.
 #  -DZIC_MAX_ABBR_LEN_WO_WARN=3
 #	(or some other number) to set the maximum time zone abbreviation length
 #	that zic will accept without a warning (the default is 6)
@@ -364,7 +384,9 @@ ZIC=		$(zic) $(ZFLAGS)
 
 # To shrink the size of installed TZif files,
 # append "-r @N" to omit data before N-seconds-after-the-Epoch.
-# See the zic man page for more about -r.
+# You can also append "-b slim" if that is not already the default;
+# see ZIC_BLOAT_DEFAULT above.
+# See the zic man page for more about -b and -r.
 ZFLAGS=
 
 # How to use zic to install TZif files.
@@ -388,6 +410,9 @@ KSHELL=		/bin/bash
 # Name of curl <https://curl.haxx.se/>, used for HTML validation.
 CURL=		curl
 
+# Name of GNU Privacy Guard <https://gnupg.org/>, used to sign distributions.
+GPG=		gpg
+
 # The path where SGML DTDs are kept and the catalog file(s) to use when
 # validating HTML 4.01.  The default should work on both Debian and Red Hat.
 SGML_TOPDIR= /usr
@@ -562,7 +587,9 @@ install:	all $(DATA) $(REDO) $(MANS)
 			'$(DESTDIR)$(LIBDIR)' \
 			'$(DESTDIR)$(MANDIR)/man3' '$(DESTDIR)$(MANDIR)/man5' \
 			'$(DESTDIR)$(MANDIR)/man8'
-		$(ZIC_INSTALL) -l $(LOCALTIME) -p $(POSIXRULES) \
+		$(ZIC_INSTALL) -l $(LOCALTIME) \
+			`case '$(POSIXRULES)' in ?*) echo '-p';; esac \
+			` $(POSIXRULES) \
 			-t '$(DESTDIR)$(TZDEFAULT)'
 		cp -f $(TABDATA) '$(DESTDIR)$(TZDIR)/.'
 		cp tzselect '$(DESTDIR)$(BINDIR)/.'
@@ -781,12 +808,6 @@ CHECK_CC_LIST = { n = split($$1,a,/,/); for (i=2; i<=n; i++) print a[1], a[i]; }
 check_sorted: backward backzone iso3166.tab zone.tab zone1970.tab
 		$(AWK) '/^Link/ {print $$3}' backward | LC_ALL=C sort -cu
 		$(AWK) '/^Zone/ {print $$2}' backzone | LC_ALL=C sort -cu
-		$(AWK) '/^[^#]/ {print $$1}' iso3166.tab | LC_ALL=C sort -cu
-		$(AWK) '/^[^#]/ {print $$1}' zone.tab | LC_ALL=C sort -c
-		$(AWK) '/^[^#]/ {print substr($$0, 1, 2)}' zone1970.tab | \
-		  LC_ALL=C sort -c
-		$(AWK) '/^[^#]/ $(CHECK_CC_LIST)' zone1970.tab | \
-		  LC_ALL=C sort -cu
 		touch $@
 
 check_links:	checklinks.awk $(TDATA_TO_CHECK) tzdata.zi
@@ -1051,7 +1072,7 @@ tzdata$(VERSION).tar.gz.asc: tzdata$(VERSION).tar.gz
 tzdata$(VERSION)-rearguard.tar.gz.asc: tzdata$(VERSION)-rearguard.tar.gz
 tzdb-$(VERSION).tar.lz.asc: tzdb-$(VERSION).tar.lz
 $(ALL_ASC):
-		gpg2 --armor --detach-sign $?
+		$(GPG) --armor --detach-sign $?
 
 TYPECHECK_CFLAGS = $(CFLAGS) -DTYPECHECK -D__time_t_defined -D_TIME_T
 typecheck: typecheck_long_long typecheck_unsigned
diff --git a/tz/NEWS b/tz/NEWS
index 9d0e9c0..8b05f8f 100644
--- a/tz/NEWS
+++ b/tz/NEWS
@@ -1,6 +1,100 @@
 News for the tz database
 
-Release 20198 - 2019-03-25 22:01:33 -0700
+Release 2019b - 2019-07-01 00:09:53 -0700
+
+  Briefly:
+    Brazil no longer observes DST.
+    'zic -b slim' outputs smaller TZif files; please try it out.
+    Palestine's 2019 spring-forward transition was on 03-29, not 03-30.
+
+  Changes to future timestamps
+
+    Brazil has canceled DST and will stay on standard time indefinitely.
+    (Thanks to Steffen Thorsen, Marcus Diniz, and Daniel Soares de
+    Oliveira.)
+
+    Predictions for Morocco now go through 2087 instead of 2037, to
+    work around a problem on newlib when using TZif files output by
+    zic 2019a or earlier.  (Problem reported by David Gauchard.)
+
+  Changes to past and future timestamps
+
+    Palestine's 2019 spring transition was 03-29 at 00:00, not 03-30
+    at 01:00.  (Thanks to Sharef Mustafa and Even Scharning.)  Guess
+    future transitions to be March's last Friday at 00:00.
+
+  Changes to past timestamps
+
+    Hong Kong's 1941-06-15 spring-forward transition was at 03:00, not
+    03:30.  Its 1945 transition from JST to HKT was on 11-18 at 02:00,
+    not 09-15 at 00:00.  In 1946 its spring-forward transition was on
+    04-21 at 00:00, not the previous day at 03:30.  From 1946 through
+    1952 its fall-back transitions occurred at 04:30, not at 03:30.
+    In 1947 its fall-back transition was on 11-30, not 12-30.
+    (Thanks to P Chan.)
+
+  Changes to past time zone abbreviations
+
+    Italy's 1866 transition to Rome Mean Time was on December 12, not
+    September 22.  This affects only the time zone abbreviation for
+    Europe/Rome between those dates.  (Thanks to Stephen Trainor and
+    Luigi Rosa.)
+
+  Changes affecting metadata only
+
+    Add info about the Crimea situation in zone1970.tab and zone.tab.
+    (Problem reported by Serhii Demediuk.)
+
+  Changes to code
+
+    zic's new -b option supports a way to control data bloat and to
+    test for year-2038 bugs in software that reads TZif files.
+    'zic -b fat' and 'zic -b slim' generate larger and smaller output;
+    for example, changing from fat to slim shrinks the Europe/London
+    file from 3648 to 1599 bytes, saving about 56%.  Fat and slim
+    files represent the same set of timestamps and use the same TZif
+    format as documented in tzfile(5) and in Internet RFC 8536.
+    Fat format attempts to work around bugs or incompatibilities in
+    older software, notably software that mishandles 64-bit TZif data
+    or uses obsolete TZ strings like "EET-2EEST" that lack DST rules.
+    Slim format is more efficient and does not work around 64-bit bugs
+    or obsolete TZ strings.  Currently zic defaults to fat format
+    unless you compile with -DZIC_BLOAT_DEFAULT=\"slim\"; this
+    out-of-the-box default is intended to change in future releases
+    as the buggy software often mishandles timestamps anyway.
+
+    zic no longer treats a set of rules ending in 2037 specially.
+    Previously, zic assumed that such a ruleset meant that future
+    timestamps could not be predicted, and therefore omitted a
+    POSIX-like TZ string in the TZif output.  The old behavior is no
+    longer needed for current tzdata, and caused problems with newlib
+    when used with older tzdata (reported by David Gauchard).
+
+    zic no longer generates some artifact transitions.  For example,
+    Europe/London no longer has a no-op transition in January 1996.
+
+  Changes to build procedure
+
+    tzdata.zi now assumes zic 2017c or later.  This shrinks tzdata.zi
+    by a percent or so.
+
+  Changes to documentation and commentary
+
+    The Makefile now documents the POSIXRULES macro as being obsolete,
+    and similarly, zic's -p POSIXRULES option is now documented as
+    being obsolete.  Although the POSIXRULES feature still exists and
+    works as before, in practice it is rarely used for its intended
+    purpose, and it does not work either in the default reference
+    implementation (for timestamps after 2037) or in common
+    implementations such as GNU/Linux (for contemporary timestamps).
+    Since POSIXRULES was designed primarily as a temporary transition
+    facility for System V platforms that died off decades ago, it is
+    being decommissioned rather than institutionalized.
+
+    New info on Bonin Islands and Marcus (thanks to Wakaba and Phake Nick).
+
+
+Release 2019a - 2019-03-25 22:01:33 -0700
 
   Briefly:
     Palestine "springs forward" on 2019-03-30 instead of 2019-03-23.
@@ -481,7 +575,7 @@ Release 2018d - 2018-03-22 07:05:46 -0700
     The code is a bit more portable to MS-Windows.  Installers can
     compile with -DRESERVE_STD_EXT_IDS on MS-Windows platforms that
     reserve identifiers like 'localtime'.  (Thanks to Manuela
-    Friedrich).
+    Friedrich.)
 
   Changes to documentation and commentary
 
@@ -2276,7 +2370,7 @@ Release 2014f - 2014-08-05 17:42:36 -0700
     warlord Jin Shuren in the data.
 
     Commentary about the coverage of each Russian zone has been standardized.
-    (Thanks to Tim Parenti).
+    (Thanks to Tim Parenti.)
 
     There is new commentary about contemporary timekeeping in Ethiopia.
 
@@ -2724,7 +2818,7 @@ Release 2013e - 2013-09-19 23:50:04 -0700
 
     Change the UT offset of Bern Mean Time from 0:29:44 to 0:29:46.
     This affects Europe/Zurich timestamps from 1853 to 1894.  (Thanks
-    to Alois Treindl).
+    to Alois Treindl.)
 
     Change the date of the circa-1850 Zurich transition from 1849-09-12
     to 1853-07-16, overriding Shanks with data from Messerli about
@@ -3034,7 +3128,7 @@ Release 2013a - 2013-02-27 09:20:35 -0800
     (Thanks to Arthur David Olson.)
 
     Improve the commentary about which districts observe what times
-    in Russia.  (Thanks to Oscar van Vlijmen and Arthur David Olson).
+    in Russia.  (Thanks to Oscar van Vlijmen and Arthur David Olson.)
 
     Add web page links to tz.js.
 
diff --git a/tz/africa b/tz/africa
index a58c11c..feb6017 100644
--- a/tz/africa
+++ b/tz/africa
@@ -89,7 +89,7 @@ Rule	Algeria	1980	only	-	Apr	25	 0:00	1:00	S
 Rule	Algeria	1980	only	-	Oct	31	 2:00	0	-
 # Shanks & Pottenger give 0:09:20 for Paris Mean Time; go with Howse's
 # more precise 0:09:21.
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Algiers	0:12:12 -	LMT	1891 Mar 15  0:01
 			0:09:21	-	PMT	1911 Mar 11 # Paris Mean Time
 			0:00	Algeria	WE%sT	1940 Feb 25  2:00
@@ -124,7 +124,7 @@ Zone	Africa/Algiers	0:12:12 -	LMT	1891 Mar 15  0:01
 # For now, ignore that and follow the 1911-05-26 Portuguese decree
 # (see Europe/Lisbon).
 #
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Atlantic/Cape_Verde -1:34:04 -	LMT	1912 Jan 01  2:00u # Praia
 			-2:00	-	-02	1942 Sep
 			-2:00	1:00	-01	1945 Oct 15
@@ -135,7 +135,7 @@ Zone Atlantic/Cape_Verde -1:34:04 -	LMT	1912 Jan 01  2:00u # Praia
 # See Africa/Lagos.
 
 # Chad
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Ndjamena	1:00:12 -	LMT	1912        # N'Djamena
 			1:00	-	WAT	1979 Oct 14
 			1:00	1:00	WAST	1980 Mar  8
@@ -151,7 +151,7 @@ Zone	Africa/Ndjamena	1:00:12 -	LMT	1912        # N'Djamena
 # See Africa/Lagos.
 
 # Côte d'Ivoire / Ivory Coast
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Abidjan	-0:16:08 -	LMT	1912
 			 0:00	-	GMT
 Link Africa/Abidjan Africa/Bamako	# Mali
@@ -356,7 +356,7 @@ Rule	Egypt	2014	only	-	Jun	26	24:00	0	-
 Rule	Egypt	2014	only	-	Jul	31	24:00	1:00	S
 Rule	Egypt	2014	only	-	Sep	lastThu	24:00	0	-
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Cairo	2:05:09 -	LMT	1900 Oct
 			2:00	Egypt	EE%sT
 
@@ -414,7 +414,7 @@ Zone	Africa/Cairo	2:05:09 -	LMT	1900 Oct
 # Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
 Rule	Ghana	1920	1942	-	Sep	 1	0:00	0:20	-
 Rule	Ghana	1920	1942	-	Dec	31	0:00	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Accra	-0:00:52 -	LMT	1918
 			 0:00	Ghana	GMT/+0020
 
@@ -428,13 +428,13 @@ Zone	Africa/Accra	-0:00:52 -	LMT	1918
 # evidently confusing the date of the Portuguese decree
 # (see Europe/Lisbon) with the date that it took effect.
 #
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Bissau	-1:02:20 -	LMT	1912 Jan  1  1:00u
 			-1:00	-	-01	1975
 			 0:00	-	GMT
 
 # Kenya
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Nairobi	2:27:16	-	LMT	1928 Jul
 			3:00	-	EAT	1930
 			2:30	-	+0230	1940
@@ -469,7 +469,7 @@ Link Africa/Nairobi Indian/Mayotte
 # Use the abbreviation "MMT" before 1972, as the more-accurate numeric
 # abbreviation "-004430" would be one byte over the POSIX limit.
 #
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Monrovia	-0:43:08 -	LMT	1882
 			-0:43:08 -	MMT	1919 Mar # Monrovia Mean Time
 			-0:44:30 -	MMT	1972 Jan 7 # approximately MMT
@@ -519,7 +519,7 @@ Rule	Libya	1997	only	-	Apr	 4	0:00	1:00	S
 Rule	Libya	1997	only	-	Oct	 4	0:00	0	-
 Rule	Libya	2013	only	-	Mar	lastFri	1:00	1:00	S
 Rule	Libya	2013	only	-	Oct	lastFri	2:00	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Tripoli	0:52:44 -	LMT	1920
 			1:00	Libya	CE%sT	1959
 			2:00	-	EET	1982
@@ -629,7 +629,7 @@ Rule Mauritius	1982	only	-	Oct	10	0:00	1:00	-
 Rule Mauritius	1983	only	-	Mar	21	0:00	0	-
 Rule Mauritius	2008	only	-	Oct	lastSun	2:00	1:00	-
 Rule Mauritius	2009	only	-	Mar	lastSun	2:00	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Indian/Mauritius	3:50:00 -	LMT	1907 # Port Louis
 			4:00 Mauritius	+04/+05
 # Agalega Is, Rodriguez
@@ -860,18 +860,24 @@ Zone Indian/Mauritius	3:50:00 -	LMT	1907 # Port Louis
 # the week end after....  The government does not announce yet the decision
 # about this temporary change.  But it s 99% sure that it will be the case,
 # as in previous years.  An unofficial survey was done these days, showing
-# that 64% of asked peopke are ok for moving from +1 to +0 during Ramadan.
+# that 64% of asked people are ok for moving from +1 to +0 during Ramadan.
 # https://leconomiste.com/article/1035870-enquete-l-economiste-sunergia-64-des-marocains-plebiscitent-le-gmt-pendant-ramadan
+
+# From Naoufal Semlali (2019-04-16):
+# Morocco will be on GMT starting from Sunday, May 5th 2019 at 3am.
+# The switch to GMT+1 will occur on Sunday, June 9th 2019 at 2am....
+# http://fr.le360.ma/societe/voici-la-date-du-retour-a-lheure-legale-au-maroc-188222
 #
-# From Paul Eggert (2018-11-01):
-# For now, guess that Morocco will fall back at 03:00 the last Sunday
-# before Ramadan, and spring forward at 02:00 the first Sunday after
+# From Paul Eggert (2019-05-20):
+# This agrees with our 2018-11-01 guess that the Moroccan government
+# would continue the practice of falling back at 03:00 the last Sunday
+# before Ramadan, and of springing forward at 02:00 the first Sunday after
 # Ramadan, as this has been the practice since 2012.  To implement this,
-# transition dates for 2019 through 2037 were determined by running the
-# following program under GNU Emacs 26.1.
+# transition dates for 2019 through 2087 were determined by running the
+# following program under GNU Emacs 26.2.
 # (let ((islamic-year 1440))
 #   (require 'cal-islam)
-#   (while (< islamic-year 1460)
+#   (while (< islamic-year 1511)
 #     (let ((a (calendar-islamic-to-absolute (list 9 1 islamic-year)))
 #           (b (calendar-islamic-to-absolute (list 10 1 islamic-year)))
 #           (sunday 0))
@@ -970,8 +976,114 @@ Rule	Morocco	2036	only	-	Oct	19	 3:00	-1:00	-
 Rule	Morocco	2036	only	-	Nov	23	 2:00	0	-
 Rule	Morocco	2037	only	-	Oct	 4	 3:00	-1:00	-
 Rule	Morocco	2037	only	-	Nov	15	 2:00	0	-
-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+Rule	Morocco	2038	only	-	Sep	26	 3:00	-1:00	-
+Rule	Morocco	2038	only	-	Oct	31	 2:00	0	-
+Rule	Morocco	2039	only	-	Sep	18	 3:00	-1:00	-
+Rule	Morocco	2039	only	-	Oct	23	 2:00	0	-
+Rule	Morocco	2040	only	-	Sep	 2	 3:00	-1:00	-
+Rule	Morocco	2040	only	-	Oct	14	 2:00	0	-
+Rule	Morocco	2041	only	-	Aug	25	 3:00	-1:00	-
+Rule	Morocco	2041	only	-	Sep	29	 2:00	0	-
+Rule	Morocco	2042	only	-	Aug	10	 3:00	-1:00	-
+Rule	Morocco	2042	only	-	Sep	21	 2:00	0	-
+Rule	Morocco	2043	only	-	Aug	 2	 3:00	-1:00	-
+Rule	Morocco	2043	only	-	Sep	 6	 2:00	0	-
+Rule	Morocco	2044	only	-	Jul	24	 3:00	-1:00	-
+Rule	Morocco	2044	only	-	Aug	28	 2:00	0	-
+Rule	Morocco	2045	only	-	Jul	 9	 3:00	-1:00	-
+Rule	Morocco	2045	only	-	Aug	20	 2:00	0	-
+Rule	Morocco	2046	only	-	Jul	 1	 3:00	-1:00	-
+Rule	Morocco	2046	only	-	Aug	 5	 2:00	0	-
+Rule	Morocco	2047	only	-	Jun	23	 3:00	-1:00	-
+Rule	Morocco	2047	only	-	Jul	28	 2:00	0	-
+Rule	Morocco	2048	only	-	Jun	 7	 3:00	-1:00	-
+Rule	Morocco	2048	only	-	Jul	19	 2:00	0	-
+Rule	Morocco	2049	only	-	May	30	 3:00	-1:00	-
+Rule	Morocco	2049	only	-	Jul	 4	 2:00	0	-
+Rule	Morocco	2050	only	-	May	15	 3:00	-1:00	-
+Rule	Morocco	2050	only	-	Jun	26	 2:00	0	-
+Rule	Morocco	2051	only	-	May	 7	 3:00	-1:00	-
+Rule	Morocco	2051	only	-	Jun	11	 2:00	0	-
+Rule	Morocco	2052	only	-	Apr	28	 3:00	-1:00	-
+Rule	Morocco	2052	only	-	Jun	 2	 2:00	0	-
+Rule	Morocco	2053	only	-	Apr	13	 3:00	-1:00	-
+Rule	Morocco	2053	only	-	May	25	 2:00	0	-
+Rule	Morocco	2054	only	-	Apr	 5	 3:00	-1:00	-
+Rule	Morocco	2054	only	-	May	10	 2:00	0	-
+Rule	Morocco	2055	only	-	Mar	28	 3:00	-1:00	-
+Rule	Morocco	2055	only	-	May	 2	 2:00	0	-
+Rule	Morocco	2056	only	-	Mar	12	 3:00	-1:00	-
+Rule	Morocco	2056	only	-	Apr	23	 2:00	0	-
+Rule	Morocco	2057	only	-	Mar	 4	 3:00	-1:00	-
+Rule	Morocco	2057	only	-	Apr	 8	 2:00	0	-
+Rule	Morocco	2058	only	-	Feb	17	 3:00	-1:00	-
+Rule	Morocco	2058	only	-	Mar	31	 2:00	0	-
+Rule	Morocco	2059	only	-	Feb	 9	 3:00	-1:00	-
+Rule	Morocco	2059	only	-	Mar	16	 2:00	0	-
+Rule	Morocco	2060	only	-	Feb	 1	 3:00	-1:00	-
+Rule	Morocco	2060	only	-	Mar	 7	 2:00	0	-
+Rule	Morocco	2061	only	-	Jan	16	 3:00	-1:00	-
+Rule	Morocco	2061	only	-	Feb	27	 2:00	0	-
+Rule	Morocco	2062	only	-	Jan	 8	 3:00	-1:00	-
+Rule	Morocco	2062	only	-	Feb	12	 2:00	0	-
+Rule	Morocco	2062	only	-	Dec	31	 3:00	-1:00	-
+Rule	Morocco	2063	only	-	Feb	 4	 2:00	0	-
+Rule	Morocco	2063	only	-	Dec	16	 3:00	-1:00	-
+Rule	Morocco	2064	only	-	Jan	20	 2:00	0	-
+Rule	Morocco	2064	only	-	Dec	 7	 3:00	-1:00	-
+Rule	Morocco	2065	only	-	Jan	11	 2:00	0	-
+Rule	Morocco	2065	only	-	Nov	22	 3:00	-1:00	-
+Rule	Morocco	2066	only	-	Jan	 3	 2:00	0	-
+Rule	Morocco	2066	only	-	Nov	14	 3:00	-1:00	-
+Rule	Morocco	2066	only	-	Dec	19	 2:00	0	-
+Rule	Morocco	2067	only	-	Nov	 6	 3:00	-1:00	-
+Rule	Morocco	2067	only	-	Dec	11	 2:00	0	-
+Rule	Morocco	2068	only	-	Oct	21	 3:00	-1:00	-
+Rule	Morocco	2068	only	-	Dec	 2	 2:00	0	-
+Rule	Morocco	2069	only	-	Oct	13	 3:00	-1:00	-
+Rule	Morocco	2069	only	-	Nov	17	 2:00	0	-
+Rule	Morocco	2070	only	-	Oct	 5	 3:00	-1:00	-
+Rule	Morocco	2070	only	-	Nov	 9	 2:00	0	-
+Rule	Morocco	2071	only	-	Sep	20	 3:00	-1:00	-
+Rule	Morocco	2071	only	-	Oct	25	 2:00	0	-
+Rule	Morocco	2072	only	-	Sep	11	 3:00	-1:00	-
+Rule	Morocco	2072	only	-	Oct	16	 2:00	0	-
+Rule	Morocco	2073	only	-	Aug	27	 3:00	-1:00	-
+Rule	Morocco	2073	only	-	Oct	 8	 2:00	0	-
+Rule	Morocco	2074	only	-	Aug	19	 3:00	-1:00	-
+Rule	Morocco	2074	only	-	Sep	23	 2:00	0	-
+Rule	Morocco	2075	only	-	Aug	11	 3:00	-1:00	-
+Rule	Morocco	2075	only	-	Sep	15	 2:00	0	-
+Rule	Morocco	2076	only	-	Jul	26	 3:00	-1:00	-
+Rule	Morocco	2076	only	-	Sep	 6	 2:00	0	-
+Rule	Morocco	2077	only	-	Jul	18	 3:00	-1:00	-
+Rule	Morocco	2077	only	-	Aug	22	 2:00	0	-
+Rule	Morocco	2078	only	-	Jul	10	 3:00	-1:00	-
+Rule	Morocco	2078	only	-	Aug	14	 2:00	0	-
+Rule	Morocco	2079	only	-	Jun	25	 3:00	-1:00	-
+Rule	Morocco	2079	only	-	Jul	30	 2:00	0	-
+Rule	Morocco	2080	only	-	Jun	16	 3:00	-1:00	-
+Rule	Morocco	2080	only	-	Jul	21	 2:00	0	-
+Rule	Morocco	2081	only	-	Jun	 1	 3:00	-1:00	-
+Rule	Morocco	2081	only	-	Jul	13	 2:00	0	-
+Rule	Morocco	2082	only	-	May	24	 3:00	-1:00	-
+Rule	Morocco	2082	only	-	Jun	28	 2:00	0	-
+Rule	Morocco	2083	only	-	May	16	 3:00	-1:00	-
+Rule	Morocco	2083	only	-	Jun	20	 2:00	0	-
+Rule	Morocco	2084	only	-	Apr	30	 3:00	-1:00	-
+Rule	Morocco	2084	only	-	Jun	11	 2:00	0	-
+Rule	Morocco	2085	only	-	Apr	22	 3:00	-1:00	-
+Rule	Morocco	2085	only	-	May	27	 2:00	0	-
+Rule	Morocco	2086	only	-	Apr	14	 3:00	-1:00	-
+Rule	Morocco	2086	only	-	May	19	 2:00	0	-
+Rule	Morocco	2087	only	-	Mar	30	 3:00	-1:00	-
+Rule	Morocco	2087	only	-	May	 4	 2:00	0	-
+# For dates after the somewhat-arbitrary cutoff of 2087, assume that
+# Morocco will no longer observe DST.  At some point this table will
+# need to be extended, though quite possibly Morocco will change the
+# rules first.
+
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Africa/Casablanca	-0:30:20 -	LMT	1913 Oct 26
 			 0:00	Morocco	+00/+01	1984 Mar 16
 			 1:00	-	+01	1986
@@ -1001,7 +1113,7 @@ Zone Africa/El_Aaiun	-0:52:48 -	LMT	1934 Jan # El Aaiún
 # https://dre.pt/pdf1sdip/1911/05/12500/23132313.pdf
 # merely made it official?
 #
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Maputo	2:10:20 -	LMT	1903 Mar
 			2:00	-	CAT
 Link Africa/Maputo Africa/Blantyre	# Malawi
@@ -1073,7 +1185,7 @@ Rule	Namibia	1995	2017	-	Apr	Sun>=1	2:00	-1:00	WAT
 #Rule	Namibia	1995	2017	-	Apr	Sun>=1	2:00	0	WAT
 # End of rearguard section.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Windhoek	1:08:24 -	LMT	1892 Feb 8
 			1:30	-	+0130	1903 Mar
 			2:00	-	SAST	1942 Sep 20  2:00
@@ -1094,7 +1206,7 @@ Zone	Africa/Windhoek	1:08:24 -	LMT	1892 Feb 8
 # See Africa/Lagos.
 
 # Nigeria
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Lagos	0:13:36 -	LMT	1919 Sep
 			1:00	-	WAT
 Link Africa/Lagos Africa/Bangui	     # Central African Republic
@@ -1108,7 +1220,7 @@ Link Africa/Lagos Africa/Niamey	     # Niger
 Link Africa/Lagos Africa/Porto-Novo  # Benin
 
 # Réunion
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Indian/Reunion	3:41:52 -	LMT	1911 Jun # Saint-Denis
 			4:00	-	+04
 #
@@ -1168,7 +1280,7 @@ Zone	Africa/Sao_Tome	 0:26:56 -	LMT	1884
 # See Africa/Abidjan.
 
 # Seychelles
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Indian/Mahe	3:41:48 -	LMT	1906 Jun # Victoria
 			4:00	-	+04
 # From Paul Eggert (2001-05-30):
@@ -1188,7 +1300,7 @@ Zone	Indian/Mahe	3:41:48 -	LMT	1906 Jun # Victoria
 # Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
 Rule	SA	1942	1943	-	Sep	Sun>=15	2:00	1:00	-
 Rule	SA	1943	1944	-	Mar	Sun>=15	2:00	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Africa/Johannesburg 1:52:00 -	LMT	1892 Feb 8
 			1:30	-	SAST	1903 Mar
 			2:00	SA	SAST
@@ -1223,14 +1335,14 @@ Rule	Sudan	1970	only	-	May	 1	0:00	1:00	S
 Rule	Sudan	1970	1985	-	Oct	15	0:00	0	-
 Rule	Sudan	1971	only	-	Apr	30	0:00	1:00	S
 Rule	Sudan	1972	1985	-	Apr	lastSun	0:00	1:00	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Khartoum	2:10:08 -	LMT	1931
 			2:00	Sudan	CA%sT	2000 Jan 15 12:00
 			3:00	-	EAT	2017 Nov  1
 			2:00	-	CAT
 
 # South Sudan
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Juba	2:06:28 -	LMT	1931
 			2:00	Sudan	CA%sT	2000 Jan 15 12:00
 			3:00	-	EAT
@@ -1336,7 +1448,7 @@ Rule	Tunisia	2006	2008	-	Oct	lastSun	 2:00s	0	-
 # Shanks & Pottenger give 0:09:20 for Paris Mean Time; go with Howse's
 # more precise 0:09:21.
 # Shanks & Pottenger say the 1911 switch was on Mar 9; go with Howse's Mar 11.
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
 			1:00	Tunisia	CE%sT
diff --git a/tz/antarctica b/tz/antarctica
index 1dd9b00..2059983 100644
--- a/tz/antarctica
+++ b/tz/antarctica
@@ -13,7 +13,7 @@
 # for information.
 # Unless otherwise specified, we have no time zone information.
 
-# FORMAT is '-00' and GMTOFF is 0 for locations while uninhabited.
+# FORMAT is '-00' and STDOFF is 0 for locations while uninhabited.
 
 # Argentina - year-round bases
 # Belgrano II, Confin Coast, -770227-0343737, since 1972-02-05
@@ -70,7 +70,7 @@
 # Australian Antarctica Division informed us that Casey changed time
 # zone to UTC+11 in "the morning of 22nd October 2016".
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Antarctica/Casey	0	-	-00	1969
 			8:00	-	+08	2009 Oct 18  2:00
 			11:00	-	+11	2010 Mar  5  2:00
@@ -142,7 +142,7 @@ Zone Antarctica/Mawson	0	-	-00	1954 Feb 13
 # St Paul Island - near Amsterdam, uninhabited
 #	fishing stations operated variously 1819/1931
 #
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Indian/Kerguelen	0	-	-00	1950 # Port-aux-Français
 			5:00	-	+05
 #
@@ -153,7 +153,7 @@ Zone Indian/Kerguelen	0	-	-00	1950 # Port-aux-Français
 # Another base at Port-Martin, 50km east, began operation in 1947.
 # It was destroyed by fire on 1952-01-14.
 #
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Antarctica/DumontDUrville 0 -	-00	1947
 			10:00	-	+10	1952 Jan 14
 			0	-	-00	1956 Nov
@@ -181,7 +181,7 @@ Zone Antarctica/DumontDUrville 0 -	-00	1947
 # 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		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Antarctica/Syowa	0	-	-00	1957 Jan 29
 			3:00	-	+03
 # See:
@@ -231,7 +231,7 @@ Rule	Troll	2005	max	-	Mar	lastSun	1:00u	2:00	+02
 #Rule	Troll	2004	max	-	Nov	 7	1:00u	0:00	+00
 # Remove the following line when uncommenting the above '#Rule' lines.
 Rule	Troll	2004	max	-	Oct	lastSun	1:00u	0:00	+00
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Antarctica/Troll	0	-	-00	2005 Feb 12
 			0:00	Troll	%s
 
@@ -305,7 +305,7 @@ Zone Antarctica/Vostok	0	-	-00	1957 Dec 16
 # From Paul Eggert (2002-10-22)
 # <http://webexhibits.org/daylightsaving/g.html> says Rothera is -03 all year.
 #
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Antarctica/Rothera	0	-	-00	1976 Dec  1
 			-3:00	-	-03
 
diff --git a/tz/asia b/tz/asia
index d790da5..348e2b5 100644
--- a/tz/asia
+++ b/tz/asia
@@ -84,7 +84,7 @@ Rule RussiaAsia	1985	2010	-	Mar	lastSun	 2:00s	1:00	-
 Rule RussiaAsia	1996	2010	-	Oct	lastSun	 2:00s	0	-
 
 # Afghanistan
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Kabul	4:36:48 -	LMT	1890
 			4:00	-	+04	1945
 			4:30	-	+0430
@@ -117,7 +117,7 @@ Zone	Asia/Kabul	4:36:48 -	LMT	1890
 # Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
 Rule Armenia	2011	only	-	Mar	lastSun	 2:00s	1:00	-
 Rule Armenia	2011	only	-	Oct	lastSun	 2:00s	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Yerevan	2:58:00 -	LMT	1924 May  2
 			3:00	-	+03	1957 Mar
 			4:00 RussiaAsia +04/+05	1991 Mar 31  2:00s
@@ -143,7 +143,7 @@ Zone	Asia/Yerevan	2:58:00 -	LMT	1924 May  2
 # Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
 Rule	Azer	1997	2015	-	Mar	lastSun	 4:00	1:00	-
 Rule	Azer	1997	2015	-	Oct	lastSun	 5:00	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Baku	3:19:24 -	LMT	1924 May  2
 			3:00	-	+03	1957 Mar
 			4:00 RussiaAsia +04/+05	1991 Mar 31  2:00s
@@ -231,7 +231,7 @@ Zone	Asia/Baku	3:19:24 -	LMT	1924 May  2
 Rule	Dhaka	2009	only	-	Jun	19	23:00	1:00	-
 Rule	Dhaka	2009	only	-	Dec	31	24:00	0	-
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Dhaka	6:01:40 -	LMT	1890
 			5:53:20	-	HMT	1941 Oct    # Howrah Mean Time?
 			6:30	-	+0630	1942 May 15
@@ -241,7 +241,7 @@ Zone	Asia/Dhaka	6:01:40 -	LMT	1890
 			6:00	Dhaka	+06/+07
 
 # Bhutan
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Thimphu	5:58:36 -	LMT	1947 Aug 15 # or Thimbu
 			5:30	-	+0530	1987 Oct
 			6:00	-	+06
@@ -252,13 +252,13 @@ Zone	Asia/Thimphu	5:58:36 -	LMT	1947 Aug 15 # or Thimbu
 # We have no information as to when standard time was introduced;
 # assume it occurred in 1907, the same year as Mauritius (which
 # then contained the Chagos Archipelago).
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Indian/Chagos	4:49:40	-	LMT	1907
 			5:00	-	+05	1996
 			6:00	-	+06
 
 # Brunei
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -273,7 +273,7 @@ Zone	Asia/Brunei	7:39:40 -	LMT	1926 Mar # Bandar Seri Begawan
 # of Greenwich."  This refers to the period before Burma's transition to +0630,
 # a transition for which Shanks is the only source.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Yangon	6:24:47 -	LMT	1880        # or Rangoon
 			6:24:47	-	RMT	1920        # Rangoon local time
 			6:30	-	+0630	1942 May
@@ -561,7 +561,7 @@ Rule	PRC	1987	1991	-	Apr	Sun>=11	 2:00	1:00	D
 # that the sort of users who prefer Asia/Urumqi now typically ignored the
 # +08 mandate back then.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -652,11 +652,41 @@ Zone	Asia/Urumqi	5:50:20	-	LMT	1928
 #   https://i.imgur.com/05KkvtC.png
 # * 1941-09-30, Hong Kong Daily Press, Winter Time Warning.
 #   https://i.imgur.com/dge4kFJ.png
-# Also, the Liberation day of Hong Kong after WWII which British rule
-# over the territory resumed was August 30, 1945, which I think should
-# be the termination date for the use of JST in the territory....
 
-# From Paul Eggert (2018-11-17):
+# From P Chan (2018-12-31):
+# * According to the Hong Kong Daylight-Saving Regulations, 1941, the
+#   1941 spring-forward transition was at 03:00.
+#	http://sunzi.lib.hku.hk/hkgro/view/g1941/304271.pdf
+#	http://sunzi.lib.hku.hk/hkgro/view/g1941/305516.pdf
+# * According to some articles from South China Morning Post, +08 was
+#   resumed on 1945-11-18 at 02:00.
+#	https://i.imgur.com/M2IsZ3c.png
+#	https://i.imgur.com/iOPqrVo.png
+#	https://i.imgur.com/fffcGDs.png
+# * Some newspapers ... said the 1946 spring-forward transition was on
+#   04-21 at 00:00.  The Kung Sheung Evening News 1946-04-20 (Chinese)
+#	https://i.imgur.com/ZSzent0.png
+#	https://mmis.hkpl.gov.hk///c/portal/cover?c=QF757YsWv5%2FH7zGe%2FKF%2BFLYsuqGhRBfe p.4
+#   The Kung Sheung Daily News 1946-04-21 (Chinese)
+#	https://i.imgur.com/7ecmRlcm.png
+#	https://mmis.hkpl.gov.hk///c/portal/cover?c=QF757YsWv5%2BQBGt1%2BwUj5qG2GqtwR3Wh p.4
+# * According to the Summer Time Ordinance (1946), the fallback
+#   transitions between 1946 and 1952 were at 03:30 Standard Time (+08)
+#	http://oelawhk.lib.hku.hk/archive/files/bb74b06a74d5294620a15de560ab33c6.pdf
+# * Some other laws and regulations related to DST from 1953 to 1979
+#   Summer Time Ordinance 1953
+#	https://i.imgur.com/IOlJMav.jpg
+#   Summer Time (Amendment) Ordinance 1965
+#	https://i.imgur.com/8rofeLa.jpg
+#   Interpretation and General Clauses Ordinance (1966)
+#	https://i.imgur.com/joy3msj.jpg
+#   Emergency (Summer Time) Regulation 1973 <https://i.imgur.com/OpRWrKz.jpg>
+#   Interpretation and General Clauses (Amendment) Ordinance 1977
+#	https://i.imgur.com/RaNqnc4.jpg
+#   Resolution of the Legislative Council passed on 9 May 1979
+#	https://www.legco.gov.hk/yr78-79/english/lc_sitg/hansard/h790509.pdf#page=39
+
+# From Paul Eggert (2019-05-31):
 # Here are the dates given at
 # https://www.hko.gov.hk/gts/time/Summertime.htm
 # as of 2014-06-19:
@@ -667,7 +697,7 @@ Zone	Asia/Urumqi	5:50:20	-	LMT	1928
 # 1944        Whole year
 # 1945        Whole year
 # 1946        20 Apr to 1 Dec
-# 1947        13 Apr to 30 Dec
+# 1947        13 Apr to 30 Nov
 # 1948        2 May to 31 Oct
 # 1949        3 Apr to 30 Oct
 # 1950        2 Apr to 29 Oct
@@ -704,36 +734,28 @@ Zone	Asia/Urumqi	5:50:20	-	LMT	1928
 # The page does not give times of day for transitions,
 # or dates for the 1942 and 1945 transitions.
 # The Japanese occupation of Hong Kong began 1941-12-25.
-# The Japanese surrender of Hong Kong was signed 1945-09-16; see:
-# Heaver S. The days after the Pacific war ended: unsettling times
-# in Hong Kong. Post Magazine. 2016-06-13.
-# https://www.scmp.com/magazines/post-magazine/article/1852990/days-after-pacific-war-ended-unsettling-times-hong-kong
-# For lack of anything better, use start of those days as the
-# transition times.
 
 # Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
-Rule	HK	1946	only	-	Apr	20	3:30	1:00	S
-Rule	HK	1946	only	-	Dec	1	3:30	0	-
-Rule	HK	1947	only	-	Apr	13	3:30	1:00	S
-Rule	HK	1947	only	-	Dec	30	3:30	0	-
-Rule	HK	1948	only	-	May	2	3:30	1:00	S
-Rule	HK	1948	1951	-	Oct	lastSun	3:30	0	-
-Rule	HK	1952	1953	-	Nov	Sun>=1	3:30	0	-
+Rule	HK	1946	only	-	Apr	21	0:00	1:00	S
+Rule	HK	1946	only	-	Dec	1	3:30s	0	-
+Rule	HK	1947	only	-	Apr	13	3:30s	1:00	S
+Rule	HK	1947	only	-	Nov	30	3:30s	0	-
+Rule	HK	1948	only	-	May	2	3:30s	1:00	S
+Rule	HK	1948	1952	-	Oct	Sun>=28	3:30s	0	-
 Rule	HK	1949	1953	-	Apr	Sun>=1	3:30	1:00	S
+Rule	HK	1953	1964	-	Oct	Sun>=31	3:30	0	-
 Rule	HK	1954	1964	-	Mar	Sun>=18	3:30	1:00	S
-Rule	HK	1954	only	-	Oct	31	3:30	0	-
-Rule	HK	1955	1964	-	Nov	Sun>=1	3:30	0	-
 Rule	HK	1965	1976	-	Apr	Sun>=16	3:30	1:00	S
 Rule	HK	1965	1976	-	Oct	Sun>=16	3:30	0	-
 Rule	HK	1973	only	-	Dec	30	3:30	1:00	S
-Rule	HK	1979	only	-	May	Sun>=8	3:30	1:00	S
-Rule	HK	1979	only	-	Oct	Sun>=16	3:30	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+Rule	HK	1979	only	-	May	13	3:30	1:00	S
+Rule	HK	1979	only	-	Oct	21	3:30	0	-
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Hong_Kong	7:36:42 -	LMT	1904 Oct 30  0:36:42
-			8:00	-	HKT	1941 Jun 15  3:30
+			8:00	-	HKT	1941 Jun 15  3:00
 			8:00	1:00	HKST	1941 Oct  1  4:00
 			8:30	-	HKT	1941 Dec 25
-			9:00	-	JST	1945 Sep 16
+			9:00	-	JST	1945 Nov 18  2:00
 			8:00	HK	HK%sT
 
 ###############################################################################
@@ -857,7 +879,7 @@ Rule	Taiwan	1974	1975	-	Oct	1	0:00	0	S
 Rule	Taiwan	1979	only	-	Jul	1	0:00	1:00	D
 Rule	Taiwan	1979	only	-	Oct	1	0:00	0	S
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 # Taipei or Taibei or T'ai-pei
 Zone	Asia/Taipei	8:06:00 -	LMT	1896 Jan  1
 			8:00	-	CST	1937 Oct  1
@@ -995,7 +1017,7 @@ Rule	Macau	1975	1976	-	Apr	Sun>=16	03:30	1:00	D
 Rule	Macau	1979	only	-	May	13	03:30	1:00	D
 Rule	Macau	1979	only	-	Oct	Sun>=16	03:30	0	S
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Macau	7:34:10 -	LMT	1904 Oct 30
 			8:00	-	CST	1941 Dec 21 23:00
 			9:00	Macau	+09/+10	1945 Sep 30 24:00
@@ -1034,7 +1056,7 @@ Rule	Cyprus	1977	only	-	Sep	25	0:00	0	-
 Rule	Cyprus	1978	only	-	Oct	2	0:00	0	-
 Rule	Cyprus	1979	1997	-	Sep	lastSun	0:00	0	-
 Rule	Cyprus	1981	1998	-	Mar	lastSun	0:00	1:00	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Nicosia	2:13:28 -	LMT	1921 Nov 14
 			2:00	Cyprus	EE%sT	1998 Sep
 			2:00	EUAsia	EE%sT
@@ -1083,7 +1105,7 @@ Link	Asia/Nicosia	Europe/Nicosia
 # Byalokoz 1919 says Georgia was 2:59:11.
 # Go with Byalokoz.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Tbilisi	2:59:11 -	LMT	1880
 			2:59:11	-	TBMT	1924 May  2 # Tbilisi Mean Time
 			3:00	-	+03	1957 Mar
@@ -1120,7 +1142,7 @@ Zone	Asia/Tbilisi	2:59:11 -	LMT	1880
 # which will be permanent, with no seasonal adjustment, will happen at
 # midnight on Saturday, September 16.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Dili	8:22:20 -	LMT	1912 Jan  1
 			8:00	-	+08	1942 Feb 21 23:00
 			9:00	-	+09	1976 May  3
@@ -1186,7 +1208,7 @@ Zone	Asia/Dili	8:22:20 -	LMT	1912 Jan  1
 # time for 1870-1941.  Shanks is our only (and dubious) source for the
 # 1941-1945 data.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Kolkata	5:53:28 -	LMT	1854 Jun 28 # Kolkata
 			5:53:20	-	HMT	1870	    # Howrah Mean Time?
 			5:21:10	-	MMT	1906 Jan  1 # Madras local time
@@ -1238,7 +1260,7 @@ Zone	Asia/Kolkata	5:53:28 -	LMT	1854 Jun 28 # Kolkata
 # WITA - +08 - Waktu Indonesia Tengah (Indonesia central time)
 # WIT  - +09 - Waktu Indonesia Timur (Indonesia eastern time)
 #
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 # Java, Sumatra
 Zone Asia/Jakarta	7:07:12 -	LMT	1867 Aug 10
 # Shanks & Pottenger say the next transition was at 1924 Jan 1 0:13,
@@ -1314,9 +1336,9 @@ Zone Asia/Jayapura	9:22:48 -	LMT	1932 Nov
 # I used the following code in GNU Emacs 26.1 to generate the "Rule Iran"
 # lines from 2008 through 2087.  Emacs 26.1 uses Ed Reingold's
 # cal-persia implementation of Birashk's approximation, which in the
-# 2008-2087 range disagrees with the the astronomical Persian calendar
-# for Persian years 1404 (Gregorian 2025) and 1437 (Gregorian 2058),
-# so the following code special-case those years.  See Table 15.1, page 264, of:
+# 2008-2087 range disagrees with the astronomical Persian calendar
+# for Persian years 1404 (Gregorian 2025) and 1437 (Gregorian 2058), so
+# the following code special-cases those years.  See Table 15.1, page 264, of:
 # Edward M. Reingold and Nachum Dershowitz, Calendrical Calculations:
 # The Ultimate Edition, Cambridge University Press (2018).
 # https://www.cambridge.org/fr/academic/subjects/computer-science/computing-general-interest/calendrical-calculations-ultimate-edition-4th-edition
@@ -1510,7 +1532,7 @@ Rule	Iran	2087	only	-	Sep	21	24:00	0	-
 Rule	Iran	2088	max	-	Mar	20	24:00	1:00	-
 Rule	Iran	2088	max	-	Sep	20	24:00	0	-
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Tehran	3:25:44	-	LMT	1916
 			3:25:44	-	TMT	1946     # Tehran Mean Time
 			3:30	-	+0330	1977 Nov
@@ -1555,7 +1577,7 @@ Rule	Iraq	1986	1990	-	Mar	lastSun	1:00s	1:00	-
 #
 Rule	Iraq	1991	2007	-	Apr	 1	3:00s	1:00	-
 Rule	Iraq	1991	2007	-	Oct	 1	3:00s	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Baghdad	2:57:40	-	LMT	1890
 			2:57:36	-	BMT	1918     # Baghdad Mean Time?
 			3:00	-	+03	1982 May
@@ -1622,7 +1644,7 @@ Rule	Zion	1975	only	-	Apr	20	0:00	1:00	D
 Rule	Zion	1975	only	-	Aug	31	0:00	0	S
 
 # From Alois Treindl (2019-03-06):
-# http://www.moin.gov.il/Documents/שעון קיץ/clock-50-years-7-2014.pdf
+# http://www.moin.gov.il/Documents/שעון%20קיץ/clock-50-years-7-2014.pdf
 # From Isaac Starkman (2019-03-06):
 # Summer time was in that period in 1980 and 1984, see
 # https://www.ynet.co.il/articles/0,7340,L-3951073,00.html
@@ -1760,32 +1782,15 @@ Rule	Zion	2004	only	-	Sep	22	1:00	0	S
 #
 #	ftp://ftp.cs.huji.ac.il/pub/tz/announcements/2005+beyond.ps
 
-# From Paul Eggert (2012-10-26):
-# I used Ephraim Silverberg's dst-israel.el program
-# <ftp://ftp.cs.huji.ac.il/pub/tz/software/dst-israel.el> (2005-02-20)
-# along with Ed Reingold's cal-hebrew in GNU Emacs 21.4,
-# to generate the transitions from 2005 through 2012.
-# (I replaced "lastFri" with "Fri>=26" by hand.)
-# The spring transitions all correspond to the following Rule:
-#
-# Rule	Zion	2005	2012	-	Mar	Fri>=26	2:00	1:00	D
-#
-# but older zic implementations (e.g., Solaris 8) do not support
-# "Fri>=26" to mean April 1 in years like 2005, so for now we list the
-# springtime transitions explicitly.
-
 # Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
-Rule	Zion	2005	only	-	Apr	 1	2:00	1:00	D
+Rule	Zion	2005	2012	-	Apr	Fri<=1	2:00	1:00	D
 Rule	Zion	2005	only	-	Oct	 9	2:00	0	S
-Rule	Zion	2006	2010	-	Mar	Fri>=26	2:00	1:00	D
 Rule	Zion	2006	only	-	Oct	 1	2:00	0	S
 Rule	Zion	2007	only	-	Sep	16	2:00	0	S
 Rule	Zion	2008	only	-	Oct	 5	2:00	0	S
 Rule	Zion	2009	only	-	Sep	27	2:00	0	S
 Rule	Zion	2010	only	-	Sep	12	2:00	0	S
-Rule	Zion	2011	only	-	Apr	 1	2:00	1:00	D
 Rule	Zion	2011	only	-	Oct	 2	2:00	0	S
-Rule	Zion	2012	only	-	Mar	Fri>=26	2:00	1:00	D
 Rule	Zion	2012	only	-	Sep	23	2:00	0	S
 
 # From Ephraim Silverberg (2013-06-27):
@@ -1801,7 +1806,7 @@ Rule	Zion	2012	only	-	Sep	23	2:00	0	S
 Rule	Zion	2013	max	-	Mar	Fri>=23	2:00	1:00	D
 Rule	Zion	2013	max	-	Oct	lastSun	2:00	0	S
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Jerusalem	2:20:54 -	LMT	1880
 			2:20:40	-	JMT	1918 # Jerusalem Mean Time?
 			2:00	Zion	I%sT
@@ -1893,7 +1898,7 @@ Rule	Japan	1950	1951	-	May	Sat>=1	24:00	1:00	D
 # Central Time (UT+9). The adoption began on Oct 1, 1937.
 # https://ja.wikisource.org/wiki/明治二十八年勅令第百六十七號標準時ニ關スル件中改正ノ件
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Tokyo	9:18:59	-	LMT	1887 Dec 31 15:00u
 			9:00	Japan	J%sT
 # Since 1938, all Japanese possessions have been like Asia/Tokyo,
@@ -1996,7 +2001,7 @@ Rule	Jordan	2006	2011	-	Oct	lastFri	0:00s	0	-
 Rule	Jordan	2013	only	-	Dec	20	0:00	0	-
 Rule	Jordan	2014	max	-	Mar	lastThu	24:00	1:00	S
 Rule	Jordan	2014	max	-	Oct	lastFri	0:00s	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Amman	2:23:44 -	LMT	1931
 			2:00	Jordan	EE%sT
 
@@ -2037,8 +2042,8 @@ Zone	Asia/Amman	2:23:44 -	LMT	1931
 # text.
 #
 # According to Izvestia newspaper No. 68 (23334) from 1991-03-20
-# (page 6; available at http://libinfo.org/newsr/newsr2574.djvu via
-# http://libinfo.org/index.php?id=58564) on 1991-03-31 at 2:00 during
+# -- page 6; available at http://libinfo.org/newsr/newsr2574.djvu via
+# http://libinfo.org/index.php?id=58564 -- on 1991-03-31 at 2:00 during
 # transition to "summer" time:
 # Republic of Georgia, Latvian SSR, Lithuanian SSR, SSR Moldova,
 # Estonian SSR; Komi ASSR; Kaliningrad oblast; Nenets autonomous okrug
@@ -2054,7 +2059,7 @@ Zone	Asia/Amman	2:23:44 -	LMT	1931
 # Apparently there were last minute changes. Apparently Kazakh act No. 170
 # was one of such changes.
 #
-# https://ru.wikipedia.org/wiki/Декретное время
+# https://ru.wikipedia.org/wiki/Декретное_время
 # claims that Sovetskaya Rossiya newspaper on 1991-03-29 published that
 # Nenets autonomous okrug, Komi and Kazakhstan (excluding Uralsk oblast)
 # were to not move clocks and Uralsk oblast was to move clocks
@@ -2193,7 +2198,7 @@ Zone	Asia/Amman	2:23:44 -	LMT	1931
 # UTC+6 to UTC+5 effective December 21st, 2018. The legal document is
 # located here: http://adilet.zan.kz/rus/docs/P1800000817 (russian language).
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 #
 # Almaty (formerly Alma-Ata), representing most locations in Kazakhstan
 # This includes KZ-AKM, KZ-ALA, KZ-ALM, KZ-AST, KZ-BAY, KZ-VOS, KZ-ZHA,
@@ -2295,7 +2300,7 @@ Rule	Kyrgyz	1992	1996	-	Apr	Sun>=7	0:00s	1:00	-
 Rule	Kyrgyz	1992	1996	-	Sep	lastSun	0:00	0	-
 Rule	Kyrgyz	1997	2005	-	Mar	lastSun	2:30	1:00	-
 Rule	Kyrgyz	1997	2004	-	Oct	lastSun	2:30	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Bishkek	4:58:24 -	LMT	1924 May  2
 			5:00	-	+05	1930 Jun 21
 			6:00 RussiaAsia +06/+07	1991 Mar 31  2:00s
@@ -2410,7 +2415,7 @@ Rule	ROK	1987	1988	-	Oct	Sun>=8	 3:00	0	S
 # The BBC reported that the transition was from 23:30 to 24:00 today.
 # https://www.bbc.com/news/world-asia-44010705
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Seoul	8:27:52	-	LMT	1908 Apr  1
 			8:30	-	KST	1912 Jan  1
 			9:00	-	JST	1945 Sep  8
@@ -2459,7 +2464,7 @@ Rule	Lebanon	1992	only	-	Oct	4	0:00	0	-
 Rule	Lebanon	1993	max	-	Mar	lastSun	0:00	1:00	S
 Rule	Lebanon	1993	1998	-	Sep	lastSun	0:00	0	-
 Rule	Lebanon	1999	max	-	Oct	lastSun	0:00	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Beirut	2:22:00 -	LMT	1880
 			2:00	Lebanon	EE%sT
 
@@ -2471,7 +2476,7 @@ 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		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -2485,7 +2490,7 @@ Zone Asia/Kuala_Lumpur	6:46:46 -	LMT	1901 Jan  1
 # 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		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -2493,7 +2498,7 @@ Zone Asia/Kuching	7:21:20	-	LMT	1926 Mar
 			8:00	-	+08
 
 # Maldives
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -2636,7 +2641,7 @@ Rule	Mongol	2002	2006	-	Mar	lastSat	2:00	1:00	-
 Rule	Mongol	2015	2016	-	Mar	lastSat	2:00	1:00	-
 Rule	Mongol	2015	2016	-	Sep	lastSat	0:00	0	-
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 # Hovd, a.k.a. Chovd, Dund-Us, Dzhargalant, Khovd, Jirgalanta
 Zone	Asia/Hovd	6:06:36 -	LMT	1905 Aug
 			6:00	-	+06	1978
@@ -2654,7 +2659,7 @@ Zone	Asia/Choibalsan	7:38:00 -	LMT	1905 Aug
 			8:00	Mongol	+08/+09
 
 # Nepal
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Kathmandu	5:41:16 -	LMT	1920
 			5:30	-	+0530	1986
 			5:45	-	+0545
@@ -2804,7 +2809,7 @@ Rule Pakistan	2008	only	-	Jun	1	0:00	1:00	S
 Rule Pakistan	2008	2009	-	Nov	1	0:00	0	-
 Rule Pakistan	2009	only	-	Apr	15	0:00	1:00	S
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Karachi	4:28:12 -	LMT	1907
 			5:30	-	+0530	1942 Sep
 			5:30	1:00	+0630	1945 Oct 15
@@ -3091,13 +3096,21 @@ Zone	Asia/Karachi	4:28:12 -	LMT	1907
 # http://www.palestinecabinet.gov.ps/Website/AR/NDecrees/ViewFile.ashx?ID=e7a42ab7-ee23-435a-b9c8-a4f7e81f3817
 
 # From Even Scharning (2019-03-23):
-# DST in Palestine will start on 30 March this year, not 23 March as the time
-# zone database predicted.
-# https://ramallah.news/post/123610
+# http://pnn.ps/news/401130
+# http://palweather.ps/ar/node/50136.html
+#
+# From Sharif Mustafa (2019-03-26):
+# The Palestinian cabinet announced today that the switch to DST will
+# be on Fri Mar 29th 2019 by advancing the clock by 60 minutes.
+# The decree signing date is Mar 12th but it was not published till today.
+# The decree does not specify the exact time of switch.
+# http://palestinecabinet.gov.ps/Website/AR/NDecrees/ViewFile.ashx?ID=e54e9ea1-50ee-4137-84df-0d6c78da259b
+#
+# From Even Scharning (2019-04-10):
+# Our source in Palestine said it happened Friday 29 at 00:00 local time....
 #
-# From Tim Parenti (2019-03-23):
-# Combining this with the rules observed since 2016, adjust our spring
-# transition guess to Mar Sat>=24.
+# From Paul Eggert (2019-04-10):
+# For now, guess spring-ahead transitions are March's last Friday at 00:00.
 
 # Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
 Rule EgyptAsia	1957	only	-	May	10	0:00	1:00	S
@@ -3128,10 +3141,11 @@ Rule Palestine	2012	only	-	Sep	21	1:00	0	-
 Rule Palestine	2013	only	-	Sep	Fri>=21	0:00	0	-
 Rule Palestine	2014	2015	-	Oct	Fri>=21	0:00	0	-
 Rule Palestine	2015	only	-	Mar	lastFri	24:00	1:00	S
-Rule Palestine	2016	max	-	Mar	Sat>=24	1:00	1:00	S
+Rule Palestine	2016	2018	-	Mar	Sat>=24	1:00	1:00	S
 Rule Palestine	2016	max	-	Oct	lastSat	1:00	0	-
+Rule Palestine	2019	max	-	Mar	lastFri	0:00	1:00	S
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Gaza	2:17:52	-	LMT	1900 Oct
 			2:00	Zion	EET/EEST 1948 May 15
 			2:00 EgyptAsia	EE%sT	1967 Jun  5
@@ -3205,7 +3219,7 @@ Rule	Phil	1954	only	-	Apr	12	0:00	1:00	D
 Rule	Phil	1954	only	-	Jul	1	0:00	0	S
 Rule	Phil	1978	only	-	Mar	22	0:00	1:00	D
 Rule	Phil	1978	only	-	Sep	21	0:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Manila	-15:56:00 -	LMT	1844 Dec 31
 			8:04:00 -	LMT	1899 May 11
 			8:00	Phil	P%sT	1942 May
@@ -3213,7 +3227,7 @@ Zone	Asia/Manila	-15:56:00 -	LMT	1844 Dec 31
 			8:00	Phil	P%sT
 
 # Qatar
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Qatar	3:26:08 -	LMT	1920     # Al Dawhah / Doha
 			4:00	-	+04	1972 Jun
 			3:00	-	+03
@@ -3261,7 +3275,7 @@ Link Asia/Qatar Asia/Bahrain
 # the country.  Presumably this is documenting airline time.  Ignore this,
 # as it's before our 1970 cutoff.
 #
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Riyadh	3:06:52 -	LMT	1947 Mar 14
 			3:00	-	+03
 Link Asia/Riyadh Asia/Aden	# Yemen
@@ -3270,7 +3284,7 @@ Link Asia/Riyadh Asia/Kuwait
 # Singapore
 # taken from Mok Ly Yng (2003-10-30)
 # http://www.math.nus.edu.sg/aslaksen/teaching/timezone.html
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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.
 			7:00	-	+07	1933 Jan  1
@@ -3334,7 +3348,7 @@ Zone	Asia/Singapore	6:55:25 -	LMT	1901 Jan  1
 # even worse.  For now, let's use a numeric abbreviation; we can
 # switch to "SLST" if it catches on.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Colombo	5:19:24 -	LMT	1880
 			5:19:32	-	MMT	1906        # Moratuwa Mean Time
 			5:30	-	+0530	1942 Jan  5
@@ -3504,13 +3518,13 @@ Rule	Syria	2010	2011	-	Apr	Fri>=1	0:00	1:00	S
 Rule	Syria	2012	max	-	Mar	lastFri	0:00	1:00	S
 Rule	Syria	2009	max	-	Oct	lastFri	0:00	0	-
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Damascus	2:25:12 -	LMT	1920 # Dimashq
 			2:00	Syria	EE%sT
 
 # Tajikistan
 # From Shanks & Pottenger.
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Dushanbe	4:35:12 -	LMT	1924 May  2
 			5:00	-	+05	1930 Jun 21
 			6:00 RussiaAsia +06/+07	1991 Mar 31  2:00s
@@ -3518,7 +3532,7 @@ Zone	Asia/Dushanbe	4:35:12 -	LMT	1924 May  2
 			5:00	-	+05
 
 # Thailand
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -3527,7 +3541,7 @@ Link Asia/Bangkok Asia/Vientiane	# Laos
 
 # Turkmenistan
 # From Shanks & Pottenger.
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Ashgabat	3:53:32 -	LMT	1924 May  2 # or Ashkhabad
 			4:00	-	+04	1930 Jun 21
 			5:00 RussiaAsia	+05/+06	1991 Mar 31  2:00
@@ -3535,14 +3549,14 @@ Zone	Asia/Ashgabat	3:53:32 -	LMT	1924 May  2 # or Ashkhabad
 			5:00	-	+05
 
 # United Arab Emirates
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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.
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Samarkand	4:27:53 -	LMT	1924 May  2
 			4:00	-	+04	1930 Jun 21
 			5:00	-	+05	1981 Apr  1
@@ -3608,7 +3622,7 @@ Zone	Asia/Tashkent	4:37:11 -	LMT	1924 May  2
 # Lê Thành Lân: "Lịch hai thế kỷ (1802-2010) và các lịch vĩnh cửu",
 # NXB Thuận Hoá, Huế, 1995.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Asia/Ho_Chi_Minh	7:06:40 -	LMT	1906 Jul  1
 			7:06:30	-	PLMT	1911 May  1 # Phù Liễn MT
 			7:00	-	+07	1942 Dec 31 23:00
diff --git a/tz/australasia b/tz/australasia
index dfe73d3..0544e58 100644
--- a/tz/australasia
+++ b/tz/australasia
@@ -25,7 +25,7 @@ Rule	Aus	1943	only	-	Oct	 3	2:00	1:00	D
 # says W Australia didn't use DST in 1943/1944.  Ignore Whitman's claim that
 # 1944/1945 was just like 1943/1944.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 # Northern Territory
 Zone Australia/Darwin	 8:43:20 -	LMT	1895 Feb
 			 9:00	-	ACST	1899 May
@@ -102,7 +102,7 @@ Rule	AS	2006	only	-	Apr	2	2:00s	0	S
 Rule	AS	2007	only	-	Mar	lastSun	2:00s	0	S
 Rule	AS	2008	max	-	Apr	Sun>=1	2:00s	0	S
 Rule	AS	2008	max	-	Oct	Sun>=1	2:00s	1:00	D
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Australia/Adelaide	9:14:20 -	LMT	1895 Feb
 			9:00	-	ACST	1899 May
 			9:30	Aus	AC%sT	1971
@@ -134,7 +134,7 @@ Rule	AT	2001	max	-	Oct	Sun>=1	2:00s	1:00	D
 Rule	AT	2006	only	-	Apr	Sun>=1	2:00s	0	S
 Rule	AT	2007	only	-	Mar	lastSun	2:00s	0	S
 Rule	AT	2008	max	-	Apr	Sun>=1	2:00s	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Australia/Hobart	9:49:16	-	LMT	1895 Sep
 			10:00	-	AEST	1916 Oct  1  2:00
 			10:00	1:00	AEDT	1917 Feb
@@ -162,7 +162,7 @@ Rule	AV	2006	only	-	Apr	Sun>=1	2:00s	0	S
 Rule	AV	2007	only	-	Mar	lastSun	2:00s	0	S
 Rule	AV	2008	max	-	Apr	Sun>=1	2:00s	0	S
 Rule	AV	2008	max	-	Oct	Sun>=1	2:00s	1:00	D
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Australia/Melbourne 9:39:52 -	LMT	1895 Feb
 			10:00	Aus	AE%sT	1971
 			10:00	AV	AE%sT
@@ -185,7 +185,7 @@ Rule	AN	2006	only	-	Apr	Sun>=1	2:00s	0	S
 Rule	AN	2007	only	-	Mar	lastSun	2:00s	0	S
 Rule	AN	2008	max	-	Apr	Sun>=1	2:00s	0	S
 Rule	AN	2008	max	-	Oct	Sun>=1	2:00s	1:00	D
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Australia/Sydney	10:04:52 -	LMT	1895 Feb
 			10:00	Aus	AE%sT	1971
 			10:00	AN	AE%sT
@@ -256,14 +256,14 @@ Zone Antarctica/Macquarie 0	-	-00	1899 Nov
 			11:00	-	+11
 
 # Christmas
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Indian/Christmas	7:02:52 -	LMT	1895 Feb
 			7:00	-	+07
 
 # 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		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Indian/Cocos	6:27:40	-	LMT	1900
 			6:30	-	+0630
 
@@ -386,12 +386,12 @@ Rule	Fiji	2012	2013	-	Jan	Sun>=18	3:00	0	-
 Rule	Fiji	2014	only	-	Jan	Sun>=18	2:00	0	-
 Rule	Fiji	2014	max	-	Nov	Sun>=1	2:00	1:00	-
 Rule	Fiji	2015	max	-	Jan	Sun>=13	3:00	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Pacific/Fiji	11:55:44 -	LMT	1915 Oct 26 # Suva
 			12:00	Fiji	+12/+13
 
 # French Polynesia
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -434,7 +434,7 @@ Rule	Guam	1977	only	-	Apr	24	2:00	1:00	D
 # http://documents.guam.gov/wp-content/uploads/E.O.-77-18-Guam-Standard-Time.pdf
 Rule	Guam	1977	only	-	Aug	28	2:00	0	S
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Pacific/Guam	-14:21:00 -	LMT	1844 Dec 31
 			 9:39:00 -	LMT	1901        # Agana
 			10:00	-	GST	1941 Dec 10 # Guam
@@ -444,7 +444,7 @@ Zone	Pacific/Guam	-14:21:00 -	LMT	1844 Dec 31
 Link Pacific/Guam Pacific/Saipan # N Mariana Is
 
 # Kiribati
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -460,7 +460,7 @@ Zone Pacific/Kiritimati	-10:29:20 -	LMT	1901
 # See Pacific/Guam.
 
 # Marshall Is
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -478,7 +478,7 @@ Zone Pacific/Kwajalein	 11:09:20 -	LMT	1901
 			 12:00	-	+12
 
 # Micronesia
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -506,7 +506,7 @@ Zone Pacific/Kosrae	-13:08:04 -	LMT	1844 Dec 31
 			 11:00	-	+11
 
 # Nauru
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Pacific/Nauru	11:07:40 -	LMT	1921 Jan 15 # Uaobe
 			11:30	-	+1130	1942 Aug 29
 			 9:00	-	+09	1945 Sep  8
@@ -520,7 +520,7 @@ Rule	NC	1978	1979	-	Feb	27	0:00	0	-
 Rule	NC	1996	only	-	Dec	 1	2:00s	1:00	-
 # Shanks & Pottenger say the following was at 2:00; go with IATA.
 Rule	NC	1997	only	-	Mar	 2	2:00s	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Pacific/Noumea	11:05:48 -	LMT	1912 Jan 13 # Nouméa
 			11:00	NC	+11/+12
 
@@ -559,7 +559,7 @@ Rule	NZ	2007	max	-	Sep	lastSun	2:00s	1:00	D
 Rule	Chatham	2007	max	-	Sep	lastSun	2:45s	1:00	-
 Rule	NZ	2008	max	-	Apr	Sun>=1	2:00s	0	S
 Rule	Chatham	2008	max	-	Apr	Sun>=1	2:45s	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Pacific/Auckland	11:39:04 -	LMT	1868 Nov  2
 			11:30	NZ	NZ%sT	1946 Jan  1
 			12:00	NZ	NZ%sT
@@ -585,7 +585,7 @@ Link Pacific/Auckland Antarctica/McMurdo
 Rule	Cook	1978	only	-	Nov	12	0:00	0:30	-
 Rule	Cook	1979	1991	-	Mar	Sun>=1	0:00	0	-
 Rule	Cook	1979	1990	-	Oct	lastSun	0:00	0:30	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Pacific/Rarotonga	-10:39:04 -	LMT	1901        # Avarua
 			-10:30	-	-1030	1978 Nov 12
 			-10:00	Cook	-10/-0930
@@ -594,14 +594,14 @@ Zone Pacific/Rarotonga	-10:39:04 -	LMT	1901        # Avarua
 
 
 # Niue
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Pacific/Niue	-11:19:40 -	LMT	1901        # Alofi
 			-11:20	-	-1120	1951
 			-11:30	-	-1130	1978 Oct  1
 			-11:00	-	-11
 
 # Norfolk
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Pacific/Norfolk	11:11:52 -	LMT	1901 # Kingston
 			11:12	-	+1112	1951
 			11:30	-	+1130	1974 Oct 27 02:00
@@ -610,13 +610,13 @@ Zone	Pacific/Norfolk	11:11:52 -	LMT	1901 # Kingston
 			11:00	-	+11
 
 # Palau (Belau)
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
 
 # Papua New Guinea
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -646,7 +646,7 @@ Zone Pacific/Bougainville 10:22:16 -	LMT	1880
 			11:00	-	+11
 
 # Pitcairn
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Pacific/Pitcairn	-8:40:20 -	LMT	1901        # Adamstown
 			-8:30	-	-0830	1998 Apr 27  0:00
 			-8:00	-	-08
@@ -731,7 +731,7 @@ Rule	WS	2011	only	-	Apr	Sat>=1	4:00	0	-
 Rule	WS	2011	only	-	Sep	lastSat	3:00	1	-
 Rule	WS	2012	max	-	Apr	Sun>=1	4:00	0	-
 Rule	WS	2012	max	-	Sep	lastSun	3:00	1	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Pacific/Apia	 12:33:04 -	LMT	1892 Jul  5
 			-11:26:56 -	LMT	1911
 			-11:30	-	-1130	1950
@@ -740,7 +740,7 @@ Zone Pacific/Apia	 12:33:04 -	LMT	1892 Jul  5
 
 # Solomon Is
 # excludes Bougainville, for which see Papua New Guinea
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Pacific/Guadalcanal 10:39:48 -	LMT	1912 Oct # Honiara
 			11:00	-	+11
 
@@ -763,7 +763,7 @@ Zone Pacific/Guadalcanal 10:39:48 -	LMT	1912 Oct # Honiara
 # was "11 hours slow on G.M.T."  Go with Thorsen and assume Shanks & Pottenger
 # are off by an hour starting in 1901.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Pacific/Fakaofo	-11:24:56 -	LMT	1901
 			-11:00	-	-11	2011 Dec 30
 			13:00	-	+13
@@ -776,14 +776,14 @@ Rule	Tonga	2000	2001	-	Nov	Sun>=1	2:00	1:00	-
 Rule	Tonga	2001	2002	-	Jan	lastSun	2:00	0	-
 Rule	Tonga	2016	only	-	Nov	Sun>=1	2:00	1:00	-
 Rule	Tonga	2017	only	-	Jan	Sun>=15	3:00	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Pacific/Tongatapu	12:19:20 -	LMT	1901
 			12:20	-	+1220	1941
 			13:00	-	+13	1999
 			13:00	Tonga	+13/+14
 
 # Tuvalu
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Pacific/Funafuti	11:56:52 -	LMT	1901
 			12:00	-	+12
 
@@ -844,7 +844,7 @@ Zone Pacific/Funafuti	11:56:52 -	LMT	1901
 # uninhabited since World War II; was probably like Pacific/Kiritimati
 
 # Wake
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Pacific/Wake	11:06:28 -	LMT	1901
 			12:00	-	+12
 
@@ -857,12 +857,12 @@ Rule	Vanuatu	1984	only	-	Oct	23	0:00	1:00	-
 Rule	Vanuatu	1985	1991	-	Sep	Sun>=23	0:00	1:00	-
 Rule	Vanuatu	1992	1993	-	Jan	Sun>=23	0:00	0	-
 Rule	Vanuatu	1992	only	-	Oct	Sun>=23	0:00	1:00	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Pacific/Efate	11:13:16 -	LMT	1912 Jan 13 # Vila
 			11:00	Vanuatu	+11/+12
 
 # Wallis and Futuna
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Pacific/Wallis	12:15:20 -	LMT	1901
 			12:00	-	+12
 
@@ -1248,6 +1248,22 @@ Zone	Pacific/Wallis	12:15:20 -	LMT	1901
 # in WA or its introduction in SA had anything to do with the genesis
 # of this time zone.  My hunch is that it's been around since well
 # before 1975.  I remember seeing it noted on road maps decades ago.
+#
+# From Gilmore Davidson (2019-04-08):
+# https://www.abc.net.au/news/2019-04-08/this-remote-stretch-of-desert-has-its-own-custom-time-zone/10981000
+# ... include[s] a rough description of the geographical boundaries...
+# "The time zone exists for about 340 kilometres and takes in the tiny
+# roadhouse communities of Cocklebiddy, Madura, Eucla and Border Village."
+# ... and an indication that the zone has definitely been in existence
+# since before the 1970 cut-off of the database ...
+# From Paul Eggert (2019-05-17):
+# That ABC Esperance story by Christien de Garis also says:
+#    Although the Central Western Time Zone is not officially recognised (your
+#    phones won't automatically change), there is a sign instructing you which
+#    way to wind your clocks 45 minutes and scrawled underneath one of them in
+#    Texta is the word: 'Why'?
+#    "Good question," Mr Pike said.
+#    "I don't even know that, and it's been going for over 50 years."
 
 # From Paul Eggert (2006-12-15):
 # For lack of better info, assume the tradition dates back to the
@@ -1566,6 +1582,42 @@ Zone	Pacific/Wallis	12:15:20 -	LMT	1901
 ###############################################################################
 
 
+# Bonin (Ogasawara) Islands and Marcus Island (Minami-Tori-shima)
+
+# From Wakaba (2019-01-28) via Phake Nick:
+# National Diet Library of Japan has several reports by Japanese Government
+# officers that describe the time used in islands when they visited there.
+# According to them (and other sources such as newspapers), standard time UTC
+# + 10 (JST + 1) and DST UTC + 11 (JST + 2) was used until its return to Japan
+# at 1968-06-26 00:00 JST.  The exact periods of DST are still unknown.
+# I guessed Guam, Mariana, and Bonin and Marcus districts might have
+# synchronized their DST periods, but reports imply they had their own
+# decisions, i.e. there were three or more different time zones....
+#
+# https://wiki.suikawiki.org/n/小笠原諸島の標準時
+
+# From Phake Nick (2019-02-12):
+# Because their last time change to return to Japanese time when they returned
+# to Japanese rule was right before 1970, ... per the current tz database
+# rule, the information doesn't warrant creation of a new timezone for Bonin
+# Islands itself and is thus as an anecdotal note for interest purpose only.
+# ... [The abovementioned link] described some special timekeeping phenomenon
+# regarding Marcus island, another remote island currently owned by Japanese
+# in the same administrative unit as Bonin Islands.  Many reports claim that
+# the American coastal guard on the American quarter of the island use its own
+# coastal guard time, and most sources describe the time as UTC+11, being two
+# hours faster than JST used by some Japanese personnel on the island.  Some
+# sites describe it as same as Wake Island/Guam time although it would be
+# incorrect to be same as Guam.  And then in a few Japanese governmental
+# report from 1980s (from National Institute of Information and Communications
+# Technology) regarding the construction of VLBI facility on the Marcus
+# Island, it claimed that there are three time standards being used on the
+# island at the time which include not just JST (UTC+9) or [US]CG time
+# (UTC+11) but also a JMSDF time (UTC+10) (Japan Maritime Self-Defense
+# Force).  Unfortunately there are no other sources that mentioned such time
+# and there are also no information on things like how the time was used.
+
+
 # Fiji
 
 # Howse writes (p 153) that in 1879 the British governor of Fiji
diff --git a/tz/backzone b/tz/backzone
index 380c492..2a54e6c 100644
--- a/tz/backzone
+++ b/tz/backzone
@@ -38,7 +38,7 @@
 # commentary and rules associated with the entry.
 #
 # As explained in the zic man page, the zone columns are:
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 
 # Ethiopia
 # From Paul Eggert (2014-07-31):
diff --git a/tz/checktab.awk b/tz/checktab.awk
index 393ab19..ec145b5 100644
--- a/tz/checktab.awk
+++ b/tz/checktab.awk
@@ -63,12 +63,19 @@ BEGIN {
 		coordinates = $2
 		tz = $3
 		comments = $4
-		if (cc < cc0) {
+
+		# Don't complain about a special case for Crimea in zone.tab.
+		# FIXME: zone.tab should be removed, since it is obsolete.
+		# Or at least put just "XX" in its country-code column.
+		if (cc < cc0 \
+		    && !(zone_table == "zone.tab" \
+			 && tz0 == "Europe/Simferopol")) {
 			printf "%s:%d: country code '%s' is out of order\n", \
 				zone_table, zone_NR, cc >>"/dev/stderr"
 			status = 1
 		}
 		cc0 = cc
+		tz0 = tz
 		tztab[tz] = 1
 		tz2comments[tz] = comments
 		tz2NR[tz] = zone_NR
diff --git a/tz/europe b/tz/europe
index b735a48..5dc0397 100644
--- a/tz/europe
+++ b/tz/europe
@@ -122,7 +122,7 @@
 # position is 51° 28' 30" N, 0° 18' 45" W. The longitude should
 # be within about ±2". The Ordnance Survey grid reference is TQ172761.
 #
-# [This yields GMTOFF = -0:01:15 for London LMT in the 18th century.]
+# [This yields STDOFF = -0:01:15 for London LMT in the 18th century.]
 
 # From Paul Eggert (1993-11-18):
 #
@@ -500,7 +500,7 @@ Rule	GB-Eire 1990	1995	-	Oct	Sun>=22	1:00u	0	GMT
 #
 # Use Europe/London for Jersey, Guernsey, and the Isle of Man.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/London	-0:01:15 -	LMT	1847 Dec  1  0:00s
 			 0:00	GB-Eire	%s	1968 Oct 27
 			 1:00	-	BST	1971 Oct 31  2:00u
@@ -538,7 +538,7 @@ Rule	Eire	1981	1989	-	Oct	Sun>=23	 1:00u	-1:00	-
 Rule	Eire	1990	1995	-	Oct	Sun>=22	 1:00u	-1:00	-
 Rule	Eire	1996	max	-	Oct	lastSun	 1:00u	-1:00	-
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Dublin	-0:25:00 -	LMT	1880 Aug  2
 			-0:25:21 -	DMT	1916 May 21  2:00s
 			-0:25:21 1:00	IST	1916 Oct  1  2:00s
@@ -737,7 +737,7 @@ Rule	Russia	1996	2010	-	Oct	lastSun	 2:00s	0	-
 
 # These are for backward compatibility with older versions.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	WET		0:00	EU	WE%sT
 Zone	CET		1:00	C-Eur	CE%sT
 Zone	MET		1:00	C-Eur	ME%sT
@@ -797,14 +797,14 @@ Rule	Albania	1982	only	-	Oct	 3	0:00	0	-
 Rule	Albania	1983	only	-	Apr	18	0:00	1:00	S
 Rule	Albania	1983	only	-	Oct	 1	0:00	0	-
 Rule	Albania	1984	only	-	Apr	 1	0:00	1:00	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Tirane	1:19:20 -	LMT	1914
 			1:00	-	CET	1940 Jun 16
 			1:00	Albania	CE%sT	1984 Jul
 			1:00	EU	CE%sT
 
 # Andorra
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Andorra	0:06:04 -	LMT	1901
 			0:00	-	WET	1946 Sep 30
 			1:00	-	CET	1985 Mar 31  2:00
@@ -830,7 +830,7 @@ Rule	Austria	1947	only	-	Apr	 6	2:00s	1:00	S
 Rule	Austria	1948	only	-	Apr	18	2:00s	1:00	S
 Rule	Austria	1980	only	-	Apr	 6	0:00	1:00	S
 Rule	Austria	1980	only	-	Sep	28	0:00	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Vienna	1:05:21 -	LMT	1893 Apr
 			1:00	C-Eur	CE%sT	1920
 			1:00	Austria	CE%sT	1940 Apr  1  2:00s
@@ -862,7 +862,7 @@ Zone	Europe/Vienna	1:05:21 -	LMT	1893 Apr
 # Belarussian government decided against changing to winter time....
 # http://eng.belta.by/all_news/society/Belarus-decides-against-adjusting-time-in-Russias-wake_i_76335.html
 #
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Minsk	1:50:16 -	LMT	1880
 			1:50	-	MMT	1924 May  2 # Minsk Mean Time
 			2:00	-	EET	1930 Jun 21
@@ -926,7 +926,7 @@ Rule	Belgium	1945	only	-	Apr	 2	 2:00s	1:00	S
 Rule	Belgium	1945	only	-	Sep	16	 2:00s	0	-
 Rule	Belgium	1946	only	-	May	19	 2:00s	1:00	S
 Rule	Belgium	1946	only	-	Oct	 7	 2:00s	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Brussels	0:17:30 -	LMT	1880
 			0:17:30	-	BMT	1892 May  1 12:00  # Brussels MT
 			0:00	-	WET	1914 Nov  8
@@ -953,7 +953,7 @@ Rule	Bulg	1979	only	-	Oct	 1	 1:00	0	-
 Rule	Bulg	1980	1982	-	Apr	Sat>=1	23:00	1:00	S
 Rule	Bulg	1980	only	-	Sep	29	 1:00	0	-
 Rule	Bulg	1981	only	-	Sep	27	 2:00	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Sofia	1:33:16 -	LMT	1880
 			1:56:56	-	IMT	1894 Nov 30 # Istanbul MT?
 			2:00	-	EET	1942 Nov  2  3:00
@@ -986,7 +986,7 @@ Rule	Czech	1946	only	-	May	 6	2:00s	1:00	S
 Rule	Czech	1946	1949	-	Oct	Sun>=1	2:00s	0	-
 Rule	Czech	1947	1948	-	Apr	Sun>=15	2:00s	1:00	S
 Rule	Czech	1949	only	-	Apr	 9	2:00s	1:00	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Prague	0:57:44 -	LMT	1850
 			0:57:44	-	PMT	1891 Oct    # Prague Mean Time
 			1:00	C-Eur	CE%sT	1945 May  9
@@ -1048,7 +1048,7 @@ 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		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -1145,7 +1145,7 @@ Rule	Thule	1993	2006	-	Oct	lastSun	2:00	0	S
 Rule	Thule	2007	max	-	Mar	Sun>=8	2:00	1:00	D
 Rule	Thule	2007	max	-	Nov	Sun>=1	2:00	0	S
 #
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Danmarkshavn -1:14:40 -	LMT	1916 Jul 28
 			-3:00	-	-03	1980 Apr  6  2:00
 			-3:00	EU	-03/-02	1996
@@ -1211,7 +1211,7 @@ Zone America/Thule	-4:35:08 -	LMT	1916 Jul 28 # Pituffik air base
 # From Urmet Jänes (2002-03-28):
 # The legislative reference is Government decree No. 84 on 2002-02-21.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Tallinn	1:39:00	-	LMT	1880
 			1:39:00	-	TMT	1918 Feb    # Tallinn Mean Time
 			1:00	C-Eur	CE%sT	1919 Jul
@@ -1274,7 +1274,7 @@ Rule	Finland	1981	1982	-	Sep	lastSun	3:00	0	-
 # Milne says Helsinki (Helsingfors) time was 1:39:49.2 (official document);
 # round to nearest.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 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
@@ -1364,7 +1364,7 @@ Rule	France	1976	only	-	Sep	26	 1:00	0	-
 # but Howse quotes the actual French legislation as saying 0:09:21.
 # Go with Howse.  Howse writes that the time in France was officially based
 # on PMT-0:09:21 until 1978-08-09, when the time base finally switched to UTC.
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Paris	0:09:21 -	LMT	1891 Mar 15  0:01
 			0:09:21	-	PMT	1911 Mar 11  0:01 # Paris MT
 # Shanks & Pottenger give 1940 Jun 14 0:00; go with Excoffier and Le Corre.
@@ -1412,7 +1412,7 @@ Rule SovietZone	1945	only	-	May	24	2:00	2:00	M # Midsummer
 Rule SovietZone	1945	only	-	Sep	24	3:00	1:00	S
 Rule SovietZone	1945	only	-	Nov	18	2:00s	0	-
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Berlin	0:53:28 -	LMT	1893 Apr
 			1:00	C-Eur	CE%sT	1945 May 24  2:00
 			1:00 SovietZone	CE%sT	1946
@@ -1440,7 +1440,7 @@ Link	Europe/Zurich	Europe/Busingen
 # is in Europe.  Our reference location Tbilisi is in the Asian part.
 
 # Gibraltar
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Europe/Gibraltar	-0:21:24 -	LMT	1880 Aug  2  0:00s
 			0:00	GB-Eire	%s	1957 Apr 14  2:00
 			1:00	-	CET	1982
@@ -1471,7 +1471,7 @@ Rule	Greece	1979	only	-	Apr	 1	9:00	1:00	S
 Rule	Greece	1979	only	-	Sep	29	2:00	0	-
 Rule	Greece	1980	only	-	Apr	 1	0:00	1:00	S
 Rule	Greece	1980	only	-	Sep	28	0:00	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Athens	1:34:52 -	LMT	1895 Sep 14
 			1:34:52	-	AMT	1916 Jul 28  0:01 # Athens MT
 			2:00	Greece	EE%sT	1941 Apr 30
@@ -1508,7 +1508,7 @@ Rule	Hungary	1956	only	-	Sep	lastSun	 0:00	0	-
 Rule	Hungary	1957	only	-	Jun	Sun>=1	 1:00	1:00	S
 Rule	Hungary	1957	only	-	Sep	lastSun	 3:00	0	-
 Rule	Hungary	1980	only	-	Apr	 6	 1:00	1:00	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Budapest	1:16:20 -	LMT	1890 Oct
 			1:00	C-Eur	CE%sT	1918
 			1:00	Hungary	CE%sT	1941 Apr  8
@@ -1569,7 +1569,7 @@ Rule	Iceland	1947	1967	-	Apr	Sun>=1	 1:00s	1:00	-
 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		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -1583,6 +1583,25 @@ Zone Atlantic/Reykjavik	-1:28	-	LMT	1908
 # But these events all occurred before the 1970 cutoff,
 # so record only the time in Rome.
 #
+# From Stephen Trainor (2019-05-06):
+# http://www.ac-ilsestante.it/MERIDIANE/ora_legale/ORA_LEGALE_ESTIVA_IN_ITALIA.htm
+# ... the [1866] law went into effect on 12 December 1866, rather than
+# the date of the decree (22 Sep 1866)
+# https://web.archive.org/web/20070824155341/http://www.iav.it/planetario/didastro/didastro/english.htm
+# ... "In Italy in 1866 there were 6 railway times (Torino, Verona, Firenze,
+# Roma, Napoli, Palermo). On that year it was decided to unify them, adopting
+# the average time of Rome (even if this city was not yet part of the
+# kingdom).  On the 12th December 1866, on the starting of the winter time
+# table, it took effect in the railways, the post office and the telegraph,
+# not only for the internal service but also for the public....  Milano set
+# the public watches on the Rome time on the same day (12th December 1866),
+# Torino and Bologna on the 1st January 1867, Venezia the 1st May 1880 and the
+# last city was Cagliari in 1886."
+#
+# From Luigi Rosa (2019-05-07):
+# this is the scan of the decree:
+# http://www.radiomarconi.com/marconi/filopanti/1866c.jpg
+#
 # From Michael Deckers (2016-10-24):
 # http://www.ac-ilsestante.it/MERIDIANE/ora_legale quotes a law of 1893-08-10
 # ... [translated as] "The preceding dispositions will enter into
@@ -1593,6 +1612,7 @@ Zone Atlantic/Reykjavik	-1:28	-	LMT	1908
 # The authoritative source for time in Italy is the national metrological
 # institute, which has a summary page of historical DST data at
 # http://www.inrim.it/res/tf/ora_legale_i.shtml
+# [now at http://oldsite.inrim.it/res/tf/ora_legale_i.shtml as of 2017]
 # (2016-10-24):
 # http://www.renzobaldini.it/le-ore-legali-in-italia/
 # has still different data for 1944.  It divides Italy in two, as
@@ -1656,8 +1676,8 @@ Rule	Italy	1976	only	-	May	30	 0:00s	1:00	S
 Rule	Italy	1977	1979	-	May	Sun>=22	 0:00s	1:00	S
 Rule	Italy	1978	only	-	Oct	 1	 0:00s	0	-
 Rule	Italy	1979	only	-	Sep	30	 0:00s	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
-Zone	Europe/Rome	0:49:56 -	LMT	1866 Sep 22
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
+Zone	Europe/Rome	0:49:56 -	LMT	1866 Dec 12
 			0:49:56	-	RMT	1893 Oct 31 23:49:56 # Rome Mean
 			1:00	Italy	CE%sT	1943 Sep 10
 			1:00	C-Eur	CE%sT	1944 Jun  4
@@ -1732,7 +1752,7 @@ Rule	Latvia	1989	1996	-	Sep	lastSun	 2:00s	0	-
 # Byalokoz 1919 says Latvia was 1:36:34.
 # Go with Byalokoz.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Riga	1:36:34	-	LMT	1880
 			1:36:34	-	RMT	1918 Apr 15  2:00 # Riga MT
 			1:36:34	1:00	LST	1918 Sep 16  3:00 # Latvian ST
@@ -1802,7 +1822,7 @@ Link Europe/Zurich Europe/Vaduz
 # http://www.lrvk.lt/nut/11/n1749.htm
 
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Vilnius	1:41:16	-	LMT	1880
 			1:24:00	-	WMT	1917        # Warsaw Mean Time
 			1:35:36	-	KMT	1919 Oct 10 # Kaunas Mean Time
@@ -1846,7 +1866,7 @@ 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		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -1871,7 +1891,7 @@ Rule	Malta	1974	only	-	Sep	16	0:00s	0	-
 Rule	Malta	1975	1979	-	Apr	Sun>=15	2:00	1:00	S
 Rule	Malta	1975	1980	-	Sep	Sun>=15	2:00	0	-
 Rule	Malta	1980	only	-	Mar	31	2:00	1:00	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Malta	0:58:04 -	LMT	1893 Nov  2  0:00s # Valletta
 			1:00	Italy	CE%sT	1973 Mar 31
 			1:00	Malta	CE%sT	1981
@@ -1940,7 +1960,7 @@ Zone	Europe/Malta	0:58:04 -	LMT	1893 Nov  2  0:00s # Valletta
 Rule	Moldova	1997	max	-	Mar	lastSun	 2:00	1:00	S
 Rule	Moldova	1997	max	-	Oct	lastSun	 3:00	0	-
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Chisinau	1:55:20 -	LMT	1880
 			1:55	-	CMT	1918 Feb 15 # Chisinau MT
 			1:44:24	-	BMT	1931 Jul 24 # Bucharest MT
@@ -1956,7 +1976,7 @@ Zone	Europe/Chisinau	1:55:20 -	LMT	1880
 # Monaco
 # Shanks & Pottenger give 0:09:20 for Paris Mean Time; go with Howse's
 # more precise 0:09:21.
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Monaco	0:29:32 -	LMT	1891 Mar 15
 			0:09:21	-	PMT	1911 Mar 11 # Paris Mean Time
 			0:00	France	WE%sT	1945 Sep 16  3:00
@@ -2031,8 +2051,8 @@ 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 GMTOFF to be an integer.
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -2051,7 +2071,7 @@ 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		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -2142,7 +2162,7 @@ Rule	Poland	1959	1961	-	Oct	Sun>=1	1:00s	0	-
 Rule	Poland	1960	only	-	Apr	 3	1:00s	1:00	S
 Rule	Poland	1961	1964	-	May	lastSun	1:00s	1:00	S
 Rule	Poland	1962	1964	-	Sep	lastSun	1:00s	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Warsaw	1:24:00 -	LMT	1880
 			1:24:00	-	WMT	1915 Aug  5 # Warsaw Mean Time
 			1:00	C-Eur	CE%sT	1918 Sep 16  3:00
@@ -2247,7 +2267,7 @@ Rule	Port	1980	only	-	Mar	lastSun	 0:00s	1:00	S
 Rule	Port	1981	1982	-	Mar	lastSun	 1:00s	1:00	S
 Rule	Port	1983	only	-	Mar	lastSun	 2:00s	1:00	S
 #
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Lisbon	-0:36:45 -	LMT	1884
 			-0:36:45 -	LMT	1912 Jan  1  0:00u # Lisbon MT
 			 0:00	Port	WE%sT	1966 Apr  3  2:00
@@ -2306,7 +2326,7 @@ Rule	Romania	1980	only	-	Apr	 5	23:00	1:00	S
 Rule	Romania	1980	only	-	Sep	lastSun	 1:00	0	-
 Rule	Romania	1991	1993	-	Mar	lastSun	 0:00s	1:00	S
 Rule	Romania	1991	1993	-	Sep	lastSun	 0:00s	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Europe/Bucharest	1:44:24 -	LMT	1891 Oct
 			1:44:24	-	BMT	1931 Jul 24 # Bucharest MT
 			2:00	Romania	EE%sT	1981 Mar 29  2:00s
@@ -3345,7 +3365,7 @@ Zone Asia/Anadyr	11:49:56 -	LMT	1924 May  2
 # See Europe/Rome.
 
 # Serbia
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Belgrade	1:22:00	-	LMT	1884
 			1:00	-	CET	1941 Apr 18 23:00
 			1:00	C-Eur	CE%sT	1945
@@ -3451,7 +3471,7 @@ Rule SpainAfrica 1976	only	-	Aug	 1	 0:00	0	-
 Rule SpainAfrica 1977	only	-	Sep	28	 0:00	0	-
 Rule SpainAfrica 1978	only	-	Jun	 1	 0:00	1:00	S
 Rule SpainAfrica 1978	only	-	Aug	 4	 0:00	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Madrid	-0:14:44 -	LMT	1900 Dec 31 23:45:16
 			 0:00	Spain	WE%sT	1940 Mar 16 23:00
 			 1:00	Spain	CE%sT	1979
@@ -3519,7 +3539,7 @@ Zone	Atlantic/Canary	-1:01:36 -	LMT	1922 Mar # Las Palmas de Gran C.
 #
 # Source: The newspaper "Dagens Nyheter", 1916-10-01, page 7 upper left.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -3622,7 +3642,7 @@ Zone Europe/Stockholm	1:12:12 -	LMT	1879 Jan  1
 # Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
 Rule	Swiss	1941	1942	-	May	Mon>=1	1:00	1:00	S
 Rule	Swiss	1941	1942	-	Oct	Mon>=1	2:00	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Zurich	0:34:08 -	LMT	1853 Jul 16 # See above comment.
 			0:29:46	-	BMT	1894 Jun    # Bern Mean Time
 			1:00	Swiss	CE%sT	1981
@@ -3772,7 +3792,7 @@ Rule	Turkey	1986	1995	-	Sep	lastSun	1:00s	0	-
 Rule	Turkey	1994	only	-	Mar	20	1:00s	1:00	S
 Rule	Turkey	1995	2006	-	Mar	lastSun	1:00s	1:00	S
 Rule	Turkey	1996	2006	-	Oct	lastSun	1:00s	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Istanbul	1:55:52 -	LMT	1880
 			1:56:56	-	IMT	1910 Oct # Istanbul Mean Time?
 			2:00	Turkey	EE%sT	1978 Oct 15
@@ -3869,16 +3889,8 @@ Link	Europe/Istanbul	Asia/Istanbul	# Istanbul is in both continents.
 # controversial, and some day "Kyiv" may become substantially more popular in
 # English; in the meantime, stick with the traditional English "Kiev" as that
 # means less disruption for our users.
-#
-# Anyway, none of the common English-language spellings (Kiev, Kyiv, Kieff,
-# Kijeff, Kijev, Kiyef, Kiyeff) do justice to the common pronunciation in
-# Ukrainian, namely [ˈkɪjiu̯] (IPA).  This pronunciation has nothing like an
-# English "v" or "f", and instead trails off with what an English-speaker
-# would call a demure "oo" sound, and it would would be better anglicized as
-# "Kuiyu".  Here's a sound file, if you would like to do as the Kuiyuvians do:
-# https://commons.wikimedia.org/wiki/File:Uk-Київ.ogg
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 # This represents most of Ukraine.  See above for the spelling of "Kiev".
 Zone Europe/Kiev	2:02:04 -	LMT	1880
 			2:02:04	-	KMT	1924 May  2 # Kiev Mean Time
diff --git a/tz/factory b/tz/factory
index d4e7659..9f5fc33 100644
--- a/tz/factory
+++ b/tz/factory
@@ -8,5 +8,5 @@
 # time zone abbreviation "-00", indicating that the actual time zone
 # is unknown.
 
-# Zone	NAME	GMTOFF	RULES	FORMAT
+# Zone	NAME	STDOFF	RULES	FORMAT
 Zone	Factory	0	-	-00
diff --git a/tz/localtime.c b/tz/localtime.c
index ac3790a..033e88f 100644
--- a/tz/localtime.c
+++ b/tz/localtime.c
@@ -98,11 +98,11 @@ static const char	gmt[] = "GMT";
 #endif
 
 struct ttinfo {				/* time type information */
-	int_fast32_t	tt_gmtoff;	/* UT offset in seconds */
+	int_fast32_t	tt_utoff;	/* UT offset in seconds */
 	bool		tt_isdst;	/* used to set tm_isdst */
-	int		tt_abbrind;	/* abbreviation list index */
+	int		tt_desigidx;	/* abbreviation list index */
 	bool		tt_ttisstd;	/* transition is std time */
-	bool		tt_ttisgmt;	/* transition is UT */
+	bool		tt_ttisut;	/* transition is UT */
 };
 
 struct lsinfo {				/* leap second information */
@@ -209,15 +209,15 @@ long			altzone;
 # endif
 #endif
 
-/* Initialize *S to a value based on GMTOFF, ISDST, and ABBRIND.  */
+/* Initialize *S to a value based on UTOFF, ISDST, and DESIGIDX.  */
 static void
-init_ttinfo(struct ttinfo *s, int_fast32_t gmtoff, bool isdst, int abbrind)
+init_ttinfo(struct ttinfo *s, int_fast32_t utoff, bool isdst, int desigidx)
 {
-  s->tt_gmtoff = gmtoff;
+  s->tt_utoff = utoff;
   s->tt_isdst = isdst;
-  s->tt_abbrind = abbrind;
+  s->tt_desigidx = desigidx;
   s->tt_ttisstd = false;
-  s->tt_ttisgmt = false;
+  s->tt_ttisut = false;
 }
 
 static int_fast32_t
@@ -270,15 +270,15 @@ static void
 update_tzname_etc(struct state const *sp, struct ttinfo const *ttisp)
 {
 #if HAVE_TZNAME
-  tzname[ttisp->tt_isdst] = (char *) &sp->chars[ttisp->tt_abbrind];
+  tzname[ttisp->tt_isdst] = (char *) &sp->chars[ttisp->tt_desigidx];
 #endif
 #if USG_COMPAT
   if (!ttisp->tt_isdst)
-    timezone = - ttisp->tt_gmtoff;
+    timezone = - ttisp->tt_utoff;
 #endif
 #ifdef ALTZONE
   if (ttisp->tt_isdst)
-    altzone = - ttisp->tt_gmtoff;
+    altzone = - ttisp->tt_utoff;
 #endif
 }
 
@@ -335,7 +335,7 @@ scrub_abbrs(struct state *sp)
 	*/
 	for (i = 0; i < sp->typecnt; ++i) {
 		register const struct ttinfo * const	ttisp = &sp->ttis[i];
-		register char *				cp = &sp->chars[ttisp->tt_abbrind];
+		char *cp = &sp->chars[ttisp->tt_desigidx];
 
 		if (strlen(cp) > TZ_ABBR_MAX_LEN &&
 			strcmp(cp, GRANDPARENTED) != 0)
@@ -452,7 +452,7 @@ tzloadbody(char const *name, struct state *sp, bool doextend,
 	  return errno;
 	for (stored = 4; stored <= 8; stored *= 2) {
 		int_fast32_t ttisstdcnt = detzcode(up->tzhead.tzh_ttisstdcnt);
-		int_fast32_t ttisgmtcnt = detzcode(up->tzhead.tzh_ttisgmtcnt);
+		int_fast32_t ttisutcnt = detzcode(up->tzhead.tzh_ttisutcnt);
 		int_fast64_t prevtr = 0;
 		int_fast32_t prevcorr = 0;
 		int_fast32_t leapcnt = detzcode(up->tzhead.tzh_leapcnt);
@@ -468,7 +468,7 @@ tzloadbody(char const *name, struct state *sp, bool doextend,
 		       && 0 <= timecnt && timecnt < TZ_MAX_TIMES
 		       && 0 <= charcnt && charcnt < TZ_MAX_CHARS
 		       && (ttisstdcnt == typecnt || ttisstdcnt == 0)
-		       && (ttisgmtcnt == typecnt || ttisgmtcnt == 0)))
+		       && (ttisutcnt == typecnt || ttisutcnt == 0)))
 		  return EINVAL;
 		if (nread
 		    < (tzheadsize		/* struct tzhead */
@@ -478,7 +478,7 @@ tzloadbody(char const *name, struct state *sp, bool doextend,
 		       + charcnt		/* chars */
 		       + leapcnt * (stored + 4)	/* lsinfos */
 		       + ttisstdcnt		/* ttisstds */
-		       + ttisgmtcnt))		/* ttisgmts */
+		       + ttisutcnt))		/* ttisuts */
 		  return EINVAL;
 		sp->leapcnt = leapcnt;
 		sp->timecnt = timecnt;
@@ -519,19 +519,19 @@ tzloadbody(char const *name, struct state *sp, bool doextend,
 		sp->timecnt = timecnt;
 		for (i = 0; i < sp->typecnt; ++i) {
 			register struct ttinfo *	ttisp;
-			unsigned char isdst, abbrind;
+			unsigned char isdst, desigidx;
 
 			ttisp = &sp->ttis[i];
-			ttisp->tt_gmtoff = detzcode(p);
+			ttisp->tt_utoff = detzcode(p);
 			p += 4;
 			isdst = *p++;
 			if (! (isdst < 2))
 			  return EINVAL;
 			ttisp->tt_isdst = isdst;
-			abbrind = *p++;
-			if (! (abbrind < sp->charcnt))
+			desigidx = *p++;
+			if (! (desigidx < sp->charcnt))
 			  return EINVAL;
-			ttisp->tt_abbrind = abbrind;
+			ttisp->tt_desigidx = desigidx;
 		}
 		for (i = 0; i < sp->charcnt; ++i)
 			sp->chars[i] = *p++;
@@ -578,12 +578,12 @@ tzloadbody(char const *name, struct state *sp, bool doextend,
 			register struct ttinfo *	ttisp;
 
 			ttisp = &sp->ttis[i];
-			if (ttisgmtcnt == 0)
-				ttisp->tt_ttisgmt = false;
+			if (ttisutcnt == 0)
+				ttisp->tt_ttisut = false;
 			else {
 				if (*p != true && *p != false)
 						return EINVAL;
-				ttisp->tt_ttisgmt = *p++;
+				ttisp->tt_ttisut = *p++;
 			}
 		}
 		/*
@@ -612,11 +612,11 @@ tzloadbody(char const *name, struct state *sp, bool doextend,
 			  int gotabbr = 0;
 			  int charcnt = sp->charcnt;
 			  for (i = 0; i < ts->typecnt; i++) {
-			    char *tsabbr = ts->chars + ts->ttis[i].tt_abbrind;
+			    char *tsabbr = ts->chars + ts->ttis[i].tt_desigidx;
 			    int j;
 			    for (j = 0; j < charcnt; j++)
 			      if (strcmp(sp->chars + j, tsabbr) == 0) {
-				ts->ttis[i].tt_abbrind = j;
+				ts->ttis[i].tt_desigidx = j;
 				gotabbr++;
 				break;
 			      }
@@ -625,7 +625,7 @@ tzloadbody(char const *name, struct state *sp, bool doextend,
 			      if (j + tsabbrlen < TZ_MAX_CHARS) {
 				strcpy(sp->chars + j, tsabbr);
 				charcnt = j + tsabbrlen + 1;
-				ts->ttis[i].tt_abbrind = j;
+				ts->ttis[i].tt_desigidx = j;
 				gotabbr++;
 			      }
 			    }
@@ -764,12 +764,13 @@ typesequiv(const struct state *sp, int a, int b)
 	else {
 		register const struct ttinfo *	ap = &sp->ttis[a];
 		register const struct ttinfo *	bp = &sp->ttis[b];
-		result = ap->tt_gmtoff == bp->tt_gmtoff &&
-			ap->tt_isdst == bp->tt_isdst &&
-			ap->tt_ttisstd == bp->tt_ttisstd &&
-			ap->tt_ttisgmt == bp->tt_ttisgmt &&
-			strcmp(&sp->chars[ap->tt_abbrind],
-			&sp->chars[bp->tt_abbrind]) == 0;
+		result = (ap->tt_utoff == bp->tt_utoff
+			  && ap->tt_isdst == bp->tt_isdst
+			  && ap->tt_ttisstd == bp->tt_ttisstd
+			  && ap->tt_ttisut == bp->tt_ttisut
+			  && (strcmp(&sp->chars[ap->tt_desigidx],
+				     &sp->chars[bp->tt_desigidx])
+			      == 0));
 	}
 	return result;
 }
@@ -1234,7 +1235,7 @@ tzparse(const char *name, struct state *sp, bool lastditch)
 				j = sp->types[i];
 				if (!sp->ttis[j].tt_isdst) {
 					theirstdoffset =
-						-sp->ttis[j].tt_gmtoff;
+						- sp->ttis[j].tt_utoff;
 					break;
 				}
 			}
@@ -1243,7 +1244,7 @@ tzparse(const char *name, struct state *sp, bool lastditch)
 				j = sp->types[i];
 				if (sp->ttis[j].tt_isdst) {
 					theirdstoffset =
-						-sp->ttis[j].tt_gmtoff;
+						- sp->ttis[j].tt_utoff;
 					break;
 				}
 			}
@@ -1259,7 +1260,7 @@ tzparse(const char *name, struct state *sp, bool lastditch)
 			for (i = 0; i < sp->timecnt; ++i) {
 				j = sp->types[i];
 				sp->types[i] = sp->ttis[j].tt_isdst;
-				if (sp->ttis[j].tt_ttisgmt) {
+				if (sp->ttis[j].tt_ttisut) {
 					/* No adjustment to transition time */
 				} else {
 					/*
@@ -1285,7 +1286,7 @@ tzparse(const char *name, struct state *sp, bool lastditch)
 							theirstdoffset;
 					}
 				}
-				theiroffset = -sp->ttis[j].tt_gmtoff;
+				theiroffset = -sp->ttis[j].tt_utoff;
 				if (sp->ttis[j].tt_isdst)
 					theirdstoffset = theiroffset;
 				else	theirstdoffset = theiroffset;
@@ -1532,14 +1533,14 @@ localsub(struct state const *sp, time_t const *timep, int_fast32_t setname,
 	/*
 	** To get (wrong) behavior that's compatible with System V Release 2.0
 	** you'd replace the statement below with
-	**	t += ttisp->tt_gmtoff;
+	**	t += ttisp->tt_utoff;
 	**	timesub(&t, 0L, sp, tmp);
 	*/
-	result = timesub(&t, ttisp->tt_gmtoff, sp, tmp);
+	result = timesub(&t, ttisp->tt_utoff, sp, tmp);
 	if (result) {
 	  result->tm_isdst = ttisp->tt_isdst;
 #ifdef TM_ZONE
-	  result->TM_ZONE = (char *) &sp->chars[ttisp->tt_abbrind];
+	  result->TM_ZONE = (char *) &sp->chars[ttisp->tt_desigidx];
 #endif /* defined TM_ZONE */
 	  if (setname)
 	    update_tzname_etc(sp, ttisp);
@@ -2059,8 +2060,8 @@ time2sub(struct tm *const tmp,
 			for (j = sp->typecnt - 1; j >= 0; --j) {
 				if (sp->ttis[j].tt_isdst == yourtm.tm_isdst)
 					continue;
-				newt = t + sp->ttis[j].tt_gmtoff -
-					sp->ttis[i].tt_gmtoff;
+				newt = (t + sp->ttis[j].tt_utoff
+					- sp->ttis[i].tt_utoff);
 				if (! funcp(sp, &newt, offset, &mytm))
 					continue;
 				if (tmcomp(&mytm, &yourtm) != 0)
@@ -2163,14 +2164,14 @@ time1(struct tm *const tmp,
 			otheri = types[otherind];
 			if (sp->ttis[otheri].tt_isdst == tmp->tm_isdst)
 				continue;
-			tmp->tm_sec += sp->ttis[otheri].tt_gmtoff -
-					sp->ttis[samei].tt_gmtoff;
+			tmp->tm_sec += (sp->ttis[otheri].tt_utoff
+					- sp->ttis[samei].tt_utoff);
 			tmp->tm_isdst = !tmp->tm_isdst;
 			t = time2(tmp, funcp, sp, offset, &okay);
 			if (okay)
 				return t;
-			tmp->tm_sec -= sp->ttis[otheri].tt_gmtoff -
-					sp->ttis[samei].tt_gmtoff;
+			tmp->tm_sec -= (sp->ttis[otheri].tt_utoff
+					- sp->ttis[samei].tt_utoff);
 			tmp->tm_isdst = !tmp->tm_isdst;
 		}
 	}
diff --git a/tz/newtzset.3 b/tz/newtzset.3
index 29e8a21..4959851 100644
--- a/tz/newtzset.3
+++ b/tz/newtzset.3
@@ -65,8 +65,8 @@ falls back on Universal Time (UT).
 .PP
 If
 .B TZ
-is null, the best available approximation to local wall
-clock time, as specified by the
+is null, the best available approximation to local (wall
+clock) time, as specified by the
 .IR tzfile (5)-format
 file
 .B localtime
diff --git a/tz/northamerica b/tz/northamerica
index eee8de0..9e3577b 100644
--- a/tz/northamerica
+++ b/tz/northamerica
@@ -93,10 +93,33 @@
 # was the first nationwide legal time standard, and apparently
 # time was just called "Standard Time" or "Daylight Saving Time".
 
-# From Arthur David Olson:
-# US Daylight Saving Time ended on the last Sunday of *October* in 1974.
-# See, for example, the front page of the Saturday, 1974-10-26
-# and Sunday, 1974-10-27 editions of the Washington Post.
+# From Paul Eggert (2019-06-04):
+# Here is the legal basis for the US federal rules.
+# * Public Law 65-106 (1918-03-19) implemented standard and daylight saving
+#   time for the first time across the US, springing forward on March's last
+#   Sunday and falling back on October's last Sunday.
+#   https://www.loc.gov/law/help/statutes-at-large/65th-congress/session-2/c65s2ch24.pdf
+# * Public Law 66-40 (1919-08-20) repealed DST on October 1919's last Sunday.
+#   https://www.loc.gov/law/help/statutes-at-large/66th-congress/session-1/c66s1ch51.pdf
+# * Public Law 77-403 (1942-01-20) started wartime DST on 1942-02-09.
+#   https://www.loc.gov/law/help/statutes-at-large/77th-congress/session-2/c77s2ch7.pdf
+# * Public Law 79-187 (1945-09-25) ended wartime DST on 1945-09-30.
+#   https://www.loc.gov/law/help/statutes-at-large/79th-congress/session-1/c79s1ch388.pdf
+# * Public Law 89-387 (1966-04-13) reinstituted a national standard for DST,
+#   from April's last Sunday to October's last Sunday, effective 1967.
+#   https://www.govinfo.gov/content/pkg/STATUTE-80/pdf/STATUTE-80-Pg107.pdf
+# * Public Law 93-182 (1973-12-15) moved the 1974 spring-forward to 01-06.
+#   https://www.govinfo.gov/content/pkg/STATUTE-87/pdf/STATUTE-87-Pg707.pdf
+# * Public Law 93-434 (1974-10-05) moved the 1975 spring-forward to
+#   February's last Sunday.
+#   https://www.govinfo.gov/content/pkg/STATUTE-88/pdf/STATUTE-88-Pg1209.pdf
+# * Public Law 99-359 (1986-07-08) moved the spring-forward to April's first
+#   Sunday.
+#   https://www.govinfo.gov/content/pkg/STATUTE-100/pdf/STATUTE-100-Pg764.pdf
+# * Public Law 109-58 (2005-08-08), effective 2007, moved the spring-forward
+#   to March's second Sunday and the fall-back to November's first Sunday.
+#   https://www.govinfo.gov/content/pkg/PLAW-109publ58/pdf/PLAW-109publ58.pdf
+# All transitions are at 02:00 local time.
 
 # From Arthur David Olson:
 # Before the Uniform Time Act of 1966 took effect in 1967, observance of
@@ -152,11 +175,11 @@ Rule	US	1918	1919	-	Mar	lastSun	2:00	1:00	D
 Rule	US	1918	1919	-	Oct	lastSun	2:00	0	S
 Rule	US	1942	only	-	Feb	9	2:00	1:00	W # War
 Rule	US	1945	only	-	Aug	14	23:00u	1:00	P # Peace
-Rule	US	1945	only	-	Sep	lastSun	2:00	0	S
+Rule	US	1945	only	-	Sep	30	2:00	0	S
 Rule	US	1967	2006	-	Oct	lastSun	2:00	0	S
 Rule	US	1967	1973	-	Apr	lastSun	2:00	1:00	D
 Rule	US	1974	only	-	Jan	6	2:00	1:00	D
-Rule	US	1975	only	-	Feb	23	2:00	1:00	D
+Rule	US	1975	only	-	Feb	lastSun	2:00	1:00	D
 Rule	US	1976	1986	-	Apr	lastSun	2:00	1:00	D
 Rule	US	1987	2006	-	Apr	Sun>=1	2:00	1:00	D
 Rule	US	2007	max	-	Mar	Sun>=8	2:00	1:00	D
@@ -173,7 +196,7 @@ Rule	US	2007	max	-	Nov	Sun>=1	2:00	0	S
 # increase the chances that they'll actually get compiled and to
 # avoid the need to duplicate the US rules in another file.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	EST		 -5:00	-	EST
 Zone	MST		 -7:00	-	MST
 Zone	HST		-10:00	-	HST
@@ -330,7 +353,7 @@ Rule	NYC	1920	only	-	Oct	lastSun	2:00	0	S
 Rule	NYC	1921	1966	-	Apr	lastSun	2:00	1:00	D
 Rule	NYC	1921	1954	-	Sep	lastSun	2:00	0	S
 Rule	NYC	1955	1966	-	Oct	lastSun	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/New_York	-4:56:02 -	LMT	1883 Nov 18 12:03:58
 			-5:00	US	E%sT	1920
 			-5:00	NYC	E%sT	1942
@@ -390,7 +413,7 @@ Rule	Chicago	1921	only	-	Mar	lastSun	2:00	1:00	D
 Rule	Chicago	1922	1966	-	Apr	lastSun	2:00	1:00	D
 Rule	Chicago	1922	1954	-	Sep	lastSun	2:00	0	S
 Rule	Chicago	1955	1966	-	Oct	lastSun	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Chicago	-5:50:36 -	LMT	1883 Nov 18 12:09:24
 			-6:00	US	C%sT	1920
 			-6:00	Chicago	C%sT	1936 Mar  1  2:00
@@ -458,7 +481,7 @@ Rule	Denver	1920	only	-	Oct	lastSun	2:00	0	S
 Rule	Denver	1921	only	-	May	22	2:00	0	S
 Rule	Denver	1965	1966	-	Apr	lastSun	2:00	1:00	D
 Rule	Denver	1965	1966	-	Oct	lastSun	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Denver	-6:59:56 -	LMT	1883 Nov 18 12:00:04
 			-7:00	US	M%sT	1920
 			-7:00	Denver	M%sT	1942
@@ -511,7 +534,7 @@ Rule	CA	1949	only	-	Jan	 1	2:00	0	S
 Rule	CA	1950	1966	-	Apr	lastSun	1:00	1:00	D
 Rule	CA	1950	1961	-	Sep	lastSun	2:00	0	S
 Rule	CA	1962	1966	-	Oct	lastSun	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Los_Angeles -7:52:58 -	LMT	1883 Nov 18 12:07:02
 			-8:00	US	P%sT	1946
 			-8:00	CA	P%sT	1967
@@ -619,7 +642,7 @@ Zone America/Los_Angeles -7:52:58 -	LMT	1883 Nov 18 12:07:02
 # So they won't be waiting for Alaska to join them on 2019-03-10, but will
 # rather change their clocks twice in seven weeks.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Juneau	 15:02:19 -	LMT	1867 Oct 19 15:33:32
 			 -8:57:41 -	LMT	1900 Aug 20 12:00
 			 -8:00	-	PST	1942
@@ -739,7 +762,7 @@ Zone America/Adak	 12:13:22 -	LMT	1867 Oct 19 12:44:35
 # Note that 1933-05-21 was a Sunday.
 # We're left to guess the time of day when Act 163 was approved; guess noon.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Pacific/Honolulu	-10:31:26 -	LMT	1896 Jan 13 12:00
 			-10:30	-	HST	1933 Apr 30  2:00
 			-10:30	1:00	HDT	1933 May 21 12:00
@@ -769,7 +792,7 @@ Zone Pacific/Honolulu	-10:31:26 -	LMT	1896 Jan 13 12:00
 # Shanks says the 1944 experiment came to an end on 1944-03-17.
 # Go with the Arizona State Library instead.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Phoenix	-7:28:18 -	LMT	1883 Nov 18 11:31:42
 			-7:00	US	M%sT	1944 Jan  1  0:01
 			-7:00	-	MST	1944 Apr  1  0:01
@@ -795,7 +818,7 @@ Zone America/Phoenix	-7:28:18 -	LMT	1883 Nov 18 11:31:42
 # quarter of Idaho county) and eastern Oregon (most of Malheur County)
 # switched four weeks late in 1974.
 #
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Boise	-7:44:49 -	LMT	1883 Nov 18 12:15:11
 			-8:00	US	P%sT	1923 May 13  2:00
 			-7:00	US	M%sT	1974
@@ -867,7 +890,7 @@ Zone America/Boise	-7:44:49 -	LMT	1883 Nov 18 12:15:11
 Rule Indianapolis 1941	only	-	Jun	22	2:00	1:00	D
 Rule Indianapolis 1941	1954	-	Sep	lastSun	2:00	0	S
 Rule Indianapolis 1946	1954	-	Apr	lastSun	2:00	1:00	D
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Indiana/Indianapolis -5:44:38 - LMT	1883 Nov 18 12:15:22
 			-6:00	US	C%sT	1920
 			-6:00 Indianapolis C%sT	1942
@@ -887,7 +910,7 @@ Rule	Marengo	1951	only	-	Apr	lastSun	2:00	1:00	D
 Rule	Marengo	1951	only	-	Sep	lastSun	2:00	0	S
 Rule	Marengo	1954	1960	-	Apr	lastSun	2:00	1:00	D
 Rule	Marengo	1954	1960	-	Sep	lastSun	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Indiana/Marengo -5:45:23 -	LMT	1883 Nov 18 12:14:37
 			-6:00	US	C%sT	1951
 			-6:00	Marengo	C%sT	1961 Apr 30  2:00
@@ -911,7 +934,7 @@ Rule Vincennes	1956	1963	-	Apr	lastSun	2:00	1:00	D
 Rule Vincennes	1960	only	-	Oct	lastSun	2:00	0	S
 Rule Vincennes	1961	only	-	Sep	lastSun	2:00	0	S
 Rule Vincennes	1962	1963	-	Oct	lastSun	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Indiana/Vincennes -5:50:07 - LMT	1883 Nov 18 12:09:53
 			-6:00	US	C%sT	1946
 			-6:00 Vincennes	C%sT	1964 Apr 26  2:00
@@ -932,7 +955,7 @@ Rule Perry	1956	1963	-	Apr	lastSun	2:00	1:00	D
 Rule Perry	1960	only	-	Oct	lastSun	2:00	0	S
 Rule Perry	1961	only	-	Sep	lastSun	2:00	0	S
 Rule Perry	1962	1963	-	Oct	lastSun	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Indiana/Tell_City -5:47:03 - LMT	1883 Nov 18 12:12:57
 			-6:00	US	C%sT	1946
 			-6:00 Perry	C%sT	1964 Apr 26  2:00
@@ -948,7 +971,7 @@ Rule	Pike	1955	only	-	May	 1	0:00	1:00	D
 Rule	Pike	1955	1960	-	Sep	lastSun	2:00	0	S
 Rule	Pike	1956	1964	-	Apr	lastSun	2:00	1:00	D
 Rule	Pike	1961	1964	-	Oct	lastSun	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Indiana/Petersburg -5:49:07 - LMT	1883 Nov 18 12:10:53
 			-6:00	US	C%sT	1955
 			-6:00	Pike	C%sT	1965 Apr 25  2:00
@@ -970,7 +993,7 @@ Rule	Starke	1947	1954	-	Sep	lastSun	2:00	0	S
 Rule	Starke	1955	1956	-	Oct	lastSun	2:00	0	S
 Rule	Starke	1957	1958	-	Sep	lastSun	2:00	0	S
 Rule	Starke	1959	1961	-	Oct	lastSun	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Indiana/Knox -5:46:30 -	LMT	1883 Nov 18 12:13:30
 			-6:00	US	C%sT	1947
 			-6:00	Starke	C%sT	1962 Apr 29  2:00
@@ -986,7 +1009,7 @@ Rule	Pulaski	1946	1960	-	Apr	lastSun	2:00	1:00	D
 Rule	Pulaski	1946	1954	-	Sep	lastSun	2:00	0	S
 Rule	Pulaski	1955	1956	-	Oct	lastSun	2:00	0	S
 Rule	Pulaski	1957	1960	-	Sep	lastSun	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Indiana/Winamac -5:46:25 - LMT	1883 Nov 18 12:13:35
 			-6:00	US	C%sT	1946
 			-6:00	Pulaski	C%sT	1961 Apr 30  2:00
@@ -997,7 +1020,7 @@ Zone America/Indiana/Winamac -5:46:25 - LMT	1883 Nov 18 12:13:35
 			-5:00	US	E%sT
 #
 # Switzerland County, Indiana, did not observe DST from 1973 through 2005.
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Indiana/Vevay -5:40:16 -	LMT	1883 Nov 18 12:19:44
 			-6:00	US	C%sT	1954 Apr 25  2:00
 			-5:00	-	EST	1969
@@ -1022,7 +1045,7 @@ Rule Louisville	1941	only	-	Sep	lastSun	2:00	0	S
 Rule Louisville	1946	only	-	Jun	2	2:00	0	S
 Rule Louisville	1950	1955	-	Sep	lastSun	2:00	0	S
 Rule Louisville	1956	1960	-	Oct	lastSun	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Kentucky/Louisville -5:43:02 -	LMT	1883 Nov 18 12:16:58
 			-6:00	US	C%sT	1921
 			-6:00 Louisville C%sT	1942
@@ -1128,7 +1151,7 @@ Zone America/Kentucky/Monticello -5:39:24 - LMT	1883 Nov 18 12:20:36
 # Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER
 Rule	Detroit	1948	only	-	Apr	lastSun	2:00	1:00	D
 Rule	Detroit	1948	only	-	Sep	lastSun	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Detroit	-5:32:11 -	LMT	1905
 			-6:00	-	CST	1915 May 15  2:00
 			-5:00	-	EST	1942
@@ -1145,7 +1168,7 @@ Rule Menominee	1946	only	-	Apr	lastSun	2:00	1:00	D
 Rule Menominee	1946	only	-	Sep	lastSun	2:00	0	S
 Rule Menominee	1966	only	-	Apr	lastSun	2:00	1:00	D
 Rule Menominee	1966	only	-	Oct	lastSun	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Menominee	-5:50:27 -	LMT	1885 Sep 18 12:00
 			-6:00	US	C%sT	1946
 			-6:00 Menominee	C%sT	1969 Apr 27  2:00
@@ -1379,7 +1402,7 @@ Rule	StJohns	2007	2011	-	Mar	Sun>=8	0:01	1:00	D
 Rule	StJohns	2007	2010	-	Nov	Sun>=1	0:01	0	S
 #
 # St John's has an apostrophe, but Posix file names can't have apostrophes.
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/St_Johns	-3:30:52 -	LMT	1884
 			-3:30:52 StJohns N%sT	1918
 			-3:30:52 Canada	N%sT	1919
@@ -1392,7 +1415,7 @@ Zone America/St_Johns	-3:30:52 -	LMT	1884
 # most of east Labrador
 
 # The name 'Happy Valley-Goose Bay' is too long; use 'Goose Bay'.
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Goose_Bay	-4:01:40 -	LMT	1884 # Happy Valley-Goose Bay
 			-3:30:52 -	NST	1918
 			-3:30:52 Canada N%sT	1919
@@ -1466,7 +1489,7 @@ Rule	Halifax	1956	1959	-	Apr	lastSun	2:00	1:00	D
 Rule	Halifax	1956	1959	-	Sep	lastSun	2:00	0	S
 Rule	Halifax	1962	1973	-	Apr	lastSun	2:00	1:00	D
 Rule	Halifax	1962	1973	-	Oct	lastSun	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Halifax	-4:14:24 -	LMT	1902 Jun 15
 			-4:00	Halifax	A%sT	1918
 			-4:00	Canada	A%sT	1919
@@ -1504,7 +1527,7 @@ Rule	Moncton	1946	1956	-	Sep	lastSun	2:00	0	S
 Rule	Moncton	1957	1972	-	Oct	lastSun	2:00	0	S
 Rule	Moncton	1993	2006	-	Apr	Sun>=1	0:01	1:00	D
 Rule	Moncton	1993	2006	-	Oct	lastSun	0:01	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Moncton	-4:19:08 -	LMT	1883 Dec  9
 			-5:00	-	EST	1902 Jun 15
 			-4:00	Canada	A%sT	1933
@@ -1533,7 +1556,7 @@ Zone America/Moncton	-4:19:08 -	LMT	1883 Dec  9
 # For lack of better info, guess this practice began around 1970, contra to
 # Shanks & Pottenger who have this region observing AST/ADT.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Blanc-Sablon -3:48:28 -	LMT	1884
 			-4:00	Canada	A%sT	1970
 			-4:00	-	AST
@@ -1701,19 +1724,10 @@ Rule	Toronto	1922	1923	-	May	Sun>=8	2:00	1:00	D
 # was meant.
 Rule	Toronto	1922	1926	-	Sep	Sun>=15	2:00	0	S
 Rule	Toronto	1924	1927	-	May	Sun>=1	2:00	1:00	D
-# The 1927-to-1939 rules can be expressed more simply as
-# Rule	Toronto	1927	1937	-	Sep	Sun>=25	2:00	0	S
-# Rule	Toronto	1928	1937	-	Apr	Sun>=25	2:00	1:00	D
-# Rule	Toronto	1938	1940	-	Apr	lastSun	2:00	1:00	D
-# Rule	Toronto	1938	1939	-	Sep	lastSun	2:00	0	S
-# The rules below avoid use of Sun>=25
-# (which pre-2004 versions of zic cannot handle).
-Rule	Toronto	1927	1932	-	Sep	lastSun	2:00	0	S
-Rule	Toronto	1928	1931	-	Apr	lastSun	2:00	1:00	D
-Rule	Toronto	1932	only	-	May	1	2:00	1:00	D
-Rule	Toronto	1933	1940	-	Apr	lastSun	2:00	1:00	D
-Rule	Toronto	1933	only	-	Oct	1	2:00	0	S
-Rule	Toronto	1934	1939	-	Sep	lastSun	2:00	0	S
+Rule	Toronto	1927	1937	-	Sep	Sun>=25	2:00	0	S
+Rule	Toronto	1928	1937	-	Apr	Sun>=25	2:00	1:00	D
+Rule	Toronto	1938	1940	-	Apr	lastSun	2:00	1:00	D
+Rule	Toronto	1938	1939	-	Sep	lastSun	2:00	0	S
 Rule	Toronto	1945	1946	-	Sep	lastSun	2:00	0	S
 Rule	Toronto	1946	only	-	Apr	lastSun	2:00	1:00	D
 Rule	Toronto	1947	1949	-	Apr	lastSun	0:00	1:00	D
@@ -1746,7 +1760,7 @@ Rule	Toronto	1957	1973	-	Oct	lastSun	2:00	0	S
 # War,... [t]he cities agreed to implement DST during the summer
 # months for the remainder of the war years.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Toronto	-5:17:32 -	LMT	1895
 			-5:00	Canada	E%sT	1919
 			-5:00	Toronto	E%sT	1942 Feb  9  2:00s
@@ -1821,7 +1835,7 @@ Rule	Winn	1963	only	-	Sep	22	2:00	0	S
 Rule	Winn	1966	1986	-	Apr	lastSun	2:00s	1:00	D
 Rule	Winn	1966	2005	-	Oct	lastSun	2:00s	0	S
 Rule	Winn	1987	2005	-	Apr	Sun>=1	2:00s	1:00	D
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Winnipeg	-6:28:36 -	LMT	1887 Jul 16
 			-6:00	Winn	C%sT	2006
 			-6:00	Canada	C%sT
@@ -1843,6 +1857,13 @@ Zone America/Winnipeg	-6:28:36 -	LMT	1887 Jul 16
 # Willett (1914-03) notes that DST "has been in operation ... in the
 # City of Moose Jaw, Saskatchewan, for one year."
 
+# From Paul Eggert (2019-04-26):
+# Chris Pearce's book "The Great Daylight Saving Time Controversy" (2017)
+# says that Regina observed DST in 1914-1917.  No dates and times,
+# unfortunately.  It also says that in 1914 Saskatoon observed DST
+# from 1 June to 6 July, and that DST was also tried out in Davidson,
+# Melfort, and Prince Albert.
+
 # From Paul Eggert (2006-03-22):
 # Shanks & Pottenger say that since 1970 this region has mostly been as Regina.
 # Some western towns (e.g. Swift Current) switched from MST/MDT to CST in 1972.
@@ -1905,7 +1926,7 @@ Rule	Swift	1957	only	-	Oct	lastSun	2:00	0	S
 Rule	Swift	1959	1961	-	Apr	lastSun	2:00	1:00	D
 Rule	Swift	1959	only	-	Oct	lastSun	2:00	0	S
 Rule	Swift	1960	1961	-	Sep	lastSun	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Regina	-6:58:36 -	LMT	1905 Sep
 			-7:00	Regina	M%sT	1960 Apr lastSun  2:00
 			-6:00	-	CST
@@ -1936,7 +1957,7 @@ Rule	Edm	1969	only	-	Apr	lastSun	2:00	1:00	D
 Rule	Edm	1969	only	-	Oct	lastSun	2:00	0	S
 Rule	Edm	1972	1986	-	Apr	lastSun	2:00	1:00	D
 Rule	Edm	1972	2006	-	Oct	lastSun	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Edmonton	-7:33:52 -	LMT	1906 Sep
 			-7:00	Edm	M%sT	1987
 			-7:00	Canada	M%sT
@@ -2029,7 +2050,7 @@ Rule	Vanc	1946	1986	-	Apr	lastSun	2:00	1:00	D
 Rule	Vanc	1946	only	-	Oct	13	2:00	0	S
 Rule	Vanc	1947	1961	-	Sep	lastSun	2:00	0	S
 Rule	Vanc	1962	2006	-	Oct	lastSun	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Vancouver	-8:12:28 -	LMT	1884
 			-8:00	Vanc	P%sT	1987
 			-8:00	Canada	P%sT
@@ -2100,7 +2121,7 @@ Zone America/Creston	-7:46:04 -	LMT	1884
 #     varying the manner of reckoning standard time.
 #
 # * Yukon Territory Commissioner's Order 1966-20 Interpretation Ordinance
-#   http://? - no online source found
+#   [no online source found]
 #
 # * Standard Time and Time Zones in Canada; Thomson, Malcolm M.; JRASC,
 #   Vol. 64, pp.129-162; June 1970; SAO/NASA Astrophysics Data System (ADS)
@@ -2133,7 +2154,7 @@ Zone America/Creston	-7:46:04 -	LMT	1884
 #     to say eight hours behind Greenwich Time.
 #
 # * O.I.C. 1980/02 INTERPRETATION ACT
-#   http://? - no online source found
+#   [no online source found]
 #
 # * Yukon Daylight Saving Time, YOIC 1987/56
 #   https://www.canlii.org/en/yk/laws/regu/yoic-1987-56/latest/yoic-1987-56.html
@@ -2349,7 +2370,7 @@ Rule	NT_YK	1965	only	-	Oct	lastSun	2:00	0	S
 Rule	NT_YK	1980	1986	-	Apr	lastSun	2:00	1:00	D
 Rule	NT_YK	1980	2006	-	Oct	lastSun	2:00	0	S
 Rule	NT_YK	1987	2006	-	Apr	Sun>=1	2:00	1:00	D
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 # aka Panniqtuuq
 Zone America/Pangnirtung 0	-	-00	1921 # trading post est.
 			-4:00	NT_YK	A%sT	1995 Apr Sun>=1  2:00
@@ -2496,7 +2517,7 @@ Zone America/Dawson	-9:17:40 -	LMT	1900 Aug 20
 
 # From Paul Eggert (2001-03-03):
 #
-# http://www.latimes.com/news/nation/20010303/t000018766.html
+# https://www.latimes.com/archives/la-xpm-2001-mar-03-mn-32561-story.html
 # James F. Smith writes in today's LA Times
 # * Sonora will continue to observe standard time.
 # * Last week Mexico City's mayor Andrés Manuel López Obrador decreed that
@@ -2623,7 +2644,7 @@ Rule	Mexico	2001	only	-	May	Sun>=1	2:00	1:00	D
 Rule	Mexico	2001	only	-	Sep	lastSun	2:00	0	S
 Rule	Mexico	2002	max	-	Apr	Sun>=1	2:00	1:00	D
 Rule	Mexico	2002	max	-	Oct	lastSun	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 # Quintana Roo; represented by Cancún
 Zone America/Cancun	-5:47:04 -	LMT	1922 Jan  1  0:12:56
 			-6:00	-	CST	1981 Dec 23
@@ -2816,7 +2837,7 @@ Zone America/Tijuana	-7:48:04 -	LMT	1922 Jan  1  0:11:56
 # Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
 Rule	Bahamas	1964	1975	-	Oct	lastSun	2:00	0	S
 Rule	Bahamas	1964	1975	-	Apr	lastSun	2:00	1:00	D
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -2831,7 +2852,7 @@ Rule	Barb	1977	1978	-	Oct	Sun>=1	2:00	0	S
 Rule	Barb	1978	1980	-	Apr	Sun>=15	2:00	1:00	D
 Rule	Barb	1979	only	-	Sep	30	2:00	0	S
 Rule	Barb	1980	only	-	Sep	25	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Barbados	-3:58:29 -	LMT	1924 # Bridgetown
 			-3:58:29 -	BMT	1932 # Bridgetown Mean Time
 			-4:00	Barb	A%sT
@@ -2845,7 +2866,7 @@ Rule	Belize	1973	only	-	Dec	 5	0:00	1:00	CDT
 Rule	Belize	1974	only	-	Feb	 9	0:00	0	CST
 Rule	Belize	1982	only	-	Dec	18	0:00	1:00	CDT
 Rule	Belize	1983	only	-	Feb	12	0:00	0	CST
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	America/Belize	-5:52:48 -	LMT	1912 Apr
 			-6:00	Belize	%s
 
@@ -2862,7 +2883,7 @@ Zone	America/Belize	-5:52:48 -	LMT	1912 Apr
 # Friday, the same thing will happen in Bermuda.
 # http://www.theroyalgazette.com/apps/pbcs.dll/article?AID=/20060529/NEWS/105290135
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Atlantic/Bermuda	-4:19:18 -	LMT	1930 Jan  1  2:00 # Hamilton
 			-4:00	-	AST	1974 Apr 28  2:00
 			-4:00	Canada	A%sT	1976
@@ -2884,7 +2905,7 @@ Rule	CR	1991	1992	-	Jan	Sat>=15	0:00	1:00	D
 Rule	CR	1991	only	-	Jul	 1	0:00	0	S
 Rule	CR	1992	only	-	Mar	15	0:00	0	S
 # There are too many San Josés elsewhere, so we'll use 'Costa Rica'.
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Costa_Rica	-5:36:13 -	LMT	1890        # San José
 			-5:36:13 -	SJMT	1921 Jan 15 # San José Mean Time
 			-6:00	CR	C%sT
@@ -3090,7 +3111,7 @@ Rule	Cuba	2012	only	-	Apr	1	0:00s	1:00	D
 Rule	Cuba	2012	max	-	Nov	Sun>=1	0:00s	0	S
 Rule	Cuba	2013	max	-	Mar	Sun>=8	0:00s	1:00	D
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	America/Havana	-5:29:28 -	LMT	1890
 			-5:29:36 -	HMT	1925 Jul 19 12:00 # Havana MT
 			-5:00	Cuba	C%sT
@@ -3125,7 +3146,7 @@ Rule	DR	1969	1973	-	Oct	lastSun	0:00	0:30	-0430
 Rule	DR	1970	only	-	Feb	21	0:00	0	EST
 Rule	DR	1971	only	-	Jan	20	0:00	0	EST
 Rule	DR	1972	1974	-	Jan	21	0:00	0	EST
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Santo_Domingo -4:39:36 -	LMT	1890
 			-4:40	-	SDMT	1933 Apr  1 12:00 # S. Dom. MT
 			-5:00	DR	%s	1974 Oct 27
@@ -3140,7 +3161,7 @@ Rule	Salv	1987	1988	-	May	Sun>=1	0:00	1:00	D
 Rule	Salv	1987	1988	-	Sep	lastSun	0:00	0	S
 # There are too many San Salvadors elsewhere, so use America/El_Salvador
 # instead of America/San_Salvador.
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/El_Salvador -5:56:48 -	LMT	1921 # San Salvador
 			-6:00	Salv	C%sT
 
@@ -3173,7 +3194,7 @@ Rule	Guat	1991	only	-	Mar	23	0:00	1:00	D
 Rule	Guat	1991	only	-	Sep	 7	0:00	0	S
 Rule	Guat	2006	only	-	Apr	30	0:00	1:00	D
 Rule	Guat	2006	only	-	Oct	 1	0:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Guatemala	-6:02:04 -	LMT	1918 Oct 5
 			-6:00	Guat	C%sT
 
@@ -3259,7 +3280,7 @@ Rule	Haiti	2012	2015	-	Mar	Sun>=8	2:00	1:00	D
 Rule	Haiti	2012	2015	-	Nov	Sun>=1	2:00	0	S
 Rule	Haiti	2017	max	-	Mar	Sun>=8	2:00	1:00	D
 Rule	Haiti	2017	max	-	Nov	Sun>=1	2:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Port-au-Prince -4:49:20 -	LMT	1890
 			-4:49	-	PPMT	1917 Jan 24 12:00 # P-a-P MT
 			-5:00	Haiti	E%sT
@@ -3298,7 +3319,7 @@ Rule	Hond	1987	1988	-	May	Sun>=1	0:00	1:00	D
 Rule	Hond	1987	1988	-	Sep	lastSun	0:00	0	S
 Rule	Hond	2006	only	-	May	Sun>=1	0:00	1:00	D
 Rule	Hond	2006	only	-	Aug	Mon>=1	0:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Tegucigalpa -5:48:52 -	LMT	1921 Apr
 			-6:00	Hond	C%sT
 #
@@ -3319,7 +3340,7 @@ Zone America/Tegucigalpa -5:48:52 -	LMT	1921 Apr
 # Neita L. The politician in all of us. Jamaica Observer 2014-09-20
 # http://www.jamaicaobserver.com/columns/The-politician-in-all-of-us_17573647
 #
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	America/Jamaica	-5:07:10 -	LMT	1890        # Kingston
 			-5:07:10 -	KMT	1912 Feb    # Kingston Mean Time
 			-5:00	-	EST	1974
@@ -3327,7 +3348,7 @@ Zone	America/Jamaica	-5:07:10 -	LMT	1890        # Kingston
 			-5:00	-	EST
 
 # Martinique
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Martinique	-4:04:20 -      LMT	1890        # Fort-de-France
 			-4:04:20 -	FFMT	1911 May    # Fort-de-France MT
 			-4:00	-	AST	1980 Apr  6
@@ -3391,7 +3412,7 @@ Rule	Nic	2005	only	-	Apr	10	0:00	1:00	D
 Rule	Nic	2005	only	-	Oct	Sun>=1	0:00	0	S
 Rule	Nic	2006	only	-	Apr	30	2:00	1:00	D
 Rule	Nic	2006	only	-	Oct	Sun>=1	1:00	0	S
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	America/Managua	-5:45:08 -	LMT	1890
 			-5:45:12 -	MMT	1934 Jun 23 # Managua Mean Time?
 			-6:00	-	CST	1973 May
@@ -3403,7 +3424,7 @@ Zone	America/Managua	-5:45:08 -	LMT	1890
 			-6:00	Nic	C%sT
 
 # Panama
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	America/Panama	-5:18:08 -	LMT	1890
 			-5:19:36 -	CMT	1908 Apr 22 # Colón Mean Time
 			-5:00	-	EST
@@ -3411,7 +3432,7 @@ Link America/Panama America/Cayman
 
 # Puerto Rico
 # There are too many San Juans elsewhere, so we'll use 'Puerto_Rico'.
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 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
@@ -3423,7 +3444,7 @@ Zone America/Puerto_Rico -4:24:25 -	LMT	1899 Mar 28 12:00 # San Juan
 
 # St Pierre and Miquelon
 # There are too many St Pierres elsewhere, so we'll use 'Miquelon'.
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Miquelon	-3:44:40 -	LMT	1911 May 15 # St Pierre
 			-4:00	-	AST	1980 May
 			-3:00	-	-03	1987
@@ -3469,7 +3490,7 @@ Zone America/Miquelon	-3:44:40 -	LMT	1911 May 15 # St Pierre
 # by March 2018 for TCI. Magnetic Media. 2017-08-25.
 # http://magneticmediatv.com/2017/08/time-change-back-by-march-2018-for-tci/
 #
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Grand_Turk	-4:44:32 -	LMT	1890
 			-5:07:10 -	KMT	1912 Feb # Kingston Mean Time
 			-5:00	-	EST	1979
diff --git a/tz/pacificnew b/tz/pacificnew
index 0e6cf07..8403219 100644
--- a/tz/pacificnew
+++ b/tz/pacificnew
@@ -21,7 +21,7 @@
 ## Rule	Twilite	XXXX	max	uspres	Nov	Sun>=7	2:00	0	S
 ## Rule	Twilite	XXXX	max	nonpres	Oct	lastSun	2:00	0	S
 
-# Zone	NAME			GMTOFF	RULES/SAVE	FORMAT	[UNTIL]
+# Zone	NAME			STDOFF	RULES/SAVE	FORMAT	[UNTIL]
 ## Zone	America/Los_Angeles-PET	-8:00	US		P%sT	XXXX
 ##				-8:00	Twilite		P%sT
 
diff --git a/tz/southamerica b/tz/southamerica
index b66cb88..397a2cc 100644
--- a/tz/southamerica
+++ b/tz/southamerica
@@ -396,7 +396,7 @@ Rule	Arg	2008	only	-	Oct	Sun>=15	0:00	1:00	-
 # plus is that this silences a zic complaint that there's no POSIX TZ
 # setting for timestamps past 2038.
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 #
 # Buenos Aires (BA), Capital Federal (CF),
 Zone America/Argentina/Buenos_Aires -3:53:48 - LMT	1894 Oct 31
@@ -577,7 +577,7 @@ Zone America/Argentina/Ushuaia -4:33:12 - LMT	1894 Oct 31
 Link America/Curacao America/Aruba
 
 # Bolivia
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# 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
@@ -920,14 +920,13 @@ Rule	Brazil	2012	only	-	Feb	Sun>=22	0:00	0	-
 # removed Tocantins.
 Rule	Brazil	2013	2014	-	Feb	Sun>=15	0:00	0	-
 Rule	Brazil	2015	only	-	Feb	Sun>=22	0:00	0	-
-Rule	Brazil	2016	2022	-	Feb	Sun>=15	0:00	0	-
+Rule	Brazil	2016	2019	-	Feb	Sun>=15	0:00	0	-
 # From Steffen Thorsen (2017-12-18):
 # According to many media sources, next year's DST start in Brazil will move to
-# the first Sunday of November, and it will stay like that for the years after.
+# the first Sunday of November
 # ... https://www.timeanddate.com/news/time/brazil-delays-dst-2018.html
 # From Steffen Thorsen (2017-12-20):
 # http://www.planalto.gov.br/ccivil_03/_ato2015-2018/2017/decreto/D9242.htm
-#
 # From Fábio Gomes (2018-10-04):
 # The Brazilian president just announced a new change on this year DST.
 # It was scheduled to start on November 4th and it was changed to November 18th.
@@ -935,22 +934,21 @@ Rule	Brazil	2016	2022	-	Feb	Sun>=15	0:00	0	-
 # The Brazilian government just announced that the change in DST was
 # canceled....  Maybe the president Michel Temer also woke up one hour
 # earlier today. :)
-Rule	Brazil	2018	max	-	Nov	Sun>=1	0:00	1:00	-
-Rule	Brazil	2023	only	-	Feb	Sun>=22	0:00	0	-
-Rule	Brazil	2024	2025	-	Feb	Sun>=15	0:00	0	-
-Rule	Brazil	2026	only	-	Feb	Sun>=22	0:00	0	-
-Rule	Brazil	2027	2033	-	Feb	Sun>=15	0:00	0	-
-Rule	Brazil	2034	only	-	Feb	Sun>=22	0:00	0	-
-Rule	Brazil	2035	2036	-	Feb	Sun>=15	0:00	0	-
-Rule	Brazil	2037	only	-	Feb	Sun>=22	0:00	0	-
-# From Arthur David Olson (2008-09-29):
-# The next is wrong in some years but is better than nothing.
-Rule	Brazil	2038	max	-	Feb	Sun>=15	0:00	0	-
-
-# The latest ruleset listed above says that the following states observe DST:
+Rule	Brazil	2018	only	-	Nov	Sun>=1	0:00	1:00	-
+# The last ruleset listed above says that the following states observed DST:
 # DF, ES, GO, MG, MS, MT, PR, RJ, RS, SC, SP.
+#
+# From Steffen Thorsen (2019-04-05):
+# According to multiple sources the Brazilian president wants to get rid of DST.
+# https://gmconline.com.br/noticias/politica/bolsonaro-horario-de-verao-deve-acabar-este-ano
+# https://g1.globo.com/economia/noticia/2019/04/05/governo-anuncia-fim-do-horario-de-verao.ghtml
+# From Marcus Diniz (2019-04-25):
+# Brazil no longer has DST changes - decree signed today
+# https://g1.globo.com/politica/noticia/2019/04/25/bolsonaro-assina-decreto-que-acaba-com-o-horario-de-verao.ghtml
+# From Daniel Soares de Oliveira (2019-04-26):
+# http://www.planalto.gov.br/ccivil_03/_Ato2019-2022/2019/Decreto/D9772.htm
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 #
 # Fernando de Noronha (administratively part of PE)
 Zone America/Noronha	-2:09:40 -	LMT	1914
@@ -1258,6 +1256,8 @@ Zone America/Rio_Branco	-4:31:12 -	LMT	1914
 # https://twitter.com/MinEnergia/status/1029009354001973248
 # "We will keep the new time policy unchanged for at least the next 4 years."
 # So we extend the new rules on Saturdays at 24:00 mainland time indefinitely.
+# From Juan Correa (2019-02-04):
+# http://www.diariooficial.interior.gob.cl/publicaciones/2018/11/23/42212/01/1498738.pdf
 
 # Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
 Rule	Chile	1927	1931	-	Sep	 1	0:00	1:00	-
@@ -1298,7 +1298,7 @@ Rule	Chile	2019	max	-	Apr	Sun>=2	3:00u	0	-
 Rule	Chile	2019	max	-	Sep	Sun>=2	4:00u	1:00	-
 # IATA SSIM anomalies: (1992-02) says 1992-03-14;
 # (1996-09) says 1998-03-08.  Ignore these.
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Santiago	-4:42:46 -	LMT	1890
 			-4:42:46 -	SMT	1910 Jan 10 # Santiago Mean Time
 			-5:00	-	-05	1916 Jul  1
@@ -1347,7 +1347,7 @@ Zone Pacific/Easter	-7:17:28 -	LMT	1890
 # Palmer has followed Chile.  Prior to that, before the Falklands War,
 # Palmer used to be supplied from Argentina.
 #
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Antarctica/Palmer	0	-	-00	1965
 			-4:00	Arg	-04/-03	1969 Oct  5
 			-3:00	Arg	-03/-02	1982 May
@@ -1362,7 +1362,7 @@ Zone Antarctica/Palmer	0	-	-00	1965
 # Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
 Rule	CO	1992	only	-	May	 3	0:00	1:00	-
 Rule	CO	1993	only	-	Apr	 4	0:00	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	America/Bogota	-4:56:16 -	LMT	1884 Mar 13
 			-4:56:16 -	BMT	1914 Nov 23 # Bogotá Mean Time
 			-5:00	CO	-05/-04
@@ -1387,7 +1387,7 @@ Zone	America/Bogota	-4:56:16 -	LMT	1884 Mar 13
 # Netherlands as Kingdom Islands.  This won't affect their time zones
 # though, as far as we know.
 #
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	America/Curacao	-4:35:47 -	LMT	1912 Feb 12 # Willemstad
 			-4:30	-	-0430	1965
 			-4:00	-	AST
@@ -1423,7 +1423,7 @@ Link	America/Curacao	America/Kralendijk	# Caribbean Netherlands
 Rule	Ecuador	1992	only	-	Nov	28	0:00	1:00	-
 Rule	Ecuador	1993	only	-	Feb	 5	0:00	0	-
 #
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Guayaquil	-5:19:20 -	LMT	1890
 			-5:14:00 -	QMT	1931 # Quito Mean Time
 			-5:00	Ecuador	-05/-04
@@ -1526,7 +1526,7 @@ Rule	Falk	1985	2000	-	Sep	Sun>=9	0:00	1:00	-
 Rule	Falk	1986	2000	-	Apr	Sun>=16	0:00	0	-
 Rule	Falk	2001	2010	-	Apr	Sun>=15	2:00	0	-
 Rule	Falk	2001	2010	-	Sep	Sun>=1	2:00	1:00	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Atlantic/Stanley	-3:51:24 -	LMT	1890
 			-3:51:24 -	SMT	1912 Mar 12 # Stanley Mean Time
 			-4:00	Falk	-04/-03	1983 May
@@ -1535,13 +1535,13 @@ Zone Atlantic/Stanley	-3:51:24 -	LMT	1890
 			-3:00	-	-03
 
 # French Guiana
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Cayenne	-3:29:20 -	LMT	1911 Jul
 			-4:00	-	-04	1967 Oct
 			-3:00	-	-03
 
 # Guyana
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	America/Guyana	-3:52:40 -	LMT	1915 Mar    # Georgetown
 			-3:45	-	-0345	1975 Jul 31
 			-3:00	-	-03	1991
@@ -1635,7 +1635,7 @@ Rule	Para	2010	2012	-	Apr	Sun>=8	0:00	0	-
 # http://www.presidencia.gov.py/archivos/documentos/DECRETO1264_ey9r8zai.pdf
 Rule	Para	2013	max	-	Mar	Sun>=22	0:00	0	-
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Asuncion	-3:50:40 -	LMT	1890
 			-3:50:40 -	AMT	1931 Oct 10 # Asunción Mean Time
 			-4:00	-	-04	1972 Oct
@@ -1664,13 +1664,13 @@ Rule	Peru	1990	only	-	Apr	 1	0:00	0	-
 # IATA is ambiguous for 1993/1995; go with Shanks & Pottenger.
 Rule	Peru	1994	only	-	Jan	 1	0:00	1:00	-
 Rule	Peru	1994	only	-	Apr	 1	0:00	0	-
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	America/Lima	-5:08:12 -	LMT	1890
 			-5:08:36 -	LMT	1908 Jul 28 # Lima Mean Time?
 			-5:00	Peru	-05/-04
 
 # South Georgia
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Atlantic/South_Georgia -2:26:08 -	LMT	1890 # Grytviken
 			-2:00	-	-02
 
@@ -1678,7 +1678,7 @@ Zone Atlantic/South_Georgia -2:26:08 -	LMT	1890 # Grytviken
 # uninhabited; scientific personnel have wintered
 
 # Suriname
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Paramaribo	-3:40:40 -	LMT	1911
 			-3:40:52 -	PMT	1935     # Paramaribo Mean Time
 			-3:40:36 -	PMT	1945 Oct    # The capital moved?
@@ -1686,7 +1686,7 @@ Zone America/Paramaribo	-3:40:40 -	LMT	1911
 			-3:00	-	-03
 
 # Trinidad and Tobago
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Port_of_Spain -4:06:04 -	LMT	1912 Mar 2
 			-4:00	-	AST
 
@@ -1957,7 +1957,7 @@ Zone America/Montevideo	-3:44:51 -	LMT	1908 Jun 10
 # ... published in the official Gazette [2016-04-18], here:
 # http://historico.tsj.gob.ve/gaceta_ext/abril/1842016/E-1842016-4551.pdf
 
-# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	America/Caracas	-4:27:44 -	LMT	1890
 			-4:27:40 -	CMT	1912 Feb 12 # Caracas Mean Time?
 			-4:30	-	-0430	1965 Jan  1  0:00
diff --git a/tz/systemv b/tz/systemv
index 24c8f64..a8c037c 100644
--- a/tz/systemv
+++ b/tz/systemv
@@ -23,7 +23,7 @@ Rule	SystemV	1975	only	-	Oct	lastSun	2:00	0	S
 Rule	SystemV	1976	max	-	Apr	lastSun	2:00	1:00	D
 Rule	SystemV	1976	max	-	Oct	lastSun	2:00	0	S
 
-# Zone	NAME		GMTOFF	RULES/SAVE	FORMAT	[UNTIL]
+# Zone	NAME		STDOFF	RULES/SAVE	FORMAT	[UNTIL]
 ## Zone	SystemV/AST4ADT	-4:00	SystemV		A%sT
 ## Zone	SystemV/EST5EDT	-5:00	SystemV		E%sT
 ## Zone	SystemV/CST6CDT	-6:00	SystemV		C%sT
diff --git a/tz/theory.html b/tz/theory.html
index e373022..e0b3233 100644
--- a/tz/theory.html
+++ b/tz/theory.html
@@ -88,7 +88,7 @@ href="https://en.wikipedia.org/wiki/POSIX">POSIX</a>, an international
 standard for <a
 href="https://en.wikipedia.org/wiki/Unix">UNIX</a>-like systems.
 As of this writing, the current edition of POSIX is: <a
-href="http://pubs.opengroup.org/onlinepubs/9699919799/"> The Open
+href="https://pubs.opengroup.org/onlinepubs/9699919799/"> The Open
 Group Base Specifications Issue 7</a>, IEEE Std 1003.1-2017, 2018
 Edition.
 Because the database's scope encompasses real-world changes to civil
@@ -186,7 +186,7 @@ in decreasing order of importance:
     href="https://en.wikipedia.org/wiki/ASCII">ASCII</a> letters,
     '<code>.</code>', '<code>-</code>' and '<code>_</code>'.
     Do not use digits, as that might create an ambiguity with <a
-    href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03">POSIX
+    href="https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03">POSIX
     <code>TZ</code> strings</a>.
     A file name component must not exceed 14 characters or start with
     '<code>-</code>'.
@@ -301,7 +301,7 @@ in decreasing order of importance:
 
 <p>
 Guidelines have evolved with time, and names following old versions of
-this guideline might not follow the current version. When guidelines
+these guidelines might not follow the current version. When guidelines
 have changed, old names continue to be supported. Guideline changes
 have included the following:
 </p>
@@ -330,7 +330,7 @@ and the file '<code>northamerica</code>' defines the legacy names
 </li>
 
 <li>
-Older versions of this guideline said that
+Older versions of these guidelines said that
 there should typically be at least one name for each <a
 href="https://en.wikipedia.org/wiki/ISO_3166-1"><abbr
 title="International Organization for Standardization">ISO</abbr>
@@ -379,8 +379,8 @@ in decreasing order of importance:
     special meaning to the
     <a href="https://en.wikipedia.org/wiki/Unix_shell">UNIX shell</a>
     and cause commands like
-    '<code><a href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#set">set</a>
-    `<a href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/date.html">date</a>`</code>'
+    '<code><a href="https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#set">set</a>
+    `<a href="https://pubs.opengroup.org/onlinepubs/9699919799/utilities/date.html">date</a>`</code>'
     to have unexpected effects.
     Previous editions of this guideline required upper-case letters, but the
     Congressman who introduced
@@ -955,7 +955,7 @@ an older <code>zic</code>.
   </li>
   <li>
     In POSIX, there is no tamper-proof way for a process to learn the
-    system's best idea of local wall clock.
+    system's best idea of local (wall clock) time.
     This is important for applications that an administrator wants
     used only at certain times &ndash; without regard to whether the
     user has fiddled the
@@ -1052,14 +1052,14 @@ an older <code>zic</code>.
   </li>
   <li>
     A function <code>tzsetwall</code> has been added to arrange for the
-    system's best approximation to local wall clock time to be delivered
+    system's best approximation to local (wall clock) time to be delivered
     by subsequent calls to <code>localtime</code>.
-    Source code for portable applications that "must" run on local wall
-    clock time should call <code>tzsetwall</code>;
+    Source code for portable applications that "must" run on local
+    time should call <code>tzsetwall</code>;
     if such code is moved to "old" systems that do not
     provide <code>tzsetwall</code>, you will not be able to generate an
     executable program.
-    (These functions also arrange for local wall clock time to
+    (These functions also arrange for local time to
     be used if <code>tzset</code> is called &ndash; directly or
     indirectly &ndash; and there is no <code>TZ</code> environment
     variable; portable applications should not, however, rely on this
@@ -1354,11 +1354,11 @@ Sources for time on other planets:
     Michael Allison and Robert Schmunk,
     "<a href="https://www.giss.nasa.gov/tools/mars24/help/notes.html">Technical
       Notes on Mars Solar Time as Adopted by the Mars24 Sunclock</a>"
-    (2015-06-30).
+    (2018-12-13).
   </li>
   <li>
     Jia-Rui Chong,
-    "<a href="http://articles.latimes.com/2004/jan/14/science/sci-marstime14">Workdays
+    "<a href="https://www.latimes.com/archives/la-xpm-2004-jan-14-sci-marstime14-story.html">Workdays
     Fit for a Martian</a>", <cite>Los Angeles Times</cite>
     (2004-01-14), pp A1, A20&ndash;A21.
   </li>
diff --git a/tz/tz-art.html b/tz/tz-art.html
index 32f523e..8c57174 100644
--- a/tz/tz-art.html
+++ b/tz/tz-art.html
@@ -25,7 +25,7 @@ briefly says why France has more time zones than Russia.
 "About Time" (1962; 59 minutes) is part of the
 Bell Science extravaganza, with Frank Baxter, Richard Deacon, and Les Tremayne.
 Its advisor was Richard Feynman, and it was voiced by Mel Blanc.
-(<a href="http://www.imdb.com/title/tt0154110/">IMDb entry</a>.)</li>
+(<a href="https://www.imdb.com/title/tt0154110/">IMDb entry</a>.)</li>
 </ul>
 <h2>Movies</h2>
 <ul>
@@ -36,14 +36,14 @@ there is a reference to British Double Summer Time.
 The time does not play a large part in the plot;
 it's just a passing reference to the time when one of the
 characters was supposed to have died (but didn't).
-(<a href="http://us.imdb.com/title/tt0038733/">IMDb entry.</a>)
+(<a href="https://www.imdb.com/title/tt0038733/">IMDb entry.</a>)
 (Dave Cantor)
 <li>
 The 1953 railway comedy movie <em>The Titfield Thunderbolt</em> includes a
 play on words on British Double Summer Time. Valentine's wife wants
 him to leave the pub and asks him, "Do you know what time it is?"
 And he, happy where he is, replies: "Yes, my love. Summer double time."
-(<a href="http://us.imdb.com/title/tt0046436/">IMDb entry.</a>)
+(<a href="https://www.imdb.com/title/tt0046436/">IMDb entry.</a>)
 (Mark Brader, 2009-10-02)
 </li>
 <li>
@@ -56,7 +56,7 @@ a gigantic computerized theft. To achieve this, at one location the
 crooks interfere with the microwave system supplying time signals to
 the computer, advancing the time by 0.1 second each minute over the
 last hour of 1999. (So this movie teaches us that 0.1 &times; 60 = 10.)
-(<a href="http://us.imdb.com/title/tt0137494/">IMDb entry.</a>)
+(<a href="https://www.imdb.com/title/tt0137494/">IMDb entry.</a>)
 (Mark Brader, 2009-10-02)
 </li>
 <li>
@@ -183,7 +183,7 @@ European readers of the 1870s clearly held the U.S. press in
 deep contempt; the protagonists cross the U.S. without once
 reading a paper.
 Available versions include
-<a href="http://www.literature.org/Works/Jules-Verne/eighty">an English
+<a href="https://www.gutenberg.org/ebooks/103">an English
 translation</a>, and
 <a href="https://fourmilab.ch/etexts/www/tdm80j">the original French</a>
 "with illustrations from the original 1873 French-language edition".
@@ -203,7 +203,7 @@ part in the novel." (Paul Eggert, 2006-04-22)
 </li>
 <li>
 John Dunning, <a
-href="http://books.simonandschuster.com/Two-OClock-Eastern-Wartime/John-Dunning/9781439171530"><em>Two
+href="https://www.simonandschuster.com/books/Two-OClock-Eastern-Wartime/John-Dunning/9781439171530"><em>Two
 O'Clock, Eastern Wartime</em></a>, 2001.
 Mystery, history, daylight saving time, and old-time radio.
 </li>
@@ -234,7 +234,7 @@ Todd Strait, drums</td></tr>
 <tr><td>Notes</td><td>CD notes "additional lyric by Karrin Allyson;
 arranged by Russ Long and Karrin Allyson"</td></tr>
 <tr><td>ADO Rating</td><td>1 star</td></tr>
-<tr><td><a href="http://www.allmusic.com/album/i-didnt-know-about-you-mw0000618657">AMG Rating</a></td><td>4 stars</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/i-didnt-know-about-you-mw0000618657">AMG Rating</a></td><td>4 stars</td></tr>
 <tr><td>Penguin Rating</td><td>3.5 stars</td></tr>
 <tr><td>&nbsp;</td><td></td></tr>
 <tr><td>Artist</td><td>Kevin Mahogany</td></tr>
@@ -249,7 +249,7 @@ Ray Drummond, bass;
 Ralph Moore, tenor saxophone;
 Lewis Nash, drums</td></tr>
 <tr><td>ADO Rating</td><td>1.5 stars</td></tr>
-<tr><td><a href="http://www.allmusic.com/album/double-rainbow-mw0000620371">AMG Rating</a></td><td>3 stars</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/double-rainbow-mw0000620371">AMG Rating</a></td><td>3 stars</td></tr>
 <tr><td>Penguin Rating</td><td>3 stars</td></tr>
 <tr><td>&nbsp;</td><td></td></tr>
 <tr><td>Artist</td><td>Joe Williams</td></tr>
@@ -263,7 +263,7 @@ The Robert Farnon [39 piece] Orchestra</td></tr>
 <tr><td>Notes</td><td>This CD is also available as part of a 3-CD package from
 Telarc, "Triple Play" (CD-83461)</td></tr>
 <tr><td>ADO Rating</td><td>black dot</td></tr>
-<tr><td><a href="http://www.allmusic.com/album/heres-to-life-mw0000623648">AMG Rating</a></td><td>2 stars</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/heres-to-life-mw0000623648">AMG Rating</a></td><td>2 stars</td></tr>
 <tr><td>Penguin Rating</td><td>3 stars</td></tr>
 <tr><td>&nbsp;</td><td></td></tr>
 <tr><td>Artist</td><td>Charles Fambrough</td></tr>
@@ -278,7 +278,7 @@ Edward Simon, piano;
 Lenny White, drums;
 Marion Simon, percussion</td></tr>
 <tr><td>ADO Rating</td><td>2 stars</td></tr>
-<tr><td><a href="http://www.allmusic.com/album/keeper-of-the-spirit-mw0000176559">AMG Rating</a></td><td>unrated</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/keeper-of-the-spirit-mw0000176559">AMG Rating</a></td><td>unrated</td></tr>
 <tr><td>Penguin Rating</td><td>3 stars</td></tr>
 </table>
 <hr>
@@ -296,7 +296,7 @@ David Piltch, string bass</td></tr>
 <tr><td>Notes</td><td>Lyrical reference to "Eastern Standard Time" in
 Tom Waits' "Purple Avenue"</td></tr>
 <tr><td>ADO Rating</td><td>2.5 stars</td></tr>
-<tr><td><a href="http://www.allmusic.com/album/blame-it-on-my-youth-mw0000274303">AMG Rating</a></td><td>3 stars</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/blame-it-on-my-youth-mw0000274303">AMG Rating</a></td><td>3 stars</td></tr>
 <tr><td>Penguin Rating</td><td>unrated</td></tr>
 <tr><td>&nbsp;</td><td></td></tr>
 <tr><td>Artist</td><td>Milt Hinton</td></tr>
@@ -327,7 +327,7 @@ and Good Time Charlie.
 <a href="http://www.chiaroscurojazz.com/album.php?C=310">Album info</a>
 is available.</td></tr>
 <tr><td>ADO Rating</td><td>3 stars</td></tr>
-<tr><td><a href="http://www.allmusic.com/album/old-man-time-mw0000269353">AMG Rating</a></td><td>4.5 stars</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/old-man-time-mw0000269353">AMG Rating</a></td><td>4.5 stars</td></tr>
 <tr><td>Penguin Rating</td><td>3 stars</td></tr>
 <tr><td>&nbsp;</td><td></td></tr>
 <tr><td>Artist</td><td>Alan Broadbent</td></tr>
@@ -341,7 +341,7 @@ Putter Smith, Bass;
 Frank Gibson, Jr., drums</td></tr>
 <tr><td>Notes</td><td>The CD cover features an analemma for equation-of-time fans</td></tr>
 <tr><td>ADO Rating</td><td>1 star</td></tr>
-<tr><td><a href="http://www.allmusic.com/album/pacific-standard-time-mw0000645433">AMG Rating</a></td><td>4 stars</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/pacific-standard-time-mw0000645433">AMG Rating</a></td><td>4 stars</td></tr>
 <tr><td>Penguin Rating</td><td>3.5 stars</td></tr>
 <tr><td>&nbsp;</td><td></td></tr>
 <tr><td>Artist</td><td>Anthony Braxton/Richard Teitelbaum</td></tr>
@@ -356,7 +356,7 @@ Leo Smith, trumpet and miscellaneous instruments;
 Leroy Jenkins, violin and miscellaneous instruments;
 Richard Teitelbaum, modular moog and micromoog synthesizer</td></tr>
 <tr><td>ADO Rating</td><td>black dot</td></tr>
-<tr><td><a href="http://www.allmusic.com/album/silence-time-zones-mw0000595735">AMG Rating</a></td><td>4 stars</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/silence-time-zones-mw0000595735">AMG Rating</a></td><td>4 stars</td></tr>
 <tr><td>&nbsp;</td><td></td></tr>
 <tr><td>Artist</td><td>Charles Gayle</td></tr>
 <tr><td>CD</td><td>Time Zones</td></tr>
@@ -366,7 +366,7 @@ Richard Teitelbaum, modular moog and micromoog synthesizer</td></tr>
 <tr><td>Total Time</td><td>49:06</td></tr>
 <tr><td>Personnel</td><td>Charles Gayle, piano</td></tr>
 <tr><td>ADO Rating</td><td>1 star</td></tr>
-<tr><td><a href="http://www.allmusic.com/album/time-zones-mw0000349642">AMG Rating</a></td><td>4.5 stars</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/time-zones-mw0000349642">AMG Rating</a></td><td>4.5 stars</td></tr>
 <tr><td>&nbsp;</td><td></td></tr>
 <tr><td>Artist</td><td>The Get Up Kids</td></tr>
 <tr><td>CD</td><td>Eudora</td></tr>
@@ -375,7 +375,7 @@ Richard Teitelbaum, modular moog and micromoog synthesizer</td></tr>
 <tr><td>ID</td><td>357</td></tr>
 <tr><td>Total Time</td><td>65:12</td></tr>
 <tr><td>Notes</td><td>Includes the song "Central Standard Time." Thanks to Colin Bowern for this information.</td></tr>
-<tr><td><a href="http://www.allmusic.com/album/eudora-mw0000592063">AMG Rating</a></td><td>2.5 stars</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/eudora-mw0000592063">AMG Rating</a></td><td>2.5 stars</td></tr>
 <tr><td>&nbsp;</td><td></td></tr>
 
 <tr><td>Artist</td><td>Coldplay</td></tr>
@@ -420,7 +420,7 @@ Supernaw.</td></tr>
 <tr><td>ID</td><td>272</td></tr>
 <tr><td>Total Time</td><td>73:05</td></tr>
 <tr><td>Notes</td><td>Includes the song "Twilight Time Zone."</td></tr>
-<tr><td><a href="http://www.allmusic.com/album/lobster-leaps-in-mw0000794929">AMG Rating</a></td><td>3.5 stars</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/lobster-leaps-in-mw0000794929">AMG Rating</a></td><td>3.5 stars</td></tr>
 <tr><td>ADO Rating</td><td>2 stars</td></tr>
 
 <tr><td>&nbsp;</td><td></td></tr>
@@ -431,7 +431,7 @@ Supernaw.</td></tr>
 <tr><td>Label</td><td>Columbia</td></tr>
 <tr><td>ID</td><td>CK-8905</td></tr>
 <tr><td>Total Time</td><td>45:36</td></tr>
-<tr><td><a href="http://www.allmusic.com/album/the-times-they-a-changin-mw0000202344">AMG Rating</a></td><td>4.5 stars</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/the-times-they-a-changin-mw0000202344">AMG Rating</a></td><td>4.5 stars</td></tr>
 <tr><td>ADO Rating</td><td>1.5 stars</td></tr>
 <tr><td>Notes<td>The title song is also available on "Bob Dylan's Greatest Hits" and "The Essential Bob Dylan."</td></tr>
 <tr><td>&nbsp;</td><td></td></tr>
@@ -442,7 +442,7 @@ Supernaw.</td></tr>
 <tr><td>Label</td><td>Universal Jazz France</td></tr>
 <tr><td>ID</td><td>B0012688-02</td></tr>
 <tr><td>Total Time</td><td>42:31</td></tr>
-<tr><td><a href="http://www.allmusic.com/album/tide-mw0000815692">AMG Rating</a></td><td>3.5 stars</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/tide-mw0000815692">AMG Rating</a></td><td>3.5 stars</td></tr>
 <tr><td>ADO Rating</td><td>2.5 stars</td></tr>
 <tr><td>Notes<td>Includes the song "Fire and Wood" with the lyric
 "The clocks were turned back you remember/Think it's still November."
@@ -455,7 +455,7 @@ Supernaw.</td></tr>
 <tr><td>ID</td><td>B0005171-02</td></tr>
 <tr><td>Total Time</td><td>156:22</td></tr>
 <tr><td>ADO Rating</td><td>1 star</td></tr>
-<tr><td><a href="http://www.allmusic.com/album/youre-getting-better-the-word-jazz-dot-masters-mw0000736197">AMG Rating</a></td><td>4.5 stars</td></tr>
+<tr><td><a href="https://www.allmusic.com/album/youre-getting-better-the-word-jazz-dot-masters-mw0000736197">AMG Rating</a></td><td>4.5 stars</td></tr>
 <tr><td>Notes</td><td>Includes the piece "What Time Is It"
 ("He knew what time it was everywhere...that counted").</td></tr>
 </table>
@@ -478,16 +478,16 @@ The related book <em>What If?</em> has an entry
 </li>
 <li>
 Pig kills time in <a
-href="http://www.gocomics.com/pearlsbeforeswine/2016/11/06"><em>Pearls
+href="https://www.gocomics.com/pearlsbeforeswine/2016/11/06"><em>Pearls
 Before Swine</em> (2016-11-06)</a>.
 </li>
 <li>
 Stonehenge is abandoned in <a
-href='http://www.gocomics.com/nonsequitur/2017/03/12'><em>Non Sequitur</em>
+href='https://www.gocomics.com/nonsequitur/2017/03/12'><em>Non Sequitur</em>
 (2017-03-12)</a>.
 <li>
 The boss freaks out in <a
-href='http://dilbert.com/strip/1998-03-14'><em>Dilbert</em> (1998-03-14)</a>.
+href='https://dilbert.com/strip/1998-03-14'><em>Dilbert</em> (1998-03-14)</a>.
 </li>
 <li>
 Peppermint Patty: "What if the world comes to an end tonight, Marcie?"
@@ -495,7 +495,7 @@ Peppermint Patty: "What if the world comes to an end tonight, Marcie?"
 Marcie: "I promise there'll be a tomorrow, sir ... in fact,
 it's already tomorrow in Australia!"
 <br>
-(Charles M. Schulz, <a href='http://www.gocomics.com/peanuts/1980/06/13'><em>Peanuts</em>, 1980-06-13</a>)
+(Charles M. Schulz, <a href='https://www.gocomics.com/peanuts/1980/06/13'><em>Peanuts</em>, 1980-06-13</a>)
 </li>
 </ul>
 <h2>Jokes</h2>
diff --git a/tz/tz-how-to.html b/tz/tz-how-to.html
index 8471b67..2e4842d 100644
--- a/tz/tz-how-to.html
+++ b/tz/tz-how-to.html
@@ -102,7 +102,7 @@ in some localizable way. It&rsquo;s used in the file, <code>pacificnew</code>,
 to determine whether a given year will have a US presidential election;
 but everything related to that use is commented out.)
 
-<p>The <code>SAVE</code> column contains the wall clock offset from
+<p>The <code>SAVE</code> column contains the local (wall clock) offset from
 local standard time.
 This is usually either zero for standard time or one hour for daylight
 saving time; but there&rsquo;s no reason, in principle, why it can&rsquo;t
@@ -250,10 +250,10 @@ Rule  US   2007 max   -   Nov Sun&gt;=1   2:00  0    S
 <p>There are two interesting things to note here.</p>
 
 <p>First, the time that something happens (in the <code>AT</code>
-column) is not necessarily the local wall clock time. The time can be
+column) is not necessarily the local (wall clock) time. The time can be
 suffixed with &lsquo;s&rsquo; (for &ldquo;standard&rdquo;) to mean
-local standard time (different from wall clock time when observing
-daylight saving time); or it can be suffixed with &lsquo;g&rsquo;,
+local standard time, different from local (wall clock) time when observing
+daylight saving time; or it can be suffixed with &lsquo;g&rsquo;,
 &lsquo;u&rsquo;, or &lsquo;z&rsquo;, all three of which mean the
 standard time at the
 <a href="https://en.wikipedia.org/wiki/Prime_Meridian">prime meridian</a>.
@@ -265,8 +265,8 @@ href="https://en.wikipedia.org/wiki/Coordinated_Universal_Time">UTC</a>&rdquo;
 (whichever was official at the time); &lsquo;z&rsquo; stands for the
 <a href="https://en.wikipedia.org/wiki/Nautical_time">nautical time zone</a>
 Z (a.k.a. &ldquo;Zulu&rdquo; which, in turn, stands for &lsquo;Z&rsquo;).
-The time can also be suffixed with &lsquo;w&rsquo; meaning &ldquo;wall
-clock time;&rdquo; but it usually isn&rsquo;t because that&rsquo;s the
+The time can also be suffixed with &lsquo;w&rsquo; meaning local (wall
+clock) time; but it usually isn&rsquo;t because that&rsquo;s the
 default.</p>
 
 <p>Second, the day in the <code>ON</code> column, in addition to
@@ -314,7 +314,7 @@ rule, so there should be no change.</li>
 <tr>
   <td colspan="6" align="center"><table><tr><td>
 <pre>
-#Zone       NAME      GMTOFF   RULES FORMAT [UNTIL]
+#Zone       NAME      STDOFF   RULES FORMAT [UNTIL]
 Zone  America/Chicago -5:50:36 -       LMT  1883 Nov 18 12:09:24
                       -6:00    US      C%sT 1920
                       -6:00    Chicago C%sT 1936 Mar  1  2:00
@@ -419,7 +419,7 @@ differing by 24 hours; this corresponds to a movement of the Date
 Line.  For example:</p>
 
 <pre>
-#Zone NAME          GMTOFF   RULES FORMAT [UNTIL]
+#Zone NAME          STDOFF   RULES FORMAT [UNTIL]
 Zone America/Juneau 15:02:19 -     LMT    1867 Oct 18
                     -8:57:41 -     LMT    ...
 </pre>
@@ -458,7 +458,7 @@ given alphabetic string.</li>
 
 <p>An example of a specific amount of time is:</p>
 <pre>
-#Zone NAME            GMTOFF RULES FORMAT [UNTIL]
+#Zone NAME            STDOFF RULES FORMAT [UNTIL]
 Zone Pacific/Honolulu ...                 1933 Apr 30  2:00
                       -10:30 1:00  HDT    1933 May 21 12:00
                       ...
@@ -466,8 +466,8 @@ Zone Pacific/Honolulu ...                 1933 Apr 30  2:00
 
 <p>Hawaii tried daylight saving time for three weeks in 1933 and
 decided they didn&rsquo;t like it. <code>8-) </code>Note that
-the <code>GMTOFF</code> column always contains the standard time
-offset, so the wall clock time during this period was GMT &minus;
+the <code>STDOFF</code> column always contains the standard time
+offset, so the local (wall clock) time during this period was GMT &minus;
 10:30 + 1:00 = GMT &minus; 9:30.</p>
 
 <p>The <code>FORMAT</code> column specifies the usual abbreviation of
@@ -492,7 +492,7 @@ appropriate Rule&rsquo;s <code>LETTER</code> column</li>
 
 <p>An example of a slash is:</p>
 <pre>
-#Zone NAME          GMTOFF RULES FORMAT  [UNTIL]
+#Zone NAME          STDOFF RULES FORMAT  [UNTIL]
 Zone  Europe/London ...                  1996
                     0:00   EU    GMT/BST
 </pre>
@@ -535,9 +535,9 @@ href="https://en.wikipedia.org/wiki/Internationalization_and_localization">local
 the abbreviations. They are intended to be the values returned through the
 <code>"%Z"</code> format specifier to
 <a href="https://en.wikipedia.org/wiki/C_(programming_language)">C</a>&rsquo;s
-<a href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/strftime.html"><code>strftime</code></a>
+<a href="https://pubs.opengroup.org/onlinepubs/9699919799/functions/strftime.html"><code>strftime</code></a>
 function in the
-<a href="http://kirste.userpage.fu-berlin.de/chemnet/use/info/libc/libc_19.html#SEC324">&ldquo;C&rdquo; locale</a>.
+<a href="https://kirste.userpage.fu-berlin.de/chemnet/use/info/libc/libc_19.html#SEC324">&ldquo;C&rdquo; locale</a>.
 
 <li>If there is no generally-accepted abbreviation for a time zone,
 a numeric offset is used instead, e.g., <code>+07</code> for 7 hours
@@ -569,7 +569,7 @@ Rule  US   1945 only -    Sep lastSun  2:00  0    S
 <tr>
   <td colspan="6" align="center"><table><tr><td>
 <pre>
-#Zone NAME            GMTOFF    RULES FORMAT [UNTIL]
+#Zone NAME            STDOFF    RULES FORMAT [UNTIL]
 Zone Pacific/Honolulu -10:31:26 -     LMT    1896 Jan 13 12:00
                       -10:30    -     HST    1933 Apr 30  2:00
                       -10:30    1:00  HDT    1933 May 21  2:00
diff --git a/tz/tz-link.html b/tz/tz-link.html
index 89ebd40..85fc001 100644
--- a/tz/tz-link.html
+++ b/tz/tz-link.html
@@ -18,6 +18,46 @@ histories and planned futures are often recorded only fitfully. Here
 is a summary of attempts to organize and record relevant data in this
 area.
 </p>
+  <h3>Outline</h3>
+  <nav>
+    <ul>
+      <li>The <code><abbr>tz</abbr></code> database product and process
+	<ul>
+	  <li><a href="#tzdb">The <code><abbr>tz</abbr></code> database</a></li>
+	  <li><a href="#download">Downloading the <code><abbr>tz</abbr></code> database</a></li>
+	  <li><a href="#changes">Changes to the <code><abbr>tz</abbr></code> database</a></li>
+	  <li><a href="#commentary">Commentary on the <code><abbr>tz</abbr></code> database</a></li>
+	</ul>
+      </li>
+      <li>Uses of the <code><abbr>tz</abbr></code> database
+	<ul>
+	  <li><a href="#web">Web sites using recent versions of the <code><abbr>tz</abbr></code> database</a></li>
+	  <li><a href="#protocols">Network protocols for <code><abbr>tz</abbr></code> data</a></li>
+	  <li><a href="#compilers">Other <code><abbr>tz</abbr></code> compilers</a></li>
+	  <li><a href="#TZif">Other <abbr>TZif</abbr> readers</a></li>
+	  <li><a href="#software">Other <code><abbr>tz</abbr></code>-based time zone software</a></li>
+	</ul>
+      </li>
+      <li>Related data
+	<ul>
+	  <li><a href="#other-dbs">Other time zone databases</a></li>
+	  <li><a href="#maps">Maps</a></li>
+	  <li><a href="#boundaries">Time zone boundaries</a></li>
+	</ul>
+      </li>
+      <li>Timekeeping concepts
+	<ul>
+	  <li><a href="#civil">Civil time concepts and history</a></li>
+	  <li><a href="#national">National histories of legal time</a></li>
+	  <li><a href="#precision">Precision timekeeping</a></li>
+	  <li><a href="#notation">Time notation</a></li>
+	  <li><a href="#see-also">See also</a></li>
+	</ul>
+      </li>
+    </ul>
+  </nav>
+
+<section>
 <h2 id="tzdb">The <code><abbr title="time zone">tz</abbr></code> database</h2>
 <p>
 The <a href="https://en.wikipedia.org/wiki/Public_domain">public-domain</a>
@@ -41,8 +81,6 @@ title="Berkeley Software Distribution">BSD</abbr></a>,
 <a href="https://www.openbsd.org">Open<abbr>BSD</abbr></a>,
 <a href="https://www.chromium.org/chromium-os">Chromium OS</a>,
 <a href="https://cygwin.com">Cygwin</a>,
-<a href="http://www.delorie.com/djgpp/"><abbr
-title="DJ's GNU Programming Platform">DJGPP</abbr></a>,
 <a href="https://en.wikipedia.org/wiki/MINIX">MINIX</a>,
 <a href="https://www.mysql.com">MySQL</a>,
 <a href="https://en.wikipedia.org/wiki/WebOS"><abbr
@@ -50,13 +88,13 @@ title="Web Operating System">webOS</abbr></a>,
 <a href="https://ibm.com/aix"><abbr
 title="Advanced Interactive eXecutive">AIX</abbr></a>,
 <a href="https://en.wikipedia.org/wiki/BlackBerry_10">BlackBerry 10</a>,
-<a href="https://www.apple.com/ios/"><abbr
+<a href="https://www.apple.com/ios"><abbr
 title="iPhone OS">iOS</abbr></a>,
-<a href="https://www.apple.com/macos/">macOS</a>,
+<a href="https://www.apple.com/macos">macOS</a>,
 <a href="https://www.microsoft.com/en-us/windows">Microsoft Windows</a>,
-<a href="https://www.hpe.com/info/openvms">Open<abbr
+<a href="https://www.vmssoftware.com">Open<abbr
 title="Virtual Memory System">VMS</abbr></a>,
-<a href="https://www.oracle.com/database/index.html">Oracle Database</a>, and
+<a href="https://www.oracle.com/database/">Oracle Database</a>, and
 <a href="https://www.oracle.com/solaris">Oracle Solaris</a>.</p>
 <p>
 Each main entry in the database represents a <dfn>timezone</dfn>
@@ -90,6 +128,9 @@ Universal Time</a> (<abbr>UTC</abbr>).
 The database also records when daylight saving time was in use,
 along with some time zone abbreviations such as <abbr>EST</abbr>
 for Eastern Standard Time in the <abbr>US</abbr>.</p>
+</section>
+
+<section>
 <h2 id="download">Downloading the <code><abbr>tz</abbr></code> database</h2>
 <p>
 The following <a
@@ -150,6 +191,9 @@ specified by <a href="https://tools.ietf.org/html/8536">Internet
 The code also lets
 you read a <abbr>TZif</abbr> file and interpret timestamps for that
 location.</p>
+</section>
+
+<section>
 <h2 id="changes">Changes to the <code><abbr>tz</abbr></code> database</h2>
 <p>
 The <code><abbr>tz</abbr></code> code and data
@@ -228,6 +272,9 @@ found in <a href="theory.html">Theory and pragmatics of the tz code and data</a>
 <a href="https://a0.github.io/a0-tzmigration/">A0 TimeZone Migration</a>
 displays changes between recent <code><abbr>tzdb</abbr></code> versions.
 </p>
+</section>
+
+<section>
 <h2 id="commentary">Commentary on the <code><abbr>tz</abbr></code> database</h2>
 <ul>
 <li>The article
@@ -241,6 +288,9 @@ href="https://blog.jonudell.net/2009/10/23/a-literary-appreciation-of-the-olsonz
 literary appreciation of the Olson/Zoneinfo/tz database</a> comments on the
 database's style.</li>
 </ul>
+</section>
+
+<section>
 <h2 id="web">Web sites using recent versions of the
 <code><abbr>tz</abbr></code> database</h2>
 <p>
@@ -251,16 +301,15 @@ These are listed roughly in ascending order of complexity and fanciness.
 time and zones.</li>
 <li><a href="https://www.timejones.com">TimeJones.com</a>,
 <a href="https://timezoneconverterapp.com">Time Zone Converter</a> and
-<a href="http://worldclock.com">The World Clock</a>
+<a href="https://worldclock.com">The World Clock</a>
 are time zone converters.</li>
 <li><a
-href="http://twiki.org/cgi-bin/xtra/tzdatepick.html">Date and Time Gateway</a>
+href="https://twiki.org/cgi-bin/xtra/tzdatepick.html">Date and Time Gateway</a>
 lets you see the <code><abbr>TZ</abbr></code> values directly.</li>
 <li><a
 href="http://www.convertit.com/Go/ConvertIt/World_Time/Current_Time.ASP">Current
 Time in 1000 Places</a> uses descriptions of the values.</li>
-<li><a href="http://www.timezoneconverter.com/cgi-bin/tzc.tzc">Time Zone
-Converter</a>
+<li><a href="https://timezoneconverterapp.com/">Time Zone Converter</a>
 uses a pulldown menu.</li>
 <li><a href="http://home.kpn.nl/vanadovv/time/TZworld.html">Complete
 timezone information for all countries</a> displays tables of DST rules.
@@ -273,6 +322,9 @@ calculates the current time difference between locations.</li>
 <li><a href="http://www.wx-now.com">Weather Now</a> and
 <a href="http://www.thetimenow.com">The Time Now</a> list the weather too.</li>
 </ul>
+</section>
+
+<section>
 <h2 id="protocols">Network protocols for <code><abbr>tz</abbr></code> data</h2>
 <ul>
 <li>The <a href="https://www.ietf.org">Internet Engineering Task Force</a>'s
@@ -284,10 +336,10 @@ along with <a href="https://tools.ietf.org/html/rfc7809">CalDAV</a>
 (Internet <abbr>RFC</abbr> 7809), a calendar access protocol for
 transferring time zone data by reference.
 The <a href="https://www.ietf.org/mailman/listinfo/tzdist-bis">tzdist-bis
-mailing list</a> discusses the Internet draft <a
+mailing list</a> discussed the Internet draft <a
 id="TZDIST-Geolocate"
 href="https://tools.ietf.org/html/draft-murchison-tzdist-geolocate">TZDIST
-Geolocate Extension</a>, which lets a client determine its timezone
+Geolocate Extension</a> (now expired), which let a client determine its timezone
 from its geographic location using a <a
 href="https://tools.ietf.org/html/rfc5870">'geo' URI</a>.</li>
 <li>The <a href="https://tools.ietf.org/html/rfc5545">
@@ -305,6 +357,9 @@ title="Extensible Markup Language">XML</abbr></a> format, and a variant
 uses <a href="https://www.json.org"><abbr
 title="JavaScript Object Notation">JSON</abbr></a> format.</li>
 </ul>
+</section>
+
+<section>
 <h2 id="compilers">Other <code><abbr>tz</abbr></code> compilers</h2>
 <ul>
 <li><a href="https://sourceforge.net/projects/vzic/">Vzic</a> is a <a
@@ -318,7 +373,7 @@ General Public License (<abbr
 title="General Public License">GPL</abbr>)</a>.</li>
 <li><a href="https://sourceforge.net/projects/tzical/">tziCal &ndash; tz
 database conversion utility</a> is like Vzic, except for the <a
-href="https://www.microsoft.com/net">.NET framework</a>
+href="https://dotnet.microsoft.com">.NET framework</a>
 and with a <abbr>BSD</abbr>-style license.</li>
 <li><a
 href="https://metacpan.org/release/DateTime-TimeZone">DateTime::TimeZone</a>
@@ -336,11 +391,9 @@ Database Parser</a> is a
 <a href="https://en.wikipedia.org/wiki/C%2B%2B">C++</a> parser and
 runtime library that is <a
 href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0355r4.html">moving
-forward</a> for inclusion in the next iteration of <a
-href="https://isocpp.org/std/the-standard"><em><abbr
-title="International Organization for Standardization">ISO</abbr>
-International Standard ISO/IEC 14882:2017(E) &ndash; Programming
-Language C++</em></a>.
+forward</a> for inclusion in
+<a href="https://en.wikipedia.org/wiki/C++20">C++20</a>,
+the next iteration of the C++ standard.
 It is freely available under the
 <abbr title="Massachusetts Institute of Technology">MIT</abbr> license.</li>
 <li><a id="ICU" href="http://site.icu-project.org">International Components for
@@ -366,8 +419,7 @@ tool</a> compiles <code><abbr>tz</abbr></code> source into the format used by
 Oracle Java.</li>
 <li>The <a
 href="https://www.oracle.com/technetwork/articles/java/jf14-date-time-2125367.html">Java
-SE <code>java.time</code> <abbr>API</abbr></a> in Java 8 and later
-can be supplemented by <a
+SE 8 Date and Time</a> <abbr>API</abbr> can be supplemented by <a
 href="https://www.threeten.org/threeten-extra/">ThreeTen-Extra</a>,
 which is freely available under a <abbr>BSD</abbr>-style license.</li>
 <li><a href="https://www.joda.org/joda-time/">Joda-Time &ndash; Java date
@@ -409,16 +461,14 @@ license.</li>
 <li><a href="https://github.com/mde/timezone-js">TimezoneJS.Date</a>'s
 <abbr>API</abbr> is upward compatible with standard JavaScript
 Dates. It is freely available under the Apache License.</li>
-<li><a href="https://github.com/sproutsocial/walltime-js">Walltime-js</a>
-translates <abbr>UT</abbr> to local time. It is freely available under
-the <abbr>MIT</abbr> license.</li>
 </ul>
 <li><a href="https://github.com/JuliaTime/">JuliaTime</a> contains a
 compiler from <code><abbr>tz</abbr></code> source into
 <a href="https://julialang.org/">Julia</a>. It is freely available
 under the <abbr>MIT</abbr> license.</li>
-<li><a href="https://github.com/pavkam/tzdb">Delphi/<abbr
-title="Free Pascal Compiler">FPC</abbr> Time Zone Database</a>
+<li><a href="https://github.com/pavkam/tzdb"><abbr>TZDB</abbr> &ndash;
+<abbr>IANA</abbr> Time Zone Database for Delphi/<abbr
+title="Free Pascal Compiler">FPC</abbr></a>
 compiles from <code><abbr>tz</abbr></code> source into
 <a href="https://en.wikipedia.org/wiki/Object_Pascal">Object Pascal</a>
 as compiled by <a href="https://en.wikipedia.org/wiki/Delphi_(IDE)">Delphi</a>
@@ -447,6 +497,9 @@ source into text files, along with a runtime that can read those
 files. Tcl is freely available under a <abbr>BSD</abbr>-style
 license.</li>
 </ul>
+</section>
+
+<section>
 <h2 id="TZif">Other <abbr>TZif</abbr> readers</h2>
 <ul>
 <li>The <a
@@ -505,6 +558,9 @@ package contains <a href="https://www.haskell.org">Haskell</a> code that
 parses and uses <abbr>TZif</abbr> data. It is freely
 available under a <abbr>BSD</abbr>-style license.</li>
 </ul>
+</section>
+
+<section>
 <h2 id="software">Other <code><abbr>tz</abbr></code>-based time zone software</h2>
 <ul>
 <li><a href="https://foxclocks.org">FoxClocks</a>
@@ -542,7 +598,7 @@ which stores time zone data in the
 <a
 href="https://unicode.org/cldr/charts/latest/supplemental/zone_tzid.html">Zone &rarr;
 Tzid table</a> or <a
-href="https://unicode.org/repos/cldr/trunk/common/supplemental/windowsZones.xml"><abbr>XML</abbr>
+href="https://github.com/unicode-org/cldr/blob/master/common/supplemental/windowsZones.xml"><abbr>XML</abbr>
 file</a> of the <abbr>CLDR</abbr> data maps proprietary zone IDs
 to <code><abbr>tz</abbr></code> names.
 These mappings can be performed programmatically via the <a href="https://github.com/mj1856/TimeZoneConverter">TimeZoneConverter</a> .NET library,
@@ -562,6 +618,9 @@ a macOS program. Its developers
 <a href="http://veladg.com/tzoffer.html">offer free
 licenses</a> to <code><abbr>tz</abbr></code> contributors.</li>
 </ul>
+</section>
+
+<section>
 <h2 id="other-dbs">Other time zone databases</h2>
 <ul>
 <li><a href="https://www.astro.com/atlas">Time-zone Atlas</a>
@@ -590,6 +649,9 @@ Schedules Information Manual</a> of the
 International Air Transport Association
 gives current time zone rules for airports served by commercial aviation.</li>
 </ul>
+</section>
+
+<section>
 <h2 id="maps">Maps</h2>
 <ul>
 <li>The <a href="https://www.cia.gov/index.html">United States Central
@@ -598,15 +660,15 @@ title="Central Intelligence Agency">CIA</abbr>)</a> publishes a <a
 href="https://www.cia.gov/library/publications/the-world-factbook/graphics/ref_maps/physical/pdf/standard_time_zones_of_the_world.pdf">time
 zone map</a>; the
 <a
-href="https://www.lib.utexas.edu/maps/world.html">Perry&ndash;Casta&ntilde;eda
+href="https://legacy.lib.utexas.edu/maps/world.html">Perry&ndash;Casta&ntilde;eda
 Library Map Collection</a>
 of the University of Texas at Austin has copies of
 recent editions.
 The pictorial quality is good,
 but the maps do not indicate daylight saving time,
 and parts of the data are a few years out of date.</li>
-<li><a href="https://www.worldtimezone.com">Current time around the world
-and standard time zones map of the world</a>
+<li><a href="https://www.worldtimezone.com">World Time Zone Map
+with current time</a>
 has several fancy time zone maps; it covers Russia particularly well.
 The maps' pictorial quality is not quite as good as the
 <abbr>CIA</abbr>'s
@@ -617,6 +679,9 @@ much is time wrong around the world?</a> maps the difference between
 mean solar and standard time, highlighting areas such as western China
 where the two differ greatly. It's a bit out of date, unfortunately.</li>
 </ul>
+</section>
+
+<section>
 <h2 id="boundaries">Time zone boundaries</h2>
 <p>Geographical boundaries between timezones are available
 from several <a href="https://en.wikipedia.org/wiki/Geolocation">geolocation</a>
@@ -691,6 +756,9 @@ for land and territorial waters only). A captain can change ship's
 clocks any time after entering a new time zone; midnight changes are
 common.</li>
 </ul>
+</section>
+
+<section>
 <h2 id="civil">Civil time concepts and history</h2>
 <ul>
 <li><a href="https://www.nist.gov/pml/time-and-frequency-division/popular-links/walk-through-time">A
@@ -712,10 +780,13 @@ time zone boundary.</li>
 <li><a href="http://statoids.com/tconcept.html">Basic Time
 Zone Concepts</a> discusses terminological issues behind time zones.</li>
 </ul>
+</section>
+
+<section>
 <h2 id="national">National histories of legal time</h2>
 <dl>
 <dt>Australia</dt>
-<dd>The Parliamentary Library has commissioned a <a
+<dd>The Parliamentary Library commissioned a <a
 href="https://www.aph.gov.au/binaries/library/pubs/rp/2009-10/10rp10.pdf">research
 paper on daylight saving time in Australia</a>.
 The Bureau of Meteorology publishes a list of <a
@@ -733,8 +804,8 @@ Portuguese)</a>.</dd>
 <dt>Canada</dt>
 <dd>National Research Council Canada publishes current
 and some older information about <a
-href="https://www.nrc-cnrc.gc.ca/eng/services/time/time_zones.html">time
-zones &amp; daylight saving time</a>.</dd>
+href="https://nrc.canada.ca/en/certifications-evaluations-standards/canadas-official-time/time-zones-daylight-saving-time">time
+zones and daylight saving time</a>.</dd>
 <dt>Chile</dt>
 <dd>The Hydrographic and Oceanographic Service of the Chilean Navy publishes a
 <a href="https://www.horaoficial.cl/historia_hora.html" hreflang="es">history of
@@ -760,7 +831,7 @@ of Legal Time in Germany</a>.</dd>
 href="ftp://ftp.cs.huji.ac.il/pub/tz/announcements"
 hreflang="he">announcements (in Hebrew)</a>.</dd>
 <dt>Italy</dt>
-<dd>The National Institute of Metrological Research maintains a
+<dd>The National Institute of Metrological Research publishes a
 <a href="http://oldsite.inrim.it/res/tf/ora_legale_i.shtml" hreflang="it">table
 of civil time (in Italian)</a>.</dd>
 <dt>Malaysia</dt>
@@ -777,22 +848,17 @@ covers the history of local time in the Netherlands from ancient times.</dd>
 <dt>New Zealand</dt>
 <dd>The Department of Internal Affairs maintains a brief <a
 href="https://www.dia.govt.nz/Daylight-Saving-History">History of
-Daylight Saving</a>. The privately-maintained <a
-href="http://astrologyschool.com/nztime.html">History of New Zealand
-time</a> has more details.</dd>
+Daylight Saving</a>.</dd>
 <dt>Singapore</dt>
 <dd><a id="Singapore"
-href="http://www.math.nus.edu.sg/aslaksen/teaching/timezone.html">Why
+href="http://www.math.nus.edu.sg/~mathelmr/teaching/timezone.html">Why
 is Singapore in the "Wrong" Time Zone?</a> details the
 history of legal time in Singapore and Malaysia.</dd>
 <dt>United Kingdom</dt>
 <dd><a
 href="https://www.polyomino.org.uk/british-time/">History of
 legal time in Britain</a> discusses in detail the country
-with perhaps the best-documented history of clock adjustments.
-The National Physical Laboratory also maintains an <a
-href="http://www.npl.co.uk/educate-explore/what-is-time/archive-of-summer-time-dates">Archive
-of Summer time dates</a>.</dd>
+with perhaps the best-documented history of clock adjustments.</dd>
 <dt>United States</dt>
 <dd>The Department of Transportation's <a
 href="https://www.transportation.gov/regulations/recent-time-zone-proceedings">Recent
@@ -800,9 +866,12 @@ Time Zone Proceedings</a> lists changes to time zone boundaries.</dd>
 <dt>Uruguay</dt>
 <dd>The Oceanography, Hydrography, and Meteorology Service of the Uruguayan
 Navy (SOHMA) publishes an annual <a
-href="http://www.armada.mil.uy/Pagina/institucion/dimat/sohma/almanaque.html" hreflang="es">almanac
+href="http://www.armada.gub.uy/sohma/index.php/servicios/datos-astronomicos" hreflang="es">almanac
 (in Spanish)</a>.</dd>
 </dl>
+</section>
+
+<section>
 <h2 id="precision">Precision timekeeping</h2>
 <ul>
 <li><a
@@ -891,6 +960,9 @@ without Leap Seconds</a> gives pointers on this
 contentious issue, which was active until 2015 and could become active
 again.</li>
 </ul>
+</section>
+
+<section>
 <h2 id="notation">Time notation</h2>
 <ul>
 <li>The <a id="CLDR" href="http://cldr.unicode.org">Unicode Common Locale Data
@@ -905,14 +977,14 @@ both <abbr title="Locale Data Markup Language">LDML</abbr>
 (an <abbr>XML</abbr> format) and <abbr>JSON</abbr>.
 <li>
 <a href="https://www.cl.cam.ac.uk/~mgk25/iso-time.html">A summary of
-the international standard date and time notation</a> is a good
-summary of
+the international standard date and time notation</a> covers
 <a
-href="https://www.iso.org/standard/40874.html"><em><abbr>ISO</abbr>
-8601:2004 &ndash; Data elements and interchange formats &ndash; Information
-interchange &ndash; Representation of dates and times</em></a>.</li>
+href="https://www.iso.org/standard/70907.html"><em><abbr
+title="International Organization for Standardization">ISO</abbr>
+8601-1:2019 &ndash; Date and time &ndash; Representations for information
+interchange &ndash; Part 1: Basic rules</em></a>.</li>
 <li>
-<a href="https://www.w3.org/TR/xmlschema-2/#dateTime"><abbr>XML</abbr>
+<a href="https://www.w3.org/TR/xmlschema/#dateTime"><abbr>XML</abbr>
 Schema: Datatypes &ndash; dateTime</a> specifies a format inspired by
 <abbr>ISO</abbr> 8601 that is in common use in <abbr>XML</abbr> data.</li>
 <li><a href="https://tools.ietf.org/html/rfc5322#section-3.3">&sect;3.3 of
@@ -959,18 +1031,23 @@ any future changes to the rules. One should never set
 local time is nine hours ahead of <abbr>UT</abbr> and the time zone
 is called "<abbr>GMT</abbr>".</li>
 </ul>
+</section>
+
+<section>
 <h2 id="see-also">See also</h2>
 <ul>
 <li><a href="theory.html">Theory and pragmatics of the tz code and data</a></li>
 <li><a href="tz-art.html">Time and the Arts</a></li>
 </ul>
+</section>
+
+<footer>
 <hr>
-<address>
 This web page is in the public domain, so clarified as of
 2009-05-17 by Arthur David Olson.
 <br>
 Please send corrections to this web page to the
 <a href="mailto:tz@iana.org">time zone mailing list</a>.
-</address>
+</footer>
 </body>
 </html>
diff --git a/tz/tzfile.5 b/tz/tzfile.5
index 2f70915..cd4c483 100644
--- a/tz/tzfile.5
+++ b/tz/tzfile.5
@@ -16,6 +16,13 @@ The timezone information files used by
 are typically found under a directory with a name like
 .IR /usr/share/zoneinfo .
 These files use the format described in Internet RFC 8536.
+Each file is a sequence of 8-bit bytes.
+In a file, a binary integer is represented by a sequence of one or
+more bytes in network order (bigendian, or high-order byte first),
+with all bits significant,
+a signed binary integer is represented using two's complement,
+and a boolean is represented by a one-byte binary integer that is
+either 0 (false) or 1 (true).
 The format begins with a 44-byte header containing the following fields:
 .IP * 2
 The magic four-byte ASCII sequence
@@ -30,14 +37,10 @@ or
 .IP *
 Fifteen bytes containing zeros reserved for future use.
 .IP *
-Six four-byte integer values
-written in a standard byte order
-(the high-order byte of the value is written first).
-These values are,
-in order:
+Six four-byte integer values, in the following order:
 .RS
 .TP
-.I tzh_ttisgmtcnt
+.I tzh_ttisutcnt
 The number of UT/local indicators stored in the file.
 .TP
 .I tzh_ttisstdcnt
@@ -64,7 +67,7 @@ depend on the contents of the header:
 .IP * 2
 .I tzh_timecnt
 four-byte signed integer values sorted in ascending order.
-These values are written in standard byte order.
+These values are written in network byte order.
 Each is used as a transition time (as returned by
 .BR time (2))
 at which the rules for computing local time change.
@@ -87,21 +90,21 @@ entries, each defined as follows:
 .nf
 .ta .5i +\w'unsigned char\0\0'u
 struct ttinfo {
-	int32_t	tt_gmtoff;
+	int32_t	tt_utoff;
 	unsigned char	tt_isdst;
-	unsigned char	tt_abbrind;
+	unsigned char	tt_desigidx;
 };
 .in -.5i
 .fi
 .sp
 Each structure is written as a four-byte signed integer value for
-.IR tt_gmtoff ,
-in a standard byte order, followed by a one-byte value for
+.IR tt_utoff ,
+in network byte order, followed by a one-byte boolean for
 .I tt_isdst
 and a one-byte value for
-.IR tt_abbrind .
+.IR tt_desigidx .
 In each structure,
-.I tt_gmtoff
+.I tt_utoff
 gives the number of seconds to be added to UT,
 .I tt_isdst
 tells whether
@@ -109,19 +112,28 @@ tells whether
 should be set by
 .BR localtime (3)
 and
-.I tt_abbrind
+.I tt_desigidx
 serves as an index into the array of time zone abbreviation bytes
 that follow the
 .I ttinfo
 structure(s) in the file.
+The
+.I tt_utoff
+value is never equal to \-2**31, to let 32-bit clients negate it without
+overflow.
+Also, in realistic applications
+.I tt_utoff
+is in the range [\-89999, 93599] (i.e., more than \-25 hours and less
+than 26 hours); this allows easy support by implementations that
+already support the POSIX-required range [\-24:59:59, 25:59:59].
 .IP *
 .I tzh_leapcnt
-pairs of four-byte values, written in standard byte order;
+pairs of four-byte values, written in network byte order;
 the first value of each pair gives the nonnegative time
 (as returned by
 .BR time (2))
 at which a leap second occurs;
-the second gives the
+the second is a signed integer specifying the
 .I total
 number of leap seconds to be applied during the time period
 starting at the given time.
@@ -130,28 +142,38 @@ Each transition is for one leap second, either positive or negative;
 transitions always separated by at least 28 days minus 1 second.
 .IP *
 .I tzh_ttisstdcnt
-standard/wall indicators, each stored as a one-byte value;
+standard/wall indicators, each stored as a one-byte boolean;
 they tell whether the transition times associated with local time types
-were specified as standard time or wall clock time,
-and are used when a timezone file is used in handling POSIX-style
-timezone environment variables.
+were specified as standard time or local (wall clock) time.
 .IP *
-.I tzh_ttisgmtcnt
-UT/local indicators, each stored as a one-byte value;
+.I tzh_ttisutcnt
+UT/local indicators, each stored as a one-byte boolean;
 they tell whether the transition times associated with local time types
-were specified as UT or local time,
-and are used when a timezone file is used in handling POSIX-style
-timezone environment variables.
+were specified as UT or local time.
+If a UT/local indicator is set, the corresponding standard/wall indicator
+must also be set.
+.PP
+The standard/wall and UT/local indicators were designed for
+transforming a TZif file's transition times into transitions appropriate
+for another time zone specified via a POSIX-style TZ string that lacks rules.
+For example, when TZ="EET\*-2EEST" and there is no TZif file "EET\*-2EEST",
+the idea was to adapt the transition times from a TZif file with the
+well-known name "posixrules" that is present only for this purpose and
+is a copy of the file "Europe/Brussels", a file with a different UT offset.
+POSIX does not specify this obsolete transformational behavior,
+the default rules are installation-dependent, and no implementation
+is known to support this feature for timestamps past 2037,
+so users desiring (say) Greek time should instead specify
+TZ="Europe/Athens" for better historical coverage, falling back on
+TZ="EET\*-2EEST,M3.5.0/3,M10.5.0/4" if POSIX conformance is required
+and older timestamps need not be handled accurately.
 .PP
 The
 .BR localtime (3)
 function
-uses the first standard-time
+normally uses the first
 .I ttinfo
 structure in the file
-(or simply the first
-.I ttinfo
-structure in the absence of a standard-time structure)
 if either
 .I tzh_timecnt
 is zero or the time argument is less than the first transition time recorded
@@ -184,7 +206,7 @@ For version-3-format timezone files, the POSIX-TZ-style string may
 use two minor extensions to the POSIX TZ format, as described in
 .BR newtzset (3).
 First, the hours part of its transition times may be signed and range from
-\*-167 through 167 instead of the POSIX-required unsigned values
+\-167 through 167 instead of the POSIX-required unsigned values
 from 0 through 24.
 Second, DST is in effect all year if it starts
 January 1 at 00:00 and ends December 31 at 24:00 plus the difference
@@ -219,7 +241,7 @@ in the version 1 data block to save space.
 Time zone designations should consist of at least three (3)
 and no more than six (6) ASCII characters from the set of
 alphanumerics,
-.q "-",
+.q "\*-",
 and
 .q "+".
 This is for compatibility with POSIX requirements for
@@ -278,11 +300,11 @@ mishandled by version 2 readers.
 Some readers designed for version 2 do not support
 permanent daylight saving time, e.g., a TZ string
 .q "EST5EDT,0/0,J365/25"
-denoting permanent Eastern Daylight Time (\*-04).
+denoting permanent Eastern Daylight Time (\-04).
 As a partial workaround, a writer can substitute standard time
 for the next time zone east, e.g.,
 .q "AST4"
-for permanent Atlantic Standard Time (\*-04).
+for permanent Atlantic Standard Time (\-04).
 .IP *
 Some readers ignore the footer, and instead predict future
 timestamps from the time type of the last transition.
@@ -296,17 +318,17 @@ As a partial workaround, a writer can output a dummy (no-op)
 first transition at an early time.
 .IP *
 Some readers mishandle timestamps before the first
-transition that has a timestamp not less than -2**31.
+transition that has a timestamp not less than \-2**31.
 Readers that support only 32-bit timestamps are likely to be
 more prone to this problem, for example, when they process
 64-bit transitions only some of which are representable in 32
 bits.
 As a partial workaround, a writer can output a dummy
-transition at timestamp \*-2**31.
+transition at timestamp \-2**31.
 .IP *
 Some readers mishandle a transition if its timestamp has
 the minimum possible signed 64-bit value.
-Timestamps less than \*-2**59 are not recommended.
+Timestamps less than \-2**59 are not recommended.
 .IP *
 Some readers mishandle POSIX-style TZ strings that
 contain
@@ -327,7 +349,7 @@ These characters are not recommended.
 Some readers may mishandle time zone abbreviations that
 contain fewer than 3 or more than 6 characters, or that
 contain ASCII characters other than alphanumerics,
-.q "-",
+.q "\*-",
 and
 .q "+".
 These abbreviations are not recommended.
@@ -361,18 +383,18 @@ Readers that do not support negative timestamps are likely to
 be more prone to this problem.
 .IP *
 Some readers mishandle time zone abbreviations like
-.q "-08"
+.q "\*-08"
 that contain
 .q "+",
-.q "-",
+.q "\*-",
 or digits.
 .IP *
 Some readers mishandle UT offsets that are out of the
-traditional range of \*-12 through +12 hours, and so do not
+traditional range of \-12 through +12 hours, and so do not
 support locations like Kiritimati that are outside this
 range.
 .IP *
-Some readers mishandle UT offsets in the range [\*-3599, \*-1]
+Some readers mishandle UT offsets in the range [\-3599, \-1]
 seconds from UT, because they integer-divide the offset by
 3600 to get 0 and then display the hour part as
 .q "+00".
diff --git a/tz/tzfile.h b/tz/tzfile.h
index 446c8d5..ee91104 100644
--- a/tz/tzfile.h
+++ b/tz/tzfile.h
@@ -46,7 +46,7 @@ struct tzhead {
 	char	tzh_magic[4];		/* TZ_MAGIC */
 	char	tzh_version[1];		/* '\0' or '2' or '3' as of 2013 */
 	char	tzh_reserved[15];	/* reserved; must be zero */
-	char	tzh_ttisgmtcnt[4];	/* coded number of trans. time flags */
+	char	tzh_ttisutcnt[4];	/* coded number of trans. time flags */
 	char	tzh_ttisstdcnt[4];	/* coded number of trans. time flags */
 	char	tzh_leapcnt[4];		/* coded number of leap seconds */
 	char	tzh_timecnt[4];		/* coded number of transition times */
@@ -69,14 +69,15 @@ struct tzhead {
 **		one (char [4])		total correction after above
 **	tzh_ttisstdcnt (char)s		indexed by type; if 1, transition
 **					time is standard time, if 0,
-**					transition time is wall clock time
-**					if absent, transition times are
-**					assumed to be wall clock time
-**	tzh_ttisgmtcnt (char)s		indexed by type; if 1, transition
-**					time is UT, if 0,
-**					transition time is local time
-**					if absent, transition times are
+**					transition time is local (wall clock)
+**					time; if absent, transition times are
 **					assumed to be local time
+**	tzh_ttisutcnt (char)s		indexed by type; if 1, transition
+**					time is UT, if 0, transition time is
+**					local time; if absent, transition
+**					times are assumed to be local time.
+**					When this is 1, the corresponding
+**					std/wall indicator must also be 1.
 */
 
 /*
diff --git a/tz/zic.8 b/tz/zic.8
index 524a113..dc0220f 100644
--- a/tz/zic.8
+++ b/tz/zic.8
@@ -45,6 +45,32 @@ Output version information and exit.
 .B \*-\*-help
 Output short usage message and exit.
 .TP
+.BI "\*-b " bloat
+Output backward-compatibility data as specified by
+.IR bloat .
+If
+.I bloat
+is
+.BR fat ,
+generate additional data entries that work around potential bugs or
+incompatibilities in older software, such as software that mishandles
+the 64-bit generated data.
+If
+.I bloat
+is
+.BR slim ,
+keep the output files small; this can help check for the bugs
+and incompatibilities.
+Although the default is currently
+.BR fat ,
+this is intended to change in future
+.B zic
+versions, as software that mishandles the 64-bit data typically
+mishandles timestamps after the year 2038 anyway.
+Also see the
+.B \*-r
+option for another way to shrink output size.
+.TP
 .BI "\*-d " directory
 Create time conversion information files in the named directory rather than
 in the standard directory named below.
@@ -57,27 +83,32 @@ as local time.
 will act as if the input contained a link line of the form
 .sp
 .ti +.5i
+.ta \w'Link\0\0'u  +\w'\fItimezone\fP\0\0'u
 Link	\fItimezone\fP		localtime
 .TP
+.BI "\*-L " leapsecondfilename
+Read leap second information from the file with the given name.
+If this option is not used,
+no leap second information appears in output files.
+.TP
 .BI "\*-p " timezone
 Use
 .IR timezone 's
-rules when handling POSIX-format
-TZ strings like "CST6CDT" that lack transition rules.
+rules when handling nonstandard
+TZ strings like "EET\*-2EEST" that lack transition rules.
 .B zic
 will act as if the input contained a link line of the form
 .sp
 .ti +.5i
 Link	\fItimezone\fP		posixrules
-.TP
-.BI "\*-t " file
-When creating local time information, put the configuration link in
-the named file rather than in the standard location.
-.TP
-.BI "\*-L " leapsecondfilename
-Read leap second information from the file with the given name.
-If this option is not used,
-no leap second information appears in output files.
+.sp
+This feature is obsolete and poorly supported.
+Among other things it should not be used for timestamps after the year 2037,
+and it should not be combined with
+.B "\*-b slim"
+if
+.IR timezone 's
+transitions are at standard time or UT instead of local time.
 .TP
 .BR "\*-r " "[\fB@\fP\fIlo\fP][\fB/@\fP\fIhi\fP]"
 Reduce the size of output files by limiting their applicability
@@ -102,6 +133,13 @@ On platforms with GNU
 .BR date ,
 .q "zic \-r @$(date +%s)"
 omits data intended for past timestamps.
+Also see the
+.B "\*-b slim"
+option for another way to shrink output size.
+.TP
+.BI "\*-t " file
+When creating local time information, put the configuration link in
+the named file rather than in the standard location.
 .TP
 .B \*-v
 Be more verbose, and complain about the following situations:
@@ -110,9 +148,7 @@ Be more verbose, and complain about the following situations:
 The input specifies a link to a link.
 .PP
 A year that appears in a data file is outside the range
-of years representable by
-.BR time (2)
-values.
+of representable years.
 .PP
 A time of 24:00 or more appears in the input.
 Pre-1998 versions of
@@ -124,6 +160,36 @@ Pre-2004 versions of
 .B zic
 prohibit this.
 .PP
+A time zone abbreviation uses a
+.B %z
+format.
+Pre-2015 versions of
+.B zic
+do not support this.
+.PP
+A timestamp contains fractional seconds.
+Pre-2018 versions of
+.B zic
+do not support this.
+.PP
+The input contains abbreviations that are mishandled by pre-2018 versions of
+.B zic
+due to a longstanding coding bug.
+These abbreviations include
+.q L
+for
+.q Link ,
+.q mi
+for
+.q min ,
+.q Sa
+for
+.q Sat ,
+and
+.q Su
+for
+.q Sun .
+.PP
 The output file does not contain all the information about the
 long-term future of a timezone, because the future cannot be summarized as
 an extended POSIX TZ string.  For example, as of 2019 this problem
@@ -137,8 +203,15 @@ code designed for older
 output formats.  These compatibility issues affect only timestamps
 before 1970 or after the start of 2038.
 .PP
-A time zone abbreviation has fewer than 3 characters.
-POSIX requires at least 3.
+The output file contains more than 1200 transitions,
+which may be mishandled by some clients.
+The current reference client supports at most 2000 transitions;
+pre-2014 versions of the reference client support at most 1200
+transitions.
+.PP
+A time zone abbreviation has fewer than 3 or more than 6 characters.
+POSIX requires at least 3, and requires implementations to support
+at least 6.
 .PP
 An output file name contains a byte that is not an ASCII letter,
 .q "\*-" ,
@@ -279,9 +352,18 @@ or a weekday name preceded by
 (e.g.,
 .BR "lastSunday" )
 may be abbreviated or spelled out in full.
-Note that there must be no spaces within the
+There must be no white space characters within the
 .B ON
 field.
+The
+.q <=
+and
+.q >=
+constructs can result in a day in the neighboring month;
+for example, the IN-ON combination
+.q "Oct Sun>=31"
+stands for the first Sunday on or after October 31,
+even if that Sunday occurs in November.
 .TP
 .B AT
 Gives the time of day at which the rule takes effect,
@@ -312,13 +394,12 @@ to other applications requiring greater precision.
 The source format does not specify any maximum precision.
 Any of these forms may be followed by the letter
 .B w
-if the given time is local
+if the given time is local or
 .q "wall clock"
 time,
 .B s
-if the given time is local
-.q "standard"
-time, or
+if the given time is standard time without any adjustment for daylight saving,
+or
 .B u
 (or
 .B g
@@ -326,7 +407,7 @@ or
 .BR z )
 if the given time is universal time;
 in the absence of an indicator,
-wall clock time is assumed.
+local (wall clock) time is assumed.
 These forms ignore leap seconds; for example,
 if a leap second occurs at 00:59:60 local time,
 .q "1:00"
@@ -382,8 +463,8 @@ A zone line has the form
 .sp
 .nf
 .ti +.5i
-.ta \w'Zone\0\0'u +\w'Asia/Amman\0\0'u +\w'UTOFF\0\0'u +\w'Jordan\0\0'u +\w'FORMAT\0\0'u
-Zone	NAME	UTOFF	RULES	FORMAT	[UNTIL]
+.ta \w'Zone\0\0'u +\w'Asia/Amman\0\0'u +\w'STDOFF\0\0'u +\w'Jordan\0\0'u +\w'FORMAT\0\0'u
+Zone	NAME	STDOFF	RULES	FORMAT	[UNTIL]
 .sp
 For example:
 .sp
@@ -392,7 +473,7 @@ Zone	Asia/Amman	2:00	Jordan	EE%sT	2017 Oct 27 01:00
 .sp
 .fi
 The fields that make up a zone line are:
-.TP "\w'UTOFF'u"
+.TP "\w'STDOFF'u"
 .B NAME
 The name of the timezone.
 This is the name used in creating the time conversion information file for the
@@ -404,8 +485,9 @@ or
 a file name component is a maximal substring that does not contain
 .q "/" .
 .TP
-.B UTOFF
-The amount of time to add to UT to get standard time.
+.B STDOFF
+The amount of time to add to UT to get standard time,
+without any adjustment for daylight saving.
 This field has the same format as the
 .B AT
 and
@@ -455,7 +537,7 @@ and
 .TP
 .B UNTIL
 The time at which the UT offset or the rule(s) change for a location.
-It takes the form of YEAR [MONTH [DAY [TIME]]].
+It takes the form of one to four fields YEAR [MONTH [DAY [TIME]]].
 If this is specified,
 the time zone information is generated from the given UT offset
 and rule change until the time specified, which is interpreted using
@@ -563,7 +645,7 @@ or
 (an abbreviation of)
 .q "Rolling"
 if the leap second time given by the other fields should be interpreted as
-local wall clock time.
+local (wall clock) time.
 .SH "EXTENDED EXAMPLE"
 Here is an extended example of
 .B zic
@@ -587,10 +669,10 @@ Rule	EU	1979	1995	\*-	Sep	lastSun	1:00u	0	\*-
 Rule	EU	1981	max	\*-	Mar	lastSun	1:00u	1:00	S
 Rule	EU	1996	max	\*-	Oct	lastSun	1:00u	0	\*-
 .sp
-.ta \w'# Zone\0\0'u +\w'Europe/Zurich\0\0'u +\w'0:34:08\0\0'u +\w'RULES\0\0'u +\w'FORMAT\0\0'u
-# Zone	NAME	UTOFF	RULES	FORMAT	[UNTIL]
+.ta \w'# Zone\0\0'u +\w'Europe/Zurich\0\0'u +\w'0:29:45.50\0\0'u +\w'RULES\0\0'u +\w'FORMAT\0\0'u
+# Zone	NAME	STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Zurich	0:34:08	\*-	LMT	1853 Jul 16
-		0:29:46	\*-	BMT	1894 Jun
+		0:29:45.50	\*-	BMT	1894 Jun
 		1:00	Swiss	CE%sT	1981
 		1:00	EU	CE%sT
 .sp
@@ -601,9 +683,14 @@ Link	Europe/Zurich	Europe/Vaduz
 In this example, the timezone is named Europe/Zurich but it has an alias
 as Europe/Vaduz.  This example says that Zurich was 34 minutes and 8
 seconds east of UT until 1853-07-16 at 00:00, when the legal offset
-was changed to 7\(de\|26\(fm\|22.50\(sd; although this works out to
-0:29:45.50, the input format cannot represent fractional seconds so it
-is rounded here.  After 1894-06-01 at 00:00 the UT offset became one hour
+was changed to
+.ds o 7 degrees 26 minutes 22.50 seconds
+.if \n(.g .if c \(de .if c \(fm .if c \(sd .ds o 7\(de\|26\(fm\|22.50\(sd
+\*o,
+which works out to 0:29:45.50;
+.B zic
+treats this by rounding it to 0:29:46.
+After 1894-06-01 at 00:00 the UT offset became one hour
 and Swiss daylight saving rules (defined with lines beginning with
 .q "Rule Swiss")
 apply.  From 1981 to the present, EU daylight saving rules have
@@ -646,7 +733,7 @@ coincides with and is equal to
 a clock retreat caused by a change in UT offset,
 .B zic
 produces a single transition to daylight saving at the new UT offset
-(without any change in wall clock time).
+without any change in local (wall clock) time.
 To get separate transitions
 use multiple zone continuation lines
 specifying transition instants using universal time.
diff --git a/tz/zic.c b/tz/zic.c
index 4bafe5d..8bf5628 100644
--- a/tz/zic.c
+++ b/tz/zic.c
@@ -92,13 +92,10 @@ struct rule {
 	int		r_wday;
 
 	zic_t		r_tod;		/* time from midnight */
-	bool		r_todisstd;	/* above is standard time if 1 */
-					/* or wall clock time if 0 */
-	bool		r_todisgmt;	/* above is GMT if 1 */
-					/* or local time if 0 */
+	bool		r_todisstd;	/* is r_tod standard time? */
+	bool		r_todisut;	/* is r_tod UT? */
 	bool		r_isdst;	/* is this daylight saving time? */
-	zic_t		r_stdoff;	/* offset from default time (which is
-					   usually standard time) */
+	zic_t		r_save;		/* offset from standard time */
 	const char *	r_abbrvar;	/* variable part of abbreviation */
 
 	bool		r_todo;		/* a rule to do (used in outzone) */
@@ -118,13 +115,13 @@ struct zone {
 	lineno		z_linenum;
 
 	const char *	z_name;
-	zic_t		z_gmtoff;
+	zic_t		z_stdoff;
 	char *		z_rule;
 	const char *	z_format;
 	char		z_format_specifier;
 
 	bool		z_isdst;
-	zic_t		z_stdoff;
+	zic_t		z_save;
 
 	struct rule *	z_rules;
 	ptrdiff_t	z_nrules;
@@ -162,7 +159,7 @@ static void	associate(void);
 static void	dolink(const char *, const char *, bool);
 static char **	getfields(char * buf);
 static zic_t	gethms(const char * string, const char * errstring);
-static zic_t	getstdoff(char *, bool *);
+static zic_t	getsave(char *, bool *);
 static void	infile(const char * filename);
 static void	inleap(char ** fields, int nfields);
 static void	inlink(char ** fields, int nfields);
@@ -233,7 +230,7 @@ static int		typecnt;
 */
 
 #define ZF_NAME		1
-#define ZF_GMTOFF	2
+#define ZF_STDOFF	2
 #define ZF_RULE		3
 #define ZF_FORMAT	4
 #define ZF_TILYEAR	5
@@ -247,7 +244,7 @@ static int		typecnt;
 ** Which fields are which on a Zone continuation line.
 */
 
-#define ZFC_GMTOFF	0
+#define ZFC_STDOFF	0
 #define ZFC_RULE	1
 #define ZFC_FORMAT	2
 #define ZFC_TILYEAR	3
@@ -268,7 +265,7 @@ static int		typecnt;
 #define RF_MONTH	5
 #define RF_DAY		6
 #define RF_TOD		7
-#define RF_STDOFF	8
+#define RF_SAVE		8
 #define RF_ABBRVAR	9
 #define RULE_FIELDS	10
 
@@ -409,11 +406,11 @@ static struct attype {
 	bool		dontmerge;
 	unsigned char	type;
 } *			attypes;
-static zic_t		gmtoffs[TZ_MAX_TYPES];
+static zic_t		utoffs[TZ_MAX_TYPES];
 static char		isdsts[TZ_MAX_TYPES];
-static unsigned char	abbrinds[TZ_MAX_TYPES];
+static unsigned char	desigidx[TZ_MAX_TYPES];
 static bool		ttisstds[TZ_MAX_TYPES];
-static bool		ttisgmts[TZ_MAX_TYPES];
+static bool		ttisuts[TZ_MAX_TYPES];
 static char		chars[TZ_MAX_CHARS];
 static zic_t		trans[TZ_MAX_LEAPS];
 static zic_t		corr[TZ_MAX_LEAPS];
@@ -574,8 +571,9 @@ usage(FILE *stream, int status)
 {
   fprintf(stream,
 	  _("%s: usage is %s [ --version ] [ --help ] [ -v ] \\\n"
-	    "\t[ -l localtime ] [ -p posixrules ] [ -d directory ] \\\n"
-	    "\t[ -t localtime-link ] [ -L leapseconds ] [ -r '[@lo][/@hi]' ] \\\n"
+	    "\t[ -b {slim|fat} ] [ -d directory ] [ -l localtime ]"
+	    " [ -L leapseconds ] \\\n"
+	    "\t[ -p posixrules ] [ -r '[@lo][/@hi]' ] [ -t localtime-link ] \\\n"
 	    "\t[ filename ... ]\n\n"
 	    "Report bugs to %s.\n"),
 	  progname, progname, REPORT_BUGS_TO);
@@ -650,6 +648,21 @@ static const char *	leapsec;
 static const char *	tzdefault;
 static const char *	yitcommand;
 
+/* -1 if the TZif output file should be slim, 0 if default, 1 if the
+   output should be fat for backward compatibility.  Currently the
+   default is fat, although this may change.  */
+static int bloat;
+
+static bool
+want_bloat(void)
+{
+  return 0 <= bloat;
+}
+
+#ifndef ZIC_BLOAT_DEFAULT
+# define ZIC_BLOAT_DEFAULT "fat"
+#endif
+
 int
 main(int argc, char **argv)
 {
@@ -681,10 +694,22 @@ main(int argc, char **argv)
 		} else if (strcmp(argv[k], "--help") == 0) {
 			usage(stdout, EXIT_SUCCESS);
 		}
-	while ((c = getopt(argc, argv, "d:l:L:p:r:st:vy:")) != EOF && c != -1)
+	while ((c = getopt(argc, argv, "b:d:l:L:p:r:st:vy:")) != EOF && c != -1)
 		switch (c) {
 			default:
 				usage(stderr, EXIT_FAILURE);
+			case 'b':
+				if (strcmp(optarg, "slim") == 0) {
+				  if (0 < bloat)
+				    error(_("incompatible -b options"));
+				  bloat = -1;
+				} else if (strcmp(optarg, "fat") == 0) {
+				  if (bloat < 0)
+				    error(_("incompatible -b options"));
+				  bloat = 1;
+				} else
+				  error(_("invalid option: -b '%s'"), optarg);
+				break;
 			case 'd':
 				if (directory == NULL)
 					directory = optarg;
@@ -770,6 +795,8 @@ _("%s: invalid time range: %s\n"),
 		}
 	if (optind == argc - 1 && strcmp(argv[optind], "=") == 0)
 		usage(stderr, EXIT_FAILURE);	/* usage message by request */
+	if (bloat == 0)
+	  bloat = strcmp(ZIC_BLOAT_DEFAULT, "slim") == 0 ? -1 : 1;
 	if (directory == NULL)
 		directory = TZDIR;
 	if (tzdefault == NULL)
@@ -1123,7 +1150,7 @@ associate(void)
 			** Maybe we have a local standard time offset.
 			*/
 			eat(zp->z_filename, zp->z_linenum);
-			zp->z_stdoff = getstdoff(zp->z_rule, &zp->z_isdst);
+			zp->z_save = getsave(zp->z_rule, &zp->z_isdst);
 			/*
 			** Note, though, that if there's no rule,
 			** a '%s' in the format is a bad thing.
@@ -1281,10 +1308,10 @@ warning(_("values over 24 hours not handled by pre-2007 versions of zic"));
 }
 
 static zic_t
-getstdoff(char *field, bool *isdst)
+getsave(char *field, bool *isdst)
 {
   int dst = -1;
-  zic_t stdoff;
+  zic_t save;
   size_t fieldlen = strlen(field);
   if (fieldlen != 0) {
     char *ep = field + fieldlen - 1;
@@ -1293,9 +1320,9 @@ getstdoff(char *field, bool *isdst)
       case 's': dst = 0; *ep = '\0'; break;
     }
   }
-  stdoff = gethms(field, _("invalid saved time"));
-  *isdst = dst < 0 ? stdoff != 0 : dst;
-  return stdoff;
+  save = gethms(field, _("invalid saved time"));
+  *isdst = dst < 0 ? save != 0 : dst;
+  return save;
 }
 
 static void
@@ -1318,7 +1345,7 @@ inrule(char **fields, int nfields)
 	}
 	r.r_filename = filename;
 	r.r_linenum = linenum;
-	r.r_stdoff = getstdoff(fields[RF_STDOFF], &r.r_isdst);
+	r.r_save = getsave(fields[RF_SAVE], &r.r_isdst);
 	rulesub(&r, fields[RF_LOYEAR], fields[RF_HIYEAR], fields[RF_COMMAND],
 		fields[RF_MONTH], fields[RF_DAY], fields[RF_TOD]);
 	r.r_name = ecpyalloc(fields[RF_NAME]);
@@ -1379,13 +1406,13 @@ inzsub(char **fields, int nfields, bool iscont)
 	register char *		cp;
 	char *			cp1;
 	static struct zone	z;
-	register int		i_gmtoff, i_rule, i_format;
+	register int		i_stdoff, i_rule, i_format;
 	register int		i_untilyear, i_untilmonth;
 	register int		i_untilday, i_untiltime;
 	register bool		hasuntil;
 
 	if (iscont) {
-		i_gmtoff = ZFC_GMTOFF;
+		i_stdoff = ZFC_STDOFF;
 		i_rule = ZFC_RULE;
 		i_format = ZFC_FORMAT;
 		i_untilyear = ZFC_TILYEAR;
@@ -1396,7 +1423,7 @@ inzsub(char **fields, int nfields, bool iscont)
 	} else if (!namecheck(fields[ZF_NAME]))
 		return false;
 	else {
-		i_gmtoff = ZF_GMTOFF;
+		i_stdoff = ZF_STDOFF;
 		i_rule = ZF_RULE;
 		i_format = ZF_FORMAT;
 		i_untilyear = ZF_TILYEAR;
@@ -1407,7 +1434,7 @@ inzsub(char **fields, int nfields, bool iscont)
 	}
 	z.z_filename = filename;
 	z.z_linenum = linenum;
-	z.z_gmtoff = gethms(fields[i_gmtoff], _("invalid UT offset"));
+	z.z_stdoff = gethms(fields[i_stdoff], _("invalid UT offset"));
 	if ((cp = strchr(fields[i_format], '%')) != 0) {
 		if ((*++cp != 's' && *cp != 'z') || strchr(cp, '%')
 		    || strchr(fields[i_format], '/')) {
@@ -1600,26 +1627,26 @@ rulesub(struct rule *rp, const char *loyearp, const char *hiyearp,
 	}
 	rp->r_month = lp->l_value;
 	rp->r_todisstd = false;
-	rp->r_todisgmt = false;
+	rp->r_todisut = false;
 	dp = ecpyalloc(timep);
 	if (*dp != '\0') {
 		ep = dp + strlen(dp) - 1;
 		switch (lowerit(*ep)) {
 			case 's':	/* Standard */
 				rp->r_todisstd = true;
-				rp->r_todisgmt = false;
+				rp->r_todisut = false;
 				*ep = '\0';
 				break;
 			case 'w':	/* Wall */
 				rp->r_todisstd = false;
-				rp->r_todisgmt = false;
+				rp->r_todisut = false;
 				*ep = '\0';
 				break;
 			case 'g':	/* Greenwich */
 			case 'u':	/* Universal */
 			case 'z':	/* Zulu */
 				rp->r_todisstd = true;
-				rp->r_todisgmt = true;
+				rp->r_todisut = true;
 				*ep = '\0';
 				break;
 		}
@@ -1786,17 +1813,6 @@ atcomp(const void *avp, const void *bvp)
 	return (a < b) ? -1 : (a > b);
 }
 
-static void
-swaptypes(int i, int j)
-{
-  { zic_t t = gmtoffs[i]; gmtoffs[i] = gmtoffs[j]; gmtoffs[j] = t; }
-  { char t = isdsts[i]; isdsts[i] = isdsts[j]; isdsts[j] = t; }
-  { unsigned char t = abbrinds[i]; abbrinds[i] = abbrinds[j];
-    abbrinds[j] = t; }
-  { bool t = ttisstds[i]; ttisstds[i] = ttisstds[j]; ttisstds[j] = t; }
-  { bool t = ttisgmts[i]; ttisgmts[i] = ttisgmts[j]; ttisgmts[j] = t; }
-}
-
 struct timerange {
   int defaulttype;
   ptrdiff_t base, count;
@@ -1863,17 +1879,24 @@ writezone(const char *const name, const char *const string, char version,
 		toi = 0;
 		fromi = 0;
 		for ( ; fromi < timecnt; ++fromi) {
-			if (toi != 0 && ((attypes[fromi].at +
-				gmtoffs[attypes[toi - 1].type]) <=
-				(attypes[toi - 1].at + gmtoffs[toi == 1 ? 0
-				: attypes[toi - 2].type]))) {
+			if (toi != 0
+			    && ((attypes[fromi].at
+				 + utoffs[attypes[toi - 1].type])
+				<= (attypes[toi - 1].at
+				    + utoffs[toi == 1 ? 0
+					     : attypes[toi - 2].type]))) {
 					attypes[toi - 1].type =
 						attypes[fromi].type;
 					continue;
 			}
 			if (toi == 0
 			    || attypes[fromi].dontmerge
-			    || attypes[toi - 1].type != attypes[fromi].type)
+			    || (utoffs[attypes[toi - 1].type]
+				!= utoffs[attypes[fromi].type])
+			    || (isdsts[attypes[toi - 1].type]
+				!= isdsts[attypes[fromi].type])
+			    || (desigidx[attypes[toi - 1].type]
+				!= desigidx[attypes[fromi].type]))
 					attypes[toi++] = attypes[fromi];
 		}
 		timecnt = toi;
@@ -1916,7 +1939,7 @@ writezone(const char *const name, const char *const string, char version,
 	   seconds, as the idea is to insert a transition just before
 	   32-bit time_t rolls around, and this occurs at a slightly
 	   different moment if transitions are leap-second corrected.  */
-	if (WORK_AROUND_QTBUG_53071 && timecnt != 0
+	if (WORK_AROUND_QTBUG_53071 && timecnt != 0 && want_bloat()
 	    && ats[timecnt - 1] < y2038_boundary - 1 && strchr(string, '<')) {
 	  ats[timecnt] = y2038_boundary - 1;
 	  types[timecnt] = types[timecnt - 1];
@@ -1965,7 +1988,7 @@ writezone(const char *const name, const char *const string, char version,
 		int old0;
 		char		omittype[TZ_MAX_TYPES];
 		int		typemap[TZ_MAX_TYPES];
-		register int	thistypecnt;
+		int		thistypecnt, stdcnt, utcnt;
 		char		thischars[TZ_MAX_CHARS];
 		int		thischarcnt;
 		bool		toomanytimes;
@@ -2037,7 +2060,6 @@ writezone(const char *const name, const char *const string, char version,
 		   THISDEFAULTTYPE appears as type 0 in the output instead
 		   of OLD0.  TYPEMAP also omits unused types.  */
 		old0 = strlen(omittype);
-		swaptypes(old0, thisdefaulttype);
 
 #ifndef LEAVE_SOME_PRE_2011_SYSTEMS_IN_THE_LURCH
 		/*
@@ -2048,7 +2070,7 @@ writezone(const char *const name, const char *const string, char version,
 		** (to help get global "altzone" and "timezone" variables
 		** set correctly).
 		*/
-		{
+		if (want_bloat()) {
 			register int	mrudst, mrustd, hidst, histd, type;
 
 			hidst = histd = mrudst = mrustd = -1;
@@ -2056,31 +2078,35 @@ writezone(const char *const name, const char *const string, char version,
 				if (isdsts[types[i]])
 					mrudst = types[i];
 				else	mrustd = types[i];
-			for (i = old0; i < typecnt; i++)
-				if (!omittype[i]) {
-					if (isdsts[i])
-						hidst = i;
-					else	histd = i;
-				}
+			for (i = old0; i < typecnt; i++) {
+			  int h = (i == old0 ? thisdefaulttype
+				   : i == thisdefaulttype ? old0 : i);
+			  if (!omittype[h]) {
+			    if (isdsts[h])
+			      hidst = i;
+			    else
+			      histd = i;
+			  }
+			}
 			if (hidst >= 0 && mrudst >= 0 && hidst != mrudst &&
-				gmtoffs[hidst] != gmtoffs[mrudst]) {
+				utoffs[hidst] != utoffs[mrudst]) {
 					isdsts[mrudst] = -1;
-					type = addtype(gmtoffs[mrudst],
-						&chars[abbrinds[mrudst]],
+					type = addtype(utoffs[mrudst],
+						&chars[desigidx[mrudst]],
 						true,
 						ttisstds[mrudst],
-						ttisgmts[mrudst]);
+						ttisuts[mrudst]);
 					isdsts[mrudst] = 1;
 					omittype[type] = false;
 			}
 			if (histd >= 0 && mrustd >= 0 && histd != mrustd &&
-				gmtoffs[histd] != gmtoffs[mrustd]) {
+				utoffs[histd] != utoffs[mrustd]) {
 					isdsts[mrustd] = -1;
-					type = addtype(gmtoffs[mrustd],
-						&chars[abbrinds[mrustd]],
+					type = addtype(utoffs[mrustd],
+						&chars[desigidx[mrustd]],
 						false,
 						ttisstds[mrustd],
-						ttisgmts[mrustd]);
+						ttisuts[mrustd]);
 					isdsts[mrustd] = 0;
 					omittype[type] = false;
 			}
@@ -2095,15 +2121,19 @@ writezone(const char *const name, const char *const string, char version,
 
 		for (i = 0; i < sizeof indmap / sizeof indmap[0]; ++i)
 			indmap[i] = -1;
-		thischarcnt = 0;
+		thischarcnt = stdcnt = utcnt = 0;
 		for (i = old0; i < typecnt; i++) {
 			register char *	thisabbr;
 
 			if (omittype[i])
 				continue;
-			if (indmap[abbrinds[i]] >= 0)
+			if (ttisstds[i])
+			  stdcnt = thistypecnt;
+			if (ttisuts[i])
+			  utcnt = thistypecnt;
+			if (indmap[desigidx[i]] >= 0)
 				continue;
-			thisabbr = &chars[abbrinds[i]];
+			thisabbr = &chars[desigidx[i]];
 			for (j = 0; j < thischarcnt; ++j)
 				if (strcmp(&thischars[j], thisabbr) == 0)
 					break;
@@ -2111,14 +2141,20 @@ writezone(const char *const name, const char *const string, char version,
 				strcpy(&thischars[thischarcnt], thisabbr);
 				thischarcnt += strlen(thisabbr) + 1;
 			}
-			indmap[abbrinds[i]] = j;
+			indmap[desigidx[i]] = j;
+		}
+		if (pass == 1 && !want_bloat()) {
+		  utcnt = stdcnt = thisleapcnt = 0;
+		  thistimecnt = - locut - hicut;
+		  thistypecnt = thischarcnt = 1;
+		  thistimelim = thistimei;
 		}
 #define DO(field)	fwrite(tzh.field, sizeof tzh.field, 1, fp)
 		tzh = tzh0;
 		memcpy(tzh.tzh_magic, TZ_MAGIC, sizeof tzh.tzh_magic);
 		tzh.tzh_version[0] = version;
-		convert(thistypecnt, tzh.tzh_ttisgmtcnt);
-		convert(thistypecnt, tzh.tzh_ttisstdcnt);
+		convert(utcnt, tzh.tzh_ttisutcnt);
+		convert(stdcnt, tzh.tzh_ttisstdcnt);
 		convert(thisleapcnt, tzh.tzh_leapcnt);
 		convert(locut + thistimecnt + hicut, tzh.tzh_timecnt);
 		convert(thistypecnt, tzh.tzh_typecnt);
@@ -2126,13 +2162,22 @@ writezone(const char *const name, const char *const string, char version,
 		DO(tzh_magic);
 		DO(tzh_version);
 		DO(tzh_reserved);
-		DO(tzh_ttisgmtcnt);
+		DO(tzh_ttisutcnt);
 		DO(tzh_ttisstdcnt);
 		DO(tzh_leapcnt);
 		DO(tzh_timecnt);
 		DO(tzh_typecnt);
 		DO(tzh_charcnt);
 #undef DO
+		if (pass == 1 && !want_bloat()) {
+		  /* Output a minimal data block with just one time type.  */
+		  puttzcode(0, fp);	/* utoff */
+		  putc(0, fp);		/* dst */
+		  putc(0, fp);		/* index of abbreviation */
+		  putc(0, fp);		/* empty-string abbreviation */
+		  continue;
+		}
+
 		/* Output a LO_TIME transition if needed; see limitrange.
 		   But do not go below the minimum representable value
 		   for this pass.  */
@@ -2156,12 +2201,15 @@ writezone(const char *const name, const char *const string, char version,
 		if (hicut)
 		  putc(currenttype, fp);
 
-		for (i = old0; i < typecnt; i++)
-			if (!omittype[i]) {
-				puttzcode(gmtoffs[i], fp);
-				putc(isdsts[i], fp);
-				putc((unsigned char) indmap[abbrinds[i]], fp);
-			}
+		for (i = old0; i < typecnt; i++) {
+		  int h = (i == old0 ? thisdefaulttype
+			   : i == thisdefaulttype ? old0 : i);
+		  if (!omittype[h]) {
+		    puttzcode(utoffs[h], fp);
+		    putc(isdsts[h], fp);
+		    putc(indmap[desigidx[h]], fp);
+		  }
+		}
 		if (thischarcnt != 0)
 			fwrite(thischars, sizeof thischars[0],
 				      thischarcnt, fp);
@@ -2183,18 +2231,19 @@ writezone(const char *const name, const char *const string, char version,
 							++j;
 					j = types[j - 1];
 				}
-				todo = tadd(trans[i], -gmtoffs[j]);
+				todo = tadd(trans[i], -utoffs[j]);
 			} else	todo = trans[i];
 			puttzcodepass(todo, fp, pass);
 			puttzcode(corr[i], fp);
 		}
-		for (i = old0; i < typecnt; i++)
+		if (stdcnt != 0)
+		  for (i = old0; i < typecnt; i++)
 			if (!omittype[i])
 				putc(ttisstds[i], fp);
-		for (i = old0; i < typecnt; i++)
+		if (utcnt != 0)
+		  for (i = old0; i < typecnt; i++)
 			if (!omittype[i])
-				putc(ttisgmts[i], fp);
-		swaptypes(old0, thisdefaulttype);
+				putc(ttisuts[i], fp);
 	}
 	fprintf(fp, "\n%s\n", string);
 	close_file(fp, directory, name);
@@ -2239,7 +2288,7 @@ abbroffset(char *buf, zic_t offset)
 
 static size_t
 doabbr(char *abbr, struct zone const *zp, char const *letters,
-       bool isdst, zic_t stdoff, bool doquotes)
+       bool isdst, zic_t save, bool doquotes)
 {
 	register char *	cp;
 	register char *	slashp;
@@ -2250,7 +2299,7 @@ doabbr(char *abbr, struct zone const *zp, char const *letters,
 	if (slashp == NULL) {
 	  char letterbuf[PERCENT_Z_LEN_BOUND + 1];
 	  if (zp->z_format_specifier == 'z')
-	    letters = abbroffset(letterbuf, zp->z_gmtoff + stdoff);
+	    letters = abbroffset(letterbuf, zp->z_stdoff + save);
 	  else if (!letters)
 	    letters = "%s";
 	  sprintf(abbr, format, letters);
@@ -2315,8 +2364,7 @@ stringoffset(char *result, zic_t offset)
 }
 
 static int
-stringrule(char *result, const struct rule *const rp, const zic_t dstoff,
-	   const zic_t gmtoff)
+stringrule(char *result, struct rule *const rp, zic_t save, zic_t stdoff)
 {
 	register zic_t	tod = rp->r_tod;
 	register int	compat = 0;
@@ -2363,10 +2411,10 @@ stringrule(char *result, const struct rule *const rp, const zic_t dstoff,
 		result += sprintf(result, "M%d.%d.%d",
 				  rp->r_month + 1, week, wday);
 	}
-	if (rp->r_todisgmt)
-		tod += gmtoff;
+	if (rp->r_todisut)
+	  tod += stdoff;
 	if (rp->r_todisstd && !rp->r_isdst)
-		tod += dstoff;
+	  tod += save;
 	if (tod != 2 * SECSPERMIN * MINSPERHOUR) {
 		*result++ = '/';
 		if (! stringoffset(result, tod))
@@ -2396,8 +2444,6 @@ rule_cmp(struct rule const *a, struct rule const *b)
 	return a->r_dayofmonth - b->r_dayofmonth;
 }
 
-enum { YEAR_BY_YEAR_ZONE = 1 };
-
 static int
 stringzone(char *result, struct zone const *zpfirst, ptrdiff_t zonecount)
 {
@@ -2452,31 +2498,23 @@ stringzone(char *result, struct zone const *zpfirst, ptrdiff_t zonecount)
 			if (rule_cmp(stdrp, rp) < 0)
 				stdrp = rp;
 		}
-		/*
-		** Horrid special case: if year is 2037,
-		** presume this is a zone handled on a year-by-year basis;
-		** do not try to apply a rule to the zone.
-		*/
-		if (stdrp != NULL && stdrp->r_hiyear == 2037)
-			return YEAR_BY_YEAR_ZONE;
-
 		if (stdrp != NULL && stdrp->r_isdst) {
 			/* Perpetual DST.  */
 			dstr.r_month = TM_JANUARY;
 			dstr.r_dycode = DC_DOM;
 			dstr.r_dayofmonth = 1;
 			dstr.r_tod = 0;
-			dstr.r_todisstd = dstr.r_todisgmt = false;
+			dstr.r_todisstd = dstr.r_todisut = false;
 			dstr.r_isdst = stdrp->r_isdst;
-			dstr.r_stdoff = stdrp->r_stdoff;
+			dstr.r_save = stdrp->r_save;
 			dstr.r_abbrvar = stdrp->r_abbrvar;
 			stdr.r_month = TM_DECEMBER;
 			stdr.r_dycode = DC_DOM;
 			stdr.r_dayofmonth = 31;
-			stdr.r_tod = SECSPERDAY + stdrp->r_stdoff;
-			stdr.r_todisstd = stdr.r_todisgmt = false;
+			stdr.r_tod = SECSPERDAY + stdrp->r_save;
+			stdr.r_todisstd = stdr.r_todisut = false;
 			stdr.r_isdst = false;
-			stdr.r_stdoff = 0;
+			stdr.r_save = 0;
 			stdr.r_abbrvar
 			  = (stdabbrrp ? stdabbrrp->r_abbrvar : "");
 			dstrp = &dstr;
@@ -2487,7 +2525,7 @@ stringzone(char *result, struct zone const *zpfirst, ptrdiff_t zonecount)
 		return -1;
 	abbrvar = (stdrp == NULL) ? "" : stdrp->r_abbrvar;
 	len = doabbr(result, zp, abbrvar, false, 0, true);
-	offsetlen = stringoffset(result + len, -zp->z_gmtoff);
+	offsetlen = stringoffset(result + len, - zp->z_stdoff);
 	if (! offsetlen) {
 		result[0] = '\0';
 		return -1;
@@ -2496,10 +2534,10 @@ stringzone(char *result, struct zone const *zpfirst, ptrdiff_t zonecount)
 	if (dstrp == NULL)
 		return compat;
 	len += doabbr(result + len, zp, dstrp->r_abbrvar,
-		      dstrp->r_isdst, dstrp->r_stdoff, true);
-	if (dstrp->r_stdoff != SECSPERMIN * MINSPERHOUR) {
+		      dstrp->r_isdst, dstrp->r_save, true);
+	if (dstrp->r_save != SECSPERMIN * MINSPERHOUR) {
 	  offsetlen = stringoffset(result + len,
-				   -(zp->z_gmtoff + dstrp->r_stdoff));
+				   - (zp->z_stdoff + dstrp->r_save));
 	  if (! offsetlen) {
 	    result[0] = '\0';
 	    return -1;
@@ -2507,7 +2545,7 @@ stringzone(char *result, struct zone const *zpfirst, ptrdiff_t zonecount)
 	  len += offsetlen;
 	}
 	result[len++] = ',';
-	c = stringrule(result + len, dstrp, dstrp->r_stdoff, zp->z_gmtoff);
+	c = stringrule(result + len, dstrp, dstrp->r_save, zp->z_stdoff);
 	if (c < 0) {
 		result[0] = '\0';
 		return -1;
@@ -2516,7 +2554,7 @@ stringzone(char *result, struct zone const *zpfirst, ptrdiff_t zonecount)
 		compat = c;
 	len += strlen(result + len);
 	result[len++] = ',';
-	c = stringrule(result + len, stdrp, dstrp->r_stdoff, zp->z_gmtoff);
+	c = stringrule(result + len, stdrp, dstrp->r_save, zp->z_stdoff);
 	if (c < 0) {
 		result[0] = '\0';
 		return -1;
@@ -2534,12 +2572,12 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
 	register ptrdiff_t		i, j;
 	register bool			usestart, useuntil;
 	register zic_t			starttime, untiltime;
-	register zic_t			gmtoff;
 	register zic_t			stdoff;
+	register zic_t			save;
 	register zic_t			year;
 	register zic_t			startoff;
 	register bool			startttisstd;
-	register bool			startttisgmt;
+	register bool			startttisut;
 	register int			type;
 	register char *			startbuf;
 	register char *			ab;
@@ -2575,7 +2613,7 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
 	** for noting the need to unconditionally initialize startttisstd.
 	*/
 	startttisstd = false;
-	startttisgmt = false;
+	startttisut = false;
 	min_year = max_year = EPOCH_YEAR;
 	if (leapseen) {
 		updateminmax(leapminyear);
@@ -2600,13 +2638,13 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
 	*/
 	compat = stringzone(envvar, zpfirst, zonecount);
 	version = compat < 2013 ? ZIC_VERSION_PRE_2013 : ZIC_VERSION;
-	do_extend = compat < 0 || compat == YEAR_BY_YEAR_ZONE;
+	do_extend = compat < 0;
 	if (noise) {
 		if (!*envvar)
 			warning("%s %s",
 				_("no POSIX environment variable for zone"),
 				zpfirst->z_name);
-		else if (compat != 0 && compat != YEAR_BY_YEAR_ZONE) {
+		else if (compat != 0) {
 			/* Circa-COMPAT clients, and earlier clients, might
 			   not work for this zone when given dates before
 			   1970 or after 2038.  */
@@ -2648,35 +2686,37 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
 			max_year = min_year + years_of_observations;
 		}
 	}
-	/*
-	** For the benefit of older systems,
-	** generate data from 1900 through 2038.
-	*/
-	if (min_year > 1900)
-		min_year = 1900;
 	max_year0 = max_year;
-	if (max_year < 2038)
+	if (want_bloat()) {
+	  /* For the benefit of older systems,
+	     generate data from 1900 through 2038.  */
+	  if (min_year > 1900)
+		min_year = 1900;
+	  if (max_year < 2038)
 		max_year = 2038;
+	}
+
 	for (i = 0; i < zonecount; ++i) {
+		struct rule *prevrp = NULL;
 		/*
 		** A guess that may well be corrected later.
 		*/
-		stdoff = 0;
+		save = 0;
 		zp = &zpfirst[i];
 		usestart = i > 0 && (zp - 1)->z_untiltime > min_time;
 		useuntil = i < (zonecount - 1);
 		if (useuntil && zp->z_untiltime <= min_time)
 			continue;
-		gmtoff = zp->z_gmtoff;
+		stdoff = zp->z_stdoff;
 		eat(zp->z_filename, zp->z_linenum);
 		*startbuf = '\0';
-		startoff = zp->z_gmtoff;
+		startoff = zp->z_stdoff;
 		if (zp->z_nrules == 0) {
-			stdoff = zp->z_stdoff;
-			doabbr(startbuf, zp, NULL, zp->z_isdst, stdoff, false);
-			type = addtype(oadd(zp->z_gmtoff, stdoff),
+			save = zp->z_save;
+			doabbr(startbuf, zp, NULL, zp->z_isdst, save, false);
+			type = addtype(oadd(zp->z_stdoff, save),
 				startbuf, zp->z_isdst, startttisstd,
-				startttisgmt);
+				startttisut);
 			if (usestart) {
 				addtt(starttime, type);
 				usestart = false;
@@ -2712,16 +2752,16 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
 				if (useuntil) {
 					/*
 					** Turn untiltime into UT
-					** assuming the current gmtoff and
-					** stdoff values.
+					** assuming the current stdoff and
+					** save values.
 					*/
 					untiltime = zp->z_untiltime;
-					if (!zp->z_untilrule.r_todisgmt)
+					if (!zp->z_untilrule.r_todisut)
 						untiltime = tadd(untiltime,
-							-gmtoff);
+								 -stdoff);
 					if (!zp->z_untilrule.r_todisstd)
 						untiltime = tadd(untiltime,
-							-stdoff);
+								 -save);
 				}
 				/*
 				** Find the rule (of those to do, if any)
@@ -2734,9 +2774,9 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
 						continue;
 					eats(zp->z_filename, zp->z_linenum,
 						rp->r_filename, rp->r_linenum);
-					offset = rp->r_todisgmt ? 0 : gmtoff;
+					offset = rp->r_todisut ? 0 : stdoff;
 					if (!rp->r_todisstd)
-						offset = oadd(offset, stdoff);
+						offset = oadd(offset, save);
 					jtime = rp->r_temp;
 					if (jtime == min_time ||
 						jtime == max_time)
@@ -2763,38 +2803,43 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
 				rp->r_todo = false;
 				if (useuntil && ktime >= untiltime)
 					break;
-				stdoff = rp->r_stdoff;
+				save = rp->r_save;
 				if (usestart && ktime == starttime)
 					usestart = false;
 				if (usestart) {
 					if (ktime < starttime) {
-						startoff = oadd(zp->z_gmtoff,
-							stdoff);
+						startoff = oadd(zp->z_stdoff,
+								save);
 						doabbr(startbuf, zp,
 							rp->r_abbrvar,
 							rp->r_isdst,
-							rp->r_stdoff,
+							rp->r_save,
 							false);
 						continue;
 					}
-					if (*startbuf == '\0' &&
-						startoff == oadd(zp->z_gmtoff,
-						stdoff)) {
+					if (*startbuf == '\0'
+					    && startoff == oadd(zp->z_stdoff,
+								save)) {
 							doabbr(startbuf,
 								zp,
 								rp->r_abbrvar,
 								rp->r_isdst,
-								rp->r_stdoff,
+								rp->r_save,
 								false);
 					}
 				}
 				eats(zp->z_filename, zp->z_linenum,
 					rp->r_filename, rp->r_linenum);
 				doabbr(ab, zp, rp->r_abbrvar,
-				       rp->r_isdst, rp->r_stdoff, false);
-				offset = oadd(zp->z_gmtoff, rp->r_stdoff);
+				       rp->r_isdst, rp->r_save, false);
+				offset = oadd(zp->z_stdoff, rp->r_save);
+				if (!want_bloat() && !useuntil && !do_extend
+				    && prevrp
+				    && rp->r_hiyear == ZIC_MAX
+				    && prevrp->r_hiyear == ZIC_MAX)
+				  break;
 				type = addtype(offset, ab, rp->r_isdst,
-					rp->r_todisstd, rp->r_todisgmt);
+					rp->r_todisstd, rp->r_todisut);
 				if (defaulttype < 0 && !rp->r_isdst)
 				  defaulttype = type;
 				if (rp->r_hiyear == ZIC_MAX
@@ -2802,6 +2847,7 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
 					  && ktime < attypes[lastatmax].at))
 				  lastatmax = timecnt;
 				addtt(ktime, type);
+				prevrp = rp;
 			}
 		}
 		if (usestart) {
@@ -2814,9 +2860,9 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
 			if (*startbuf == '\0')
 error(_("can't determine time zone abbreviation to use just after until time"));
 			else {
-			  bool isdst = startoff != zp->z_gmtoff;
+			  bool isdst = startoff != zp->z_stdoff;
 			  type = addtype(startoff, startbuf, isdst,
-					 startttisstd, startttisgmt);
+					 startttisstd, startttisut);
 			  if (defaulttype < 0 && !isdst)
 			    defaulttype = type;
 			  addtt(starttime, type);
@@ -2827,12 +2873,12 @@ error(_("can't determine time zone abbreviation to use just after until time"));
 		*/
 		if (useuntil) {
 			startttisstd = zp->z_untilrule.r_todisstd;
-			startttisgmt = zp->z_untilrule.r_todisgmt;
+			startttisut = zp->z_untilrule.r_todisut;
 			starttime = zp->z_untiltime;
 			if (!startttisstd)
-				starttime = tadd(starttime, -stdoff);
-			if (!startttisgmt)
-				starttime = tadd(starttime, -gmtoff);
+			  starttime = tadd(starttime, -save);
+			if (!startttisut)
+			  starttime = tadd(starttime, -stdoff);
 		}
 	}
 	if (defaulttype < 0)
@@ -2882,20 +2928,28 @@ addtt(zic_t starttime, int type)
 }
 
 static int
-addtype(zic_t gmtoff, char const *abbr, bool isdst, bool ttisstd, bool ttisgmt)
+addtype(zic_t utoff, char const *abbr, bool isdst, bool ttisstd, bool ttisut)
 {
 	register int	i, j;
 
-	/*
-	** See if there's already an entry for this zone type.
-	** If so, just return its index.
-	*/
-	for (i = 0; i < typecnt; ++i) {
-		if (gmtoff == gmtoffs[i] && isdst == isdsts[i] &&
-			strcmp(abbr, &chars[abbrinds[i]]) == 0 &&
-			ttisstd == ttisstds[i] &&
-			ttisgmt == ttisgmts[i])
-				return i;
+	if (! (-1L - 2147483647L <= utoff && utoff <= 2147483647L)) {
+		error(_("UT offset out of range"));
+		exit(EXIT_FAILURE);
+	}
+	if (!want_bloat())
+	  ttisstd = ttisut = false;
+
+	for (j = 0; j < charcnt; ++j)
+		if (strcmp(&chars[j], abbr) == 0)
+			break;
+	if (j == charcnt)
+		newabbr(abbr);
+	else {
+	  /* If there's already an entry, return its index.  */
+	  for (i = 0; i < typecnt; i++)
+	    if (utoff == utoffs[i] && isdst == isdsts[i] && j == desigidx[i]
+		&& ttisstd == ttisstds[i] && ttisut == ttisuts[i])
+	      return i;
 	}
 	/*
 	** There isn't one; add a new one, unless there are already too
@@ -2905,22 +2959,12 @@ addtype(zic_t gmtoff, char const *abbr, bool isdst, bool ttisstd, bool ttisgmt)
 		error(_("too many local time types"));
 		exit(EXIT_FAILURE);
 	}
-	if (! (-1L - 2147483647L <= gmtoff && gmtoff <= 2147483647L)) {
-		error(_("UT offset out of range"));
-		exit(EXIT_FAILURE);
-	}
-	gmtoffs[i] = gmtoff;
+	i = typecnt++;
+	utoffs[i] = utoff;
 	isdsts[i] = isdst;
 	ttisstds[i] = ttisstd;
-	ttisgmts[i] = ttisgmt;
-
-	for (j = 0; j < charcnt; ++j)
-		if (strcmp(&chars[j], abbr) == 0)
-			break;
-	if (j == charcnt)
-		newabbr(abbr);
-	abbrinds[i] = j;
-	++typecnt;
+	ttisuts[i] = ttisut;
+	desigidx[i] = j;
 	return i;
 }
 
@@ -3140,8 +3184,8 @@ byword(const char *word, const struct lookup *table)
 			else	return NULL;	/* multiple inexact matches */
 		}
 
-	/* Warn about any backward-compatibility issue with pre-2017c zic.  */
-	if (foundlp) {
+	if (foundlp && noise) {
+	  /* Warn about any backward-compatibility issue with pre-2017c zic.  */
 	  bool pre_2017c_match = false;
 	  for (lp = table; lp->l_word; lp++)
 	    if (itsabbr(word, lp->l_word)) {
diff --git a/tz/zishrink.awk b/tz/zishrink.awk
index 8876b68..4e187ac 100644
--- a/tz/zishrink.awk
+++ b/tz/zishrink.awk
@@ -20,7 +20,8 @@ function record_hash(n, name)
 # Return a shortened rule name representing NAME,
 # and record this relationship to the hash table.
 
-function gen_rule_name(name, n)
+function gen_rule_name(name, \
+		       n)
 {
   # Use a simple memonic: the first two letters.
   n = substr(name, 1, 2)
@@ -29,7 +30,8 @@ function gen_rule_name(name, n)
   return n
 }
 
-function prehash_rule_names(name)
+function prehash_rule_names( \
+			    name)
 {
   # Rule names are not part of the tzdb API, so substitute shorter
   # ones.  Shortening them consistently from one release to the next
@@ -148,20 +150,21 @@ function prehash_rule_names(name)
   }
 }
 
-# Process an input line and save it for later output.
+# Process the input line LINE and save it for later output.
 
-function process_input_line(line, field, end, i, n, startdef)
+function process_input_line(line, \
+			    field, end, i, n, startdef, \
+			    linkline, ruleline, zoneline)
 {
   # Remove comments, normalize spaces, and append a space to each line.
   sub(/#.*/, "", line)
   line = line " "
   gsub(/[\t ]+/, " ", line)
 
-  # Abbreviate keywords.  Do not abbreviate "Link" to just "L",
-  # as pre-2017c zic erroneously diagnoses "Li" as ambiguous.
-  sub(/^Link /, "Li ", line)
-  sub(/^Rule /, "R ", line)
-  sub(/^Zone /, "Z ", line)
+  # Abbreviate keywords and determine line type.
+  linkline = sub(/^Link /, "L ", line)
+  ruleline = sub(/^Rule /, "R ", line)
+  zoneline = sub(/^Zone /, "Z ", line)
 
   # SystemV rules are not needed.
   if (line ~ /^R SystemV /) return
@@ -169,7 +172,7 @@ function process_input_line(line, field, end, i, n, startdef)
   # Replace FooAsia rules with the same rules without "Asia", as they
   # are duplicates.
   if (match(line, /[^ ]Asia /)) {
-    if (line ~ /^R /) return
+    if (ruleline) return
     line = substr(line, 1, RSTART) substr(line, RSTART + 5)
   }
 
@@ -179,21 +182,19 @@ function process_input_line(line, field, end, i, n, startdef)
   while (match(line, /:0[^:]/))
     line = substr(line, 1, RSTART - 1) substr(line, RSTART + 2)
 
-  # Abbreviate weekday names.  Do not abbreviate "Sun" and "Sat", as
-  # pre-2017c zic erroneously diagnoses "Su" and "Sa" as ambiguous.
+  # Abbreviate weekday names.
   while (match(line, / (last)?(Mon|Wed|Fri)[ <>]/)) {
     end = RSTART + RLENGTH
     line = substr(line, 1, end - 4) substr(line, end - 1)
   }
-  while (match(line, / (last)?(Tue|Thu)[ <>]/)) {
+  while (match(line, / (last)?(Sun|Tue|Thu|Sat)[ <>]/)) {
     end = RSTART + RLENGTH
     line = substr(line, 1, end - 3) substr(line, end - 1)
   }
 
-  # Abbreviate "max", "only" and month names.
-  # Do not abbreviate "min", as pre-2017c zic erroneously diagnoses "mi"
-  # as ambiguous.
+  # Abbreviate "max", "min", "only" and month names.
   gsub(/ max /, " ma ", line)
+  gsub(/ min /, " mi ", line)
   gsub(/ only /, " o ", line)
   gsub(/ Jan /, " Ja ", line)
   gsub(/ Feb /, " F ", line)
@@ -221,7 +222,7 @@ function process_input_line(line, field, end, i, n, startdef)
   n = split(line, field)
 
   # Abbreviate rule names.
-  i = field[1] == "Z" ? 4 : field[1] == "Li" ? 0 : 2
+  i = zoneline ? 4 : linkline ? 0 : 2
   if (i && field[i] ~ /^[^-+0-9]/) {
     if (!rule[field[i]])
       rule[field[i]] = gen_rule_name(field[i])
@@ -231,11 +232,11 @@ function process_input_line(line, field, end, i, n, startdef)
   # If this zone supersedes an earlier one, delete the earlier one
   # from the saved output lines.
   startdef = ""
-  if (field[1] == "Z")
+  if (zoneline)
     zonename = startdef = field[2]
-  else if (field[1] == "Li")
+  else if (linkline)
     zonename = startdef = field[3]
-  else if (field[1] == "R")
+  else if (ruleline)
     zonename = ""
   if (startdef) {
     i = zonedef[startdef]
@@ -254,7 +255,8 @@ function process_input_line(line, field, end, i, n, startdef)
   output_line[nout++] = line
 }
 
-function output_saved_lines(i)
+function output_saved_lines( \
+			    i)
 {
   for (i = 0; i < nout; i++)
     if (output_line[i])
diff --git a/tz/zone.tab b/tz/zone.tab
index 27e1dee..408fcb2 100644
--- a/tz/zone.tab
+++ b/tz/zone.tab
@@ -332,7 +332,10 @@ RO	+4426+02606	Europe/Bucharest
 RS	+4450+02030	Europe/Belgrade
 RU	+5443+02030	Europe/Kaliningrad	MSK-01 - Kaliningrad
 RU	+554521+0373704	Europe/Moscow	MSK+00 - Moscow area
-RU	+4457+03406	Europe/Simferopol	MSK+00 - Crimea
+# The obsolescent zone.tab format cannot represent Europe/Simferopol well.
+# Put it in RU section and list as UA.  See "territorial claims" above.
+# Programs should use zone1970.tab instead; see above.
+UA	+4457+03406	Europe/Simferopol	MSK+00 - Crimea
 RU	+5836+04939	Europe/Kirov	MSK+00 - Kirov
 RU	+4621+04803	Europe/Astrakhan	MSK+01 - Astrakhan
 RU	+4844+04425	Europe/Volgograd	MSK+01 - Volgograd
diff --git a/tz/zone1970.tab b/tz/zone1970.tab
index 9a8e424..822ffa1 100644
--- a/tz/zone1970.tab
+++ b/tz/zone1970.tab
@@ -289,7 +289,8 @@ RO	+4426+02606	Europe/Bucharest
 RS,BA,HR,ME,MK,SI	+4450+02030	Europe/Belgrade
 RU	+5443+02030	Europe/Kaliningrad	MSK-01 - Kaliningrad
 RU	+554521+0373704	Europe/Moscow	MSK+00 - Moscow area
-RU	+4457+03406	Europe/Simferopol	MSK+00 - Crimea
+# Mention RU and UA alphabetically.  See "territorial claims" above.
+RU,UA	+4457+03406	Europe/Simferopol	MSK+00 - Crimea
 RU	+5836+04939	Europe/Kirov	MSK+00 - Kirov
 RU	+4621+04803	Europe/Astrakhan	MSK+01 - Astrakhan
 RU	+4844+04425	Europe/Volgograd	MSK+01 - Volgograd
diff --git a/tz/zoneinfo2tdf.pl b/tz/zoneinfo2tdf.pl
index c8c5591..e07b00c 100755
--- a/tz/zoneinfo2tdf.pl
+++ b/tz/zoneinfo2tdf.pl
@@ -28,7 +28,7 @@ while (<>) {
 
   $contZone = '';
   if ($type eq 'zone') {
-    # Zone  NAME  GMTOFF  RULES/SAVE  FORMAT  [UNTIL]
+    # Zone  NAME  STDOFF  RULES/SAVE  FORMAT  [UNTIL]
     my $nfields = @fields;
     $nfields >= 5 or warn "bad zone line";
     if ($nfields > 6) {