- tz - lists.iana.org

Fun --- someone thinks there're only 24 timezones
by Bennett Todd Dec. 22, 2006

Dec. 22, 2006

<URL:http://archive.gulfnews.com/articles/06/11/30/10086170.html> (which I found via slashdot -> wired) describes a building, and mentions: [...] the company plans to build 23 more rotating towers in each of the world's time zones with finance provided by investors linked to the company. Maybe we should give 'em the bad news, they're gonna need a lot more than 23 more towers. One for that research station in the boonies of Australia? :-) -Bennett

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Re: Predictable problems with 3-character time zones, especially the EST/EST5EDT split.
by Paul Eggert Dec. 20, 2006

Dec. 20, 2006

John Stainforth <STAIN(a)uk.ibm.com> writes: > Our understanding is that: > > a) Before tzdata2005r... "EST" refers to the zone that is GMT-5 in Winter > and GMT-4 in Summer, then .... > b) Effective from tzdata2005r, "EST" refers only to some special area(s) > within the Eastern region that are GMT-5 all the year round. That sounds right as far as Java is concerned. But it's not a property of tzdata, it's a property of Java. As far as the tz database is concerned, TZ="EST" has never given you daylight-saving time. Here's the history. Before tzdata2005m, there was no TZ="EST" in the tz database. But we had a desire to support the old 1980s System V TZ names, "EST" being one of them, where "EST" was used in Indiana and meant eastern time with no daylight saving. I don't now recall why we were so focused on being backward-compatible with a long-dead system, but hey! we try hard to be backward-compatible. So, in tzdata2005m through tzdata2005q, TZ="EST" was implemented as an alias for America/Panama in the "backward" file, under the theory that Panama has observed UTC-5 since standard time was introduced in 1908. But this isn't satisfactory, as it mishandles time stamps before 1908, and maybe Panama will observe DST some day. So in tzdata2005r "EST" was given a zone in its own right, in the "northamerica" file. I suspect Java picked "EST" up only in 2005r because Java ignores the "backward" file. In retrospect perhaps we should have omitted these System V names, as they're now causing more trouble with Java than they're worth. Or perhaps we should move them to the "systemv" file now. But that is Arthur's call. >From the Java point of view, I would simply remove all the System V names from Java. I don't see the point of them; they just cause trouble. That is, I would pretend that the following entries don't exist in the "northamerica" file, so that you can continue with the traditional Java interpretation for them. # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone EST -5:00 - EST Zone MST -7:00 - MST Zone HST -10:00 - HST Zone EST5EDT -5:00 US E%sT Zone CST6CDT -6:00 US C%sT Zone MST7MDT -7:00 US M%sT Zone PST8PDT -8:00 US P%sT

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Re: Predictable problems with 3-character time zones, especially the EST/EST5EDT split.
by Paul Eggert Dec. 19, 2006

Dec. 19, 2006

John Stainforth <STAIN(a)uk.ibm.com> writes: > http://www-1.ibm.com/support/docview.wss?rs=3068&context=SSNVBF&uid=swg2125… Weird. That URL claims Indiana does not observe daylight saving time, but it does (starting this year). > http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6466476 which contains > the assertion: "This means that all legacy Applets and applications which > used EST before are now broken". This is all news to me. But it appears to be an issue with Java's old names for time zones, not with the Olson database per se. So you'll have to resolve it at the Java level. You might just want to do what Sun is doing in JDK 7, and add a compatibility mode flag. Set the flag one way, and you get the traditional Java behavior where "EST" means eastern time with daylight saving (did it really mean that? wow, that's confusing). Set the flag the other way, and "EST" means eastern time without daylight saving (which is the traditional real-world meaning in this country, and is the traditional Olson interpretation as well). Perhaps you can ask Sun exactly how that flag will work, and how it will affect "HST", "MST", "PST", etc. I'll CC: this message to the tz list to see whether others have noticed the problem.

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zone and offset designators
by LIVINGSTON Alex Dec. 19, 2006

Dec. 19, 2006

Original version sent 2006 December 09 23:22:04 GMT+11:00, but did not make it to list. I have modified it (including the subject) slightly since then. I am not in favour of alphabetic abbreviations as designators of time zones or time offsets. First, their role is not well defined. Do they apply to A: a geographic region and its entire time-offset history and future, B: a particular single offset from UTC/GMT, or C: a particular set of two or more offsets from UTC/GMT and "rules" describing when changes from one of these offsets to another occur? Second, there seems to be no requirement for them to be globally or historically unique. I would support designators of the following kinds: O-1: a numeric specification of a single offset from UTC/GMT (e.g. "-04:00") Z-1: a specification applying to a point on the earth's surface and indicating the entire history (and expected future history) of the time kept at that point by nearby human beings, as in the tz database (as I understand it) Actually, I might also consent to: O-1A: a numeric specification of two (or more) offsets from UTC/GMT that apply periodically (e.g. "+10:00/+11:00"), though preferably only if such a specifier is unique in the context it is used in (+10:00/+11:00 applies both to Tasmania and mainland southeast Australia, but the two regions change from +10:00 to +11:00 at different times at present, so using that label for a time-specification offset as things currently stand would not be ideal unless it were clear from the context which changeover dates and times applied) and Z-1A: a specification applying to a well-defined, invariant region of the earth's surface and indicating the entire history (and expected future history) of the time kept by human beings occupying that region In the headings I've used to name these types of designator, the "O" indicates applicability to offsets and "Z" indicates primary applicability to zones. However, a Z (zone) designator could also be applied to an offset, in which case it means the offset that applies in that zone (which in the case of Z-1 is a point, not a region). Type O-1 is by far the easiest to work with, and perfectly adequate for many single-instant specifications. Only if (1) a period of time (including possibly a single date) or a repeating scheduled event is to be specified for a particular geographic location or (2) the offset that will apply is not yet known with adequate certainty, as it is tied to yet-to-be-finalised conventions for a particular place, might a single offset not be up to the task. (Have I missed any?) If it is judged that a zone designator for a time specification cannot be avoided, we have the problem of what time is applicable for the period (an hour in the majority of cases) after clocks are retarded, when times that have already passed in the zone are repeated. My only suggestion of what to do about this is to establish a convention that, in the absence of indication to the contrary, the second occurrence of the time specified should be assumed. There is also, of course, the related problem of what to do if a time is specified that never occurs in a zone, because it is skipped over when clocks are advanced. What else could be done besides taking such a specification to mean the instant of the changeover? If some apparent standard or official abbreviated designator is not clear, a lot of effort seems to be put into crafting a "suitable" one for the field labelled (for reasons that aren't all that clear to me) "FORMAT" in the tzdata files. I get the impression that people derive a sense of security from the authority and credibility supposedly lent to time specifications by such labels. Only it is a false sense of security, I would contend. These abbreviations seem to be seized upon by implementors of time-management software as though "official" and indispensable and to be used wherever plausible. I would like to see such enthusiasm diverted to the use, instead, of far less ambiguous and far more informative and helpful designators (like type O-1 especially). I might also add my vehement objection to using numbers derived from time offsets to label zones when the offset indicated by the number does not always apply. An example of this is "EST5EDT". Using offsets to label zones seems from my experience to be almost standard practice in time-related software, but it is grossly misleading when, as is very often the case, the indicated offset simply does not apply for part, indeed sometimes the majority, of the year. If numeric designators of such zones _must_ be used, then _both_ (or all, should there ever be more than two) offsets should be indicated (with equal emphasis). I would, as well, completely avoid the use of the term "standard" to distinguish one of two (or more) offsets that apply in a given zone. It may sometimes be a designation given by a relevant authority, but it is by no means always used, and it is a very poor choice for a generic designation of the less advanced of two offsets that apply at a particular location, since it is far from clear that a standard exists from which the offset that applies could be unambiguously inferred. I think any attempt at pinning down a particular offset as "standard" for a place or region based on longitude should be abandoned. Exceptions - cases of times being kept that deviate considerably from what one would expect (if it is clear at all) given the longitude - are not rare but abundant. Let me list some: the Aleutians, Alaska, Argentina, the Azores, Iceland, Madeira, the Canary Islands, Spain and France, peninsula Malaysia and Singapore, central Australia, parts of far-eastern Russia, the Chatham Islands, and, of course, though not true of the zone as a whole, western China. The term "standard" is applicable to whatever offset is being observed: it is the standard set by those (in authority) observing it (and their subjects). I suggest the terms "basis" and "advanced" instead as generic distinguishers of the two offsets that are periodically observed at any particular location (the latter applying to the offset that is "ahead"), though "winter" and "summer" are also not bad, except that "summer" cannot be unambiguously abbreviated to "S". "Advanced" and "Basis" have the pleasing property of having initials "A" and "B", "A" time being ahead of "B" time. Should more than two offsets ever annually apply to a zone, subsequent letters of the alphabet could be used to distinguish them. I hope I haven't strayed into territory outside the purview of this list.

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Parliamentary Library research note on Australian DST
by Paul Eggert Dec. 16, 2006

Dec. 16, 2006

Last week the Parliamentary Library of Australia issued a research note on daylight saving time in Austrlia. <http://www.aph.gov.au/LIBRARY/Pubs/rn/2006-07/07rn13.pdf>. Of some note: "EST" is listed before "AEST", and similarly for "CST" and "WST", so this is some semiofficial sanction for the abbreviations the tz database uses. The note mentions Eucla time, giving Wikipedia as the reference! (So much for the Australian Parliament being authoritative on the subject of Australian time zones....) It has a strange copyright notice: Except to the extent of the uses permitted under the Copyright Act of 1968, no part of this publication may be reproduced or transmitted in any form or by any means including information storage and retrieval systems, without the prior written concent of the Department of Parliamentary Services, other than by senators and members of the Australian Parliemant in the course of their official duties. This makes it sound like I didn't have permission to download it off the net, but perhaps I should just ascribe this strange wording to hyperactive Australian copyright lawyers.

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Australia - Broken Hill - Yancowinna
by Oscar van Vlijmen Dec. 16, 2006

Dec. 16, 2006

Broken Hill, or more precise, the whole county of Yancowinna, differs from the rest of New South Wales, as clearly stated in the TZ database. Problem is: what is the "county of Yancowinna"? The Australian Standard Time Act 1987 mentions this county, but doesn't mention the county boundaries. Once they were known, but they have disappeared from recent maps. Finally I found a scan of an old map from the Land Registry, showing the Yancowinna county. Found on the website of The Sydney Morning Herald: <http://www.smh.com.au/articles/2003/08/29/1062050651816.html?oneclick=true> Click on field number 2 or download the map directly: <http://www.smh.com.au/specials/leases/pdf/map2.pdf> The following places are within the county boundaries: Broken Hill, The Gorge, Mount Gipps, Silverton, Stephens Creek, Wahratta, Yanco Glen. The name "Wahratta" is not perfectly readable from the map, but I've checked the name and location against the Australia file from the GEOnet Names Server <http://earth-info.nga.mil/gns/> Oscar van Vlijmen 2005-04-23

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RE: tz news from Galicia, Queensland and (of course) Indiana
by Phillip Guerra Dec. 14, 2006

Dec. 14, 2006

What a story! I wish the world would standardize, it would ease the technical issues with my time machine (The Vortal). I can't go back and forth in time for fear I'd land someplace in the moment when I shouldn't. Now, I have to just 'wing' it, and there have been a lot of close calls, I can tell you. I can also tell you that it won't happen any time soon. ;) -----Original Message----- From: Eric Muller [mailto:emuller@adobe.com] Sent: Tuesday, December 12, 2006 2:53 AM To: tz(a)lecserver.nci.nih.gov Cc: tz(a)lecserver.nci.nih.gov Subject: Re: tz news from Galicia, Queensland and (of course) Indiana Paul Eggert wrote: > The Budd Insurance Agency has a special clock with one minute hand but > two hour hands, one for each time zone: David Budd says that the clock > shows "Pulaski Time". > What about a clock with 12 hour hands and 4(?) minute hands (the "World Time" clock)? Eric. Confidentiality Notice: This email message, including any attachments, is for the sole use of the intended recipient(s), and may contain privileged or confidential information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by replying to this email, and destroy all copies of the original message.

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tz news from Galicia, Queensland and (of course) Indiana
by Paul Eggert Dec. 12, 2006

Dec. 12, 2006

The Galician nationalist party BNG voted on December 4 to move Galicia into the same time zone as Portugal and the UK. The other parties disagree, though. See <http://www.santiago-today.com/index.php?q=04-dec-2006-galician_nationalist_…> (2006-12-04). Queensland is considering holding a referendum on daylight saving early next year. The idea is that the southeast corner would observe DST. However, they haven't decided yet whether Toowoomba and half of Cooloola shire fall into that southeast corner. See <http://www.smh.com.au/news/National/Qld-to-study-daylight-saving-early-2007…>. The Democrats have regained control of the Indiana House and are pushing for a "nonbinding" referendum on daylight saving time for Indiana. Republicans seem firmly in the pro-daylight-saving camp. See Dan Shaw's story in the Journal and Courier <http://www.jconline.com/apps/pbcs.dll/article?AID=/20061109/ELECTION01/6110…>. Tom Wyatt of the Post-Tribune reports that the citizens of Pulaski county, Indiana have mostly voted with their feet for eastern time, and it's likely this will become official soon. Because the federal government threatened to cut off funds if the county did not observe central time while central time is official, government offices all observe central time. However, they've moved their hours to be consistent with eastern time. For example, the post office is now open 07:30/15:30 central time, whereas it used to be open 08:30/16:30. The school district observes eastern time but calls it "Commerce Time" so that they won't run afoul of the feds. Many businesses (e.g., the 1st Source Bank) use eastern time, but some (e.g., Ed's Barbershop) use central time. The Budd Insurance Agency has a special clock with one minute hand but two hour hands, one for each time zone: David Budd says that the clock shows "Pulaski Time". See <http://www.post-trib.com/news/150389,winamac.article> (2006-11-27).

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time-zone designators
by LIVINGSTON Alex Dec. 9, 2006

Dec. 9, 2006

I am not in favour of alphabetic abbreviations as designators of time zones. First, their role is not well defined. Do they apply to A: a geographic region and its entire time-offset history and future, B: a particular single offset from UTC/GMT, or C: a particular set of two or more offsets from UTC/GMT and "rules" describing when changes from one of these offsets to another occur? Second, there seems to be no requirement for them to be globally or historically unique. I would support two types of time-offset designation: 1: a numeric specification of a single offset from UTC/GMT (e.g. -04:00) 2: a specification applying to a point on the earth's surface and indicating the entire history (and expected future history) of the time kept at that point by nearby human beings, as in the tz database (as I understand it) Actually, I might also consent to: 1A: a numeric specification of two (or more) offsets from UTC/GMT that apply periodically (e.g. +10:00/11:00), though only if such a specifier is unique in the context it is used in (+10:00/+11:00 applies both to Tasmania and mainland southeast Australia, but the two regions change from +10:00 to +11:00 at different times at present, so using that label for a zone as things currently stand would not be on) 2A: a specification applying to a well-defined, invariant region of the earth's surface and indicating the entire history (and expected future history) of the time kept by human beings occupying that region Type 1 is by far the easiest to work with, and perfectly adequate for single-instant specifications. Only if, for a particular geographic location, a period of time (including possibly a single date) or a repeating scheduled event is to be specified might a single offset not be up to the task. If some apparent standard abbreviated designator is not clear, a lot of effort seems to be put into crafting a "suitable" one for the field labelled (for reasons that aren't all that clear to me) "FORMAT" in the tzdata files. I get the impression that people derive a sense of security from the authority and credibility supposedly lent to time specifications by such labels. Only it is a false sense of security, I would contend. These abbreviations seem to be seized upon by implementors of time-management software as though "official" and indispensable and to be appended enthusiastically to time specifications. I would like to see such enthusiasm diverted to the use, instead, of far less ambiguous and far more informative and helpful designators (like type 1 especially). (I realise now that I have somewhat conflated time zones with time specifications. I don't think my comments are affected that much by this.) I hope I haven't strayed into territory outside the purview of this list.

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FW: time in southeastern Western Australia
by Olson, Arthur David (NIH/NCI) [E] Dec. 8, 2006

Dec. 8, 2006

I'm forwarding this message from Alex Livingston who, since sending it, has subscribed to the time zone mailing list. --ado -----Original Message----- From: LIVINGSTON Alex [mailto:lial@mac.com] Sent: Friday, December 08, 2006 1:03 AM To: tz(a)lecserver.nci.nih.gov Subject: re: time in southeastern Western Australia Further to my previous message, here is a link to a picture of the sign I referred to: http://www.confluence.org/photo.php?visitid=10280&pic=7 It shows that my memory did not serve me perfectly.

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