October 2018 - tz - lists.iana.org

Timezone for East Asian traditional calendar
by Phake Nick Oct. 26, 2018

Oct. 26, 2018

Because computation of East Asian traditional calendar depends on time when various astronomical phenomenon occur, especially nowadays when almost all places that are still using the old calendar have switched to use the actual observed/predicted time for those astronomical phenomenon to occur based on modern scientific prediction methodology, yet the time standard being used to compute those traditional calendar differ in each regions and there are multiple occasions in different countries that the time used to compute the traditional calendar, do not directly correspond to the time when the standard time were changed. Is it viable to record such information in another region within tz database? Having such a region could also remind vendors in East Asia area that the world have more than one timezone when computing traditional East Asian calendar and also remind vendors outside East Asia that there are not just Chinese-time-based-Chinese-calendar when computing days, especially when it come to computing festivals based on the traditional East Asian calendars like Lunar New Year, Double Nine Festival, Winter Solstice and Mid-Autumn Festival.

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Morocco decided to stay in UTC+1
by Mounir EL MOKHTARI Oct. 26, 2018

Oct. 26, 2018

Hi, It's official. Morocco has decided to stay in UTC+1. http://www.mapnews.ma/en/top-news/general/morocco-will-stay-summer-time Thanks. Mounir El Mokhtari

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Re: [tz] 2018e Morocco
by Paul Eggert Oct. 25, 2018

Oct. 25, 2018

On 10/23/18 7:53 AM, Brian Basarich wrote: > I understand the need for a rule that supports 2038 and beyond, but instead of having overlapping rules, why not create the rules like this: Because that would be more complicated to maintain. > I realize in 2038 the DST end date will likely be in September, and the 2038-max rule would have to be adjusted as future DST end date rules are added. But I don't see how the above is any different than leaving the 2013-max rule. Exactly. What we have for Morocco has the same effect as the rules you suggested, except it's easier to maintain. > And aren't you eventually going to cap the 2013 rule end rule at 2035 down the road? Nobody knows. It's possible Morocco will cancel DST entirely next year and that this will all be moot. > Does this happen elsewhere in the database? That is, where multiple rules apply to the same year, but one rule operationally supersedes the other? I think so, yes.

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Bad 32 bit data in 2018f
by Daniel Fischer Oct. 25, 2018

Oct. 25, 2018

Hi, I'm getting bad data in the 32 bit section of some of the compiled files in zoneinfo-leaps. The affected time zones are zones that only transition before 1901, usually from LMT to some UTC offset: Indian/Christmas Indian/Cocos Atlantic/South_Georgia Pacific/Port_Moresby Pacific/Chuuk Pacific/Yap Pacific/Wallis Pacific/Funafuti Pacific/Palau Pacific/Ponape Pacific/Wake Pacific/Pohnpei Pacific/Truk Pacific/Tarawa The files in zoneinfo-leaps contain no transitions, and only the offset used before the transition. This causes applications that only read the 32 bit section to use LMT for these zones. The 64 bit section, and both sections in the zoneinfo version of these files, contain >=2 transitions and offsets (e.g. one real transition and one in 2038). For example, zdump with a break added after /old file/ in localtime.c: $ ./zdump $PWD/TZ/usr/share/zoneinfo*/Atlantic/South_Georgia .../TZ/usr/share/zoneinfo/Atlantic/South_Georgia Tue Oct 23 12:31:33 2018 -02 .../TZ/usr/share/zoneinfo-leaps/Atlantic/South_Georgia Tue Oct 23 12:04:58 2018 LMT $ ./zdump -V $PWD/TZ/usr/share/zoneinfo-leaps/Atlantic/South_Georgia .../TZ/usr/share/zoneinfo-leaps/Atlantic/South_Georgia Sat Jul 1 00:00:00 1972 UT = Fri Jun 30 21:33:52 1972 LMT isdst=0 gmtoff=-8768 .../TZ/usr/share/zoneinfo-leaps/Atlantic/South_Georgia Sat Jul 1 00:00:01 1972 UT = Fri Jun 30 21:33:52 1972 LMT isdst=0 gmtoff=-8768 [..] .../TZ/usr/share/zoneinfo-leaps/Atlantic/South_Georgia Sun Jan 1 00:00:27 2017 UT = Sat Dec 31 21:33:52 2016 LMT isdst=0 gmtoff=-8768 I found that before commit 83c119f4d ("Remove Big Bang hack"), the one offset present in the leaps version was the correct one. The structural difference is older; it just didn't affect my application because the offset was the one currently in use. The cause appears to be this sequence of events starting at zic.c /Work around QTBUG-53071/: 1) y2038_boundary-1 transition is added (== INT32_MAX) 2) leap seconds are added to all times, pushing the 2038 transition above INT32_MAX 3) affected zones again only have transition times outside the 32 bit range => timecnt32 is 0 4) because timecnt32 is 0, timei32 is also 0, and the INT32_MIN transition isn't output either 5) because of omittype[defaulttype] = false, the oldest offset is always output regardless of the above The workaround could probably be moved to after the leap seconds are added, especially if it's supposed to apply to the 32 bit leaps files. This will also fix this bug, because the code that determines the 32 bit limits assumes there's at least one time after 1901, and the workaround provides one. (This is why the non-leaps version is correct.) I'm unfortunately not familiar enough with the tz database to suggest a complete fix. Danny -- Daniel Fischer ORACLE Deutschland B.V. & Co. KG, Riesstr. 25, 80992 München - HRA MUC 95603 Komplementaer: ORACLE DE Verw.B.V., Hertogswetering 163/167, 3543 AS Utrecht Geschaeftsfuehrer: Alexander van der Ven, Jan Schultheiss, Val Maher NL

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[PROPOSED] * northamerica: El Paso time zone rebellion.
by Paul Eggert Oct. 25, 2018

Oct. 25, 2018

--- northamerica | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/northamerica b/northamerica index fb0103f..9d5bad2 100644 --- a/northamerica +++ b/northamerica @@ -439,6 +439,19 @@ Zone America/North_Dakota/Beulah -6:47:07 - LMT 1883 Nov 18 12:12:53 # western South Dakota, far western Texas (El Paso County, Hudspeth County, # and Pine Springs and Nickel Creek in Culberson County), Utah, Wyoming # +# From Paul Eggert (2018-10-25): +# On 1921-03-04 federal law placed all of Texas into the central time zone. +# However, El Paso ignored the law for decades and continued to observe +# mountain time, on the grounds that that's what they had always done +# and they weren't about to let the federal government tell them what to do. +# Eventually the federal government gave in and changed the law on +# 1970-04-10 to match what El Paso was actually doing. Although +# that's slightly after our 1970 cutoff, there is no need to create a +# separate zone for El Paso since they were ignoring the law anyway. See: +# Long T. El Pasoans were time rebels, fought to stay in Mountain zone. +# El Paso Times. 2018-10-24 06:40 -06. +# https://www.elpasotimes.com/story/news/local/el-paso/2018/10/24/el-pasoans-… +# # Rule NAME FROM TO TYPE IN ON AT SAVE LETTER Rule Denver 1920 1921 - Mar lastSun 2:00 1:00 D Rule Denver 1920 only - Oct lastSun 2:00 0 S -- 2.17.1

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[PROPOSED] Add interoperability sections to tzfile.5
by Paul Eggert Oct. 25, 2018

Oct. 25, 2018

This change consists of text that I contributed to https://tools.ietf.org/html/draft-murchison-tzdist-tzif-15 and that should be useful generally. * NEWS, tzfile.5: New sections. --- NEWS | 4 ++ tzfile.5 | 192 ++++++++++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 195 insertions(+), 1 deletion(-) diff --git a/NEWS b/NEWS index 943db3e..68f826e 100644 --- a/NEWS +++ b/NEWS @@ -16,6 +16,10 @@ Unreleased, experimental changes This reverts to 2011h, as the abbreviation change in 2011i was likely inadvertent. + Changes to documentation + + tzfile.5 has new sections on interoperability issues. + Release 2018f - 2018-10-18 00:14:18 -0700 diff --git a/tzfile.5 b/tzfile.5 index 79b19bf..bbdccfc 100644 --- a/tzfile.5 +++ b/tzfile.5 @@ -9,6 +9,8 @@ tzfile \- timezone information .de q \\$3\*(lq\\$1\*(rq\\$2 .. +.ie \n(.g .ds - \f(CW-\fP +.el ds - \- The timezone information files used by .BR tzset (3) are typically found under a directory with a name like @@ -186,8 +188,196 @@ 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 between daylight saving and standard time. -.PP +.SS Interoperability considerations Future changes to the format may append more data. +.PP +Version 1 files are considered a legacy format and +should be avoided, as they do not support transition +times after the year 2038. +Readers that only understand Version 1 must ignore +any data that extends beyond the calculated end of the version +1 data block. +.PP +Writers should generate a version 3 file if +TZ string extensions are necessary to accurately +model transition times. +Otherwise, version 2 files should be generated. +.PP +The sequence of time changes defined by the version 1 +header and data block should be a contiguous subsequence +of the time changes defined by the version 2+ header and data +block, and by the footer. +This guideline helps obsolescent version 1 readers +agree with current readers about timestamps within the +contiguous subsequence. It also lets writers not +supporting obsolescent readers use a +.I tzh_timecnt +of zero +in the version 1 data block to save space. +.PP +Time zone designations should consist of at least three (3) +and no more than six (6) ASCII characters from the set of +alphanumerics, +.q "-", +and +.q "+". +This is for compatibility with POSIX requirements for +time zone abbreviations. +.PP +When reading a version 2 or 3 file, readers +should ignore the version 1 header and data block except for +the purpose of skipping over them. +.PP +Readers should calculate the total lengths of the +headers and data blocks and check that they all fit within +the actual file size, as part of a validity check for the file. +.SS Common interoperability issues +This section documents common problems in reading or writing TZif files. +Most of these are problems in generating TZif files for use by +older readers. +The goals of this section are: +.IP * 2 +to help TZif writers output files that avoid common +pitfalls in older or buggy TZif readers, +.IP * +to help TZif readers avoid common pitfalls when reading +files generated by future TZif writers, and +.IP * +to help any future specification authors see what sort of +problems arise when the TZif format is changed. +.PP +When new versions of the TZif format have been defined, a +design goal has been that a reader can successfully use a TZif +file even if the file is of a later TZif version than what the +reader was designed for. +When complete compatibility was not achieved, an attempt was +made to limit glitches to rarely-used timestamps, and to allow +simple partial workarounds in writers designed to generate +new-version data useful even for older-version readers. +This section attempts to document these compatibility issues and +workarounds, as well as to document other common bugs in +readers. +.PP +Interoperability problems with TZif include the following: +.IP * 2 +Some readers examine only version 1 data. +As a partial workaround, a writer can output as much version 1 +data as possible. +However, a reader should ignore version 1 data, and should use +version 2+ data even if the reader's native timestamps have only +32 bits. +.IP * +Some readers designed for version 2 might mishandle +timestamps after a version 3 file's last transition, because +they cannot parse extensions to POSIX in the TZ-like string. +As a partial workaround, a writer can output more transitions +than necessary, so that only far-future timestamps are +mishandled by version 2 readers. +.IP * +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). +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). +.IP * +Some readers ignore the footer, and instead predict future +timestamps from the time type of the last transition. +As a partial workaround, a writer can output more transitions +than necessary. +.IP * +Some readers do not use time type 0 for timestamps before +the first transition, in that they infer a time type using a +heuristic that does not always select time type 0. +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. +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. +.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. +.IP * +Some readers mishandle POSIX-style TZ strings that +contain +.q "<" +or +.q ">". +As a partial workaround, a writer can avoid using +.q "<" +or +.q ">" +for time zone abbreviations containing only alphabetic +characters. +.IP * +Many readers mishandle time zone abbreviations that contain +non-ASCII characters. +These characters are not recommended. +.IP * +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 "-", +and +.q "+". +These abbreviations are not recommended. +.IP * +Some readers mishandle TZif files that specify +daylight-saving time UT offsets that are less than the UT +offsets for the corresponding standard time. +These readers do not support locations like Ireland, which +uses the equivalent of the POSIX TZ string +.q "IST\*-1GMT0,M10.5.0,M3.5.0/1", +observing standard time +(IST, +01) in summer and daylight saving time (GMT, +00) in winter. +As a partial workaround, a writer can output data for the +equivalent of the POSIX TZ string +.q "GMT0IST,M3.5.0/1,M10.5.0", +thus swapping standard and daylight saving time. +Although this workaround misidentifies which part of the year +uses daylight saving time, it records UT offsets and time zone +abbreviations correctly. +.PP +Some interoperability problems are reader bugs that +are listed here mostly as warnings to developers of readers. +.IP * 2 +Some readers do not support negative timestamps. +Developers of distributed applications should keep this +in mind if they need to deal with pre-1970 data. +.IP * +Some readers mishandle timestamps before the first +transition that has a nonnegative timestamp. +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" +that contain +.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 +support locations like Kiritimati that are outside this +range. +.IP * +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". +.IP * +Some readers mishandle UT offsets that are not a multiple +of one hour, or of 15 minutes, or of 1 minute. .SH SEE ALSO .BR time (2), .BR localtime (3), -- 2.17.2

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[PROPOSED] * NEWS: Improve recent entries.
by Paul Eggert Oct. 25, 2018

Oct. 25, 2018

--- NEWS | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/NEWS b/NEWS index 4eb313f..943db3e 100644 --- a/NEWS +++ b/NEWS @@ -7,12 +7,14 @@ Unreleased, experimental changes The translator to rearguard format now rewrites the line "Rule Japan 1948 1951 - Sep Sat>=8 25:00 0 S" to "Rule Japan 1948 1951 - Sep Sun>=9 1:00 0 S". - This caters to zic before 2007 and to at least one Java-based zi - compiler of uncertain vintage. (Reported by Christos Zoulas.) + This caters to zic before 2007 and to Oracle TZUpdater 2.2.0 + and earlier. (Reported by Christos Zoulas.) Changes to past time zone abbreviations Change HDT to HWT/HPT for WWII-era abbreviations in Hawaii. + This reverts to 2011h, as the abbreviation change in 2011i was + likely inadvertent. Release 2018f - 2018-10-18 00:14:18 -0700 -- 2.17.2

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Bad 32 bit data in 2018f
by Daniel Fischer Oct. 24, 2018

Oct. 24, 2018

Hi, I'm getting bad data in the 32 bit section of some of the compiled files in zoneinfo-leaps. The affected time zones are zones that only transition before 1901, usually from LMT to some UTC offset: Indian/Christmas Indian/Cocos Atlantic/South_Georgia Pacific/Port_Moresby Pacific/Chuuk Pacific/Yap Pacific/Wallis Pacific/Funafuti Pacific/Palau Pacific/Ponape Pacific/Wake Pacific/Pohnpei Pacific/Truk Pacific/Tarawa The files in zoneinfo-leaps contain no transitions, and only the offset used before the transition. This causes applications that only read the 32 bit section to use LMT for these zones. The 64 bit section, and both sections in the zoneinfo version of these files, contain >=2 transitions and offsets (e.g. one real transition and one in 2038). For example, zdump with a break added after /old file/ in localtime.c: $ ./zdump $PWD/TZ/usr/share/zoneinfo*/Atlantic/South_Georgia .../TZ/usr/share/zoneinfo/Atlantic/South_Georgia Tue Oct 23 12:31:33 2018 -02 .../TZ/usr/share/zoneinfo-leaps/Atlantic/South_Georgia Tue Oct 23 12:04:58 2018 LMT $ ./zdump -V $PWD/TZ/usr/share/zoneinfo-leaps/Atlantic/South_Georgia .../TZ/usr/share/zoneinfo-leaps/Atlantic/South_Georgia Sat Jul 1 00:00:00 1972 UT = Fri Jun 30 21:33:52 1972 LMT isdst=0 gmtoff=-8768 .../TZ/usr/share/zoneinfo-leaps/Atlantic/South_Georgia Sat Jul 1 00:00:01 1972 UT = Fri Jun 30 21:33:52 1972 LMT isdst=0 gmtoff=-8768 [..] .../TZ/usr/share/zoneinfo-leaps/Atlantic/South_Georgia Sun Jan 1 00:00:27 2017 UT = Sat Dec 31 21:33:52 2016 LMT isdst=0 gmtoff=-8768 I found that before commit 83c119f4d ("Remove Big Bang hack"), the one offset present in the leaps version was the correct one. The structural difference is older; it just didn't affect my application because the offset was the one currently in use. The cause appears to be this sequence of events starting at zic.c /Work around QTBUG-53071/: 1) y2038_boundary-1 transition is added (== INT32_MAX) 2) leap seconds are added to all times, pushing the 2038 transition above INT32_MAX 3) affected zones again only have transition times outside the 32 bit range => timecnt32 is 0 4) because timecnt32 is 0, timei32 is also 0, and the INT32_MIN transition isn't output either 5) because of omittype[defaulttype] = false, the oldest offset is always output regardless of the above The workaround could probably be moved to after the leap seconds are added, especially if it's supposed to apply to the 32 bit leaps files. This will also fix this bug, because the code that determines the 32 bit limits assumes there's at least one time after 1901, and the workaround provides one. (This is why the non-leaps version is correct.) I'm unfortunately not familiar enough with the tz database to suggest a complete fix. Danny -- Daniel Fischer ORACLE Deutschland B.V. & Co. KG, Riesstr. 25, 80992 München - HRA MUC 95603 Komplementaer: ORACLE DE Verw.B.V., Hertogswetering 163/167, 3543 AS Utrecht Geschaeftsfuehrer: Alexander van der Ven, Jan Schultheiss, Val Maher NL

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South Korea timezone history
by Phake Nick Oct. 24, 2018

Oct. 24, 2018

On Korean Wikipedia article for DST https://ko.wikipedia.org/wiki/%EC%9D%BC%EA%B4%91_%EC%A0%88%EC%95%BD_%EC%8B%… , I saw the following lines (with machine translation): >In Korea, the standard meridian of the time was 127° 30' in Tokyo during the period of 1955 to 1960, so it was 30 minutes earlier than it is today. This information is different from what's currently described in tz database and should be investigated. Also, given the example of DST transaction in Japan, it might also worth investigating what did the "00:00[start]-00:00[end]" in Korean DST transaction mean at the time.

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[PROPOSED] * tz-link.html: Update Windows details and links
by Matt Johnson Oct. 23, 2018

Oct. 23, 2018

diff --git a/tz-link.html b/tz-link.html index b5870d3..8593ba6 100644 --- a/tz-link.html +++ b/tz-link.html @@ -524,11 +524,10 @@ clock (intclock)</a> is a clock that displays multiple time zones on under the <abbr>GPL</abbr>.</li> <li>Microsoft Windows 8.1 and later has <code><abbr>tz</abbr></code> data and <abbr>CLDR</abbr> -data (mentioned <a href="#CLDR">below</a>) used by the -<a href="https://en.wikipedia.org/wiki/Windows_Runtime">Windows Runtime</a> / -<a href="https://en.wikipedia.org/wiki/Universal_Windows_Platform">Universal Windows Platform</a> classes -<a href="https://docs.microsoft.com/uwp/api/Windows.Globalization.DateTimeFormatting…"><code>DateTimeFormatter</code></a> and -<a href="https://docs.microsoft.com/uwp/api/windows.globalization.calendar"><code>Calendar</code></a>. +data (mentioned <a href="#CLDR">below</a>) used by +<a href="https://en.wikipedia.org/wiki/Windows_Runtime">Windows Runtime</a> +classes such as <a +href="https://msdn.microsoft.com/en-us/library/windows/apps/windows.globalization…"><code>DateTimeFormatter</code></a>. <a id="System.TimeZoneInfo" href="https://blogs.msdn.microsoft.com/bclteam/2007/06/07/exploring-windows-time-…">Exploring Windows Time Zones with <code>System.TimeZoneInfo</code></a> describes

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