- tz - lists.iana.org

Request RE: academic research question re: TZ database
by Andrew Lyon Jan. 10, 2020

Jan. 10, 2020

Hello. I am a clinical biochemist and not well versed in handling the TZ database. I am investigating a software problem related to hospital patient data management that appears to be triggered when the software encounters a patient record with a date-of-birth that coincides with a historic daylight saving time Spring transition date. Through this investigation I have learned many details about the history of daylight saving time, but I often question the reliability of sources of information. It appears that many use the tz database as a source of truth. I am seeking assistance to query the tz database to determine the entries in the database for Area /Location America/Regina to determine the (1) daylight saving time Spring transition date and (2) daylight saving time Spring transition hour from 1900 to 1966. I understand there were 10 years between 1930 and 1941 when the hour of Spring daylight saving transition was 0000 (midnight) to 0100. I would like to confirm these entries are in the tz database. I have numerous references that daylight saving time was also observed in America/Regina during world war ONE ( 1914-1918) and I am uncertain if those entries are in the tz database or the hour of those transitions. I am uncertain if it is appropriate to ask for this type of assistance on this discussion group. Thank-you very much, regards, Andrew Dr. A.W. Lyon Dept Pathology and Laboratory Medicine University of Saskatchewan

6 10

Some inconsistency in times during the transitions between DST and non-DST times...
by Alan Lehotsky Jan. 9, 2020

Jan. 9, 2020

I’m supporting a “port” of the tz code where I’ve selectively embedded pieces of localtime.c into an application , so this may be something I’ve broken, but I’ve looked fairly carefully at my implementation. There seems to be a problem with the binary search to find the nearest transition times, when you are within the “fall-behind” transition. If I am in the Europe/London timezone and have a time like "2019-10-27 01:16:46” converting it to UTC is producing the same time (because it ends up finding the non-DST range. But ONE second earlier ends up thinking it’s within the DST range, so "2019-10-27 01:16:45” ends up reporting “2019-10-2 00:16:45” I tried to use the gnu date command to see if I could reproduce this in a clean tz environment using the -u -d flags, and couldn’t duplicate the problems I’m seeing, so there’s a possibility that this is something I’m doing wrong. But the following experimental change in localsub makes it consistently pick the non-dst representation of the time. } else { int lo = 1; int hi = sp->timecnt; while (lo < hi) { int mid = (lo + hi) >> 1; if (t < sp->ats[mid]) hi = mid; else lo = mid + 1; } i = (int) sp->types[lo - 1]; // Check if this is a dst setting AND 't' is within the magic hour that // replays when we fall behind. In this case we always treat a time as // not in the dst. // if (sp->ttis[i].tt_isdst && (t - sp->ttis[i].tt_gmtoff) > sp->ats[lo-1]) i = (int) sp->types[lo]; } ttisp = &sp->ttis[i]; Does this make any sense?

2 1

Updated Eggert leap-seconds.list
by Chris Woodbury Jan. 8, 2020

Jan. 8, 2020

On the occasion of a new IERS Bulletin C, I present an updated version of a public domain leap-second.list file. # -=*( This file is in the public domain )*=- # This NTP leap-second file was created with data obtained from # the United States Naval Observatory (USNO) MAIA FTP server. # # Find it at: <ftp://maia.usno.navy.mil/ser7/leapsec.dat> (down) # <ftp://cddis.gsfc.nasa.gov/pub/products/iers/leapsec.dat> (backup) # Updated using information from IERS Bulletin C 59 (7 Jan 2020) # Found at <ftp://hpiers.obspm.fr/iers/bul/bulc/bulletinc.dat> # # IERS Bulletin C 59 did not announce a new leap-second. # # The last leap-second occurred on 1 Jan 2017 (3692217600) # which was announced in IERS Bulletin C 52 on 6 July 2016. # # -=<*>=- # # This file is not produced by a national metrology laboratory. # It *is* created using data from one: # # United States Naval Observatory (USNO) # IERS Rapid Service/Prediction Center for Earth Orientation # 3450 Massachusetts Ave NW, Washington, DC 20392 # # It should be noted that anyone with proper information can # generate an NTP leap-seconds.list file. # # The generation of this file was at the behest of Dr. Eggert # on the occasion of a US government shutdown which resulted # in a lack of an NIST generated file until late in January 2019. # # -=<*>=- # # The Network Time Protocol (NTP) keeps time in Coordinated # Universal Time (UTC). UTC is a time scale based upon # Standard International (SI) seconds and derived from Temps # Atomique International (TAI). UTC is the de facto basis for # legal time for much of the world since 1 Jan 1972 0h. # # [Le] Bureau International des Poids et Mesures (BIPM) tracks # TAI, UT1, TE, UTC, etc. uses a weighted ensemble of 420+ atomic # clocks at over 80+ national metrology laboratories worldwide # to track time and Very-Long-Baseline Interferometry (VLBI) # for precision millisecond pulsars timing and to track Earth's # orientation in space. The origin of TAI has been agreed # officially to coincide with UT1 on 1 January 1958 0h. # # For further information, read BIPM monograph "Time Scales" # found at: # # <https://www.bipm.org/... # utils/common/pdf/monographies-misc/Monographie1994-1.pdf> # # And "Coordinated Universal Time" at: # # <https://www.bipm.org/cc/CCTF/Allowed/18/CCTF_09-32_noteUTC.pdf> # # And, lastly: # # "Atomic Time Scales for Dynamical Astronomy" pp.51-56 # # "How Can Millisecond Pulsars Improve the Long-Term Stability # of Atomic Time Scales?", pp.57-60: # # Proceedings of the 6th European Frequency and Time Forum # (17-19 March 1992) # # <http://www.eftf.org/proceedings/proceedingsEFTF1992.pdf> # # -=<*>=- # # Leap seconds are an official correction to UTC to keep it # within 0.9 seconds of UT1; yet another time standard # based upon the orientation of the earth in space (and the # basis of legal time until 1972). IERS Bulletin A keeps # track of and predicts the value of UT1-UTC. # # See: ftp://maia.usno.navy.mil/ser7/ser7.dat (down) # ftp://cddis.gsfc.nasa.gov/pub/products/iers/ser7.dat (backup) # # The data kept in "leap-seconds.list" are used by the # Network Time Protocol daemon (NTPd) to determine when to # apply leap seconds to Coordinated Universal Time (UTC). # "leap-seconds.list" is a symbolic link to the actual # file name, leap-seconds.xxxxxxxxxx, where xxxxxxxxxx # is derived from the NTP update timestamp (below). # # Theoretically, a leap second may be positive or negative. # Realistically, negative leap seconds are unlikely to occur. # # All timestamps in this leap seconds file are encoded using the # NTP epoch. These timestamps represent the number of seconds # since 1 Jan 1900 0:00:00. This is Modified Julian Date (MJD) # 15020 and Julian Date 2415020.5. There will be an unsigned # 32-bit overflow to the second NTP era in 2036 (07 Feb 2036 # 06:28:16 UTC to be precise). # # A leap second datum consists of an NTP timestamp and the # number of seconds difference between TAI and UTC (e.g. # currently TAI-UTC is 37). UTC was established (at # midnight) on 1 Jan 1972 0h with TAI-UTC started at 10. # There was no mechanism prior to that time defining when # to apply leap seconds. # # Note: the first datum in the leap-seconds.list file is # *not* a leap-second; it denotes the definition of the # UTC timescale. # # Leap-seconds rules are establish in: # # International Telecommunications Union-Recommendation (ITU-R) # 460-6 (Standard-frequency and Time-Signal Emissions), # Annex 1 (Time scales), Section 2 (Leap-Seconds). # # Note: Version 460-6 of the Recommendation is incorporated # by reference in the [ITU] Radio Regulations. # # <http://www.itu.int/rec/R-REC-TF.460-6-200202-I/> # # Also note that Annex 1, Section 2.1 of this document contradicts # the comments in Bulletin C regarding as to when a leap-second # may be applied. i.e. As the last second of any UTC month. # Preference is given to June and December and, secondarily, in # March and September. (All have been in June or December.) # # Section 2.3: Delegates leap-second timing/dissemination to the # International Earth Rotation and Reference System Service (IERS), # (in its role as inheritor of Bureau International de l'Heure (BIH)). # # NTP Leap second files have an update time (#$). This is often # the UTC zero (0) hour time of the day when the leap second file # is built. [I am of the opinion] it should be updated whenever # a new IERS Bulletin C is issued. CCW] # #$ 3787382231 # # Leap second data have a lifetime. Traditionally, this ends on # the twenty-eighth (28) day of the month six months after the # period of time described in the latest IERS Bulletin C. This # is the expiry time (#@). # # Updated through IERS Bulletin C 59 (7 Jan 2020) # File expires on: 28 Jul 2020 # #@ 3818102400 # # Leap second files have a hash, as define in NIST's FIPS 180 # Secure Hash Standard (SHS), current revision 4 (FIPS 180-4). # # FIPS Publications: <http://csrc.nist.gov/publications/fips/> # Direct Link: <http://dx.doi.org/10.6028/NIST.FIPS.180-4> # # It is based on an SHA[1] digest, created using the data # portions of the file including leap second data and the update # and expiry timestamps. All "white space" and comments are # ignored in the computation thereof. The 160-bit SHA[1] # digest polynomial are encoded in five hexadecimal grouping at # the end of the file (#h). The hash itself is NOT included in # the SHA[1]. It can also be calculated using GNU sha1sum which # generates the same 160-bit digest, given the same data, in # forty hexadecimal characters. # # NTP delta #timestamp T Date of Change # 2272060800 10 # 1 Jan 1972 (MJD 41317) 2287785600 11 # 1 Jul 1972 (MJD 41499) 2303683200 12 # 1 Jan 1973 (MJD 41683) 2335219200 13 # 1 Jan 1974 (MJD 42048) 2366755200 14 # 1 Jan 1975 (MJD 42413) 2398291200 15 # 1 Jan 1976 (MJD 42778) 2429913600 16 # 1 Jan 1977 (MJD 43144) 2461449600 17 # 1 Jan 1978 (MJD 43509) 2492985600 18 # 1 Jan 1979 (MJD 43874) 2524521600 19 # 1 Jan 1980 (MJD 44239) 2571782400 20 # 1 Jul 1981 (MJD 44786) 2603318400 21 # 1 Jul 1982 (MJD 45151) 2634854400 22 # 1 Jul 1983 (MJD 45516) 2698012800 23 # 1 Jul 1985 (MJD 46247) 2776982400 24 # 1 Jan 1988 (MJD 47161) 2840140800 25 # 1 Jan 1990 (MJD 47892) 2871676800 26 # 1 Jan 1991 (MJD 48257) 2918937600 27 # 1 Jul 1992 (MJD 48804) 2950473600 28 # 1 Jul 1993 (MJD 49169) 2982009600 29 # 1 Jul 1994 (MJD 49534) 3029443200 30 # 1 Jan 1996 (MJD 50083) 3076704000 31 # 1 Jul 1997 (MJD 50630) 3124137600 32 # 1 Jan 1999 (MJD 51179) 3345062400 33 # 1 Jan 2006 (MJD 53736) 3439756800 34 # 1 Jan 2009 (MJD 54832) 3550089600 35 # 1 Jul 2012 (MJD 56109) 3644697600 36 # 1 Jul 2015 (MJD 57204) 3692217600 37 # 1 Jan 2017 (MJD 57754) # #h 85073416 421bdd85 47662775 e154160c 4f1a3070

1 0

Bulletin C 59
by Chris Woodbury Jan. 8, 2020

Jan. 8, 2020

Phoo, my pasteinig into my e-mail program munged the URL of where to find the IERS Bulletin A at NASA's Goldstone Space Flight Center. It's: ftp://cddis.gsfc.nasa.gov/pub/products/iers/ser7.dat

2 1

Bulletin C 59
by Chris Woodbury Jan. 7, 2020

Jan. 7, 2020

> Steve Allen sla at ucolick.org wrote on Tue Jan 7 20:15:38 UTC 2020 > In the middle of last year the Earth's crust accelerated such that we > were rotating faster than 200 years ago. The value of Delta T > decreased during a few weeks. The Length of Day (LoD), as Dr. Allen knows better than I, is effected by many factors. Having picked a length for the atomic SI second where 86,400 of them add up to a day shorter than the mean Solar day by milliseconds, we have been playing "catch up" since UTC was defined. The tides slowing down the crustal rotation, along with torque applied directly on the Earth oblate spheroid by Sol and other celestial bodies, along with other factors, change the rate at which the LoD changes. I have been fascinated by the fact that Bulletin A projections of UT1-UTC have put the point where it reaches -0.4 (which is typically when IERS inserts a leap-second) further and further into to future. Recently, every week, the MJD where it gets to -0.3 (currently at -0.29480 on 2021-01-01) gets a week farther away. It has been proposed that the latest oddities are caused by angular momentum being transferred from the Earth's rotating solid core to the liquid surround it, the semi-solid mantle and, finally, to the crust. Not something instantaneous by any means. My favorite thought on the matter involves wondering about conservation of angular momentum as megatons of ice, melting at altitude, unaffected by friction, flows down hill to (a rising) sea-level. Much of that ice is miles in the air.... lots of potential energy realized into actual rotation by a change of position. (Think of it as an spinning ice skater pulling in her/his arms.) Change of spin would be effected by closeness of the ice to the spin axis/poles as well as height of sea level at the equator. One more thing to worry about....

1 0

Hour 26? (was: Chaning time zone for Unix based tasks)
by Paul Gilmartin Jan. 7, 2020

Jan. 7, 2020

(cross-posting to tz and IBM-MAIN) Hi, TZData, On a Linux system, I see: 1043 $ uname -a Linux Bunsen5-PG 4.9.0-11-686-pae #1 SMP Debian 4.9.189-3+deb9u2 (2019-11-11) i686 GNU/Linux 1044 $ cat /usr/share/zoneinfo/Asia/Tel_Aviv | tail -1 IST-2IDT,M3.4.4/26,M10.5.0 1045 $ ... This would seem to be Month 3, Week 4, Day 4, hour 26. 26? Is that supposed to be 02:00 the next day? But POSIX says: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#ta… ... The hour shall be between zero and 24, and the minutes (and seconds) -if present-between zero and 59. The result of using values outside of this range is unspecified. z/OS (which supports only POSIX format) seems to ignore that TZ (as allowed by "unspecified") and use UTC0: https://www.ibm.com/support/knowledgecenter/en/SSLTBW_2.1.0/com.ibm.zos.v2r… (It doesn't specify.) Ouch! -- gil

3 4

Bulletin C 59
by Chris Woodbury Jan. 7, 2020

Jan. 7, 2020

Bulletin C 59 has been released on 2020-01-07 at 12:50:44 by IERS and there will be no leap-second in June 2020. There are also a new IERS leap-seconds list file (leap-seconds.3787382231) and Leap_Second.dat file (touched but unchanged). Visit ftp://hpiers.obspm.fr/iers/bul/bulc/ By all indications, there will be an unusually long interval before the next leap-second (July 2021 or later). See IERS Bulletin A at ftp://cddis.gsfc.nasa.gov/pub/products/iers/ser7.dat. (USNO's FTP sites are under construction.)

2 1

Fake UK news
by Lester Caine Dec. 31, 2019

Dec. 31, 2019

Or rather another proposal for changes to time zones that did not happen - SDST https://www.bbc.co.uk/news/uk-50950961 -- Lester Caine - G8HFL ----------------------------- Contact - https://lsces.uk/wiki/Contact L.S.Caine Electronic Services - https://lsces.uk Model Engineers Digital Workshop - https://medw.uk Rainbow Digital Media - https://rainbowdigitalmedia.uk

1 0

Timekeeping in the news
by Arthur David Olson Dec. 27, 2019

Dec. 27, 2019

"Boeing Starliner Ends Up In Wrong Orbit After Clock Problem." https://www.nytimes.com/2019/12/20/science/boeing-starliner-launch.html @dashdashado

7 9

[PATCH] * asia: Correct Hong Kong section name.
by Jimmy Yuen Ho Wong Dec. 19, 2019

Dec. 19, 2019

There are no records of Hong Kong being referred to as Xianggang, in the past or currently. The Pinyin romanization scheme of the Mandarin pronunciation of 香港 is not officially recognized or even mentioned in official documents. https://www.basiclaw.gov.hk/en/basiclawtext/chapter_1.html https://www.elegislation.gov.hk/hk/cap5 --- asia | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/asia b/asia index cca004f..4f19d14 100644 --- a/asia +++ b/asia @@ -572,7 +572,7 @@ Zone Asia/Urumqi 5:50:20 - LMT 1928 6:00 - +06 -# Hong Kong (Xianggang) +# Hong Kong # Milne gives 7:36:41.7; round this. -- 2.24.0

2 1