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Possible bug in the tz database
by Howard Hinnant June 8, 2015

June 8, 2015

I’m new to this list, so please forgive me for my inexperience and lack of history. I am concerned about the timezone America/North_Dakota/Beula: Early of the local morning of 2010-11-07 the local timezone GMTOFF changed from -7:00 to -6:00, and the timezone abbreviation changed from MDT to CST. I am not questioning this historical fact. Rather I am concerned about exactly when it happened and does the tz database accurately reflect this event. Here are the relevant entries today: Zone America/North_Dakota/Beulah -6:47:07 - LMT 1883 Nov 18 12:12:53 -7:00 US M%sT 2010 Nov 7 2:00 -6:00 US C%sT Which says at 2:00am local time on 2010/Nov/07 the change from MDT to CST occurs. Local time is defined by GMTOFF == -7:00 + US timezone rules for 2010. Or in other words 2:00am + 7:00 + any daylight savings time adjustment. I’m sure I’m preaching to the choir with this audience. I think there is no dispute that: 2010-11-07 01:59:59 MDT == 2010-11-07 07:59:59 UTC At this point in time the GMTOFF == -7:00 and in the US rule SAVE == 1:00 for a total offset of -6:00. However according to US rules for this date, the local clock ticks from 01:59:59 MDT to 01:00:00 MST. To reach 2:00am local time we need to wait another hour: 2010-11-07 02:00:00 MST == 2010-11-07 09:00:00 UTC According to US time zone rules (speaking about the recognized practice in the US, not about tz database rules), there was no 2010-11-07 02:00:00 MDT. It simply did not exist. So 2010-11-07 02:00:00 local time in US rules is unambiguously a standard time, not a daylight savings time. Whereas the times [01:00:00, 01:59:59] *are* ambiguous (or more accurately described with a half-open range: [01:00:00, 02:00:00). Since 2010-11-07 02:00:00 is unambiguously a standard time, the database could read like this with no change in behavior: Zone America/North_Dakota/Beulah -6:47:07 - LMT 1883 Nov 18 12:12:53 -7:00 US M%sT 2010 Nov 7 2:00s -6:00 US C%sT But this data indicates that local time behaves as follows that morning: 2010-11-07 01:59:59 MDT = 2010-11-07 07:59:59 UTC 2010-11-07 01:00:00 MST = 2010-11-07 08:00:00 UTC 2010-11-07 01:00:01 MST = 2010-11-07 08:00:01 UTC … 2010-11-07 01:59:59 MST = 2010-11-07 08:59:59 UTC 2010-11-07 03:00:00 CST = 2010-11-07 09:00:00 UTC 2010-11-07 03:00:01 CST = 2010-11-07 09:00:01 UTC However I believe the intended behavior is: 2010-11-07 01:59:59 MDT = 2010-11-07 07:59:59 UTC 2010-11-07 02:00:00 CST = 2010-11-07 08:00:00 UTC 2010-11-07 02:00:01 CST = 2010-11-07 08:00:01 UTC I believe the tz database can be changed to give the desired behavior with: diff --git a/northamerica b/northamerica index 88423e6..aeaf12c 100644 --- a/northamerica +++ b/northamerica @@ -371,7 +371,7 @@ Zone America/North_Dakota/New_Salem -6:45:39 - LMT 1883 Nov 18 12:14:21 # of 6h47'07". Zone America/North_Dakota/Beulah -6:47:07 - LMT 1883 Nov 18 12:12:53 - -7:00 US M%sT 2010 Nov 7 2:00 + -7:00 US M%sT 2010 Nov 7 1:00s -6:00 US C%sT # US mountain time, represented by Denver If I have misinterpreted the meanings of the fields to the tz database in some way, I would appreciate an education. I’ve reread all of the man pages and other documentation I can find, and haven’t been able to rectify this contradiction on my own. If this is indeed a bug that can be corrected, I am volunteering to detect and correct similar issues elsewhere in the database and generate a pull request for https://github.com/eggert/tz. Howard

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NTSB investigation derailed by time zone labyrinth
by Paul Eggert June 6, 2015

June 6, 2015

When the chair of the U.S. National Transportation Safety Board appeared before the House Transportation and Infrastructure Committee this week, he was asked "Could you just tell us again in plain English why we don't know if this operator was on the phone three weeks after the accident?" He had trouble answering, because although the NTSB has detailed timestamped data for the engineer's cell phone records, and they have physical access to the phone and the phone's passwords, they can't figure out the data's time zones. The cell phone companies don't know either. My sources: Jaffe E. We still basically have no idea what happened with the Amtrak 188 derailment. CityLab 2015-06-04. http://www.citylab.com/commute/2015/06/we-still-basically-have-no-idea-what… Nixon R. Phone data labyrinth hinders investigation of Amtrak derailment. New York Times 2015-06-05. http://www.nytimes.com/2015/06/06/us/inquiry-into-amtrak-derailment-is-slow…

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DST in the US 1945-1966
by Matt Johnson June 4, 2015

June 4, 2015

Wikipedia's page at:http://en.wikipedia.org/wiki/Daylight_saving_time_in_the_United_States#H… states the following: >From 1945 to 1966 there was no federal law on daylight saving time, so localities could choose when it began and ended or drop it entirely. In 1954 only California and Nevada had statewide DST west of the Mississippi, and only a few cities between Nevada and St Louis. In the 1964 Official Railway Guide, 21 of the 48 states had no DST anywhere. I'm wondering if we have any additional details about the localities that adopted DST during this period and those that did not? Also, do we already incorporated data from the source mentioned? (the 1964 Official Railway Guide) Specifically, I was discussing this topic with another developer who was curious about Nashville, Tennessee. One could probably assume that it was on Central time - due to the Standard Time Act, but whether or not it used DST (specifically in 1949) or not is the question. The tz database entry for Chicago would say yes - but my guess is that it might not be certain that both Chicago and Nashville used DST that year. Thanks.

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[PROPOSED PATCH] tzselect: port to POSIX sh and fix a typo
by Paul Eggert May 27, 2015

May 27, 2015

* tzselect.ksh: Use portable names for trap signals. Also, fix a typo: signal 2 (INT) was meant, not signal 12. --- tzselect.ksh | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tzselect.ksh b/tzselect.ksh index 2a622f5..2c3b2f4 100644 --- a/tzselect.ksh +++ b/tzselect.ksh @@ -191,7 +191,7 @@ done tmp=${TMPDIR-/tmp}/tzselect.$$ && (umask 77 && mkdir -- "$tmp") };} && - trap 'status=$?; rm -fr -- "$tmp"; exit $status' 0 1 12 13 15 && + trap 'status=$?; rm -fr -- "$tmp"; exit $status' 0 HUP INT PIPE TERM && (iconv -f UTF-8 -t //TRANSLIT <"$TZ_COUNTRY_TABLE" >$tmp/iso3166.tab) \ 2>/dev/null && TZ_COUNTRY_TABLE=$tmp/iso3166.tab && -- 2.1.4

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proposed tz change for Latvia, Lithuania
by Paul Eggert May 25, 2015

May 25, 2015

It's March Madness time for daylight-saving rule changes. Here's a proposed change to the tz database to keep up with the latest political development, which affects time stamps starting March 29: * Latvia and Lithuania will not observe DST, starting this year. Thanks to Andrei Ivanov for this info. =================================================================== RCS file: RCS/europe,v retrieving revision 2000.3 retrieving revision 2000.3.0.1 diff -pu -r2000.3 -r2000.3.0.1 --- europe 2000/03/04 15:31:08 2000.3 +++ europe 2000/03/08 17:48:59 2000.3.0.1 @@ -1135,6 +1135,12 @@ Link Europe/Rome Europe/San_Marino # 1997-01-21 on transition to Summer time ... established the same order of # daylight savings time settings as in the States of the European Union. +# From Andrei Ivanov (2000-03-06): +# This year Latvia will not switch to Daylight Savings Time (as specified in +# <a href="http://www.lv-laiks.lv/wwwraksti/2000/071072/vd4.htm"> +# The Regulations of the Cabinet of Ministers of the Rep. of Latvia of +# 29-Feb-2000 (#79)</a>, in Latvian for subscribers only). + # Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S Rule Latvia 1989 1996 - Mar lastSun 2:00s 1:00 S Rule Latvia 1989 1996 - Sep lastSun 2:00s 0 - @@ -1151,7 +1157,8 @@ Zone Europe/Riga 1:36:24 - LMT 1880 3:00 Russia MSK/MSD 1989 Mar lastSun 2:00s 2:00 1:00 EEST 1989 Sep lastSun 2:00s 2:00 Latvia EE%sT 1997 Jan 21 - 2:00 EU EE%sT + 2:00 EU EE%sT 2000 Feb 29 + 2:00 - EET # Liechtenstein # Zone NAME GMTOFF RULES FORMAT [UNTIL] @@ -1178,6 +1185,11 @@ Zone Europe/Vaduz 0:38:04 - LMT 1894 Jun # motion to give up shifting to summer time in spring, as it was # already done by Estonia. +# From Andrei Ivanov (2000-03-06): +# I've heard that Ministers of three Baltic countries on their summit +# somewhere in February decided not to switch to summer time starting from +# this spring. + # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Europe/Vilnius 1:41:16 - LMT 1880 1:24:00 - WMT 1917 # Warsaw Mean Time @@ -1192,7 +1204,8 @@ Zone Europe/Vilnius 1:41:16 - LMT 1880 2:00 C-Eur EE%sT 1998 2:00 - EET 1998 Mar 29 1:00u 1:00 EU CE%sT 1999 Oct 31 1:00u - 2:00 EU EE%sT + 2:00 EU EE%sT 2000 Feb + 2:00 - EET # Luxembourg # Whitman disagrees with most of these dates in minor ways; go with Shanks.

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"zic -l" complains about "empty component" in /etc/localtime
by Leonardo Chiquitto May 20, 2015

May 20, 2015

Hello, With 2015d I can no longer use "zic -l" to recreate /etc/localtime. I'm getting the following error: # ./zic -l America/Sao_Paulo ./zic: file name '/etc/localtime' contains empty component If I comment out the check introduced by commit 0ddac5ef7e in componentcheck(), then it works fine again: # ./zic -l America/Sao_Paulo # ls -lai /etc/localtime 1183669 -rw-r--r-- 5 root root 2015 May 17 20:20 /etc/localtime # ls -lai /usr/share/zoneinfo/America/Sao_Paulo 1183669 -rw-r--r-- 5 root root 2015 May 17 20:20 /usr/share/zoneinfo/America/Sao_Paulo A quick analysis: when "/etc/localtime" is passed to namecheck(), in the first loop iteration componentcheck() will be called with all three arguments set to "/etc/localtime". A possible fix is to skip this call to componentcheck() in the first iteration (patch attached). Leonardo

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Leap seconds in the news
by Arthur David Olson May 20, 2015

May 20, 2015

>From the Wall Street Journal: "Markets Are Jumpy Over Coming Leap Second" http://www.wsj.com/articles/markets-are-jumpy-over-coming-leap-second-14319… @dashdashado

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[PROPOSED PATCH] Guess Cayman Is will observe DST starting 2016
by Paul Eggert May 15, 2015

May 15, 2015

* NEWS: Document this. * backzone (America/Cayman): Move from here ... * northamerica: ... back to here, and assume US-style DST starting 2016. * zone1970.tab (KY): Now a separate row, since KY and PA disagree starting 2016. --- NEWS | 5 +++++ backzone | 5 ----- northamerica | 13 +++++++++++-- zone1970.tab | 3 ++- 4 files changed, 18 insertions(+), 8 deletions(-) diff --git a/NEWS b/NEWS index 392f09b..d69a98c 100644 --- a/NEWS +++ b/NEWS @@ -2,6 +2,11 @@ News for the tz database Unreleased, experimental changes + Changes affecting future time stamps + + Assume Cayman Islands will observe DST starting next year, using US rules. + Although it isn't guaranteed, it is the most likely. + Changes affecting data format The file 'iso3166.tab' now uses UTF-8, so that its entries can better diff --git a/backzone b/backzone index 6b392bd..0316708 100644 --- a/backzone +++ b/backzone @@ -279,11 +279,6 @@ Zone America/Aruba -4:40:24 - LMT 1912 Feb 12 # Oranjestad -4:30 - ANT 1965 # Netherlands Antilles Time -4:00 - AST -# Cayman Is -Zone America/Cayman -5:25:32 - LMT 1890 # Georgetown - -5:07:11 - 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 diff --git a/northamerica b/northamerica index c3af9eb..88423e6 100644 --- a/northamerica +++ b/northamerica @@ -2661,7 +2661,17 @@ Zone Atlantic/Bermuda -4:19:18 - LMT 1930 Jan 1 2:00 # Hamilton -4:00 US A%sT # Cayman Is -# See America/Panama. + +# From Paul Eggert (2015-05-15): +# The Cayman government has decided to introduce DST in 2016, the idea being +# to keep in sync with New York. The legislation hasn't passed but the change +# seems quite likely. See: Meade B. Cayman 27. +# http://www.cayman27.com.ky/2015/05/15/clock-ticks-toward-daylight-saving-ti… + +Zone America/Cayman -5:25:32 - LMT 1890 # Georgetown + -5:07:11 - KMT 1912 Feb # Kingston Mean Time + -5:00 - EST 2016 + -5:00 US E%sT # Costa Rica @@ -3184,7 +3194,6 @@ Zone America/Managua -5:45:08 - LMT 1890 Zone America/Panama -5:18:08 - LMT 1890 -5:19:36 - CMT 1908 Apr 22 # Colón Mean Time -5:00 - EST -Link America/Panama America/Cayman # Puerto Rico # There are too many San Juans elsewhere, so we'll use 'Puerto_Rico'. diff --git a/zone1970.tab b/zone1970.tab index 5da0200..2689c00 100644 --- a/zone1970.tab +++ b/zone1970.tab @@ -206,6 +206,7 @@ KI -0308-17105 Pacific/Enderbury Phoenix Islands KI +0152-15720 Pacific/Kiritimati Line Islands KP +3901+12545 Asia/Pyongyang KR +3733+12658 Asia/Seoul +KY +1918-08123 America/Cayman KZ +4315+07657 Asia/Almaty most locations KZ +4448+06528 Asia/Qyzylorda Qyzylorda (Kyzylorda, Kzyl-Orda) KZ +5017+05710 Asia/Aqtobe Aqtobe (Aktobe) @@ -259,7 +260,7 @@ NR -0031+16655 Pacific/Nauru NU -1901-16955 Pacific/Niue NZ,AQ -3652+17446 Pacific/Auckland New Zealand time NZ -4357-17633 Pacific/Chatham Chatham Islands -PA,KY +0858-07932 America/Panama +PA +0858-07932 America/Panama PE -1203-07703 America/Lima PF -1732-14934 Pacific/Tahiti Society Islands PF -0900-13930 Pacific/Marquesas Marquesas Islands -- 2.1.0

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Time Zone Database from Portugal
by Suzana Ferreira May 15, 2015

May 15, 2015

Hi, Where can I see information about Time Zone Database related to Portugal in your site?http://www.iana.org/time-zones http://tools.ietf.org/html/rfc6557 Thank you, -- Suzana Ferreira, Astrónoma ********************************************* Observatório Astronómico de Lisboa (OAL) -------------- desde 1861 -------------- Edifício Leste, Tapada da Ajuda, PT-1349-018 LISBOA, PORTUGAL tel: (351) 213616734 / fax: (351) 213616750 www.oal.ul.pt *********************************************

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Time Zones - Canary Islands - Offshore Spain - Error
by moxhull May 15, 2015

May 15, 2015

Dear Paul Eggert, I use software which sources your data in github for time zones. The Canary Islands, located off the coast of Morocco, belong to Spain but have a different time zone. It's causing me problems because it seems your files do not take account of this. Would you kindly amend your files accordingly, please, so that my software programmer can use an updated file, so in turn I can use his software? Please see below for references. Many thanks indeed, so grateful. Yours sincerely, Sylvie ---------- Forwarded message ---------- From: Anatoly Zaytsev <astrozet(a)gmail.com> Date: Thu, May 14, 2015 at 5:41 PM Subject: Re: Zet 8 Geo, time zones To: moxhull <moxhull(a)gmail.com> Hello Sylvie, 1) This is not so important. 2) I use more (seems) relevant source: https://github.com/eggert/tz Paul Eggert tz-bounces(a)iana.org also https://github.com/eggert/tz/blob/master/europe line 2922 Please talk with him. ----------------- Anatoly Zaytsev www.astrozet.com ----- Original Message ----- From: "moxhull" <moxhull(a)gmail.com> To: <astrozet(a)gmail.com> Sent: Thursday, May 14, 2015 7:02 PM Subject: Zet 8 Geo, time zones Dear Anatoly, I hope you are well. I write for two items: - I have retired from my job in Geneva (Switzerland), sold my house in France, and I have moved to the Canary Islands, a part of Spain that is off the coast of Morocco. So my addresses, email and telephone number need to be changed in your records - see below. - The Canary Islands do not use the same time as mainland Spain, so I'm having trouble with the time changes. I tried to make a few modifications in my Zet but I do not know enough and did not succeed. Please would make the corrections in the time zone files and make them available? For reference see: http://en.wikipedia.org/wiki/Time_in_Spain#The_Canary_Islands_exception Thank you very much for correcting this. Kind regards, Sylvie Weber Calle Aceviño 49 Ed. Tarahal, Apto 201 38400 Puerto de la Cruz, Tenerife Spain Tel. +34 674 80 18 34 email: moxhull(a)gmail.com [image: Inline image 1]

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