- tz - lists.iana.org

RE: Possible TZ Data Errors with every 1st / 2nd / 3rd Xday of the month
by Andy Lipscomb June 1, 2006

June 1, 2006

No, in that case at least, the data is correct. The second Saturday of a month can be between the 8th and the 14th, inclusive; this year, the second Saturday of October is the 14th. Since the changeover occurs at 24:00 on that Saturday and Unix doesn't like 24:00, it is coded as 0:00 the following day, which is the 15th this year, and in general can run from the 9th to the 15th. Thus, Sun>=9 is correct. (This is not the "second Sunday," but the "Sunday after the second Saturday." USA readers will see the resemblance to Election Day.) ________________________________ From: Dr Hingston [mailto:dr.hingston@paradise.net.nz] Sent: Wed 31 May 2006 04:31 To: tz(a)lecserver.nci.nih.gov Subject: Possible TZ Data Errors with every 1st / 2nd / 3rd Xday of the month Dear List Members Woops, seems I got the address wrong, my apologies! I hope this is better! Regarding: Rule Chile 1999 max - Oct Sun>=9 4:00u 1:00 S Rule Chile 2000 max - Mar Sun>=9 3:00u 0 - The expression Sun>=9 from the above rules would appear to me to be incorrect, as it suggests the third Sunday in some years. e.g. October this year. Summary: Supreme Decree Number 1,489 (6 October 1970) - This law, enacted during the presidency of Eduardo Frei Montalva, declared that Daylight Saving Time will advance clocks by one hour, beginning the second Saturday of October, and ending the second Saturday of March. Chilean time is administered by the Chilean Navy's Hydrographic and Oceanographic Service (SHOA). On discussion with the Chilean Consulate the above is confirmed, and time for changeover is midnight Saturday (I take to mean 00:00 Sunday)

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Possible TZ Data Errors with every 1st / 2nd / 3rd Xday of the month
by Dr Hingston May 31, 2006

May 31, 2006

Dear List Members Woops, seems I got the address wrong, my apologies! I hope this is better! Regarding: Rule Chile 1999 max - Oct Sun>=9 4:00u 1:00 S Rule Chile 2000 max - Mar Sun>=9 3:00u 0 - The expression Sun>=9 from the above rules would appear to me to be incorrect, as it suggests the third Sunday in some years. e.g. October this year. References: http://www.twinsun.com/tz/tz-link.ht (!) which lists: http://webexhibits.org/daylightsaving/chile.html Summary: Supreme Decree Number 1,489 (6 October 1970) - This law, enacted during the presidency of Eduardo Frei Montalva, declared that Daylight Saving Time will advance clocks by one hour, beginning the second Saturday of October, and ending the second Saturday of March. Chilean time is administered by the Chilean Navy's Hydrographic and Oceanographic Service (SHOA). On discussion with the Chilean Consulate the above is confirmed, and time for changeover is midnight Saturday (I take to mean 00:00 Sunday) It would seem to be correct, to me, if it were stated as Sun>=8. Similarly, if I am correct, then there are quite a number of other instances in the database where the expression Sun>=9 perhaps might be more correctly stated as Sun>=8? Extrapolating further, if I may, some of the other instances may also be incorrect, e.g. Sun>=16 etc. Some examples: Rule ChileAQ 1966 1997 - Oct Sun>=9 0:00 1:00 S Rule Belize 1919 1943 - Feb Sun>=9 0:00 0 S Rule Falk 1985 2000 - Sep Sun>=9 0:00 1:00 S Rule Falk 1986 2000 - Apr Sun>=16 0:00 0 - Rule GB-Eire 1945 1946 - Oct Sun>=2 2:00s 0 GMT Rule GB-Eire 1946 only - Apr Sun>=9 2:00s 1:00 BST Where a week day is stipulated as the Xth day of the month then I believe the correct references should be >=1, >=8, >= 15, >= 22 etc. Therefore I question other numbers, of course they may be correct, however this does seem to suggest careful scrutiny of those numbers is indicated. I'd be grateful for list consideration and comment please. Kind regards David Hingston

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Tzcode2006g.tar.gz and tzdata2006g.tar.gz
by Olson, Arthur David (NIH/NCI) [E] May 31, 2006

May 31, 2006

The files... ftp://elsie.nci.nih.gov/pub/tzcode2006g.tar.gz ...and... ftp://elsie.nci.nih.gov/pub/tzdata2006g.tar.gz ...are now available; these reflect the northamerica changes circulated last week on the time zone mailing list by Paul Eggert. --ado

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FW: Corrections to latitudes/longitudes in zone.tab
by Olson, Arthur David (NIH/NCI) [E] May 31, 2006

May 31, 2006

Andy McDonald is not on the time zone mailing list; direct replies appropriately. --ado -----Original Message----- From: Andy McDonald [mailto:andy@stemhaus.com] Sent: Tuesday, May 23, 2006 12:28 AM To: tz(a)lecserver.nci.nih.gov Subject: Corrections to latitudes/longitudes in zone.tab Hi, A very very minor point, but I've run across a few inaccurate latitudes/longitudes in tz's zone.tab (2006g and earlier): Corrected lat/long zone.tab lat/long America/Argentina/Tucuman: -0265000, -0651300 -0312400, -0641100 America/Inuvik: +0682200, -1334400 +0682500, -1133000 America/Rainy_River: +0484300, -0943400 +0484300, -0942900 America/Rankin_Inlet +0624800, -0920500 +0624500, -0921000 America/Scoresbysund: +0703000, -0215800 +0703000, -0221500 (Tucuman's latitude and longitude in zone.tab are those of America/Argentina/Cordoba.) The corrected values come from playing with my Firefox extension (http://www.stemhaus.com/firefox/foxclocks/) and Google Earth, and are of course entirely subjective. Regards, Andy McDonald

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Manpage License question
by Martin Schulze May 30, 2006

May 30, 2006

Hi, the man-pages package for GNU/Linux has incorporated some of the tz manpages that are also distributed in tzcode$year.tar.gz, namely zic.8, zdump.8 and tzselect.8. They lack a copyright notice and a license statement. The tzcode2006g.tar.gz lacks this information as well. What license are these pages distributed under? I assume it's the BSD license, but I'd better ask. Please keep Michael Kerrisk copied who is the current man-pages maintainer, I'm just the Debian downstream. Thanks and kind regards, Joey -- Never trust an operating system you don't have source for!

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Another Windows program that uses the TZ database
by ActiveEarth Sales May 26, 2006

May 26, 2006

Dear tz Contributors, My world time clock software, ActiveEarth, also uses the tz database. Would you add a mention of that to your web page? You can see the software here: http://www.activeearth.com <http://www.activeearth.com/> . There is a new release about to come out that will contain the latest tz data. Thank you so much for this excellent resource! Best regards, Thaine Norris President Norris Family Industry

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new ISO 3166-1 entries
by Chuck Soper May 25, 2006

May 25, 2006

I recently read ISO 3166-1 Newsletter No. V-11 (2006-03-29) and noticed three new ISO 3166-1 entries: GUERNSEY; GG ISLE OF MAN;IM JERSEY;JE I found this rule in the Theory file: Include at least one location per time zone rule set per country. One such location is enough. Use ISO 3166 (see the file iso3166.tab) to help decide whether something is a country. However, uninhabited ISO 3166 regions like Bouvet Island do not need locations, since local time is not defined there. For tzdata, should all populated ISO 3166 regions be included? Does this mean that three new TZ zone descriptions should be added to zone.tab and appropriate data files? Or, should Europe/London be used instead? Should iso3166.tab be updated? Chuck

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C#/.NET tz binary reader ...
by Zbigniew Babiej May 24, 2006

May 24, 2006

Dear Sir or Madam, Recently I have posted the C#/.NET version of tz binary reader at http://www.gotdotnet.com/Community/UserSamples/Details.aspx?SampleGuid=0 C9E8F33-7214-4222-B992-D248D107652F I thought that it would be good idea to share this link on your page as well.... Best Regards, Z. Babiej, MarketXS ______________________________ DISCLAIMER: This e-mail message is intended for the addressee(s) or authorized recipient only. If you are not the addressee, or an authorized recipient, you are specifically advised that any use, distribution, publication, copying or repetition of this information is prohibited. If you have received this information in error, please notify us immediately (+31 (0)20 50 25 800) and destroy this message.

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RE: tz list searchable on Google
by Olson, Arthur David (NIH/NCI) [E] May 23, 2006

May 23, 2006

I'm also worried about spam; that's why electronic mail addresses have been purged from the time zone distribution (and most especially from the source data files such as "northamerica" which end up on millions of computers worldwide). The gmane site's archive of stuff that's gone out on the time zone mailing list extends back to July 2004; has tz-linked spam been seen since then? And...if the gmane mailing list archive is a bad thing, is the elsie ftpable mailing list archive also a bad thing (or is security through difficulty of use sufficient)? --ado

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FW: timezones offset from what?
by Olson, Arthur David (NIH/NCI) [E] May 23, 2006

May 23, 2006

Zefram is not on the time zone mailing list; direct replies appropriately. --ado -----Original Message----- From: Zefram [mailto:zefram@fysh.org] Sent: Friday, May 19, 2006 12:30 PM To: tz(a)lecserver.nci.nih.gov Subject: timezones offset from what? I've been doing work on precision timekeeping on computer systems. Naturally I don't use timezones at all inside that code, but there are places where I need to apply timezones when presenting a time to non-specialist humans. Looking through the zoneinfo database and the theory written about it, it struck me that although it deals fantastically with what time offset to use, there's no rigorous treatment of what base time scale to apply the offset to. Then it struck me that a simple treatment of this could solve a couple of other issues with the database. An example of this issue: as the zoneinfo source notes, UK legal time is currently based on mean solar time on the Greenwich meridian. Now that's not even Universal Time any more, since the prime meridian moved (slightly) off the Greenwich meridian. But everyone in the UK in practice sets their clocks based on UTC, as promulgated by the NPL and the BBC. At centisecond timescales, GMT (legal time in the UK), UTC (used in practice), UT1 (which UTC tracks in the long term), and UT2 (used for civil time in the 1950s) are all quite distinct. So I have a suggestion: it would be nice if the zoneinfo database included a field identifying exactly which time scale to apply the offsets to. The database doesn't need to understand how the time scales relate to each other; leave that to the precision horologists. All it needs is a short text string, with values such as "UTC", "UT1", "GMT". Of course, in a lot of cases this information is unavailable, or the distinction wasn't being made, so you'd then give "UT" to be explicitly ambiguous about the exact flavour of Universal Time. This field would also allow the database to handle timezones that are based on something other than UT. Currently the data files for Saudi Arabia attempt to describe apparent solar time in terms of UT, by means of a daily offset change. But it could instead be specified as a fixed offset with a base of apparent solar time on the prime meridian. To understand the zone properly the code would need to calculate the equation of time, but that only needs to be implemented once and it would give a much smoother and more accurate result than the daily UT offset changes do. A system that doesn't do the equation of time would effectively fall back to mean solar time, which is what the Riyadh8X zones do anyway. It's also a way to handle Mars time. Just specify the base to be MTC instead of UT. Ta da. What do you think? -zefram

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