- tz - lists.iana.org

America/Creston
by Chris Walton Dec. 2, 2011

Dec. 2, 2011

There are two areas within the Canadian province of British Columbia that do not currently observe daylight saving: a) The Creston Valley (includes the town of Creston and surrounding area) b) The eastern half of the Peace River Regional District (includes the cities of Dawson Creek and Fort St. John) Creston does not have a dedicated zone file; it is assumed that residents of Creston should use "America/Dawson_Creek". This assumption can be inferred from a comment that is currently embedded in the tz database's northamerica file; the comment reads: "Matthews and Vincent (1998) write that Creston is like Dawson Creek.". Earlier this year I stumbled across a detailed article about the time keeping history of Creston; it was written by Tammy Hardwick who is the manager of the Creston & District Museum. The article was written in May 2009. http://www.ilovecreston.com/?p=articles&t=spec&ar=260 According to the article, Creston has not changed its clocks since June 1918. i.e. Creston has been stuck on UTC-7 for 93 years. Dawson Creek, on the other hand, changed its clocks as recently as April 1972 (as is correctly reflected in the current tz database). The current tz rules state that a separate zone file should be created for regions that differ after 1970. So... I am proposing the addition of "America/Creston" to the database. Unfortunately the exact date for the time change in June 1918 remains unknown and will be difficult to ascertain. I e-mailed Tammy a few months ago to ask if Sunday June 2 was a reasonable guess. She said it was just as plausible as any other date (in June). She also said that after writing the article she had discovered another time change in 1916; this is the subject of another article which she wrote in October 2010. http://www.creston.museum.bc.ca/index.php?module=comments&uop=view_comment&… Here is a summary of the three clock change events in Creston's history: 1. 1884 or 1885: adoption of Mountain Standard Time (GMT-7) # Exact date unknown 2. Oct 1916: switch to Pacific Standard Time (GMT-8) # Exact date in October unknown; Sunday October 1 is a reasonable guess. 3. June 1918: switch to Pacific Daylight Time (GMT-7) # Exact date in June unknown; Sunday June 2 is a reasonable guess. note#1: On Oct 27/1918 when daylight saving ended in the rest of Canada, Creston did not change its clocks. By not changing the clocks, Creston had effectively transitioned itself back to Mountain Standard Time. note#2: During WWII when the Federal Government legislated a mandatory clock change, Creston did not oblige. Creston was able to claim that it had moved itself back to the Pacific Time Zone and could observe daylight saving (Pacific War Time) without changing the clocks. After the war, Creston conveniently moved itself back to Mountain Standard Time, again with no change to the clocks. note#3: There is no guarantee that Creston will remain on Mountain Standard Time (UTC-7) forever. The subject was debated at least once this year by the town Council. http://www.bclocalnews.com/kootenay_rockies/crestonvalleyadvance/news/11676… Here is a proposed zone entry for the northamerica file: # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone America/Creston -7:46:04 - LMT 1884 -7:00 - MST 1916 Oct 1 -8:00 - PST 1918 Jun 2 -8:00 1:00 PDT 1918 Oct 27 2:00 -7:00 - MST 1942 Feb 9 2:00 -8:00 Canada P%sT 1945 Sep 30 2:00 -7:00 - MST Alternatively the dates in Oct 1916 and June 1918 could be omitted since we don't know what they are; this would cause zic to default to Oct 1/1916 and June 1/1918. # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone America/Creston -7:46:04 - LMT 1884 -7:00 - MST 1916 Oct -8:00 - PST 1918 Jun -8:00 1:00 PDT 1918 Oct 27 2:00 -7:00 - MST 1942 Feb 9 2:00 -8:00 Canada P%sT 1945 Sep 30 2:00 -7:00 - MST Note the use of the Canada rule in 1942 results in the use of "PWT(pacific war time)" and "PPT(pacific peace time)". The zone.tab entry should look like this: CA +4906-11631 America/Creston Mountain Standard Time - Creston, British Columbia # # # # # # And now one last tidbit: In the first of Tammy's articles she quotes the Friday November 1/1918 edition of the Creston Review. The quote includes these two statements: 'Sunday the CPR went back to the old system of time...' '... The daylight saving scheme was dropped all over Canada at the same time,' These statements refer to a transition from daylight time to standard time that occurred nationally on Sunday October 27/1918. This transition was also documented in the Saturday October 26/1918 edition of the Toronto Star. The Toronto Star articles reads as follows: 'BACK TO OLD TIME - Canada Returns to Orthodox Measurement of Time To-morrow Morning. Ottawa, Oct. 26.---"Daylight saving" comes to an end Sunday morning, October 27, at 2 o'clock, when Canada returns to the orthodox measurement of time. Either the simple ceremony of stopping the clock for an hour or sliding the hands forward 11 hours should be carried out. To turn the hands back would be to injure its mechanism.' My reason for providing these two references to the October 27/1918 transition, is that the tz database currently defines it as being on Thursday October 31 instead of Sunday November 27. This is an error that presumably needs to be corrected in the rules for "Canada", "Regina", "Vanc", "Winn", and "Edm". -chris

1 1

Fiji DST 2011/12 change (again)
by Ken Rylander Nov. 29, 2011

Nov. 29, 2011

Hi, Another change to the Fiji DST end date. In the TZ database the end date for Fiji DST 2012, is currently Feb 26. This has been changed to Jan 22. >From www.fiji.gov.fj:<http://www.fiji.gov.fj:> Amendments to daylight savings Ministry of Information Oct 17 |13:59 pm The end of daylight saving scheduled initially for the 26th of February 2012 has been brought forward to the 22nd of January 2012. The commencement of daylight saving will remain unchanged and start on the 23rd of October, 2011. An official gazette reflecting this change will be released early this week. -ends- http://www.fiji.gov.fj/index.php?option=com_content&view=article&id=5017:am… Please add to next tz update. Cheers, /Ken ________________________________ Notice of Confidentiality: The information contained in this communication is intended solely for the use of the individual or entity to whom it is addressed and others authorized to receive it. It may contain confidential or legally privileged information. If you are not the intended recipient you are hereby notified that any disclosure, copying, distribution or taking any action in reliance on the contents of this information is strictly prohibited and may be unlawful. If you have received this communication in error, please notify us immediately by responding to this email and then delete it from your system.

4 7

Reading binary files
by Thom Hehl Nov. 17, 2011

Nov. 17, 2011

OK, I give up. I've tried looking at the source code and it's hopeless. Can someone please explain to me how to read the binary files and turn it into timezone information? All I need to do is write a function that will take a UTC date and convert it into a timezone with a name that I specify and convert it back again. (I understand there are precision issues with the last one.) The code is not commented and I can find no documents. Please, I beg you, help me.

7 9

U.S. abbreviations in 1942
by Garrett Wollman Nov. 15, 2011

Nov. 15, 2011

The U.S. went on permanent DST for the duration of World War II starting on February 9, 1942. The following quotation from /Broadcasting/ magazine of 1942-02-02 sheds some more light on abbreviations used in the U.S. during the early 1940s: : At present, times for network programs are nationally released in : accordance with their broadcasts on the East Coast and are labelled : EST. In previous years, during the months that daylight saving time : was in effect in certain parts of the country, including New York, : the designation was changed to EDST for that period. : [... T]he MBS publicity department stated that it will follow the : custom of other years and label program times as EDST. NBC said : that [...] Red Netowrk programs would be shown as EST after Feb. 9. : [...] CBS has announced that "concurrent with national daylight : saving beginning Feb. 9, Columbia network's time designation on news : releaess is Eastern Time. This phrase was chosen because the time : is no longer standard and because, with national daylight saving, : EDST seems unessential." -GAWollman

1 0

Barnaby
by Thom Hehl Nov. 9, 2011

Nov. 9, 2011

OK, first pass of http://code.google.com/p/barnaby is available for download of the source. This is a C++ library with two functions: 1) List all of the timezones 2) For a given timezone name, convert UTC to that timezone It will build a DLL for you if you open the project using Visual C++. The timezone data is only version 2011i, so I will need to update it soon. Please let me know any and all feedback. Blessings!

5 7

FW: Barnaby
by Thom Hehl Nov. 8, 2011

Nov. 8, 2011

>You're using zone.tab as a canonical list of timezones, which it isn't. >zone.tab is only useful for selecting timezones via countries; for a >list of all timezones you can serve you should just look at the tzfiles. Did you read the readme? That is the next thing I'm going to fix. >Your usage of time_t is not appropriate. The type you want there is >dictated by the tzfile format, not by libc. The API needs to use time_t, so the usage is dictated by the use case, not by the tzfile, which is why it's appropriate. >You're doing a linear search (in transitionTimesIndex) that should really >be a binary search. Yeah, that can be optimized. The problem with doing a binary search is that you're not looking for an equal condition, but the smallest gap the thing you're looking for fits into. I'm aware that a binary search would improve performance some, but didn't devote time to it yet. Again, this is a beta drop designed to get the job done so I can move on with other priorities that pay money. :) >Overall it looks like you're interpreting (the 32-bit part of) the tzfile >correctly, but I find the code too messy to be sure. >You have some instance methods that should be class methods ("static"). >There is much else that is poor about your object model, but that's all >off topic for this list. Feel free to email me off list as you please for any improvements you might suggest. As I indicated in the read-me there is much room for improvement, but this meets my current needs. Open source is all about refining code over iterations, right? Whatever changes you'd like to suggest will be re-visited when I get some time to come back and work on this more. Thanks for the excellent feedback. -----Original Message----- From: Zefram [mailto:zefram@fysh.org] Sent: Tuesday, November 08, 2011 12:44 PM To: Thom Hehl Cc: tz(a)iana.org Subject: Re: [tz] Barnaby Thom Hehl wrote: >http://code.google.com/p/barnaby You're using zone.tab as a canonical list of timezones, which it isn't. zone.tab is only useful for selecting timezones via countries; for a list of all timezones you can serve you should just look at the tzfiles. Your usage of time_t is not appropriate. The type you want there is dictated by the tzfile format, not by libc. You're doing a linear search (in transitionTimesIndex) that should really be a binary search. Overall it looks like you're interpreting (the 32-bit part of) the tzfile correctly, but I find the code too messy to be sure. You have some instance methods that should be class methods ("static"). There is much else that is poor about your object model, but that's all off topic for this list. -zefram

1 0

Decoding timezone data
by Thom Hehl Nov. 8, 2011

Nov. 8, 2011

OK, so I'm making some progress on my library. I'm attempting to read the timezone information for America/Kentucky/Louisville. When I run through the values for transition times, I get 177 values such as follows: 2661690496, 2693140096, 2759063296, ... The docs say these transition times are in values returned by the c time function, which returns seconds since midnight, 1/1/1970. If that is the case, then the three values above convert to: May 6, 2054 at 2:28:16 PM May 5, 2055 at 2:28:16 PM June 6, 2057 at 2:28:16 PM These are nowhere near the DST conversion dates for these years and are moving forward. This appears incorrect. Can someone show me what I'm doing wrong? Thanks.

5 8

"Standard byte order"
by Thom Hehl Nov. 8, 2011

Nov. 8, 2011

I'm assuming that "Standard byte order" referred to over and over in the docs means Most Significant Byte first? It should really be documented that way. As far as I know, there is no standard byte order.

9 15

Re: [tz] Australian time zone abbreviations
by Shaun Bouckaert Nov. 8, 2011

Nov. 8, 2011

On 6 November 2011 20:51, Eric Ulevik <eulevik(a)gmail.com> wrote: > On Sun, Nov 6, 2011 at 9:20 PM, Shaun Bouckaert > <shaun.bouckaert(a)gmail.com> wrote: > [snip]> http://australia.gov.au/about-australia/our-country/time > [snip]> I believe that the abbreviations used on the federal > government> website should be used. > Time zones in Australia are legislated by acts of state governments, > not the federal government. The acts mostly refer to "summer time" and > "standard time". > > Eg. South Australia: > http://www.austlii.edu.au/au/legis/sa/consol_act/dsa1971165/ > > Regards, > > Eric Ulevik > In the absence of any specific mention in the state legislation of an appropriate abbreviation, and considering the timezones and their abbreviations span multiple states, I see no reason why federal government documentation on the matter shouldn't be recognised, especially considering the only basis for the current system is a couple of AltaVista searches and the opinion of Australian's on the list at the time. Shaun Bouckaert

4 5

Russian TZ Samara has no offset listed since 2010g
by manprsi2 Nov. 7, 2011

Nov. 7, 2011

Hello, Europe/Samara has the follow zone.tab definition since 2010g (no offset listed) RU +5312+05009 Europe/Samara Moscow - Samara, Udmurtia It used to be RU +5312+05009 Europe/Samara Moscow+01 - Samara, Udmurtia Samara changed to Moscow but all the other regions are listed with an offset even if +00 (Volgograd, Moscow) while Samara is not. I can not tell by searching the mail archive if the change this way was intentional or not? Thanks - Manpreet

2 2