- tz - lists.iana.org

Dealing with Pre-1970 Data
by David Patte ₯ Sept. 3, 2013

Sept. 3, 2013

Though it has been handy to have some pre-1970 data within the tz database, I don't see that it is the best solution for historical tz data in the long run. It is clear that that going back far enough in time there is a different LMT for every 15 seconds of latitude. My own preference would be that historical (and perhaps all tz data) be given a numberic identifier, not a 'America/Someplace' name, for the populated areas in question. A good source of geographic identifiers already available is the geonames database. The tz data for Montreal could be identified by the geonames number for Montreal, and the tz data for Toronto associated with the geoname number for Toronto. Then, to build regions, since all geonames records already have a field for the tz region, these could reflect the numeric identifier of the tz recommended region for each location. For example, Ottawa, in the geonames database would refer to the numeric identifier of Toronto instead of 'America/Toronto', until sometime decides to add historical data for Ottawa's own tz history, at which point it would adopt the identifier for Ottawa.

10 69

Value of data ...
by Lester Caine Sept. 3, 2013

Sept. 3, 2013

Norbert supplied a link to a ecma document which makes interesting reading ... From the section on 'Time Zone Names' > All registered Zone and Link names are allowed. Implementations must recognize all such names, and use > best available current and historical information about their offsets from UTC and their daylight saving time > rules in calculations. Note the use of 'and historical information' here. One has to bare in mind the target data set when deciding what data is useful and what can be thrown away, and for much day to day work a TZ database that only provides future 'estimated' data is probably more than adequate. Banks may be able to get away with 'it's ten years old so we can throw it away' and take control of dormant funds, but for some of us the history is as important as the present day. In fifty years time a large proportion of the data we are creating today will still be available. I dug out material going back 200+ years last night which has now been scanned and archived ... material on 'time' in the Isle of Man for the record ... which helps to clarify calculations for UTC time offsets for material in the early 1900's, which if now stored as UTC normalised data need to be 'corrected' using an historic version of the TZ data. If someone tries to use that data with a 'winnowed' data set, then the wrong times will be returned? Who is to say what an end user is going to be doing with their machine? All right you can reduce 440 zones down to 300 or so, but all of the original 440 names still need to be available, and in these days does saving a few bytes really matter? 'Simplification' of access is more to do with showing the appropriate subset of options by the application and historical ones may actually be the correct answer. So the data should be as complete a record of the 'best available current and historical information' that we have! Providing a version of the data that will be WRONG for some users is not an option? -- Lester Caine - G8HFL ----------------------------- Contact - http://lsces.co.uk/wiki/?page=contact L.S.Caine Electronic Services - http://lsces.co.uk EnquirySolve - http://enquirysolve.com/ Model Engineers Digital Workshop - http://medw.co.uk Rainbow Digital Media - http://rainbowdigitalmedia.co.uk

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[PATCH] Revert recent pre-1970 changes.
by Paul Eggert Sept. 3, 2013

Sept. 3, 2013

Other tz file readers had problems with the new pre1970 file, so remove it and related changes. To recover the pre-1970 data, instead change pre-1970 Zone entries in other files back to what they were. Perhaps we'll try to find a better way someday. * .gitignore: Remove back-pre1970. * Makefile (BACKWARD): Remove. All uses changed back to 'backward'. (AWK_SCRIPTS): Remove back-pre1970.awk. (back-pre1970): Remove. (clean_misc): Don't rm back-pre1970. (check_public): Remove special case for pre1970. * back-pre1970.awk, pre1970: Remove. * backward (America/Anguilla, America/Antigua, America/Aruba) (America/Atikokan, America/Blanc-Sablon, America/Cayman) (America/Creston, America/Curacao, America/Dominica, America/Grenada) (America/Guadeloupe, America/Montreal, America/Montserrat) (America/Nassau, America/Port_of_Spain, America/St_Kitts) (America/St_Lucia, America/St_Thomas, America/St_Vincent) (America/Tortola): Remove, as these are zones again. (America/Coral_Harbour, America/Kralendijk, America/Lower_Princes) (America/Marigot, America/St_Barthelemy, America/Virgin): Revert to previous links. * northamerica (Mont, America/Blanc-Sablon, America/Montreal) (America/Atikokan, America/Creston, America/Anguilla, America/Antigua) (Bahamas, America/Nassau, America/Cayman, America/Dominica) (America/Grenada, America/Guadeloupe, America/Montserrat) (America/St_Kitts, America/St_Lucia, America/St_Vincent) (America/Tortola, America/St_Thomas): * southamerica (America/Aruba, America/Curacao, America/Port_of_Spain): Restore these rules and zones. * .gitignore: Add back-pre1970. --- .gitignore | 1 - Makefile | 34 ++----- back-pre1970.awk | 18 ---- backward | 32 ++---- northamerica | 140 ++++++++++++++++++++------ pre1970 | 291 ------------------------------------------------------- southamerica | 20 +++- 7 files changed, 140 insertions(+), 396 deletions(-) delete mode 100644 back-pre1970.awk delete mode 100644 pre1970 diff --git a/.gitignore b/.gitignore index 28b1bc9..18dbbcc 100644 --- a/.gitignore +++ b/.gitignore @@ -4,7 +4,6 @@ *.txt *~ ChangeLog -back-pre1970 date leapseconds time.tab diff --git a/Makefile b/Makefile index ffddb08..e439055 100644 --- a/Makefile +++ b/Makefile @@ -49,22 +49,6 @@ POSIXRULES= America/New_York ZONETABTYPE= zone -# How to support obsolescent time zones in a backward-compatible way. -# This variable affects only pre-1970 time stamps, on hosts that support them. -# It has two possible values, 'backward' and 'pre1970 back-pre1970'. -# -# 'backward' is the traditional approach, and is simpler and more efficient; -# it is designed to generate one zone for each region where clocks have agreed -# since 1970. -# -# 'pre1970 back-pre1970' can generate more than one zone in that situation, -# which means it can preserve a bit of pre-1970 data that 'backward' does not; -# almost all pre-1970 data is missing, though, so don't get your hopes up. -# -# Sometimes 'backward' is more-compatible with earlier versions of this database, -# and sometimes 'pre1970 back-pre1970' is; it depends on the situation. -BACKWARD= backward - # Also see TZDEFRULESTRING below, which takes effect only # if the time zone files cannot be accessed. @@ -338,7 +322,7 @@ COMMON= Makefile DOCS= README Theory $(MANS) date.1 PRIMARY_YDATA= africa antarctica asia australasia \ europe northamerica southamerica -YDATA= $(PRIMARY_YDATA) pacificnew etcetera $(BACKWARD) +YDATA= $(PRIMARY_YDATA) pacificnew etcetera backward NDATA= systemv factory SDATA= solar87 solar88 solar89 TDATA= $(YDATA) $(NDATA) $(SDATA) @@ -346,10 +330,10 @@ TABDATA= iso3166.tab time.tab zone.tab DATA= $(YDATA) $(NDATA) $(SDATA) $(TABDATA) \ leap-seconds.list yearistype.sh WEB_PAGES= tz-art.htm tz-link.htm -AWK_SCRIPTS= back-pre1970.awk checktab.awk leapseconds.awk zone-time.awk +AWK_SCRIPTS= checktab.awk leapseconds.awk zone-time.awk MISC= usno1988 usno1989 usno1989a usno1995 usno1997 usno1998 \ - $(WEB_PAGES) $(AWK_SCRIPTS) \ - workman.sh zoneinfo2tdf.pl + $(WEB_PAGES) $(AWK_SCRIPTS) workman.sh \ + zoneinfo2tdf.pl ENCHILADA= $(COMMON) $(DOCS) $(SOURCES) $(DATA) $(MISC) # And for the benefit of csh users on systems that assume the user @@ -440,9 +424,6 @@ zones: $(REDO) time.tab: $(YDATA) zone.tab zone-time.awk $(AWK) -f zone-time.awk $(YDATA) >$@ -back-pre1970: pre1970 backward - $(AWK) -v pre1970=pre1970 -f $@.awk backward >$@ - $(TZLIB): $(LIBOBJS) -mkdir $(TOPDIR) $(LIBDIR) ar ru $@ $(LIBOBJS) @@ -477,7 +458,7 @@ check_web: $(WEB_PAGES) clean_misc: rm -f core *.o *.out \ - back-pre1970 time.tab \ + time.tab \ date leapseconds tzselect version.h zdump zic yearistype clean: clean_misc rm -f -r tzpublic @@ -509,7 +490,7 @@ set-timestamps: $$cmd || exit; \ done -# The zics below ensure that each non-pre1970 data file can stand on its own. +# The zics below ensure that each data file can stand on its own. # We also do an all-files run to catch links to links. check_public: $(ENCHILADA) @@ -517,8 +498,7 @@ check_public: $(ENCHILADA) make "CFLAGS=$(GCC_DEBUG_FLAGS)" mkdir tzpublic for i in $(TDATA) ; do \ - test $$i = pre1970 || $(zic) -v -d tzpublic $$i 2>&1 \ - || exit; \ + $(zic) -v -d tzpublic $$i 2>&1 || exit; \ done $(zic) -v -d tzpublic $(TDATA) rm -f -r tzpublic diff --git a/back-pre1970.awk b/back-pre1970.awk deleted file mode 100644 index f7c54fc..0000000 --- a/back-pre1970.awk +++ /dev/null @@ -1,18 +0,0 @@ -# Generate 'back-pre1970' from the two input files 'pre1970' and 'backward'. -# The output consists of all lines in 'backward' that are not links to -# files mentioned in 'pre1970'. Think of it as 'backward' minus 'pre1970'. - -# The 'backward' file is the input. -# The awk variable 'pre1970' contains the name of the pre1970 file. - -# This file is in the public domain. - -# Contributed by Paul Eggert. - -BEGIN { - while ((getline <pre1970) == 1) - if ($1 == "Zone") - pre1970_zone[$2] = 1 -} - -! (/^Link/ && pre1970_zone[$3]) { print } diff --git a/backward b/backward index efb5353..561e2ff 100644 --- a/backward +++ b/backward @@ -7,47 +7,27 @@ Link Africa/Asmara Africa/Asmera Link Africa/Bamako Africa/Timbuktu -Link America/Puerto_Rico America/Anguilla -Link America/Puerto_Rico America/Antigua Link America/Argentina/Catamarca America/Argentina/ComodRivadavia -Link America/Puerto_Rico America/Aruba -Link America/Panama America/Atikokan Link America/Adak America/Atka -Link America/Puerto_Rico America/Blanc-Sablon Link America/Argentina/Buenos_Aires America/Buenos_Aires Link America/Argentina/Catamarca America/Catamarca -Link America/Panama America/Cayman -Link America/Panama America/Coral_Harbour +Link America/Atikokan America/Coral_Harbour Link America/Argentina/Cordoba America/Cordoba -Link America/Phoenix America/Creston -Link America/Puerto_Rico America/Curacao -Link America/Puerto_Rico America/Dominica Link America/Tijuana America/Ensenada Link America/Indiana/Indianapolis America/Fort_Wayne -Link America/Puerto_Rico America/Grenada -Link America/Puerto_Rico America/Guadeloupe Link America/Indiana/Indianapolis America/Indianapolis Link America/Argentina/Jujuy America/Jujuy Link America/Indiana/Knox America/Knox_IN -Link America/Puerto_Rico America/Kralendijk +Link America/Curacao America/Kralendijk Link America/Kentucky/Louisville America/Louisville -Link America/Puerto_Rico America/Lower_Princes -Link America/Puerto_Rico America/Marigot +Link America/Curacao America/Lower_Princes +Link America/Guadeloupe America/Marigot Link America/Argentina/Mendoza America/Mendoza -Link America/Toronto America/Montreal -Link America/Puerto_Rico America/Montserrat -Link America/Toronto America/Nassau -Link America/Puerto_Rico America/Port_of_Spain Link America/Rio_Branco America/Porto_Acre Link America/Argentina/Cordoba America/Rosario Link America/Denver America/Shiprock -Link America/Puerto_Rico America/St_Barthelemy -Link America/Puerto_Rico America/St_Kitts -Link America/Puerto_Rico America/St_Lucia -Link America/Puerto_Rico America/St_Thomas -Link America/Puerto_Rico America/St_Vincent -Link America/Puerto_Rico America/Tortola -Link America/Puerto_Rico America/Virgin +Link America/Guadeloupe America/St_Barthelemy +Link America/St_Thomas America/Virgin Link Pacific/Auckland Antarctica/McMurdo Link Pacific/Auckland Antarctica/South_Pole Link Europe/Oslo Arctic/Longyearbyen diff --git a/northamerica b/northamerica index 6210318..418261f 100644 --- a/northamerica +++ b/northamerica @@ -1341,9 +1341,13 @@ Zone America/Moncton -4:19:08 - LMT 1883 Dec 9 # Quebec -# From Paul Eggert (2013-08-26): +# From Paul Eggert (2013-08-30): # Since 1970 most of Quebec has been like Toronto. -# See America/Toronto. +# However, because earlier versions of the tz database mistakenly relied on data +# from Shanks & Pottenger saying that Quebec differed from Ontario after 1970, +# a separate entry was created for most of Quebec. We're loath to lose +# its pre-1970 info, even though the tz database is normally limited to +# zones that differ after 1970, so keep this otherwise out-of-scope entry. # Matthews and Vincent (1998) also write that Quebec east of the -63 # meridian is supposed to observe AST, but residents as far east as @@ -1357,7 +1361,50 @@ Zone America/Moncton -4:19:08 - LMT 1883 Dec 9 # says this common practice was codified into law as of 2007. # For lack of better info, guess this practice began around 1970, contra to # Shanks & Pottenger who have this region observing AST/ADT. -# See America/Puerto_Rico. +# for post-1970 data America/Puerto_Rico. + +# 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/Blanc-Sablon -3:48:28 - LMT 1884 + -4:00 Canada A%sT 1970 + -4:00 - AST +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 + # Ontario @@ -1423,16 +1470,14 @@ Zone America/Moncton -4:19:08 - LMT 1883 Dec 9 # can say for certain that Atikokan has been practicing the current # time keeping since 1952, at least. -# From Paul Eggert (2013-08-26): +# From Paul Eggert (2006-07-17): # Shanks & Pottenger say that Atikokan has agreed with Rainy River # ever since standard time was introduced, but the information from # McKinnon sounds more authoritative. For now, assume that Atikokan # switched to EST immediately after WWII era daylight saving time # ended. This matches the old (less-populous) America/Coral_Harbour # entry since our cutoff date of 1970, so we can move -# America/Coral_Harbour to the 'backward' file. And Atikokan itself -# is the same as America/Panama since 1970, so we can move -# America/Atikokan to the 'backward' file as well. +# America/Coral_Harbour to the 'backward' file. # From Mark Brader (2010-03-06): # @@ -1590,6 +1635,11 @@ Zone America/Rainy_River -6:18:16 - LMT 1895 -6:00 Canada C%sT 1940 Sep 29 -6:00 1:00 CDT 1942 Feb 9 2:00s -6:00 Canada C%sT +Zone America/Atikokan -6:06:28 - LMT 1895 + -6:00 Canada C%sT 1940 Sep 29 + -6:00 1:00 CDT 1942 Feb 9 2:00s + -6:00 Canada C%sT 1945 Sep 30 2:00 + -5:00 - EST # Manitoba @@ -1824,8 +1874,7 @@ Zone America/Edmonton -7:33:52 - LMT 1906 Sep # period should be PDT rather than MST, but that doesn't seem important enough # (to anyone) to further complicate the rules. -# From Paul Eggert (2013-08-26): -# See America/Phoenix, since Creston has agreed with Phoenix since 1970. +# The transition dates (and times) are guesses. # Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S Rule Vanc 1918 only - Apr 14 2:00 1:00 D @@ -1845,6 +1894,10 @@ Zone America/Dawson_Creek -8:00:56 - LMT 1884 -8:00 Canada P%sT 1947 -8:00 Vanc P%sT 1972 Aug 30 2:00 -7:00 - MST +Zone America/Creston -7:46:04 - LMT 1884 + -7:00 - MST 1916 Oct 1 + -8:00 - PST 1918 Jun 2 + -7:00 - MST # Northwest Territories, Nunavut, Yukon @@ -2495,10 +2548,15 @@ Zone America/Santa_Isabel -7:39:28 - LMT 1922 Jan 1 0:20:32 ############################################################################### # Anguilla -# See America/Puerto_Rico. +# Zone NAME GMTOFF RULES FORMAT [UNTIL] +Zone America/Anguilla -4:12:16 - LMT 1912 Mar 2 + -4:00 - AST # Antigua and Barbuda -# See America/Puerto_Rico. +# Zone NAME GMTOFF RULES FORMAT [UNTIL] +Zone America/Antigua -4:07:12 - LMT 1912 Mar 2 + -5:00 - EST 1951 + -4:00 - AST # Bahamas # @@ -2508,8 +2566,14 @@ Zone America/Santa_Isabel -7:39:28 - LMT 1922 Jan 1 0:20:32 # The Bahamas announced about a month ago that they plan to change their DST # rules to sync with the U.S. starting in 2007.... # http://www.jonesbahamas.com/?c=45&a=10412 -# -# See America/Toronto. + +# 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 # Barbados @@ -2559,7 +2623,10 @@ Zone Atlantic/Bermuda -4:19:18 - LMT 1930 Jan 1 2:00 # Hamilton -4:00 US A%sT # Cayman Is -# See America/Panama. +# Zone NAME GMTOFF RULES FORMAT [UNTIL] +Zone America/Cayman -5:25:32 - LMT 1890 # Georgetown + -5:07:12 - KMT 1912 Feb # Kingston Mean Time + -5:00 - EST # Costa Rica @@ -2805,7 +2872,9 @@ Zone America/Havana -5:29:28 - LMT 1890 -5:00 Cuba C%sT # Dominica -# See America/Puerto_Rico. +# Zone NAME GMTOFF RULES FORMAT [UNTIL] +Zone America/Dominica -4:05:36 - LMT 1911 Jul 1 0:01 # Roseau + -4:00 - AST # Dominican Republic @@ -2854,10 +2923,15 @@ Zone America/El_Salvador -5:56:48 - LMT 1921 # San Salvador -6:00 Salv C%sT # Grenada -# See America/Puerto_Rico. +# Zone NAME GMTOFF RULES FORMAT [UNTIL] +Zone America/Grenada -4:07:00 - LMT 1911 Jul # St George's + -4:00 - AST # Guadeloupe -# See America/Puerto_Rico. +# Zone NAME GMTOFF RULES FORMAT [UNTIL] +Zone America/Guadeloupe -4:06:08 - LMT 1911 Jun 8 # Pointe a Pitre + -4:00 - AST +# Use America/Guadeloupe also for St Barthelemy and for St Martin (French part). # Guatemala # @@ -3027,7 +3101,9 @@ Zone America/Martinique -4:04:20 - LMT 1890 # Fort-de-France # From Paul Eggert (2006-03-22): # In 1995 volcanic eruptions forced evacuation of Plymouth, the capital. # world.gazetteer.com says Cork Hill is the most populous location now. -# See America/Puerto_Rico. +# Zone NAME GMTOFF RULES FORMAT [UNTIL] +Zone America/Montserrat -4:08:52 - LMT 1911 Jul 1 0:01 # Cork Hill + -4:00 - AST # Nicaragua # @@ -3108,17 +3184,16 @@ Zone America/Puerto_Rico -4:24:25 - LMT 1899 Mar 28 12:00 # San Juan -4:00 US A%sT 1946 -4:00 - AST -# St Barthelemy -# See America/Puerto_Rico. - # St Kitts-Nevis -# See America/Puerto_Rico. +# Zone NAME GMTOFF RULES FORMAT [UNTIL] +Zone America/St_Kitts -4:10:52 - LMT 1912 Mar 2 # Basseterre + -4:00 - AST # St Lucia -# See America/Puerto_Rico. - -# St Martin (French part) -# See America/Puerto_Rico. +# Zone NAME GMTOFF RULES FORMAT [UNTIL] +Zone America/St_Lucia -4:04:00 - LMT 1890 # Castries + -4:04:00 - CMT 1912 # Castries Mean Time + -4:00 - AST # St Pierre and Miquelon # There are too many St Pierres elsewhere, so we'll use `Miquelon'. @@ -3129,7 +3204,10 @@ Zone America/Miquelon -3:44:40 - LMT 1911 May 15 # St Pierre -3:00 Canada PM%sT # St Vincent and the Grenadines -# See America/Puerto_Rico. +# Zone NAME GMTOFF RULES FORMAT [UNTIL] +Zone America/St_Vincent -4:04:56 - LMT 1890 # Kingstown + -4:04:56 - KMT 1912 # Kingstown Mean Time + -4:00 - AST # Turks and Caicos # @@ -3163,7 +3241,11 @@ Zone America/Grand_Turk -4:44:32 - LMT 1890 -5:00 TC E%sT # British Virgin Is -# See America/Puerto_Rico. +# Zone NAME GMTOFF RULES FORMAT [UNTIL] +Zone America/Tortola -4:18:28 - LMT 1911 Jul # Road Town + -4:00 - AST # Virgin Is -# See America/Puerto_Rico. +# Zone NAME GMTOFF RULES FORMAT [UNTIL] +Zone America/St_Thomas -4:19:44 - LMT 1911 Jul # Charlotte Amalie + -4:00 - AST diff --git a/pre1970 b/pre1970 deleted file mode 100644 index d8b8f34..0000000 --- a/pre1970 +++ /dev/null @@ -1,291 +0,0 @@ -# Pre-1970 data - -# This file is in the public domain. - -# This file contains zones that were formerly in other source files, -# but were later removed or replaced by backward-compatibility links -# as they differ from other zones only in pre-1970 time stamps. - -# Although the tz database focuses on post-1970 time stamps, these -# entries are retained here as they may be of some use to people -# interested in pre-1970 time stamps, even though they cover only a -# tiny sliver of pre-1970 data and are unreliable for that data. -# Also, these entries can help with backward compatibility with some -# old versions of the tz database. They are incompatible with other -# old versions of the database, though; it depends on which old -# version you're interested in. - -# Entries are sorted by Zone name. Each entry is preceded by the name -# of the country that the entry is in, along with any other commentary -# and rules associated with the entry. Some rules, e.g., 'Canada', -# are defined by other source files; this file is not intended to be -# used without those other files. - -# Zone NAME GMTOFF RULES FORMAT [UNTIL] - -# Mali -# no longer different from Bamako, but too famous to omit -Zone Africa/Timbuktu -0:12:04 - LMT 1912 - 0:00 - GMT - -# Anguilla -Zone America/Anguilla -4:12:16 - LMT 1912 Mar 2 - -4:00 - AST - -# Antigua and Barbuda -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. -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 -Zone America/Aruba -4:40:24 - LMT 1912 Feb 12 # Oranjestad - -4:30 - ANT 1965 # Netherlands Antilles Time - -4:00 - AST - -# Canada - -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 - -Zone America/Blanc-Sablon -3:48:28 - LMT 1884 - -4:00 Canada A%sT 1970 - -4:00 - AST - -# Cayman Is -Zone America/Cayman -5:25:32 - LMT 1890 # Georgetown - -5:07:12 - KMT 1912 Feb # Kingston Mean Time - -5:00 - EST - -# Canada -Zone America/Coral_Harbour -5:32:40 - LMT 1884 - -5:00 NT_YK E%sT 1946 - -5:00 - EST - -# Curacao -Zone America/Curacao -4:35:47 - LMT 1912 Feb 12 # Willemstad - -4:30 - ANT 1965 # Netherlands Antilles Time - -4:00 - AST - -# Dominica -Zone America/Dominica -4:05:36 - LMT 1911 Jul 1 0:01 # Roseau - -4:00 - AST - -# Mexico -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 -Zone America/Fort_Wayne -5:00 US E%sT 1946 - -5:00 - EST # Always EST as of 1986 - -# Grenada -Zone America/Grenada -4:07:00 - LMT 1911 Jul # St George's - -4:00 - AST - -# Guadeloupe -Zone America/Guadeloupe -4:06:08 - LMT 1911 Jun 8 # Pointe a Pitre - -4:00 - AST - -# Canada -# 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 -Zone America/Montserrat -4:08:52 - LMT 1911 Jul 1 0:01 # Cork Hill - -4:00 - AST - -# Bahamas -# 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 -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. -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) -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 -Zone America/St_Kitts -4:10:52 - LMT 1912 Mar 2 # Basseterre - -4:00 - AST - -# St Lucia -Zone America/St_Lucia -4:04:00 - LMT 1890 # Castries - -4:04:00 - CMT 1912 # Castries Mean Time - -4:00 - AST - -# Virgin Is -Zone America/St_Thomas -4:19:44 - LMT 1911 Jul # Charlotte Amalie - -4:00 - AST - -# St Vincent and the Grenadines -Zone America/St_Vincent -4:04:56 - LMT 1890 # Kingstown - -4:04:56 - KMT 1912 # Kingstown Mean Time - -4:00 - AST - -# British Virgin Is -Zone America/Tortola -4:18:28 - LMT 1911 Jul # Road Town - -4:00 - AST - -# McMurdo, Ross Island, since 1955-12 -Zone Antarctica/McMurdo 0 - zzz 1956 - 12:00 NZAQ NZ%sT - -# Japan -Zone Asia/Ishigaki 8:16:36 - LMT 1896 - 8:00 - CST - -# Israel -Zone Asia/Tel_Aviv 2:19:04 - LMT 1880 - 2:21 - JMT 1918 - 2:00 Zion I%sT - -# Russia -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 -Zone Atlantic/Jan_Mayen -1:00 - EGT - -# Australia -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 -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 -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 -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 -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 -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] -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 diff --git a/southamerica b/southamerica index 59f5fe7..ff47cef 100644 --- a/southamerica +++ b/southamerica @@ -631,7 +631,10 @@ Zone America/Argentina/Ushuaia -4:33:12 - LMT 1894 Oct 31 -3:00 - ART # Aruba -# See America/Puerto_Rico. +# Zone NAME GMTOFF RULES FORMAT [UNTIL] +Zone America/Aruba -4:40:24 - LMT 1912 Feb 12 # Oranjestad + -4:30 - ANT 1965 # Netherlands Antilles Time + -4:00 - AST # Bolivia # Zone NAME GMTOFF RULES FORMAT [UNTIL] @@ -1325,7 +1328,7 @@ Zone America/Bogota -4:56:16 - LMT 1884 Mar 13 # Curacao -# Milne gives 4:35:46.9 for Curacao mean time. +# Milne gives 4:35:46.9 for Curacao mean time; round to nearest. # # From Paul Eggert (2006-03-22): # Shanks & Pottenger say that The Bottom and Philipsburg have been at @@ -1341,7 +1344,14 @@ 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. # -# For all these regions, see America/Puerto_Rico. +# Zone NAME GMTOFF RULES FORMAT [UNTIL] +Zone America/Curacao -4:35:47 - LMT 1912 Feb 12 # Willemstad + -4:30 - ANT 1965 # Netherlands Antilles Time + -4:00 - AST + +# Sint Maarten +# Caribbean Netherlands +# Use America/Curacao. # Ecuador # @@ -1615,7 +1625,9 @@ Zone America/Paramaribo -3:40:40 - LMT 1911 -3:00 - SRT # Trinidad and Tobago -# See America/Puerto_Rico. +# Zone NAME GMTOFF RULES FORMAT [UNTIL] +Zone America/Port_of_Spain -4:06:04 - LMT 1912 Mar 2 + -4:00 - AST # Uruguay # From Paul Eggert (1993-11-18): -- 1.8.1.2

7 38

winnowing stats
by Zefram Sept. 3, 2013

Sept. 3, 2013

Here are some stats on how much difference winnowing makes to the dataset. Baseline: the source files define 441 distinct zones. Winnowing then reduces the number of distinct zones thus: YEAR COUNT 0000 440 1880 440 1890 439 1900 439 1910 437 1920 435 1930 435 1940 434 1950 425 1960 423 1970 417 1980 391 1990 365 2000 339 2010 313 2020 305 The reduction by one zone for a threshold year of 0000 comes from Pacific/Johnston, a US minor outlying island, which is defined with data identical to the "HST" zone. (Contrary to the usual practice of using LMT for the first segment of geographical zones.) As the two tzfiles are byte-for-byte identical, tzwinnow will merge them regardless of date thresholds. The results for a threshold in the future set a lower limit on the size to which the database can be reduced by this mechanism. Relative to the present full database of 441 zones, it's only a modest gain. Using a threshold later than 1970 for installation purposes will probably only be attractive in a few more decades' time, when there have been many more zone splits arising from contemporary activity. A threshold later than 1970 is currently much more valuable for tzselect purposes. Here it's saving human cognitive load rather than storage space. The reduction in the number of zones is concentrated disproportionately in the countries that have the greatest complexity. This is particularly noticeable with the US zones, the list of which is quite unwieldy in unwinnowed form. Over the period where we attempt complete coverage (1970 to today), the rate at which the number of distinct zones changes is amazingly consistent at 26 per decade. A similar pattern emerges when winnowing with a varying upper date limit, showing that there's a long-term roughly constant rate of zone churn. The number of zones distinct within a single decade is also roughly constant, around 330. The number distinct within a single year hovers around 300, possibly showing a slight rising trend, but I suspect that's an artifact of incomplete data. This suggests that a strategy of winnowing with a moving threshold that remains N years ago will produce a roughly constant zone count. By contrast, the number of zones differing at any time post-1970 (currently 417), or from any other fixed threshold, can grow without bound, and it looks like it will. -zefram

2 1

scope of tz database, scholarship
by Steve Allen Sept. 2, 2013

Sept. 2, 2013

For the sake of the scholarship I would like to see a modification of the current text that reads As for leap seconds, 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 Stephenson FR (2003), Historical eclipses and Earth's rotation, A&G 44: 2.22-2.27 <http://dx.doi.org/10.1046/j.1468-4004.2003.44222.x>. A more complete reference to the accuracy of historical Delta T is in Historical values of the Earth's clock error Delta T and the calculation of eclipses Morrison, L. V. & Stephenson, F. R. Journal for the History of Astronomy (ISSN 0021-8286), Vol. 35, Part 3, No. 120, p. 327 - 336 (2004) as can be seen at http://articles.adsabs.harvard.edu/full/2004JHA....35..327M where, in particular, Table 1 gives uncertainty estimates back nearly 3000 years. For the oldest data there is an addendum Addendum: Historical values of the Earth's clock error Morrison, L. V. & Stephenson, F. R. Journal for the History of Astronomy (ISSN 0021-8286), Vol. 36, Part 3, No. 124, p. 339 (2005) http://adsabs.harvard.edu/full/2005JHA....36..339M In addition to that, for all practical purposes, civil time prior to 1972 did not use SI seconds, but rather mean solar seconds, and for dates prior to 1955 there cannot even be an argument. Therefore in the extended range of the tz database there is an arguably unspecified point when the kind of seconds counted changes from mean solar (UT) to atomic (SI). -- Steve Allen <sla(a)ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m

3 2

Unacceptable recent changes [wasRe: [PATCH 2/4] Move obsolescent Americas entries to 'backward'.]
by Stephen Colebourne Aug. 31, 2013

Aug. 31, 2013

On 26 August 2013 18:16, Paul Eggert <eggert(a)cs.ucla.edu> wrote: > # Shanks & Pottenger say that Atikokan has agreed with Rainy River > # ever since standard time was introduced, but the information from > # McKinnon sounds more authoritative. For now, assume that Atikokan > # switched to EST immediately after WWII era daylight saving time > # ended. This matches the old (less-populous) America/Coral_Harbour > # entry since our cutoff date of 1970, so we can move > -# America/Coral_Harbour to the 'backward' file. > +# America/Coral_Harbour to the 'backward' file. And Atikokan itself > +# is the same as America/Panama since 1970, so we can move > +# America/Atikokan to the 'backward' file as well. > -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 So if I understand correctly, all changes to Atikokan before 1970 have just been lost? And they are supposed to use Panama from now on? Here is what JSR-310 can tell us about the two sets of rules: America/Atikokan Transition[Gap at 1895-01-01T00:00-06:06:28 to -06:00] Transition[Gap at 1918-04-14T02:00-06:00 to -05:00] Transition[Overlap at 1918-10-27T02:00-05:00 to -06:00] Transition[Gap at 1940-09-29T00:00-06:00 to -05:00] America/Panama Transition[Overlap at 1890-01-01T00:00-05:18:08 to -05:19:36] Transition[Gap at 1908-04-22T00:00-05:19:36 to -05:00] Merging these is clearly utterly RIDICULOUS. They contain completely different data, and the 1970 argument simply won't wash. Many users will have stored data in databases or other long term storage that refers to these time-zones being made obsolete. When they read the data back, they will get completely different times for historic events - utterly unacceptable. More broadly, no one can pretend that the IDs we use are meaningless. Whether they should or should not have been created this way is not relevent - what matters is that these IDs are meningful and getting rid of them would be a disaster. The IDs are clearly localized, and they have a huge and longstanding usage globally. Panama is nowhere near Atikokan, nor would any reasonable user connect the two. Paul, you need to STOP NOW. You need to reverse the vast majority of your recent changes. Focus on actual changes happening in 2013. Keep the rest of the database totally and utterly stable. And just accept that there is a measure of politics incumbent in time-zones. NONE of these changes should be happening. STABILITY is vital. Stephen

20 53

Proposal for new rules
by Stephen Colebourne Aug. 30, 2013

Aug. 30, 2013

A simple proposal to move forward from where we are with reliable new rules: 1) Each inhabited ISO-3166 region must have at least one fully defined zone (LMT, pre and post 1970) 2) Links must not cross ISO-3166 region bouindaries Some of the rules that would require reworking (not a complete list): Europe/Busingen America/Atikotan America/Aruba America/Anguilla America/Port_of_Spain Europe/Zagreb Europe/Vatican Note that America/Montreal does not require reworking as a result of the first two new rules, although since it looks to have detailed historical information it would be unwise to lose that. Therefore I would add a third rule: 3) Existing pre-1970 data shall be respected If accepted, then these rules would be encoded in the theory file. Stephen

13 27

Acre, Brazil will attempt to re-introduce its previous timezone
by Alexander Krivenyshev Aug. 30, 2013

Aug. 30, 2013

According to the news from Brazil, Acre, Brazil will attempt to re-introduce its previous timezone, excluding Amazonas. http://www.worldtimezone.com/dst_news/dst_news_brazil11.html Alexander Krivenyshev, http://www.WorldTimeZone.com

1 0

Introducing myself
by Stephen Colebourne Aug. 29, 2013

Aug. 29, 2013

On 29 August 2013 20:39, Kevin Lyda <kevin(a)ie.suberic.net> wrote: > No solution will avoid politics. And someone starting a number of threads on > this topic clearly has their own political agenda. I should introduce myself, as not everyone will know who I am, or what I represent. I am Stephen Colebourne - a Java developer of 15+ years - recognised as a Java Champion, a leader in the Java community - author of Joda-Time, the most widely adopted 3rd party API for date and time in Java - co-spec lead of JSR-310, the effort to write a better API for the Java JDK - have written APIs to parse the tzdb - have designed APIs to expose that data to developers - work very closely with Oracle, and have had conversations with CLDR in the past My "political agenda" is to avoid the effort I've put in over the last 12 years on date and time in Java being damaged. Recent changes give the appearance of a lack of understanding of the importance of pre-1970 data and of cross-border localization. I'm sorry that I've had to write so much and object so strongly. I want to find a solution we can all agree on. It seems harder than it should be. Stephen

3 2

Problematic/dubious commits in 2013
by Stephen Colebourne Aug. 29, 2013

Aug. 29, 2013

I have reviewed every commit since the end of 2012. Here are the ones I consider to be problematic. I suggest that others have another review of these, as it may be that not everyone has taken the time to do this. - One zone for each inhabited ISO-3166 region should not have been removed: https://github.com/eggert/tz/commit/d3b025adb25554ee10b986850371e573df92733… - Ensuing changes were wrong: https://github.com/eggert/tz/commit/df99923bde035a263493f3435db63db15df14d53 - Reversion did not revert everything, specifically the reverted links are still in the backward file, not the main file, indicating that they are deprecated which should not be the case (eg for Europe/Zagreb): https://github.com/eggert/tz/commit/ee40570d7d937de749fe89676dec2ff1526ee68b - Pre-1970 damage: https://github.com/eggert/tz/commit/5903db75e5974fbdede1fa05bcef53ff645ac13d https://github.com/eggert/tz/commit/9432f1d23d3c5bbcc14c26f781185c01679edeef - Montreal removal (looks like it changes pre-1970 history) https://github.com/eggert/tz/commit/45dcf69b45087cff50282d4da64b86a7d705ddf3 - Navajo - America/ShipRock removal https://github.com/eggert/tz/commit/d58b59dd8a1e4c10abdbab8857ae521f6c2d2536 https://github.com/eggert/tz/commit/81be53c16b97ce0bc561ce3891ce2503227e3369 - Other possibly dubious commits tzselect changes https://github.com/eggert/tz/commit/cc3f93886bcfe36dfedc8f340827fded6e43539c https://github.com/eggert/tz/commit/ebdf0c5d0ce06b20dcd7e984b7370548f74dc210 Not all of these cause damage, but some clearly do. I'm unhappy with most of them, as they break the principles I value. Stephen

1 0