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lat/lon to time offset database
by Larry Ober Feb. 7, 2011

Feb. 7, 2011

I'm a nubie at understanding the ins and outs of timezones so please forgive me for my potentially dumb questions. I am looking at building a small embedded system (No OS) that will require determining the local time from the lat/lon of a location. So basically I need lat/lon to time offset from "GMT". I don't really need the geo political information like country or city. However it seems like tz is structured continent/country/city/... Now maybe I already have what I need but I just don't understand it. I have a copy of timezone.csv that seems to include data from country code to city etc. This seems to point to what looks like coordinate data that I don't understand. An example for America/New York seems to point to an area 115. There then seem to be multiple 115 entries like the following; 115, 3907893600, -18000, EST, 0 115, 3919388400, -14400, EDT, 1 My interpretation is that 115 is the area, the next column should be some sort of latitude, next seems to be called an offset in other contexts, next is the used name of the zone followed by a true/false bit. If this is basically true, I guess that what I don't understand it how to "parse" the latitude and how to use the longitude offset. Of course maybe I have this entirely wrong. I would appreciate any help on this basic issue. Regards Larry

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2011b
by Olson, Arthur David (NIH/NCI) [E] Feb. 7, 2011

Feb. 7, 2011

The files... ftp://elsie.nci.nih.gov/pub/tzcode2011b.tar.gz ...and... ftp://elsie.nci.nih.gov/pub/tzdata2011b.tar.gz ...are now available; these reflect the changes circulated recently on the time zone mailing list. I plan to try contacting someone on Annette Island on Wednesday regarding time there. --ado

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FW: "Etc\GMT" positive and negative
by Olson, Arthur David (NIH/NCI) [E] Feb. 4, 2011

Feb. 4, 2011

-----Original Message----- From: Olson, Arthur David (NIH/NCI) [E] Sent: Tuesday, February 01, 2011 12:26 To: 'tz(a)elsie.nci.nh.gov' Cc: 'Exis.rdiaz(a)iberia.es' Subject: FW: "Etc\GMT" positive and negative I'm forwarding this message from Rodrigo Díaz López, who is not on the time one mailing list. Those of you who are on the list, please direct replies appropriately. --ado From: EXIS.Diaz Lopez, Rodrigo [mailto:EXIS.rdiaz@iberia.es] Sent: Tuesday, February 01, 2011 12:25 To: tz(a)elsie.nci.nih.gov Subject: "Etc\GMT" positive and negative Hi: I think I found a bug with the "Etc\GMT" zones. If you use a "positive zone" like Etc\GMT+2 for calculate actual local time in this zone you obtain. local time for Etc\GMT-2 (¡a negative zone!). For instance, its' 5:00 PM (UTC/GMT), so in GMT+2 zone (Greece) the local time must be 7:00 PM. But, if you use TZ Database, you obtain. ¡3:00 PM! And the opposite for "negative zones". Is a bit funny. Please, check it. I found a web page (http://www.gsp.com/support/virtual/admin/unix/tz/gmt/) that use tz database (I think) and shows this error. Best regards. P.S.: It is possible that the problem was with the "codes", because in the world there are "GMT+13" and "GMT+14" zones, and these zones do not exist in tz database. However, in tz database exists "GMT-13" and "GMT-14" zones, that not exist in the real world. -- Rodrigo Díaz López EXIS.rdiaz(a)iberia.es IBERIA.com Tu viaje de principio a fin IBERIA.com Your journey from start to finish

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Bulletin C number 41
by IERS EOP Product Center Feb. 2, 2011

Feb. 2, 2011

INTERNATIONAL EARTH ROTATION AND REFERENCE SYSTEMS SERVICE (IERS) SERVICE INTERNATIONAL DE LA ROTATION TERRESTRE ET DES SYSTEMES DE REFERENCE SERVICE DE LA ROTATION TERRESTRE OBSERVATOIRE DE PARIS 61, Av. de l'Observatoire 75014 PARIS (France) Tel. : 33 (0) 1 40 51 22 29 FAX : 33 (0) 1 40 51 22 91 Internet : services.iers(a)obspm.fr Paris, 2 February 2011 Bulletin C 41 To authorities responsible for the measurement and distribution of time INFORMATION ON UTC - TAI NO positive leap second will be introduced at the end of June 2011. The difference between Coordinated Universal Time UTC and the International Atomic Time TAI is : from 2009 January 1, 0h UTC, until further notice : UTC-TAI = -34 s Leap seconds can be introduced in UTC at the end of the months of December or June, depending on the evolution of UT1-TAI. Bulletin C is mailed every six months, either to announce a time step in UTC, or to confirm that there will be no time step at the next possible date. Daniel GAMBIS Head Earth Orientation Center of the IERS Observatoire de Paris, France __________________________________________

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FW: [Meticulous] and well researched article on Alaska time zones
by Olson, Arthur David (NIH/NCI) [E] Feb. 2, 2011

Feb. 2, 2011

I'm forwarding this message from Steve Ferguson, who is not on the time zone mailing list. Those of you who are on the list, please direct replies appropriately. --ado From: Steve Ferguson [mailto:s_t_e_v_e_f@yahoo.com] Sent: Monday, January 31, 2011 1:50 To: tz(a)lecserver.nci.nih.gov Subject: [Meticulous] and well researched article on Alaska time zones The author lives in Alaska and many of the references listed are only available to Alaskan residents. http://www.alaskahistoricalsociety.org/index.cfm?section=discover%20alaska&…

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"Etc\GMT" positive and negative
by EXIS.Diaz Lopez, Rodrigo Feb. 1, 2011

Feb. 1, 2011

Hi: I think I found a bug with the "Etc\GMT" zones. If you use a "positive zone" like Etc\GMT+2 for calculate actual local time in this zone you obtain... local time for Etc\GMT-2 (¡a negative zone!). For instance, its' 5:00 PM (UTC/GMT), so in GMT+2 zone (Greece) the local time must be 7:00 PM. But, if you use TZ Database, you obtain... ¡3:00 PM! And the opposite for "negative zones". Is a bit funny. Please, check it. I found a web page (http://www.gsp.com/support/virtual/admin/unix/tz/gmt/) that use tz database (I think) and shows this error. Best regards. P.S.: It is possible that the problem was with the "codes", because in the world there are "GMT+13" and "GMT+14" zones, and these zones do not exist in tz database. However, in tz database exists "GMT-13" and "GMT-14" zones, that not exist in the real world. -- Rodrigo Díaz López EXIS.rdiaz(a)iberia.es<mailto:EXIS.rdiaz@iberia.es> IBERIA.com<http://www.iberia.com> Tu viaje de principio a fin IBERIA.com<http://www.iberia.com/?language=en> Your journey from start to finish

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Maticulous and well researched article on Alaska time zones
by Steve Ferguson Jan. 31, 2011

Jan. 31, 2011

The author lives in Alaska and many of the references listed are only available to Alaskan residents. http://www.alaskahistoricalsociety.org/index.cfm?section=discover%20alaska&…

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proposed time zone package changes (Mercer ND, Indonesian names, date.c overflow-proofing)
by Arthur David Olson Jan. 27, 2011

Jan. 27, 2011

Here are proposed changes to the time zone package; the executive summary: * date.c Replace "comptm" with "sametm" to avoid potential overflow (with code simplification as a side effect). * northamerica Add America/North_Dakota/Beulah (Mercer County, North Dakota, moved from Mountain to Central time at end of DST in 2010); use actual version number rather than "%W%". * zone.tab Add America/North_Dakota/Beulah (Mercer County, North Dakota, moved from Mountain to Central time at end of DST in 2010); update Indonesian location names (with old names retained in parentheses). The update to "northamerica" does affect current time stamps. There's more overflow work to do; the date.c work above is just the low-hanging fruit. For Indonesian locations I referred to... https://www.cia.gov/library/publications/the-world-factbook/graphics/ref_ma… ...and... https://www.cia.gov/library/publications/the-world-factbook/graphics/ref_ma… ...but note that the island labeled "Sulawesi (Celebes)" in "asia.pdf" is labeled "Celebes" in "oceania.pdf". (This paragraph may serves to notify the CIA of the problem:-) Also, the map at... http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=maluku&aq=&sll=… ...shows islands labeled "Maluku" and "Maluku Utara" and a sea labeled "Molucca Sea." If no problems are found, I'll update the ftp site on 2011-02-07. --ado diff -r -c old/date.c new/date.c *** old/date.c Thu Dec 16 12:24:43 2010 --- new/date.c Tue Jan 25 16:12:48 2011 *************** *** 1,6 **** #ifndef lint #ifndef NOID ! static char elsieid[] = "@(#)date.c 8.4"; /* ** Modified from the UCB version with the SCCS ID appearing below. */ --- 1,6 ---- #ifndef lint #ifndef NOID ! static char elsieid[] = "@(#)date.c 8.5"; /* ** Modified from the UCB version with the SCCS ID appearing below. */ *************** *** 76,82 **** static int retval = EXIT_SUCCESS; static void checkfinal(const char *, int, time_t, time_t); - static int comptm(const struct tm *, const struct tm *); static time_t convert(const char *, int, time_t); static void display(const char *); static void dogmt(void); --- 76,81 ---- *************** *** 86,91 **** --- 85,91 ---- static const char * nondigit(const char *); static void oops(const char *); static void reset(time_t, int); + static int sametm(const struct tm *, const struct tm *); static void timeout(FILE *, const char *, const struct tm *); static void usage(void); static void wildinput(const char *, const char *, *************** *** 594,612 **** } static int ! comptm(atmp, btmp) register const struct tm * const atmp; register const struct tm * const btmp; { ! register int result; ! ! if ((result = (atmp->tm_year - btmp->tm_year)) == 0 && ! (result = (atmp->tm_mon - btmp->tm_mon)) == 0 && ! (result = (atmp->tm_mday - btmp->tm_mday)) == 0 && ! (result = (atmp->tm_hour - btmp->tm_hour)) == 0 && ! (result = (atmp->tm_min - btmp->tm_min)) == 0) ! result = atmp->tm_sec - btmp->tm_sec; ! return result; } /* --- 594,609 ---- } static int ! sametm(atmp, btmp) register const struct tm * const atmp; register const struct tm * const btmp; { ! return atmp->tm_year == btmp->tm_year && ! atmp->tm_mon == btmp->tm_mon && ! atmp->tm_mday == btmp->tm_mday && ! atmp->tm_hour == btmp->tm_hour && ! atmp->tm_min == btmp->tm_min && ! atmp->tm_sec == btmp->tm_sec; } /* *************** *** 708,714 **** tm.tm_isdst = -1; outtm = tm; outt = mktime(&outtm); ! return (comptm(&tm, &outtm) == 0) ? outt : -1; } /* --- 705,711 ---- tm.tm_isdst = -1; outtm = tm; outt = mktime(&outtm); ! return sametm(&tm, &outtm) ? outt : -1; } /* *************** *** 746,752 **** othertm.tm_isdst = !tm.tm_isdst; othert = mktime(&othertm); if (othert != -1 && othertm.tm_isdst != tm.tm_isdst && ! comptm(&tm, &othertm) == 0) iffy(t, othert, value, _("both standard and summer time versions exist")); /* --- 743,749 ---- othertm.tm_isdst = !tm.tm_isdst; othert = mktime(&othertm); if (othert != -1 && othertm.tm_isdst != tm.tm_isdst && ! sametm(&tm, &othertm)) iffy(t, othert, value, _("both standard and summer time versions exist")); /* *************** *** 776,782 **** othert = t + 60 * offset; else othert = t - 60 * offset; othertm = *localtime(&othert); ! if (comptm(&tm, &othertm) == 0) iffy(t, othert, value, _("multiple matching times exist")); } --- 773,779 ---- othert = t + 60 * offset; else othert = t - 60 * offset; othertm = *localtime(&othert); ! if (sametm(&tm, &othertm)) iffy(t, othert, value, _("multiple matching times exist")); } diff -r -c old/northamerica new/northamerica *** old/northamerica Thu Jan 20 07:14:48 2011 --- new/northamerica Wed Jan 26 17:13:48 2011 *************** *** 1,5 **** # <pre> ! # %W% # This file is in the public domain, so clarified as of # 2009-05-17 by Arthur David Olson. --- 1,5 ---- # <pre> ! # @(#)northamerica 8.40 # This file is in the public domain, so clarified as of # 2009-05-17 by Arthur David Olson. *************** *** 346,351 **** --- 346,372 ---- -7:00 US M%sT 2003 Oct 26 02:00 -6:00 US C%sT + # From Josh Findley (2011-01-21): + # ...it appears that Mercer County, North Dakota, changed from the + # mountain time zone to the central time zone at the last transition from + # daylight-saving to standard time (on Nov. 7, 2010): + # <a href="http://www.gpo.gov/fdsys/pkg/FR-2010-09-29/html/2010-24376.htm"> + # http://www.gpo.gov/fdsys/pkg/FR-2010-09-29/html/2010-24376.htm + # </a> + # <a href="http://www.bismarcktribune.com/news/local/article_1eb1b588-c758-11df-b472-0…"> + # http://www.bismarcktribune.com/news/local/article_1eb1b588-c758-11df-b472-0… + # </a> + + # From Andy Lipscomb (2011-01-24): + # ...according to the Census Bureau, the largest city is Beulah (although + # it's commonly referred to as Beulah-Hazen, with Hazen being the next + # largest city in Mercer County). Google Maps places Beulah's city hall + # at 4715'51" north, 10146'40" west, which yields an offset 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 + -6:00 US C%sT + # US mountain time, represented by Denver # # Colorado, far western Kansas, Montana, western diff -r -c old/zone.tab new/zone.tab *** old/zone.tab Thu Dec 16 12:24:20 2010 --- new/zone.tab Wed Jan 26 18:47:09 2011 *************** *** 1,5 **** # <pre> ! # @(#)zone.tab 8.38 # This file is in the public domain, so clarified as of # 2009-05-17 by Arthur David Olson. # --- 1,5 ---- # <pre> ! # @(#)zone.tab 8.40 # This file is in the public domain, so clarified as of # 2009-05-17 by Arthur David Olson. # *************** *** 211,218 **** HU +4730+01905 Europe/Budapest ID -0610+10648 Asia/Jakarta Java & Sumatra ID -0002+10920 Asia/Pontianak west & central Borneo ! ID -0507+11924 Asia/Makassar east & south Borneo, Celebes, Bali, Nusa Tengarra, west Timor ! ID -0232+14042 Asia/Jayapura Irian Jaya & the Moluccas IE +5320-00615 Europe/Dublin IL +3146+03514 Asia/Jerusalem IM +5409-00428 Europe/Isle_of_Man --- 211,218 ---- HU +4730+01905 Europe/Budapest ID -0610+10648 Asia/Jakarta Java & Sumatra ID -0002+10920 Asia/Pontianak west & central Borneo ! ID -0507+11924 Asia/Makassar east & south Borneo, Sulawesi (Celebes), Bali, Nusa Tengarra, west Timor ! ID -0232+14042 Asia/Jayapura west New Guinea (Irian Jaya) & Malukus (Moluccas) IE +5320-00615 Europe/Dublin IL +3146+03514 Asia/Jerusalem IM +5409-00428 Europe/Isle_of_Man *************** *** 404,409 **** --- 404,410 ---- US +450628-0873651 America/Menominee Central Time - Michigan - Dickinson, Gogebic, Iron & Menominee Counties US +470659-1011757 America/North_Dakota/Center Central Time - North Dakota - Oliver County US +465042-1012439 America/North_Dakota/New_Salem Central Time - North Dakota - Morton County (except Mandan area) + US +471551-1014640 America/North_Dakota/Beulah Central Time - North Dakota - Mercer County US +394421-1045903 America/Denver Mountain Time US +433649-1161209 America/Boise Mountain Time - south Idaho & east Oregon US +364708-1084111 America/Shiprock Mountain Time - Navajo

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FW: Mercer County, N. D.
by Olson, Arthur David (NIH/NCI) [E] Jan. 24, 2011

Jan. 24, 2011

I'm forwarding this message from Josh Findley, who is not on the time zone mailing list. Those of you who are on the list, please direct replies appropriately. --ado -----Original Message----- From: Josh Findley [mailto:tz.4.jfindley@spamgourmet.com] Sent: Friday, January 21, 2011 6:05 To: tz(a)lecserver.nci.nih.gov Subject: Mercer County, N. D. In case you are not aware already, it appears that Mercer County, North Dakota, changed from the mountain time zone to the central time zone at the last transition from daylight-saving to standard time (on Nov. 7, 2010): http://www.gpo.gov/fdsys/pkg/FR-2010-09-29/html/2010-24376.htm http://www.bismarcktribune.com/news/local/article_1eb1b588-c758-11df-b472-0… Josh Findley

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FW: Archaic terms for Indonesian island groups
by Olson, Arthur David (NIH/NCI) [E] Jan. 24, 2011

Jan. 24, 2011

I'm forwarding this message from Alexander Ray, who is not on the time zone mailing list. Those of you who are on the list, please direct replies appropriately. --ado From: alexander.ray(a)internode.on.net [mailto:alexander.ray@internode.on.net] Sent: Saturday, January 22, 2011 2:20 To: tz(a)lecserver.nci.nih.gov Subject: Archaic terms for Indonesian island groups A Wikipedia user has brought it to my attention that some of the terms for Indonesian islands used in the database are incorrect, archaic forms. The listings should be as follows. ID -0610+10648 Asia/Jakarta Java & Sumatra ID -0002+10920 Asia/Pontianak west & central Borneo ! ID -0507+11924 Asia/Makassar east & south Borneo, Sulawesi, Bali, Nusa Tenggara, west Timor ! ID -0232+14042 Asia/Jayapura western New Guinea, Maluku islands

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