March 1997 - tz - lists.iana.org

Commentary on time zone policy
by Chris Carrier March 25, 1997

March 25, 1997

I wrote: >>The current list is divided many ways as to what relationship local mean >>time (LMT) should have to local clock time (LCT). ... Nathan Myers > INTERNET:ncm@cantrip.org wrote: >... And all such divisions are completely irrelevant, because nobody who >decides about time zone law reads this list. You do not know that to be a fact, and if some of the more active people on this list have their way, persons in positions to make such decisions will be using this as a resource base. >Please take your opinions about national time zone policies someplace where >they will make a difference. I don't see anything wrong with including commentary on various actual and proposed changes. It is within the scope of this list, or at least not totally irrelevant to time zoning. That I voted for candidate X because I liked his stand on non-time-zone issue Y is irrelevant to this list; opinions on time zoning issues are not, have come from more people than just myself, (you may note that I was replying to another proposal in my post) and are, AFAIK, welcome from the people who run this list. Chris Carrier

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Re: DST switching dates
by ncm＠cantrip.org March 22, 1997

March 22, 1997

> Nathan Myers > INTERNET:ncm@cantrip.org wrote: > > >Clearly the only sensible approach to time would be [something] > > ... However, it's a > >waste of everybody's time and attention to discuss this here. We techies > >are constrained to chase after whatever foolish decisions are made in the > >parliaments and politburos of world. This list is about details of that > >chase. From: Chris Carrier <72157.3334(a)CompuServe.COM> > The current list is divided many ways as to what relationship local mean > time (LMT) should have to local clock time (LCT). ... ... And all such divisions are completely irrelevant, because nobody who decides about time zone law reads this list. Please take your opinions about national time zone policies someplace where they will make a difference. Nathan Myers ncm(a)cantrip.org

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DST switching dates
by Chris Carrier March 22, 1997

March 22, 1997

Nathan Myers > INTERNET:ncm@cantrip.org wrote: >Clearly the only sensible approach to time would be to leave the damn >clocks alone, and change schedules to match reality. However, it's a >waste of everybody's time and attention to discuss this here. We techies >are constrained to chase after whatever foolish decisions are made in the >parliaments and politburos of world. This list is about details of that >chase. >Maybe there should be another list to help discover strategies to influence >idiot politicians. I hope that those of you who are interested in the idea >will create that list, instead of using this one. The current list is divided many ways as to what relationship local mean time (LMT) should have to local clock time (LCT). One the one hand we have persons like yourself who advocate standard time throughout the year (at least I think that is what you are advocating) and alternatively we have advocates for up to three hours of year-round DST such as Peter Hullah, who stated that everyone "should add two hours to their current standard time" all year round. (Since he lives in France, that would be three hours ahead of local mean time.) (A thought: has anyone here in favor of DST in REVERSE?) Garrett Wollman > INTERNET:wollman@LCS.MIT.EDU wrote in reply to me: >On 20 Mar 97 23:41:37 EST, Chris Carrier <72157.3334(a)CompuServe.COM> said: >>Unfortunately things seem to be going in the other direction, given the EU's >>decision to copy the US/UK bad habit of ending DST on the last Sunday in >>OCTOBER, by the end of which the sun is rising later than the large majority >>of day-shift workers get up. >And those of us who live in cities like Boston, which have ``night >life'' rather than ``morning life'' think this is perfectly >reasonable.... DST rules should not be determined by cities such as Boston, but by cities on the western edge of timezones such as Cleveland in the Eastern or Dallas in the Central (and places like Indiana and West Texas should go back an hour into their astronomically correct zone.) Sue Ann Bowling > INTERNET:sbowling@gi.alaska.edu wrote: >The dates of daylight savings shift, and the assymmetry between the spring >shift (when we in Alaska are already pracitically going to bed in daylight) >and October (when it's already dark when we're going home in the evening) >have bothered me for years. The problem in Alaska isn't DST but that ever since October 1983 most of the state, except for Southeast, has been on DST all year with a 2 hour advance during the DST period in the Lower 48. >I wonder if the politicos who first devised the shift thought that solar >symmetry was around the middle of the winter and summer? It seems to have been a thing that evolved. When DST first went US-national in 1918-9, it run from the last Sunday in March to the last Sunday in October. When many states and localities started using it in 1920 in the absence of national legislation, they shortened it by a month on each end, from the last Sunday in April (a ridiculously late date in Lower 48 latitudes) to the (very sensible) last Sunday in September. This went on until 1942-5 when DST was national and year round for the war. It should be noted here that the War Time Act of 1942 called for DST to last until six months after the end of the war, but when the war did end in the summer of 1945 a bill was quickly passed to end War Time on the last Sunday in September, 1945. What I call the "October problem" started in Massachusetts when the legislature there extended DST to the end of October, starting in 1954. (IMHO they should have left September alone and started a month earlier if they wanted an extended DST period.) The next year New York and the rest of New England got on the bandwagon, and by 1962 most places on DST were ending on the last Sunday in October. (A few, however, shortened the end to Labor Day - - Minnesota was one.) Then along came the Uniform Time Act of 1966 which set up the dates of the last Sunday in April to October, nationwide. It should be pointed out that when this bill was originally introduced it did not put the whole country on DST but only stated that anyone using DST had to abide by April Sun=>24 to October Sun =>25 switch dates. Unfortunately the bill was then rewritten to put the whole nation on DST unless states exempted themselves. An amendment to the bill reducing the DST period from Memorial to Labor Day unfortunately failed; this was reintroduced in 1970 and also failed. After the 1974-5 experience with a much earlier start to DST, bills were introduced in each Congress from 1976 on to increase the DST period until in 1987, one passed to move the start date from the last to the first Sunday in April. My position during those years was to support the earlier change if and only if the ending date was moved back to the last Sunday in September. In 1981 I was happy to see the EEC (later known as the EC, now known as the EU) adopt last Sunday March-September for its continental members, hoping this would inspire the UK and US to do likewise and create something like the Livingston worldwide-switch-day proposal (which is what the UTA of 1966 was and should have been). But alas, this was not to be. >Anyway, a popular science article I wrote on the topic 10 >years ago is on the web at ><http://www.gi.alaska.edu/ScienceForum/ASF8/812.html>, pointing out some of >the oddities of time zones here in our 60 degree wide state. I used to write similar articles for the BARROW SUN and the ALEUTIAN EAGLE 1987-92 (when they folded). If you are interested I could send you one I wrote in October 1988 commenting on the fifth anniversary of the consolidation of time zones in Alaska five years earlier. Eric Ulevik > INTERNET:eau@ozemail.com.au wrote: >It is extremely unlikely that time zone rules will be simplified >to make life easier for computers. For example: sunrise and sunset >in Hobart vary sufficiently from Sydney that they are always going >to want to have different summer time start/end dates. Another >example: Adelaide has an offset of <hours>:30m from GMT. Nor should they. Time zone rules should be set by wake-sleep patterns, not the perceived need of the business community to have everyone on the same time: (A fabulous letter to the London Times during the British Standard Time period (1968-71) put it thusly: "We have 3000 telephone links between Britain and the Continent. Why do we need to get 55 million people out of bed in the dark to answer them?") >Having said that, I have an idea for how to simplify time zone rules. >A 'mean local time' can be calculated based upon location on the >earth's surface. This time can be algorithmically biased to >allow for daylight savings, smoothly varying over the year. Clocks >can use GPS and the standard algorithm to calculate this time. >Of course, this was the case before standard time, but transport >and communications go faster these days. Which is why it could never be practically adopted. If I were at the Meridian Convention in Washington, DC, USA, in (I believe) 1881, where they settled on Greenwich as the meridian, (a good decision IMHO) I would have advocated a planetwide version of what the German State Railways were doing. They had time zones based on Berlin, with each zone 10 minutes in time (2.5 degrees of longitude) apart. What I would have wanted would be such a system of 144 time zones, 10 minutes apart, centered on Greenwich. >The problem here is that administrative units - say Sydney - >may wish to adopt a standard time, but then we end not >having algorithmically determined time. Actually the problem is that organizations which deal in a large area such as railways and, in our century, broadcasters, need to have uniform time over a large area. There were many standard 'railway times' before standard time was introduced to reduce confusion in this area. >3) Time near the poles probably needs a special case. Would you believe the South Pole keeps DST? The first commander of the Pole Station wanted to keep GMT, but discovered it was more convenient to keep the time of their supply line; McMurdo Sound, which kept the same time as New Zealand. Since NZ has had a seasonal time change since 1974, McMurdo follows suit, and so does the Pole Station.

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Daylight savings changeover
by Sue Ann Bowling March 21, 1997

March 21, 1997

The dates of daylight savings shift, and the assymmetry between the spring shift (when we in Alaska are already pracitically going to bed in daylight) and October (when it's already dark when we're going home in the evening) have bothered me for years. I wonder if the politicos who first devised the shift thought that solar symmetry was around the middle of the winter and summer? Anyway, a popular science article I wrote on the topic 10 years ago is on the web at <http://www.gi.alaska.edu/ScienceForum/ASF8/812.html>, pointing out some of the oddities of time zones here in our 60 degree wide state. Sue Ann Bowling, Geophysical Institute, University of Alaska Fairbanks Professional URL http://climate.gi.alaska.edu/Bowling/Bowling.html Dog URL http://www.mcf.com/bowlingsite/dogpage.html

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Re: Mass switch at the equinoxes
by ncm＠cantrip.org March 21, 1997

March 21, 1997

Alex Livingston (alex(a)agsm.unsw.edu.au) wrote: >This is an ideal time for anywhere at a high enough latitude in the northern >hemisphere to advance clocks *and* anywhere at a (numerically) high enough >latitude in the southern hemisphere to retard clocks. Imagine if all the >world that did change changed on the same weekend! Chris Carrier: >I totally agree. Clearly the only sensible approach to time would be to leave the damn clocks alone, and change schedules to match reality. However, it's a waste of everybody's time and attention to discuss this here. We techies are constrained to chase after whatever foolish decisions are made in the parliaments and politburos of world. This list is about details of that chase. Maybe there should be another list to help discover strategies to influence idiot politicians. I hope that those of you who are interested in the idea will create that list, instead of using this one. Nathan Myers ncm(a)cantrip.org

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How do you generate POSIX time zone strings?
by Tony Glenning March 21, 1997

March 21, 1997

Hi, I am hoping this is the correct alias for this question (apologies of not). I am trying to find a straight forward way to generate POSIX time zone strings for the current year. For example, if this function were run on machine which has TZ set to US/Pacific in 1997 it would generate: PST8PDT7,97/3:00:00,300/1:00:00 Any suggestions welcome. Currently my best thought is parsing the zoneinfo files and generating them that way, which is quite tedious. Thanks, Tony

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Mass switch at the equinoxes
by Chris Carrier March 21, 1997

March 21, 1997

Alex Livingston (alex(a)agsm.unsw.edu.au) wrote: >This is an ideal time for anywhere at a high enough latitude in the northern >hemisphere to advance clocks *and* anywhere at a (numerically) high enough >latitude in the southern hemisphere to retard clocks. Imagine if all the >world that did change changed on the same weekend! I totally agree. I would like to see a world convention where northern- hemisphere DSTers all agree to start and end on the last Sundays in March and September, as Europe did 1981-95, and southern-hemisphere DSTers end and start on the same weekends. Unfortunately things seem to be going in the other direction, given the EU's decision to copy the US/UK bad habit of ending DST on the last Sunday in OCTOBER, by the end of which the sun is rising later than the large majority of day-shift workers get up. Chris Carrier

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Re: A Timezone Gazetteer (and Map Maybe)
by Dave Skinner March 21, 1997

March 21, 1997

The following is an excerpt from a response I recently sent to Alex Livingston followed by my response to Eric Ulevik. Since both emails to me were also sent to tz(a)elsie.nci.nih.gov, I felt this email to be needed. ------------------------------------------------------------------------------- You are quite right about Australia/Hobart. I took Paul Eggert's input as gospel, so to speak, and he mistakenly treated Australia/Hobart as the same as Australia/Sydney. At the risk of telling you in boring detail what you already told me, here are the appropriate pairs of rules for Australia/Hobart Rule AT 1991 max - Oct Sun>=1 2:00s 1:00 - Rule AT 1991 max - Mar lastSun 2:00s 0 - and Australia/Sydney Rule AN 1987 max - Oct lastSun 2:00s 1:00 - Rule AN 1996 max - Mar lastSun 2:00s 0 - Clearly "Sun>=1" is not the same as "lastSun". You may see an errata about this one to tz(a)elsie.nci.nih.gov in the not too distant future. It would have also have been clearer to append " --> None" to both rules Aus and AQ since I was concentrating on current time zones and into the future, at least for the time being. As for Indian/Cocos, it is separated from the rest of Australia in the "australasia" file, and my lack of geography knowledge means that I did not realize that it was owned by Australia. There needs to be a modification of the "australasia" file if you want it automatically collected as a time zone of Australia in my processing. I do not know who officially to notify of that to effect the change. Do you? I will be happy to make it a time zone of Australia in my personal bookkeeping right now, though. This may be another one for the errata sheet. . . . ------------------------------------------------------------------------------ I just responded to a series of comments from Alex Livingston that included the mistake with respect to Tasmania's time zone without noticing he had subsequently sent a copy of his comments to tz(a)elsie.nci.nih.gov and also without noticing that you made a similar set of comments. A copy of my response to Alex will be sent to tz(a)elsie.nci.nih.gov after I get done responding to the rest of your comments. With regard to my > planning to ignore time zones which are the same currently, but were > different historically being a mistake, it is funny that you should mention that, because Paul Eggert and I were having a similar discussion away from tz(a)elsie.nci.nih.gov (at least I think it was away from tz(a)elsie.nci.nih.gov) with me attempting to take the position you are now advocating. The problem is not in loosing geograpical information, because all that the tz database has currently in terms of lat/lon geographic information are single lat/lon points for each time locale, currently stored in "zone.tab". The problem is, or rather the problems are: (1) We need to be able to automatically process the existing tz database at any point in time in the future to get lists of what might be called "local time zones", i.e. the list of countries that only observe one time, with or without daylight savings time shifts, throughout the year, and the list of multiple time zones by country in countries where, for reasons of either standard time and/or daylight savings time observance variations, observe multiple times at one time or another throughout the year. These "local time zones" can then be combined into "regional time zones" at any point in time, where "regional time zones" are the amalgamated total of all "local time zones" whose clocks are set the same at that point in time. These lists need to be generated and compared to their previous counterparts to see if anything has changed. (2) We need to be able to conveniently respond to changes in "regional time zone" boundaries, especially if we have either previously gathered the lat/lon pairs of the boundary in question or if we have previously gathered, as I am now attempting to do, the lat/lon pairs, i.e. the digital line graph (dlg) data (properly converted to lat/lon polygon data for ease of subsequent handling) for political jurisdictions within the countries in question down to a sufficiently fine granularity that we can simply create lists of the jurisdictions associated with each of the "regional time zones" in question and automatically generate their overall boundary lat/lon polygons. With regard to > Hopefully it will be available on a web page... Any data gathered in (2) above should be made part of the tz database and will be made available in as open a manner as is reasonable/possible. It certainly will not be thrown away. So, as the time zone boundaries change and change back, it will certainly be possible to go back to a previous boundary easily. As for web pages, there currently exist somewhat cumbersome ways to provide this capability in a secure manner (maybe with Java Applets, but totally avoiding Java Applications) on a web page, and certainly if I am able to assemble a sufficiently interesting data set, I will make it a high priority to put the needed effort, around the edges of my other work, into seeing that such a web page gets created and maintained. Furthermore, it should be possible to directly support most Unix boxes with far more efficient versions of the same capability independent of the web page interface. Finally, the automatic assessment of the current situation in (1) above certainly must deal with all of the "Zones" and all of the "Rules" that show up in the tz database. Furthermore, although I am presently focusing only on present and future "regional time zone" boundary data, this is merely to keep my immediate problem as manageable as possible. This should not be construed to mean that I am not interested in historical time zone boundary data. To the contrary, I am very interested in acquiring sufficient historical lat/lon data to make the presentation of historical time zone information by the gazetteer a reality. Unfortunately, unless there is a significant breakthrough in obtaining such historical lat/lon data, present and future time zone information is all that can be reasonably expected in the foreseeable future. Dave Skinner dave(a)kirdu.jpl.nasa.gov

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Happy Equinox
by Alex LIVINGSTON March 20, 1997

March 20, 1997

Happy equinox (1997-03-20 13:55UT) one and all. This is an ideal time for anywhere at a high enough latitude in the northern hemisphere to advance clocks *and* anywhere at a (numerically) high enough latitude in the southern hemisphere to retard clocks. Imagine if all the world that did change changed on the same weekend! _______________ Alex LIVINGSTON Macintosh Support Computing & IT (C&IT) Australian Graduate School of Management (AGSM) The University of New South Wales (UNSW) Sydney NSW 2052 AUSTRALIA E-mail : alex(a)agsm.unsw.edu.au; cit(a)agsm.unsw.edu.au (C&IT) Facsimile: +61 2 9931-9349 Telephone: +61 2 9931-9264

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Re-sent: Re: A Timezone Gazetteer (and Map Maybe)
by Alex LIVINGSTON March 20, 1997

March 20, 1997

The project you are embarking on seems fantastic, and looks as though it will eventually make possible the fulfilment of a dream of mine, namely a live time-zone map on the Web showing both current time zones (labeled with UT offset) - in colors reflecting UT offset alone, and not the so-called "Standard" time in that region - and the time in each of those zones. Once such a map is operational, many other possibilities present themselves of course (e.g. zooming in, display for a past or future date). I'm afraid I can't give you any help with boundary-vector information, but I noticed a number of omissions/errors regarding Australia (where I live) in your summary information: (1) >5. australasia:Australia > Indian/Christmas 7:00 None > Australia, Western 8:00 > Australia/Perth 8:00 None > Australia, Central 9:30 > Australia/Adelaide 9:30 AS > Australia/Darwin 9:30 Aus > Australia, Eastern 10:00 > Australia/Brisbane 10:00 AQ > Australia/Sydney 10:00 AN > Australia/Lord_Howe 10:30 LH You have left out the Cocos Islands, which (unfortunately) have a time zone of their own (and not that of neighboring Christmas Island). It might look something like this: Indian/Cocos 6:30 None (2) You have also overlooked Tasmania, which starts keeping daylight-saving time before other parts of the country which observe it do: Australia, Eastern Australia/Hobart 10:00 AT (?) (3) Note also that Australia/Brisbane no longer observes daylight-saving time at all. (Could it have "None" in its DST-Rule column?) > Australia/Hobart, Australia/Melbourne \ > (duplicates of Australia/Sydney) As already intimated, this is not entirely true; Australia/Melbourne is a duplicate of Australia/Sydney, but Australia/Hobart is not. (4) > Australia/Lindeman (duplicate of Australia/Brisbane) This is only true if historical observance is irrelevant. The Australia/Lindeman entry was created for a few Queensland islands for no other reason than that they continued to switch to daylight-saving time for a couple of years after the rest of the state ceased doing so. To the best of my knowledge, however, the two zones are now indistinguishable from each other (UT+10:00 kept year-round). _______________ Alex LIVINGSTON Macintosh Support Computing & IT (C&IT) Australian Graduate School of Management (AGSM) The University of New South Wales (UNSW) Sydney NSW 2052 AUSTRALIA E-mail : alex(a)agsm.unsw.edu.au; cit(a)agsm.unsw.edu.au (C&IT) Facsimile: +61 2 9931-9349 Telephone: +61 2 9931-9264

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