February 2011 - tz - lists.iana.org

C/C++ library that parses TZ data?
by Dario Teixeira Feb. 9, 2011

Feb. 9, 2011

Hi, I have a problem which is fairly common when one is running a web application that wishes to display timestamps localised towards each user's time zone. Basically, I need a function that takes as input a timestamp in UTC and a time zone specified in the Zoneinfo convention (ex: "Europe/Lisbon"), and returns the localised version of that timestamp, including a time zone abbreviation aware of daylight savings. Example: 2010-01-01 15:30, "Europe/Lisbon" -> 2010-01-01 15:30 WET 2010-01-01 15:30, "Europe/Paris" -> 2010-01-01 16:30 CET 2010-07-01 15:30, "Europe/Lisbon" -> 2010-07-01 16:30 WEST 2010-07-01 15:30, "Europe/Paris" -> 2010-07-01 17:30 CEST Since the zoneinfo data is present in every Unix system and glibc includes routines for parsing it, interfacing with glibc seemed the obvious solution. Unfortunately, glibc was not designed with this use case in mind. In fact, the glibc interface to zoneinfo can be described as "sui generis" if one is feeling charitable, or "insane" if truth must be told. Specifically, to obtain the localised version of a given timestamp, one must first set the 'TZ' environment variable with the target timezone, and then invoke 'localtime'. The abbreviated name of the timezone can be found in the global 'tzname' array: at position 'tzname[0]' if daylight savings are not in effect and at position 'tzname[1]' if they are. A quick search through glibc's bugzilla shows I'm not the only one to find this interface anachronistic [1], but it also reveals that it is unlikely to change. So, my question is if someone is aware of some alternative library in C or C++ that provides this same functionality, but is friendlier towards concurrent applications. Best regards, Dario Teixeira [1] http://sources.redhat.com/bugzilla/show_bug.cgi?id=11620

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2011a
by Olson, Arthur David (NIH/NCI) [E] Feb. 8, 2011

Feb. 8, 2011

The files... ftp://elsie.nci.nih.gov/pub/tzcode2011a.tar.gz ...and... ftp://elsie.nci.nih.gov/pub/tzdata2011a.tar.gz ...are now available; these reflect the changes circulated in the last two weeks on the time zone mailing list. --ado

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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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