Update tzdata and zoneinfo to version 2017a.

Author: GitHub Actions

tzdata/Makefile

@@ -72,11 +72,11 @@ MANDIR=		$(TOPDIR)/man
 
 LIBDIR=		$(TOPDIR)/lib
 
-# If you always want time values interpreted as "seconds since the epoch
-# (not counting leap seconds)", use
+# If you want only POSIX time, with time values interpreted as
+# seconds since the epoch (not counting leap seconds), use
 #	REDO=		posix_only
-# below.  If you always want right time values interpreted as "seconds since
-# the epoch" (counting leap seconds)", use
+# below.  If you want want only "right" time, with values interpreted
+# as seconds since the epoch (counting leap seconds), use
 #	REDO=		right_only
 # below.  If you want both sets of data available, with leap seconds not
 # counted normally, use
@@ -85,7 +85,10 @@ LIBDIR=		$(TOPDIR)/lib
 # normally, use
 #	REDO=		right_posix
 # below.  POSIX mandates that leap seconds not be counted; for compatibility
-# with it, use "posix_only" or "posix_right".
+# with it, use "posix_only" or "posix_right".  Use POSIX time on systems with
+# leap smearing; this can work better than unsmeared "right" time with
+# applications that are not leap second aware, and is closer to unsmeared
+# "right" time than unsmeared POSIX time is (e.g., 0.5 vs 1.0 s max error).
 
 REDO=		posix_right
 
@@ -165,7 +168,7 @@ GCC_DEBUG_FLAGS = -Dlint -g3 -O3 -fno-common -fstrict-aliasing \
 	-Wshadow -Wstrict-prototypes -Wsuggest-attribute=const \
 	-Wsuggest-attribute=format -Wsuggest-attribute=noreturn \
 	-Wsuggest-attribute=pure -Wtrampolines \
-	-Wunused -Wwrite-strings \
+	-Wundef -Wunused -Wwrite-strings \
 	-Wno-address -Wno-format-nonliteral -Wno-sign-compare \
 	-Wno-type-limits -Wno-unused-parameter
 #

tzdata/NEWS

@@ -40,7 +40,7 @@ international standard for UNIX-like systems.  As of this writing, the
 current edition of POSIX is:
 
   The Open Group Base Specifications Issue 7
-  IEEE Std 1003.1, 2013 Edition
+  IEEE Std 1003.1-2008, 2016 Edition
   <http://pubs.opengroup.org/onlinepubs/9699919799/>
 
 
@@ -209,6 +209,19 @@ in decreasing order of importance:
 	If there is no common English abbreviation, use numeric offsets like
 		-05 and +0830 that are generated by zic's %z notation.
 
+	Use current abbreviations for older timestamps to avoid confusion.
+		For example, in 1910 a common English abbreviation for UT +01
+		in central Europe was 'MEZ' (short for both "Middle European
+		Zone" and for "Mitteleuropäische Zeit" in German).  Nowadays
+		'CET' ("Central European Time") is more common in English, and
+		the database uses 'CET' even for circa-1910 timestamps as this
+		is less confusing for modern users and avoids the need for
+		determining when 'CET' supplanted 'MEZ' in common usage.
+
+	Use a consistent style in a zone's history.  For example, if a zone's
+		history tends to use numeric abbreviations and a particular
+		entry could go either way, use a numeric abbreviation.
+
     [The remaining guidelines predate the introduction of %z.
     They are problematic as they mean tz data entries invent
     notation rather than record it.  These guidelines are now
@@ -226,7 +239,7 @@ in decreasing order of importance:
 			for double summer time append 'DST'; etc.
 		Otherwise, take the first three letters of an English place
 			name identifying each zone and append 'T', 'ST', etc.
-			as before; e.g. 'VLAST' for VLAdivostok Summer Time.
+			as before; e.g. 'CHAST' for CHAtham Summer Time.
 
 	Use UT (with time zone abbreviation '-00') for locations while
 		uninhabited.  The leading '-' is a flag that the time
@@ -360,12 +373,12 @@ Errors in the tz database arise from many sources:
  * Civil time was not based on atomic time before 1972, and we don't
    know the history of earth's rotation accurately enough to map SI
    seconds to historical solar time to more than about one-hour
-   accuracy.  See: Morrison LV, Stephenson FR.
-   Historical values of the Earth's clock error Delta T and the
-   calculation of eclipses. J Hist Astron. 2004;35:327-36
-   <http://adsabs.harvard.edu/full/2004JHA....35..327M>;
-   Historical values of the Earth's clock error. J Hist Astron. 2005;36:339
-   <http://adsabs.harvard.edu/full/2005JHA....36..339M>.
+   accuracy.  See: Stephenson FR, Morrison LV, Hohenkerk CY.
+   Measurement of the Earth's rotation: 720 BC to AD 2015.
+   Proc Royal Soc A. 2016 Dec 7;472:20160404.
+   http://dx.doi.org/10.1098/rspa.2016.0404
+   Also see: Espenak F. Uncertainty in Delta T (ΔT).
+   http://eclipse.gsfc.nasa.gov/SEhelp/uncertainty2004.html
 
  * The relationship between POSIX time (that is, UTC but ignoring leap
    seconds) and UTC is not agreed upon after 1972.  Although the POSIX

tzdata/Theory

@@ -6,15 +6,15 @@
 # [email protected] for general use in the future).  For more, please see
 # the file CONTRIBUTING in the tz distribution.
 
-# From Paul Eggert (2014-10-31):
+# From Paul Eggert (2017-02-20):
 #
 # Unless otherwise specified, the source for data through 1990 is:
 # Thomas G. Shanks and Rique Pottenger, The International Atlas (6th edition),
 # San Diego: ACS Publications, Inc. (2003).
 # Unfortunately this book contains many errors and cites no sources.
 #
-# Gwillim Law writes that a good source
-# for recent time zone data is the International Air Transport
+# Many years ago Gwillim Law wrote that a good source
+# for time zone data was the International Air Transport
 # Association's Standard Schedules Information Manual (IATA SSIM),
 # published semiannually.  Law sent in several helpful summaries
 # of the IATA's data after 1990.  Except where otherwise noted,
@@ -31,39 +31,33 @@
 # A reliable and entertaining source about time zones is
 # Derek Howse, Greenwich time and longitude, Philip Wilson Publishers (1997).
 #
+# European-style abbreviations are commonly used along the Mediterranean.
+# For sub-Saharan Africa abbreviations were less standardized.
 # Previous editions of this database used WAT, CAT, SAT, and EAT
-# for +0:00 through +3:00, respectively,
-# but Mark R V Murray reports that
-# 'SAST' is the official abbreviation for +2:00 in the country of South Africa,
-# 'CAT' is commonly used for +2:00 in countries north of South Africa, and
-# 'WAT' is probably the best name for +1:00, as the common phrase for
+# for UT +00 through +03, respectively,
+# but in 1997 Mark R V Murray reported that
+# 'SAST' is the official abbreviation for +02 in the country of South Africa,
+# 'CAT' is commonly used for +02 in countries north of South Africa, and
+# 'WAT' is probably the best name for +01, as the common phrase for
 # the area that includes Nigeria is "West Africa".
-# He has heard of "Western Sahara Time" for +0:00 but can find no reference.
-#
-# To make things confusing, 'WAT' seems to have been used for -1:00 long ago;
-# I'd guess that this was because people needed _some_ name for -1:00,
-# and at the time, far west Africa was the only major land area in -1:00.
-# This usage is now obsolete, as the last use of -1:00 on the African
-# mainland seems to have been 1976 in Western Sahara.
-#
-# To summarize, the following abbreviations seem to have some currency:
-#	-1:00	WAT	West Africa Time (no longer used)
-#	 0:00	GMT	Greenwich Mean Time
-#	 2:00	CAT	Central Africa Time
-#	 2:00	SAST	South Africa Standard Time
-# and Murray suggests the following abbreviation:
-#	 1:00	WAT	West Africa Time
-# I realize that this leads to 'WAT' being used for both -1:00 and 1:00
-# for times before 1976, but this is the best I can think of
-# until we get more information.
+#
+# To summarize, the following abbreviations seemed to have some currency:
+#	 +00	GMT	Greenwich Mean Time
+#	 +02	CAT	Central Africa Time
+#	 +02	SAST	South Africa Standard Time
+# and Murray suggested the following abbreviation:
+#	 +01	WAT	West Africa Time
+# Murray's suggestion seems to have caught on in news reports and the like.
+# I vaguely recall 'WAT' also being used for -01 in the past but
+# cannot now come up with solid citations.
 #
 # I invented the following abbreviations; corrections are welcome!
-#	 2:00	WAST	West Africa Summer Time
-#	 2:30	BEAT	British East Africa Time (no longer used)
-#	 2:45	BEAUT	British East Africa Unified Time (no longer used)
-#	 3:00	CAST	Central Africa Summer Time (no longer used)
-#	 3:00	SAST	South Africa Summer Time (no longer used)
-#	 3:00	EAT	East Africa Time
+#	 +02	WAST	West Africa Summer Time
+#	 +03	CAST	Central Africa Summer Time (no longer used)
+#	 +03	SAST	South Africa Summer Time (no longer used)
+#	 +03	EAT	East Africa Time
+# 'EAT' also seems to have caught on; the others are rare but are paired
+# with better-attested non-DST abbreviations.
 
 # Algeria
 # Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
@@ -121,17 +115,17 @@ Zone	Africa/Algiers	0:12:12 -	LMT	1891 Mar 15  0:01
 
 # Cape Verde / Cabo Verde
 #
-# Shanks gives 1907 for the transition to CVT.
+# Shanks gives 1907 for the transition to +02.
 # Perhaps the 1911-05-26 Portuguese decree
-# http://dre.pt/pdf1sdip/1911/05/12500/23132313.pdf
+# https://dre.pt/pdf1sdip/1911/05/12500/23132313.pdf
 # merely made it official?
 #
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
 Zone Atlantic/Cape_Verde -1:34:04 -	LMT	1907        # Praia
-			-2:00	-	CVT	1942 Sep
-			-2:00	1:00	CVST	1945 Oct 15
-			-2:00	-	CVT	1975 Nov 25  2:00
-			-1:00	-	CVT
+			-2:00	-	-02	1942 Sep
+			-2:00	1:00	-01	1945 Oct 15
+			-2:00	-	-02	1975 Nov 25  2:00
+			-1:00	-	-01
 
 # Central African Republic
 # See Africa/Lagos.
@@ -388,7 +382,7 @@ Rule	Ghana	1920	1942	-	Sep	 1	0:00	0:20	GHST
 Rule	Ghana	1920	1942	-	Dec	31	0:00	0	GMT
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Accra	-0:00:52 -	LMT	1918
-			 0:00	Ghana	%s
+			 0:00	Ghana	GMT/+0020
 
 # Guinea
 # See Africa/Abidjan.
@@ -397,20 +391,20 @@ Zone	Africa/Accra	-0:00:52 -	LMT	1918
 #
 # Shanks gives 1911-05-26 for the transition to WAT,
 # evidently confusing the date of the Portuguese decree
-# http://dre.pt/pdf1sdip/1911/05/12500/23132313.pdf
+# https://dre.pt/pdf1sdip/1911/05/12500/23132313.pdf
 # with the date that it took effect, namely 1912-01-01.
 #
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Bissau	-1:02:20 -	LMT	1912 Jan  1
-			-1:00	-	WAT	1975
+			-1:00	-	-01	1975
 			 0:00	-	GMT
 
 # Kenya
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Nairobi	2:27:16	-	LMT	1928 Jul
 			3:00	-	EAT	1930
-			2:30	-	BEAT	1940
-			2:45	-	BEAUT	1960
+			2:30	-	+0230	1940
+			2:45	-	+0245	1960
 			3:00	-	EAT
 Link Africa/Nairobi Africa/Addis_Ababa	 # Ethiopia
 Link Africa/Nairobi Africa/Asmara	 # Eritrea
@@ -437,7 +431,7 @@ Link Africa/Nairobi Indian/Mayotte
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Monrovia	-0:43:08 -	LMT	1882
 			-0:43:08 -	MMT	1919 Mar # Monrovia Mean Time
-			-0:44:30 -	LRT	1972 May # Liberia Time
+			-0:44:30 -	-004430	1972 May
 			 0:00	-	GMT
 
 ###############################################################################
@@ -596,7 +590,7 @@ Rule Mauritius	2008	only	-	Oct	lastSun	2:00	1:00	S
 Rule Mauritius	2009	only	-	Mar	lastSun	2:00	0	-
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
 Zone Indian/Mauritius	3:50:00 -	LMT	1907 # Port Louis
-			4:00 Mauritius	MU%sT	# Mauritius Time
+			4:00 Mauritius	+04/+05
 # Agalega Is, Rodriguez
 # no information; probably like Indian/Mauritius
 
@@ -915,14 +909,14 @@ Zone Africa/Casablanca	-0:30:20 -	LMT	1913 Oct 26
 # since most of it was then controlled by Morocco.
 
 Zone Africa/El_Aaiun	-0:52:48 -	LMT	1934 Jan # El Aaiún
-			-1:00	-	WAT	1976 Apr 14
+			-1:00	-	-01	1976 Apr 14
 			 0:00	Morocco	WE%sT
 
 # Mozambique
 #
 # Shanks gives 1903-03-01 for the transition to CAT.
 # Perhaps the 1911-05-26 Portuguese decree
-# http://dre.pt/pdf1sdip/1911/05/12500/23132313.pdf
+# https://dre.pt/pdf1sdip/1911/05/12500/23132313.pdf
 # merely made it official?
 #
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
@@ -949,16 +943,19 @@ Link Africa/Maputo Africa/Lusaka	# Zambia
 # the country are close to 40 minutes earlier in sunrise than the rest
 # of the country.
 #
-# From Paul Eggert (2007-03-31):
-# Apparently the Caprivi Strip informally observes Botswana time, but
-# we have no details.  In the meantime people there can use Africa/Gaborone.
+# From Paul Eggert (2017-02-22):
+# Although the Zambezi Region (formerly known as Caprivi) informally
+# observes Botswana time, we have no details about historical practice.
+# In the meantime people there can use Africa/Gaborone.
+# See: Immanuel S. The Namibian. 2017-02-23.
+# http://www.namibian.com.na/51480/read/Time-change-divides-lawmakers
 
 # RULE	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
 Rule	Namibia	1994	max	-	Sep	Sun>=1	2:00	1:00	S
 Rule	Namibia	1995	max	-	Apr	Sun>=1	2:00	0	-
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Windhoek	1:08:24 -	LMT	1892 Feb 8
-			1:30	-	SWAT	1903 Mar    # SW Africa Time
+			1:30	-	+0130	1903 Mar
 			2:00	-	SAST	1942 Sep 20  2:00
 			2:00	1:00	SAST	1943 Mar 21  2:00
 			2:00	-	SAST	1990 Mar 21 # independence
@@ -985,7 +982,7 @@ Link Africa/Lagos Africa/Porto-Novo  # Benin
 # Réunion
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
 Zone	Indian/Reunion	3:41:52 -	LMT	1911 Jun # Saint-Denis
-			4:00	-	RET	# Réunion Time
+			4:00	-	+04
 #
 # Crozet Islands also observes Réunion time; see the 'antarctica' file.
 #
@@ -1020,7 +1017,7 @@ Zone	Indian/Reunion	3:41:52 -	LMT	1911 Jun # Saint-Denis
 # Seychelles
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
 Zone	Indian/Mahe	3:41:48 -	LMT	1906 Jun # Victoria
-			4:00	-	SCT	# Seychelles Time
+			4:00	-	+04
 # From Paul Eggert (2001-05-30):
 # Aldabra, Farquhar, and Desroches, originally dependencies of the
 # Seychelles, were transferred to the British Indian Ocean Territory

tzdata/africa

@@ -110,7 +110,8 @@ Zone Antarctica/Mawson	0	-	-00	1954 Feb 13
 # O'Higgins, Antarctic Peninsula, -6319-05704, since 1948-02
 # Prat, -6230-05941
 # Villa Las Estrellas (a town), around the Frei base, since 1984-04-09
-# These locations have always used Santiago time; use TZ='America/Santiago'.
+# These locations employ Region of Magallanes time; use
+# TZ='America/Punta_Arenas'.
 
 # China - year-round bases
 # Great Wall, King George Island, -6213-05858, since 1985-02-20