[tz] attic data for the tz database

Paul Eggert eggert at cs.ucla.edu
Thu Aug 29 16:28:48 UTC 2013


Petr Machata wrote:
> I don't think you can assume stability either.

That's correct; the tz database evolves, we hope for the
better.  I've compiled some "attic" data (appended to this
email) which makes it clear that we have regularly replaced
zones by links during tz maintenance.  This practice hasn't
caused hardships for users.

I plan to propose this attic data, or something like it,
more formally as a diff, and this should address the
concerns expressed on this list about removing old data.

I'm still thinking about good ways to use the attic data.
Using it all wouldn't simply revert to version 2013d;
instead, it would resurrect old data from a few or even many
years ago in the tz database.  Although this would be an
enhancement to the backward-compatibility facility that we
already have in the "backward" file, it'd be unwise to dump
all this data into zic willy-nilly, as its reliability is
dubious (one of the entries has "????" in the data!) and
we've gotten along without the older zone data for many
years without problems.  So we need a mechanism for
conditionally including this data.

I like Zefram's suggestion for allowing a multitier
structure for the tz database.  One way to do that would be
to add a cutoff year to the Makefile.  It'd default to 1970.
People who are interested in older timestamps could decrease
the cutoff to (say) 1900; this would cause links to be
turned into zones they differ from the existing zones after
1900.  Conversely, people who are not interested in (say)
pre-2000 timestamps could increase the cutoff to 2000, which
would result in smaller database that turns a zone into a
link if it's equivalent to another zone after 2000.

Another way to filter the data might be by tz version when
the zone was turned into a link in the tz database.  The
attic data below has a Version line to help with this sort
of filtering.

Both filters could be implemented, and they could be applied
in series.


# Attic data

# This file contains zones that were formerly in the tz database,
# but were later removed or replaced by links to other locations.

# Entries are sorted by Zone name.  Each entry is preceded by the name
# of the country that the entry is in, to help identify the location,
# along with any other commentary associated with the entry.
# Data are also preceded by a Version line, which lists the last version
# of the tz database in which the corresponding entry appeared as a zone.
# This is intended for use in automated processing that selectively
# retrieves data from the attic for backward-compatibility reasons.

# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]

# Mali
# no longer different from Bamako, but too famous to omit
Version 2005k
Zone	Africa/Timbuktu	-0:12:04 -	LMT	1912
			 0:00	-	GMT

# Anguilla
Version 2013d
Zone America/Anguilla	-4:12:16 -	LMT	1912 Mar 2
			-4:00	-	AST

# Antigua and Barbuda
Version 2013d
Zone	America/Antigua	-4:07:12 -	LMT	1912 Mar 2
			-5:00	-	EST	1951
			-4:00	-	AST

# Argentina
# Chubut (CH)
# The name "Comodoro Rivadavia" exceeds the 14-byte POSIX limit.
Version 2005k
Zone America/Argentina/ComodRivadavia -4:30:00 - LMT	1894 Oct 31
			-4:16:48 -	CMT	1920 May
			-4:00	-	ART	1930 Dec
			-4:00	Arg	AR%sT	1969 Oct  5
			-3:00	Arg	AR%sT	1991 Mar  3
			-4:00	-	WART	1991 Oct 20
			-3:00	Arg	AR%sT	1999 Oct  3
			-4:00	Arg	AR%sT	2000 Mar  3
			-3:00	-	ART	2004 Jun  1
			-4:00	-	WART	2004 Jun 20
			-3:00	-	ART

# Aruba
Version 2013d
Zone	America/Aruba	-4:40:24 -	LMT	1912 Feb 12	# Oranjestad
			-4:30	-	ANT	1965 # Netherlands Antilles Time
			-4:00	-	AST

# Canada

Version 2013d
Zone America/Atikokan	-6:06:28 -	LMT	1895
			-6:00	Canada	C%sT	1940 Sep 29
			-6:00	1:00	CDT	1942 Feb  9 2:00s
			-6:00	Canada	C%sT	1945 Sep 30 2:00
			-5:00	-	EST

Version 2013d
Zone America/Blanc-Sablon -3:48:28 -	LMT	1884
			-4:00	Canada	A%sT	1970
			-4:00	-	AST

# Cayman Is
Version 2013d
Zone	America/Cayman	-5:25:32 -	LMT	1890		# Georgetown
			-5:07:12 -	KMT	1912 Feb    # Kingston Mean Time
			-5:00	-	EST

# Canada
Version 2006g
Zone America/Coral_Harbour -5:32:40 -	LMT	1884
			-5:00	NT_YK	E%sT	1946
			-5:00	-	EST

# Curacao
Version 2013d
Zone	America/Curacao	-4:35:47 -	LMT	1912 Feb 12	# Willemstad
			-4:30	-	ANT	1965 # Netherlands Antilles Time
			-4:00	-	AST

# Dominica
Version 2013d
Zone America/Dominica	-4:05:36 -	LMT	1911 Jul 1 0:01		# Roseau
			-4:00	-	AST

# Mexico
Version 1999h
Zone America/Ensenada	-7:46:28 -	LMT	1922 Jan  1  0:13:32
			-8:00	-	PST	1927 Jun 10 23:00
			-7:00	-	MST	1930 Nov 16
			-8:00	-	PST	1942 Apr
			-7:00	-	MST	1949 Jan 14
			-8:00	-	PST	1996
			-8:00	Mexico	P%sT

# US
Version 1999l
Zone America/Fort_Wayne -5:00	US	E%sT	1946
			-5:00	-	EST	# Always EST as of 1986

# Grenada
Version 2013d
Zone	America/Grenada	-4:07:00 -	LMT	1911 Jul	# St George's
			-4:00	-	AST

# Guadeloupe
Version 2013d
Zone America/Guadeloupe	-4:06:08 -	LMT	1911 Jun 8	# Pointe a Pitre
			-4:00	-	AST

# Canada
Version 2013d
# Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
Rule	Mont	1917	only	-	Mar	25	2:00	1:00	D
Rule	Mont	1917	only	-	Apr	24	0:00	0	S
Rule	Mont	1919	only	-	Mar	31	2:30	1:00	D
Rule	Mont	1919	only	-	Oct	25	2:30	0	S
Rule	Mont	1920	only	-	May	 2	2:30	1:00	D
Rule	Mont	1920	1922	-	Oct	Sun>=1	2:30	0	S
Rule	Mont	1921	only	-	May	 1	2:00	1:00	D
Rule	Mont	1922	only	-	Apr	30	2:00	1:00	D
Rule	Mont	1924	only	-	May	17	2:00	1:00	D
Rule	Mont	1924	1926	-	Sep	lastSun	2:30	0	S
Rule	Mont	1925	1926	-	May	Sun>=1	2:00	1:00	D
# The 1927-to-1937 rules can be expressed more simply as
# Rule	Mont	1927	1937	-	Apr	lastSat	24:00	1:00	D
# Rule	Mont	1927	1937	-	Sep	lastSat	24:00	0	S
# The rules below avoid use of 24:00
# (which pre-1998 versions of zic cannot handle).
Rule	Mont	1927	only	-	May	1	0:00	1:00	D
Rule	Mont	1927	1932	-	Sep	lastSun	0:00	0	S
Rule	Mont	1928	1931	-	Apr	lastSun	0:00	1:00	D
Rule	Mont	1932	only	-	May	1	0:00	1:00	D
Rule	Mont	1933	1940	-	Apr	lastSun	0:00	1:00	D
Rule	Mont	1933	only	-	Oct	1	0:00	0	S
Rule	Mont	1934	1939	-	Sep	lastSun	0:00	0	S
Rule	Mont	1946	1973	-	Apr	lastSun	2:00	1:00	D
Rule	Mont	1945	1948	-	Sep	lastSun	2:00	0	S
Rule	Mont	1949	1950	-	Oct	lastSun	2:00	0	S
Rule	Mont	1951	1956	-	Sep	lastSun	2:00	0	S
Rule	Mont	1957	1973	-	Oct	lastSun	2:00	0	S
# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
Zone America/Montreal	-4:54:16 -	LMT	1884
			-5:00	Mont	E%sT	1918
			-5:00	Canada	E%sT	1919
			-5:00	Mont	E%sT	1942 Feb  9 2:00s
			-5:00	Canada	E%sT	1946
			-5:00	Mont	E%sT	1974
			-5:00	Canada	E%sT

# Montserrat
Version 2013d
Zone America/Montserrat	-4:08:52 -	LMT	1911 Jul 1 0:01   # Cork Hill
			-4:00	-	AST

# Bahamas
Version 2013d
# 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	America/Nassau	-5:09:30 -	LMT	1912 Mar 2
			-5:00	Bahamas	E%sT	1976
			-5:00	US	E%sT

# Trinidad and Tobago
Version 2013d
Zone America/Port_of_Spain -4:06:04 -	LMT	1912 Mar 2
			-4:00	-	AST

# Brazil
# Rio_Branco is too ambiguous, since there's a Rio Branco in Uruguay too.
Version 2000h
Zone America/Porto_Acre	-4:31:12 -	LMT	1914
			-5:00	Brazil	AC%sT	1988 Sep 12
			-5:00	-	ACT

# Argentina
# Santa Fe (SF), Entre Rios (ER), Corrientes (CN), Misiones (MN), Chaco (CC),
# Formosa (FM), La Pampa (LP), Chubut (CH)
Version 2002b
Zone America/Rosario	-4:02:40 -	LMT	1894 Nov
			-4:16:44 -	CMT	1920 May
			-4:00	-	ART	1930 Dec
			-4:00	Arg	AR%sT	1969 Oct  5
			-3:00	Arg	AR%sT	1991 Jul
			-3:00	-	ART	1999 Oct  3 0:00
			-4:00	Arg	AR%sT	2000 Mar  3 0:00
			-3:00	-	ART

# St Kitts-Nevis
Version 2013d
Zone America/St_Kitts	-4:10:52 -	LMT	1912 Mar 2	# Basseterre
			-4:00	-	AST

# St Lucia
Version 2013d
Zone America/St_Lucia	-4:04:00 -	LMT	1890		# Castries
			-4:04:00 -	CMT	1912	    # Castries Mean Time
			-4:00	-	AST

# Virgin Is
Version 2013d
Zone America/St_Thomas	-4:19:44 -	LMT	1911 Jul    # Charlotte Amalie
			-4:00	-	AST

# St Vincent and the Grenadines
Version 2013d
Zone America/St_Vincent	-4:04:56 -	LMT	1890		# Kingstown
			-4:04:56 -	KMT	1912	   # Kingstown Mean Time
			-4:00	-	AST

# British Virgin Is
Version 2013d
Zone America/Tortola	-4:18:28 -	LMT	1911 Jul    # Road Town
			-4:00	-	AST

# McMurdo, Ross Island, since 1955-12
Version 2013d
Zone Antarctica/McMurdo	0	-	zzz	1956
			12:00	NZAQ	NZ%sT

# Japan
Version 1999a
Zone	Asia/Ishigaki	8:16:36	-	LMT	1896
			8:00	-	CST

# Israel
Version 1996a
Zone	Asia/Tel_Aviv	2:19:04 -	LMT	1880
			2:21	-	JMT	1918
			2:00	Zion	I%sT

# Russia
Version 1996g
Zone Asia/Tomsk		 5:39:52 -	LMT	1924 May  2
			 6:00	-	TSK	1957 Mar
			 7:00	Russia	TS%s	1991 Mar 31 2:00s
			 6:00	1:00	TSD	1991 Sep 29 2:00s
			 6:00	-	TSK	1992 Jan 19 2:00s
			 7:00	Russia	TS%s

# Svalbard & Jan Mayen
Version 2001b
Zone Atlantic/Jan_Mayen	-1:00	-	EGT

# Australia
Version 1995l
Zone Australia/Canberra	 9:56:32 -	LMT	1895 Feb
			10:00	-	EST	1917 Jan  1 0:01
			10:00	Aus	EST	1971 Oct 31 2:00
			10:00	AN	EST	1981 Oct 25 2:00
			10:00	1:00	EST	1982 Apr  4 3:00
			10:00	AN	EST

# UK
Version 2005k
Zone	Europe/Belfast	-0:23:40 -	LMT	1880 Aug  2
			-0:25:21 -	DMT	1916 May 21 2:00 # Dublin/Dunsink MT
			-0:25:21 1:00	IST	1916 Oct  1 2:00s   # Irish Summer Time
			 0:00	GB-Eire	%s	1968 Oct 27
			 1:00	-	BST	1971 Oct 31 2:00u
			 0:00	GB-Eire	%s	1996
			 0:00	EU	GMT/BST

# Slovenia
Version 1997j
Zone Europe/Ljubljana	0:58:04	-	LMT	1884
			1:00	-	CET	1941 Apr 18 23:00
			1:00	C-Eur	CE%sT	1945 May  8  2:00s
			1:00	1:00	CEST	1945 Sep 16  2:00s
			1:00	-	CET	1982 Nov 27
			1:00	EU	CE%sT

# Bosnia and Herzegovina
Version 1997j
Zone	Europe/Sarajevo	1:13:40	-	LMT	1884
			1:00	-	CET	1941 Apr 18 23:00
			1:00	C-Eur	CE%sT	1945 May  8  2:00s
			1:00	1:00	CEST	1945 Sep 16  2:00s
			1:00	-	CET	1982 Nov 27
			1:00	EU	CE%sT

# Macedonia
Version 1997j
Zone	Europe/Skopje	1:25:44	-	LMT	1884
			1:00	-	CET	1941 Apr 18 23:00
			1:00	C-Eur	CE%sT	1945 May  8  2:00s
			1:00	1:00	CEST	1945 Sep 16  2:00s
			1:00	-	CET	1982 Nov 27
			1:00	EU	CE%sT

# Moldova
Version 2000h
Zone	Europe/Tiraspol	1:58:32	-	LMT	1880
			1:55	-	CMT	1918 Feb 15 # Chisinau MT
			1:44:24	-	BMT	1931 Jul 24 # Bucharest MT
			2:00	Romania	EE%sT	1940 Aug 15
			2:00	1:00	EEST	1941 Jul 17
			1:00	C-Eur	CE%sT	1944 Aug 24
			3:00	Russia	MSK/MSD	1991 Mar 31 2:00
			2:00	Russia	EE%sT	1992 Jan 19 2:00
			3:00	Russia	MSK/MSD

# Croatia
# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
Version 1997j
Zone	Europe/Zagreb	1:03:52	-	LMT	1884
			1:00	-	CET	1941 Apr 18 23:00
			1:00	C-Eur	CE%sT	1945 May  8  2:00s
			1:00	1:00	CEST	1945 Sep 16  2:00s
			1:00	-	CET	1982 Nov 27
			1:00	EU	CE%sT

# Micronesia
Version 2005k
Zone Pacific/Yap	9:12:32	-	LMT	1901		# Colonia
			9:00	-	YAPT	1969 Oct	# Yap Time
			10:00	-	YAPT

# System V
Version 2000h
Zone	SystemV/AST4ADT	-4:00	SystemV		A%sT
Zone	SystemV/EST5EDT	-5:00	SystemV		E%sT
Zone	SystemV/CST6CDT	-6:00	SystemV		C%sT
Zone	SystemV/MST7MDT	-7:00	SystemV		M%sT
Zone	SystemV/PST8PDT	-8:00	SystemV		P%sT
Zone	SystemV/YST9YDT	-9:00	SystemV		Y%sT
Zone	SystemV/AST4	-4:00	-		AST
Zone	SystemV/EST5	-5:00	-		EST
Zone	SystemV/CST6	-6:00	-		CST
Zone	SystemV/MST7	-7:00	-		MST
Zone	SystemV/PST8	-8:00	-		PST
Zone	SystemV/YST9	-9:00	-		YST
Zone	SystemV/HST10	-10:00	-		HST

# Soviet Union
Version 1995b
Zone	W-SU		3:00	M-Eur	????




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