August 2011 - tz - lists.iana.org

Fingerprinting timezones
by Conrad Irwin Aug. 8, 2011

Aug. 8, 2011

Hello there, Thank you for the timezone database — it is a phenomenal resource. The problem I would like to solve is that of having to ask a user of a web-app for their timezone. While there is no way to directly query for the user's timezone, the javascript engine in their web-browser is capable of telling me the offset from UTC at any date. It seems like, by selecting some number of dates to query, I should be able to gather enough information to uniquely identify any given timezone (or at least make a very good guess for a large proportion of the user-base). Before I embarked on doing this, I wanted to ask if anyone has seen a similar attempt in the past? Are there some "gotchas" that mean that this isn't actually as feasible as I naïvely hope? Conrad

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America/Resolute
by Chris Walton Aug. 5, 2011

Aug. 5, 2011

Back in 2007 I initiated the creation of a new "zone file" for Resolute Bay. Resolute Bay is a small community located about 900km north of the Arctic Circle. The zone file was required because Resolute Bay had decided to use UTC-5 instead of UTC-6 for the winter of 2006-2007. http://www.nnsl.com/frames/newspapers/2006-11/nov13_06none.html According to new information which I received last week, Resolute Bay went back to using UTC-6 in the winter of 2007-2008. This new information conflicts with information I received in November 2008. Assuming the new information is correct, a change is required for "America/Resolute" Details are below. Sorry this post is so long. #---------------------------------------------------------- On March 11/2007 most of Canada went onto daylight saving. On March 14/2007 I phoned the Resolute Bay hamlet office to do a "time check". I talked to somebody that was both knowledgeable and helpful. I was able to confirm that Resolute Bay was still operating on UTC-5. It was explained to me that Resolute Bay had been on the Eastern Time zone (EST) in the winter, and was now back on the Central Time zone (CDT). i.e. the time zone had changed twice in the last year but the clocks had not moved. The residents had to know which time zone they were in so they could follow the correct TV schedule. #---------------------------------------------------------- I did not contact anybody in Resolute Bay for the next year and a half. #---------------------------------------------------------- On Nov 02/2008 most of Canada went onto standard time. On Nov 03/2008 I phoned the Resolute Bay hamlet office. I talked to a woman who had difficulty understanding anything I asked. She managed to tell me that Resolute Bay had changed to "Eastern Time" the day before. I don't recall any elaboration on what this meant. That was all I got out of the call. I don't remember whether or not I tried to do a "time check". I was left with the impression that Resolute Bay was still stuck on UTC-5 (EST in winter and CDT in summer). However, due to the challenging nature of the phone call, I decided to seek out an alternate source of information. I found an e-mail address for somebody by the name of Stephanie Adams whose job was listed as "Inns North Support Officer for Arctic Co-operatives". I was under the impression that Stephanie lived and worked in Resolute Bay. Note: I don't think this was same Stephanie Adams that appeared in the center of a well known U.S. based magazine. I sent an e-mail to Stephanie on Nov 03/2008. Stephanie forwarded my e-mail to somebody by the name of Silvano Cendou; I have no information on who Silvano is. On Nov 05/2008, Silvano responded with this: 'Hi Stephanie Resolute Bay did not turn their clocks back on Sunday! They kept the same time as they had proir to the change. Hope this helps you Silvano' Stephanie forwarded Silvano's e-mail back to me. The phone calls and the e-mails all pointed to the permanent use of UTC-5 with a "time zone change" twice a year. On Nov 13/2008 I sent a post to this mailing list; I stated that Resolute Bay was still using Eastern Standard Time in winter and Central Daylight Time in summer. #---------------------------------------------------------- I did not contact anybody in Resolute Bay for the next two and a half years. #---------------------------------------------------------- On March 14/2011 I phoned the hamlet office again. I was told that Resolute Bay had been using Central Standard Time over the winter of 2010-2011 and that the clocks had therefore been moved one hour ahead on March 13/2011. The person I talked to was aware that Resolute Bay had previously experimented with Eastern Standard Time but he could not tell me when the practice had stopped. #---------------------------------------------------------- On March 17/2011 I searched the Web to find an e-mail address of somebody that might be able to tell me exactly when Resolute Bay went off Eastern Standard Time. I stumbled on the name "Aziz Kheraj". Aziz used to be the mayor of Resolute Bay and he apparently owns half the businesses including "South Camp Inn". This website has some info on Aziz: http://www.uphere.ca/node/493 I sent Aziz an e-mail asking when Resolute Bay had stopped using Eastern Standard Time. Aziz responded quickly with this: 'hi, The time was not changed for the 1 year only, the following year, the community went back to the old way of " spring ahead-fall behind" currently we are zulu plus 5 hrs and in the winter Zulu plus 6 hrs' This of course conflicted with everything I had ascertained in November 2008. I sent Aziz a copy of my 2008 e-mail exchange with Stephanie. Aziz responded with this: 'Hi, Stephanie lives in Winnipeg. I live here, You may want to check with the weather office in Resolute Bay or do a search on the weather through Env. Canada. web site' #-------------------------------------------------------------- If I had realized the Stephanie did not live in Resolute Bay I would never have contacted her. I now believe that all the information I obtained in November 2008 should be ignored. Assuming Aziz is correct, America/Resolute needs some changes. I think it would be best to delete the "Resolute" rule, and then change "America/Resolute" to look like this: Zone America/Resolute 0 - zzz 1947 Aug 31 # Resolute founded -6:00 NT_YK C%sT 2000 Oct 29 2:00 -5:00 - EST 2001 Apr 1 3:00 -6:00 Canada C%sT 2006 Oct 29 2:00 -5:00 - EST 2007 Mar 11 3:00 -6:00 Canada C%sT The comments in zone.tab should be reverted back to: "Central Time - Resolute, Nunavut" I apologize for reporting incorrect information in 2008. -chris

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Pending changes to time of Newfoundland Time Zone for Daylight Savings Time
by Pelley, Michael Aug. 5, 2011

Aug. 5, 2011

Folks, The Government of Newfoundland and Labrador has pending changes to modify the hour for daylight savings time to come into effect in November 2011. This modification would change the time from 12:01AM to 2:00AM on the dates of the switches of Daylight Savings Time to/from Standard Time. As a matter of reference, in Canada provinces have the authority of setting time zone information. The legislation has passed our legislative body ("The House of Assembly") and is awaiting the proclamation to come into effect. You may find this information at: http://www.assembly.nl.ca/legislation/sr/lists/Proclamation.htm and search within that web page for "Standard Time (Amendment) Act". The Act may be found at: http://www.assembly.nl.ca/business/bills/Bill1106.htm We would appreciate if we could receive some guidance as to: * The official mechanism for implementing this change; * The timeframe for the implementation of the change within the TZ sources. Thank you. Cheers Mike ----------------------------------------------- MICHAEL PELLEY | Manager of Enterprise Architecture - Solution Delivery Office of the Chief Information Officer Executive Council Government of Newfoundland & Labrador P.O. Box 8700, 40 Higgins Line, St. John's NL A1B 4J6 709 729-7457 (t) | 709 729-6767 (f) | 709 690-2513 (c) | mpelley(a)gov.nl.ca <mailto:xxxxxxxxx@gov.nl.ca> “This email and any attached files are intended for the sole use of the primary and copied addressee(s) and may contain privileged and/or confidential information. Any distribution, use or copying by any means of this information is strictly prohibited. If you received this email in error, please delete it immediately and notify the sender.”

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