August 1997 - tz - lists.iana.org

Happy Leap Second!
by Chris Newman Nov. 24, 1997

Nov. 24, 1997

I hope everyone enjoys their extra second! This also serves as a test to see what really happens if there is a "60" for seconds in the date header. - Chris

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Re: ISO C strftime() extention for ISO 8601
by kuhn＠cs.purdue.edu Sept. 15, 1997

Sept. 15, 1997

"Clive D.W. Feather" wrote on 1997-06-30 13:14 UTC: > You may be interested to know that WG14 adopted last week working paper > N733, which adds the following items to the strftime() function: > > %f is replaced by the weekday as a decimal number (1-7), where > Monday is 1 (the ISO 8601 weekday number). > %F is equivalent to "%Y-%m-%d" (the ISO 8601 date format). > %T is equivalent to "%H:%M:%S" (the ISO 8601 time format). > %V is replaced by the ISO 8601 week number of the year (weeks > begin on a Monday, and week 1 is the week that includes both > January 4th and the first Thursday of the year) as a decimal > number (00-53). Thanks a lot for forwarding this interesting working paper. Please forward the following comments to the authors of N733 and whoever else might be interested. If possible, I would like to review the final text of the new strftime() definition (will the current draft be on the Web somewhere?). Comments on WG14 proposal N733 ------------------------------ Markus Kuhn <kuhn(a)cs.purdue.edu> -- 1997-06-30 (= 1997-W27-1) I appreciate this proposal and I have the following related comments. a) The valid range for %V numbers is 01-53. There is no week 00 in the ISO 8601 week numbering scheme. The week before a week 01 is either week 52 or week 53 of the previous year. b) %V alone is not sufficient to be able to use the ISO week numbering system. Each week is associated with a year, the year in which the majority of the days of this week fall, and this is not necessarily the year in which all days of the weeks fall. For instance: The week 1999-W52 goes from 1999-12-27 to 2000-01-02, in other words, the day 2000-01-02 has a week notation of the form 1999-W52-7. There should be another format descriptor for the year to which the current ISO week belongs, preferably both in 4-digit (%G) and 2-digit (%g) form. If you implement an algorithm for %V, you'll get the value of %G anyway as a by-product very easily, and therefore it should be made available to the strftime() user. c) Existing practice: The Olson tzcode package <ftp://elsie.nci.nih.gov/pub/> contains a widely used strftime() implementation that supports already: %u ISO 8601 week day number (1 = Monday, 7=Sunday) %V ISO 8601 week number (01-53) %G ISO 8601 year of current week, 4-digits %g ISO 8601 year of current week, 2-digits Unless there is a good rationale for the characters suggested by N733, I would suggest to stick with %u instead of %f for the weekday number, and I hope that you will add %G and %g as used in the Olson package and Arnold Robbins' strftime version 3.0. Therefore, if I evaluate on 1977-01-02 the string %G-W%V-%u, I should get 1976-W53-7, and on 1975-12-29 I should get 1976-W01-1. Not directly related to N733, but affecting the same part of the standard, I have a number of other suggestions: d) The range for %S and tm_sec is currently defined to be 00-61 to provide for "as many as two leap seconds". This was based on a serious missunderstanding and there can never be two leap seconds per day as it becomes very obvious by reading ITU-R Recommendation TF.460-4 (I can send you a copy if you are interested). Since this 00-61 range is being widely quoted in other standards, this error should be fixed just to stop spreading this serious missconception of how leap seconds work. The correct range is 00-60. This is not an interoperability problem, but fixing this would make WG14 look like they know what they are doing, and it is therefore a good idea. e) I wonder whether %W is anywhere used and whether this field could be dropped to simplify implementation and memory cost. Countries that start the week with Monday normally use ISO 8601 week numbers (%V) and not the scheme defined by %W. I suspect %W was defined based on a missconception of how week numbers work in Europe. Unless anyone can come up with an example where %W is used or needed, I suggest to drop it as it looks completely useless to me (and please don't quote standards that just copied the %W from ISO C). f) In the definition of %y and %Y, the first two digits of a four digit year are refered to as the "century", which is problematic, since the years 1999 and 2000 belong to the 20th century, but 2001 belongs to the 21st century. Suggested better wording: "%y is replaced by the last two digits of the year as a decimal number (00-99)". Again, not a serious interoperability problem, but it makes WG14 look like they know what they are doing. g) mktime() is the inverse function of localtime(), but there exists no portable inverse function for gmtime() that converts a struct tm given in UTC into time_t. This is a serious problem, and the addition of a new function (e.g., mkgmtime() might be a possible name) should be considered seriously. It is not possible to invert gmtime() in a 100% portable way in an application program, and in practice, I have encountered awful hacks like binary searches over the time_t range to invert gmtime() in an as portable as possible way. See <http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html> for further info. Markus -- Markus G. Kuhn, Computer Science grad student, Purdue University, Indiana, USA -- email: kuhn(a)cs.purdue.edu

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tz - proposed patch for Metropolitan France and Olveston, Montserrat
by Paul Eggert Aug. 31, 1997

Aug. 31, 1997

In the light of the recent comments about the FX country code and the latitude and longitude for Olveston, Montserrat, here's a further proposed patch, to be applied after the patch that I proposed on Aug 29. =================================================================== RCS file: RCS/iso3166.tab,v retrieving revision 1.2 retrieving revision 1.3 diff -c -r1.2 -r1.3 *** iso3166.tab 1997/07/06 07:19:55 1.2 --- iso3166.tab 1997/08/31 08:13:53 1.3 *************** *** 7,12 **** --- 7,15 ---- # 2. The usual English name for the country, # chosen so that alphabetic sorting of subsets produces helpful lists. # + # For France in Europe, we follow common practice and use FR, + # even though FX might be more technically correct. + # # Columns are separated by a single tab. # The table is sorted by country code. # *************** *** 86,91 **** --- 89,95 ---- FM Micronesia FO Faeroe Islands FR France + FX France, Metropolitan GA Gabon GB Britain (UK) GD Grenada =================================================================== RCS file: RCS/northamerica,v retrieving revision 1997.5.0.1 retrieving revision 1997.5.0.2 diff -c -r1997.5.0.1 -r1997.5.0.2 *** northamerica 1997/08/29 08:34:24 1997.5.0.1 --- northamerica 1997/08/31 08:13:53 1997.5.0.2 *************** *** 1249,1259 **** -4:00 - AST # Montserrat ! # From Paul Eggert (1997-08-29): # Recent volcanic eruptions have forced evacuation of Plymouth, the capital. ! # 4:08 is a guess at the longitude of Olveston, the current de facto capital. # Zone NAME GMTOFF RULES FORMAT [UNTIL] ! Zone America/Montserrat -4:08 - LMT 1911 Jul 1 0:01 # Olveston -4:00 - AST # Nicaragua --- 1249,1259 ---- -4:00 - AST # Montserrat ! # From Paul Eggert (1997-08-31): # Recent volcanic eruptions have forced evacuation of Plymouth, the capital. ! # Luckily, Olveston, the current de facto capital, has the same longitude. # Zone NAME GMTOFF RULES FORMAT [UNTIL] ! Zone America/Montserrat -4:08:52 - LMT 1911 Jul 1 0:01 # Olveston -4:00 - AST # Nicaragua =================================================================== RCS file: RCS/zone.tab,v retrieving revision 1.2.1.4 retrieving revision 1.2.1.5 diff -c -r1.2.1.4 -r1.2.1.5 *** zone.tab 1997/07/16 16:25:51 1.2.1.4 --- zone.tab 1997/08/31 08:13:53 1.2.1.5 *************** *** 231,237 **** MP +1512+14545 Pacific/Saipan MQ +1436-06105 America/Martinique MR +1806-01557 Africa/Nouakchott ! MS +1642-06213 America/Montserrat MT +3554+01431 Europe/Malta MU -2010+05730 Indian/Mauritius MV +0410+07330 Indian/Maldives --- 231,237 ---- MP +1512+14545 Pacific/Saipan MQ +1436-06105 America/Martinique MR +1806-01557 Africa/Nouakchott ! MS +1644-06213 America/Montserrat MT +3554+01431 Europe/Malta MU -2010+05730 Indian/Mauritius MV +0410+07330 Indian/Maldives

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Montserrat, and FX for France
by gwil＠mindspring.com Aug. 30, 1997

Aug. 30, 1997

To Mr. Eggert: The NIMA Geographic Names Server says that Olveston, Montserrat is a "populated locality" at 16 deg. 44 min. N., 62 deg. 13 min. W. In response to M. Leca's comments about FR/FX, I have a different opinion. The question is, which ISO 3166 code should be used for Paris, France: FR or FX. FR is identified in the standard as representing "France", while FX is "France, Metropolitan". First, it should be made clear that there is no one correct answer. The introductory notes to the standard clearly state that there may be areas of overlap between two codes. Without question, Paris is within the area intended to be covered by both codes, FR and FX. It may also be germane to note that FX is a new code, introduced in ISO 3166 Newsletter III-24, dated 1993-06-18. What accounts for the "areas of overlap"? The only clue that the standard provides to areas of coverage of each code are the remarks in column 5 of the countries list. About 80% of these remarks are to explain which isolated islands are or are not included in the country. The remaining 20% are about previous name or code changes. Apparently, the standard is meant to avoid overlap. The introductory notes give only one example of overlap: France (FR) and Martinique (MQ). As far as I can tell, all of the overlaps follow the same paradigm: a mother country and its remote possessions. Thus, the Netherlands (NL) presumably includes not just the European country but Netherlands Antilles (AN) and Aruba (AW) as well. Likewise with Denmark, Greenland, and the Faroe Islands. It would be very, very nice if every point of land in the world (except border points) could be assigned to one and only one country code. Until 1993, it was possible to do this, by making a single simplifying assumption: that in such cases of overlap, the mother country's code would be used only if none of the codes for the country's overseas possessions applied. This fit neatly with common sense. We would say that Copenhagen was in DK because that was the only choice. Nuuk would be coded as GL, even though DK might also be allowed by the standard, because GL conveys more information than DK. I maintain a geographical reference database, in which points are keyed to countries, and countries are taken from ISO 3166. I had assigned points to countries as described above. Paris was in FR, Fort-de-France was in MQ, and so on. When the change notice came out in 1993, I was put in a quandary. I could either leave the code for France as FR, or change it to FX. (Or I could merge all of the overseas departments and territories with FR, but that certainly didn't seem like the best choice.) Changing France to FX would have been more consistent with the principles I had followed. On the other hand, I would have had to educate all my data customers about the reasons behind the change. It would have been a hard sell. Even now, four years later, I don't think anyone I deal with is aware of FX. Besides, I personally find FX unappealing. The codes from XA to XZ are reserved, so there will never be a country code beginning with X. The only codes ending with X before 1993 were CX for tiny Christmas Island and MX for Mexico, which does have an X in it. I decided to take the position, which still seems justified, that FX is an aberration; that it was introduced for some technical purpose, not of general interest; and that the rest of us can ignore it. If new codes were created for Metropolitan Denmark, Metropolitan Netherlands, Metropolitan United States, and so on, I would probably reconsider my position. It would also depend on how the introductory notes to ISO 3166 were changed to explain the new codes. As matters stand, I prefer to act as if FX didn't exist: not because it's the only right thing to do, but because it's one of the right possibilities, and it's expedient. -- Gwillim Law

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FR entry in iso3166.tab and zone.tab
by Antoine Leca Aug. 29, 1997

Aug. 29, 1997

Hello folks, I have a problem with the entries for France in zone.tab. Currently, FR is associated with the entry for Paris, while the various overseas departements (GP, MQ, GF, RE, PM, YT) are associated each with their own entries. OTOH, FR is supposed to mean France as a state, while there is another code, FX, which specifically means "Metropolitan France". So I don't see FR to be at the same level as, say, RE. To be more in line with ISO 3166 and current practices, I think we should use the geographical related codes, i.e. FX for Europe/Paris, and change accordingly zone.tab and iso3166.tab to use FX instead of FR. Of course, as FR is much more used than FX, I think this desserves a comment in the commentary introductions of theses files, explaining why FR is "absent". Antoine Leca

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proposed tz patch for Uruguay, Montserrat, Yugoslavia, EU, etc.
by Paul Eggert Aug. 29, 1997

Aug. 29, 1997

Lee Steakley's report of the embarrassing error for Uruguay in the tz database prompted me to dust off the tz changes that have accumulated on my desk. Here's a proposed patch that combines the following: * Remove the last (bogus) transition for Uruguay. Also, I checked Shanks's 4th edition, and he disagrees with the IATA about Uruguay since 1990, but for lack of better info the following patch sticks with the IATA. * Change the pre-1911 longitude for America/Montserrat to my guess at the longitude of the new de facto capital, Olveston. (My atlas doesn't have this town.) Please see http://www.geo.mtu.edu/volcanoes/west.indies/soufriere/ for details on Montserrat's current upheavals. I suppose the zone.tab entry should also change, but I'd like better data first. * Fix Yugoslavia's legal data of transition for switching to the EU zone rules. This doesn't affect behavior; it's just documentation. (Thanks to Metod Kozelj for correcting my earlier transcription error.) * Add Peter Ilieve's commentary on the Eighth Directive of the European Parliament and of the Council of 22 July 1997 on summer-time arrangements. * Move the general comments at the top of the `africa' file to the `Theory' file, where they are more at home. Also, modernize the `Theory' file a bit. =================================================================== RCS file: RCS/Theory,v retrieving revision 1995.9 retrieving revision 1995.9.0.1 diff -c -r1995.9 -r1995.9.0.1 *** Theory 1995/12/21 17:28:25 1995.9 --- Theory 1997/08/29 08:34:24 1995.9.0.1 *************** *** 1,40 **** @(#)Theory 7.4 ! These time and date functions are much like the System V Release 2.0 (SVR2) ! time and date functions; there are a few additions and changes to extend ! the usefulness of the SVR2 functions: ! ! * In SVR2, time display in a process is controlled by the environment ! variable TZ, which "must be a three-letter time zone name, followed ! by a number representing the difference between local time and ! Greenwich Mean Time in hours, followed by an optional three-letter ! name for a daylight time zone;" when the optional daylight time zone is ! present, "standard U.S.A. Daylight Savings Time conversion is applied." ! This means that SVR2 can't deal with other (for example, Australian) ! daylight savings time rules, or situations where more than two time zone abbreviations are used in an area. ! * In SVR2, time conversion information is compiled into each program ! that does time conversion. This means that when time conversion rules change (as in the United States in 1987), all programs that do time conversion must be recompiled to ensure proper results. ! * In SVR2, time conversion fails for near-minimum or near-maximum ! time_t values when doing conversions for places that don't use GMT. ! ! * In SVR2, there's no tamper-proof way for a process to learn the system's best idea of local wall clock. (This is important for applications that an administrator wants used only at certain times-- without regard to whether the user has fiddled the "TZ" environment variable. While an administrator can "do everything in GMT" to get around the problem, doing so is inconvenient and precludes handling ! daylight savings time shifts--as might be required to limit phone calls to off-peak hours.) ! * These functions can account for leap seconds, thanks to Bradley White ! (bww(a)k.cs.cmu.edu) ! These are the changes that have been made to the SVR2 functions: * The "TZ" environment variable is used in generating the name of a file from which time zone information is read (or is interpreted a la --- 1,84 ---- @(#)Theory 7.4 ! ! ----- Outline ----- ! ! Time and date functions ! Names of time zone regions ! Time zone abbreviations ! ! ! ----- Time and date functions ----- ! ! These time and date functions are upwards compatible with POSIX.1, ! an international standard for Unix-like systems. ! As of this writing, the current edition of POSIX.1 is: ! ! Information technology --Portable Operating System Interface (POSIX (R)) ! -- Part 1: System Application Program Interface (API) [C Language] ! ISO/IEC 9945-1:1996 ! ANSI/IEEE Std 1003.1, 1996 Edition ! 1996-07-12 ! ! POSIX.1 has the following properties and limitations. ! ! * In POSIX.1, time display in a process is controlled by the ! environment variable TZ. Unfortunately, the POSIX.1 TZ string takes ! a form that is hard to describe and is error-prone in practice. ! Also, POSIX.1 TZ strings can't deal with other (for example, Israeli) ! daylight saving time rules, or situations where more than two time zone abbreviations are used in an area. ! The POSIX.1 TZ string takes the following form: ! ! stdoffset[dst[offset],date[/time],date[/time]] ! ! where: ! ! std and dst ! are 3 or more characters specifying the standard ! and daylight saving time (DST) zone names. ! offset ! is of the form `[-]hh:[mm[:ss]]' and specifies the ! offset west of UTC. The default DST offset is one hour ! ahead of standard time. ! date[/time],date[/time] ! specifies the beginning and end of DST. If this is absent, ! the system supplies its own rules for DST, and these can ! differ from year to year; typically US DST rules are used. ! time ! takes the form `hh:[mm[:ss]]' and defaults to 02:00. ! date ! takes one of the following forms: ! Jn (1<=n<=365) ! origin-1 day number not counting February 29 ! n (0<=n<=365) ! origin-0 day number counting February 29 if present ! Mm.n.d (0[Sunday]<=d<=6[Saturday], 1<=n<=5, 1<=m<=12) ! for the dth day of week n of month m of the year, ! where week 1 is the first week in which day d appears, ! and `5' stands for the last week in which day d appears ! (which may be either the 4th or 5th week). ! ! * In POSIX.1, when a TZ value like "EST5EDT" is parsed, ! typically the current US DST rules are used, ! but this means that the US DST rules are compiled into each program ! that does time conversion. This means that when US time conversion rules change (as in the United States in 1987), all programs that do time conversion must be recompiled to ensure proper results. ! * In POSIX.1, there's no tamper-proof way for a process to learn the system's best idea of local wall clock. (This is important for applications that an administrator wants used only at certain times-- without regard to whether the user has fiddled the "TZ" environment variable. While an administrator can "do everything in GMT" to get around the problem, doing so is inconvenient and precludes handling ! daylight saving time shifts--as might be required to limit phone calls to off-peak hours.) ! * POSIX.1 requires that systems ignore leap seconds. ! These are the extensions that have been made to the POSIX.1 functions: * The "TZ" environment variable is used in generating the name of a file from which time zone information is read (or is interpreted a la *************** *** 62,74 **** * To handle places where more than two time zone abbreviations are used, the functions "localtime" and "gmtime" set tzname[tmp->tm_isdst] (where "tmp" is the value the function returns) to the time zone ! abbreviation to be used. This differs from SVR2, where the elements of tzname are only changed as a result of calls to tzset. * Since the "TZ" environment variable can now be used to control time conversion, the "daylight" and "timezone" variables are no longer ! needed or supported. (You can use a compile-time option to cause ! these variables to be defined and to be set by "tzset"; however, their values will not be used by "localtime.") * The "localtime" function has been set up to deliver correct results --- 106,117 ---- * To handle places where more than two time zone abbreviations are used, the functions "localtime" and "gmtime" set tzname[tmp->tm_isdst] (where "tmp" is the value the function returns) to the time zone ! abbreviation to be used. This differs from POSIX.1, where the elements of tzname are only changed as a result of calls to tzset. * Since the "TZ" environment variable can now be used to control time conversion, the "daylight" and "timezone" variables are no longer ! needed. (These variables are defined and set by "tzset"; however, their values will not be used by "localtime.") * The "localtime" function has been set up to deliver correct results *************** *** 86,94 **** environment variable; portable applications should not, however, rely on this behavior since it's not the way SVR2 systems behave.) ! Points of interest to folks with Version 7 or BSD systems: ! * The BSD "timezone" function is not present in this package; it's impossible to reliably map timezone's arguments (a "minutes west of GMT" value and a "daylight saving time in effect" flag) to a time zone abbreviation, and we refuse to guess. --- 129,149 ---- environment variable; portable applications should not, however, rely on this behavior since it's not the way SVR2 systems behave.) ! * These functions can account for leap seconds, thanks to Bradley White ! (bww(a)k.cs.cmu.edu) ! ! Points of interest to folks with other systems: ! ! * This package is already part of many POSIX-compliant hosts, ! including BSD, HP, Linux, Network Appliance, SCO, SGI, and Sun. ! On such hosts, the primary use of this package ! is to update obsolete time zone rule tables. ! To do this, you may need to compile the time zone compiler ! `zic' supplied with this package instead of using the system `zic', ! since the format of zic's input changed slightly in late 1994, ! and many vendors still do not support the new input format. ! * The Unix Version 7 "timezone" function is not present in this package; it's impossible to reliably map timezone's arguments (a "minutes west of GMT" value and a "daylight saving time in effect" flag) to a time zone abbreviation, and we refuse to guess. *************** *** 97,108 **** zone abbreviation to use. Alternatively, use localtime(&clock)->tm_zone if this has been enabled. ! * The BSD gettimeofday function is not used in this package; ! this lets users control the time zone used in doing time conversions. ! Users who don't try to control things (that is, users who do not set ! the environment variable TZ) get the time conversion specified in the ! file "/etc/zoneinfo/localtime"; see the time zone compiler writeup for ! information on how to initialize this file. The functions that are conditionally compiled if STD_INSPIRED is defined should, at this point, be looked on primarily as food for thought. They are --- 152,164 ---- zone abbreviation to use. Alternatively, use localtime(&clock)->tm_zone if this has been enabled. ! * The 4.2BSD gettimeofday function is not used in this package. ! This formerly let users obtain the current UTC offset and DST flag, ! but this functionality was removed in later versions of BSD. ! ! * In SVR2, time conversion fails for near-minimum or near-maximum ! time_t values when doing conversions for places that don't use GMT. ! This package takes care to do these conversions correctly. The functions that are conditionally compiled if STD_INSPIRED is defined should, at this point, be looked on primarily as food for thought. They are *************** *** 115,120 **** beyond those provided here. The absence of such functions from this package is not meant to discourage the development, standardization, or use of such functions. Rather, their absence reflects the decision to make this package ! close to SVR2 (with the exceptions outlined above) to ensure its broad acceptability. If more powerful time conversion functions can be standardized, so much the better. --- 171,285 ---- beyond those provided here. The absence of such functions from this package is not meant to discourage the development, standardization, or use of such functions. Rather, their absence reflects the decision to make this package ! contain valid extensions to POSIX.1, to ensure its broad acceptability. If more powerful time conversion functions can be standardized, so much the better. + + + ----- Names of time zone rule files ----- + + The names of this package's installed time zone rule files are chosen to + help minimize possible future incompatibilities due to political events. + Ordinarily, names of countries are not used, to avoid incompatibilities + when countries change their name (e.g. Zaire->Congo) or + when locations change countries (e.g. Hong Kong from UK colony to China). + + Names normally have the form AREA/LOCATION, where AREA is the name + of a continent or ocean, and LOCATION is the name of a specific + location within that region. North and South America share the same + area, `America'. Typical names are `Africa/Cairo', `America/New_York', + and `Pacific/Honolulu'. + + Here are the general rules used for choosing location names, + in decreasing order of importance: + + Use only valid Posix file names. Use only Ascii letters, digits, `.', + `-' and `_'. Do not exceed 14 characters or start with `-'. + E.g. prefer `Brunei' to `Bandar_Seri_Begawan'. + Include at least one location per time zone rule set per country. + One such location is enough. + If all the clocks in a country's region have agreed since 1970, + don't bother to include more than one location + even if subregions' clocks disagreed before 1970. + Otherwise these tables would become annoyingly large. + If a name is ambiguous, use a less ambiguous alternative; + e.g. many cities are named San Jose and Georgetown, so + prefer `Costa_Rica' to `San_Jose' and `Guyana' to `Georgetown'. + Keep locations compact. Use cities or small islands, not countries + or regions, so that any future time zone changes do not split + locations into different time zones. E.g. prefer `Paris' + to `France', since France has had multiple time zones. + Use traditional English spelling, e.g. prefer `Rome' to `Roma', and + prefer `Athens' to the true name (which uses Greek letters). + The Posix file name restrictions encourage this rule. + Use the most populous among locations in a country's time zone, + e.g. prefer `Shanghai' to `Beijing'. Among locations with + similar populations, pick the best-known location, + e.g. prefer `Rome' to `Milan'. + Use the singular form, e.g. prefer `Canary' to `Canaries'. + Omit common suffixes like `_Islands' and `_City', unless that + would lead to ambiguity. E.g. prefer `Cayman' to + `Cayman_Islands' and `Guatemala' to `Guatemala_City', + but prefer `Mexico_City' to `Mexico' because the country + of Mexico has several time zones. + Use `_' to represent a space. + Omit `.' from abbreviations in names, e.g. prefer `St_Helena' + to `St._Helena'. + + The file `zone.tab' lists the geographical locations used to name + time zone rule files. + + Older versions of this package used a different naming scheme, + and these older names are still supported. + See the file `backwards' for most of these older names + (e.g. `US/Eastern' instead of `America/New_York'). + The other old-fashioned names still supported are + `WET', `CET', `MET', `EET' (see the file `europe'), + and `Factory' (see the file `factory'). + + + ----- Time zone abbreviations ----- + + When this package is installed, it generates time zone abbreviations + like `EST' to be compatible with human tradition and POSIX.1. + Here are the general rules used for choosing time zone abbreviations, + in decreasing order of importance: + + Use abbreviations that consist of 3 or more upper-case Ascii letters, + except use "___" for locations while uninhabited. + Posix.1 requires at least 3 characters, and the restriction to + upper-case Ascii letters follows most traditions. + Previous editions of this database also used characters like + ' ' and '?', but these characters have a special meaning to + the shell and cause commands like + set `date` + to have unexpected effects. In theory, the character set could + be !%./@A-Z^_a-z{}, but these tables use only upper-case + Ascii letters (and "___"). + Use abbreviations that are in common use among English-speakers, + e.g. `EST' for Eastern Standard Time in North America. + We assume that applications translate them to other languages + as part of the normal localization process; for example, + a French application might translate `EST' to `HNE'. + For zones whose times are taken from a city's longitude, use the + traditional xMT notation, e.g. `PMT' for Paris Mean Time. + The only name like this in current use is `GMT'. + If there is no common English abbreviation, abbreviate the English + translation of the usual phrase used by native speakers. + If this is not available or is a phrase mentioning the country + (e.g. ``Cape Verde Time''), then: + + When a country has a single or principal time zone region, + append `T' to the country's ISO code, e.g. `CVT' for + Cape Verde Time. For summer time append `ST'; + for double summer time append `DST'; etc. + When a country has multiple time zones, take the first three + letters of an English place name identifying each zone + and then append `T', `ST', etc. as before; + e.g. `VLAST' for VLAdivostok Summer Time. + + Application writers should note that these abbreviations are ambiguous + in practice: e.g. `EST' has a different meaning in Australia than + it does in the United States. In new applications, it's often better + to use numeric GMT offsets like `-0500' instead of time zone + abbreviations like `EST'; this avoids the ambiguity. =================================================================== RCS file: RCS/africa,v retrieving revision 1997.7 retrieving revision 1997.7.0.1 diff -c -r1997.7 -r1997.7.0.1 *** africa 1997/07/19 17:14:55 1997.7 --- africa 1997/08/29 08:34:24 1997.7.0.1 *************** *** 27,111 **** # Derek Howse, Greenwich time and the discovery of the longitude, # Oxford University Press (1980). # - # I added so many Zone names that the old, mostly flat name space was unwieldy. - # So I renamed the Zones to have the form AREA/LOCATION, where - # AREA is the name of a continent or ocean, and - # LOCATION is the name of a specific location within that region. - # For example, the old zone name `Egypt' is now `Africa/Cairo'. - # - # Here are the general rules I used for choosing location names, - # in decreasing order of importance: - # - # Use only valid Posix file names. Use only Ascii letters, digits, `.', - # `-' and `_'. Do not exceed 14 characters or start with `-'. - # E.g. prefer `Brunei' to `Bandar_Seri_Begawan'. - # Include at least one location per time zone rule set per country. - # One such location is enough. - # If all the clocks in a country's region have agreed since 1970, - # don't bother to include more than one location - # even if subregions' clocks disagreed before 1970. - # Otherwise these tables would become annoyingly large. - # If a name is ambiguous, use a less ambiguous alternative; - # e.g. many cities are named San Jose and Georgetown, so - # prefer `Costa_Rica' to `San_Jose' and `Guyana' to `Georgetown'. - # Keep locations compact. Use cities or small islands, not countries - # or regions, so that any future time zone changes do not split - # locations into different time zones. E.g. prefer `Paris' - # to `France', since France has had multiple time zones. - # Use traditional English spelling, e.g. prefer `Rome' to `Roma', and - # prefer `Athens' to the true name (which uses Greek letters). - # The Posix file name restrictions encourage this rule. - # Use the most populous among locations in a country's time zone, - # e.g. prefer `Shanghai' to `Beijing'. Among locations with - # similar populations, pick the best-known location, - # e.g. prefer `Rome' to `Milan'. - # Use the singular form, e.g. prefer `Canary' to `Canaries'. - # Omit common suffixes like `_Islands' and `_City', unless that - # would lead to ambiguity. E.g. prefer `Cayman' to - # `Cayman_Islands' and `Guatemala' to `Guatemala_City', - # but prefer `Mexico_City' to `Mexico' because the country - # of Mexico has several time zones. - # Use `_' to represent a space. - # Omit `.' from abbreviations in names, e.g. prefer `St_Helena' - # to `St._Helena'. - # - # For time zone abbreviations like `EST' I used the following rules, - # in decreasing order of importance: - # - # Use abbreviations that consist of 3 or more upper-case Ascii letters, - # except use "___" for locations while uninhabited. - # Posix.1 requires at least 3 characters, and the restriction to - # upper-case Ascii letters follows most traditions. - # Previous editions of this database also used characters like - # ' ' and '?', but these characters have a special meaning to - # the shell and cause commands like - # set `date` - # to have unexpected effects. In theory, the character set could - # be !%./@A-Z^_a-z{}, but these tables use only upper-case - # Ascii letters (and "___"). - # Use abbreviations that are in common use among English-speakers, - # e.g. `EST' for Eastern Standard Time in North America. - # We assume that applications translate them to other languages - # as part of the normal localization process; for example, - # a French application might translate `EST' to `HNE'. - # For zones whose times are taken from a city's longitude, use the - # traditional xMT notation, e.g. `PMT' for Paris Mean Time. - # The only name like this in current use is `GMT'. - # If there is no common English abbreviation, abbreviate the English - # translation of the usual phrase used by native speakers. - # If this is not available or is a phrase mentioning the country - # (e.g. ``Cape Verde Time''), then: - # - # When a country has a single or principal time zone region, - # append `T' to the country's ISO code, e.g. `CVT' for - # Cape Verde Time. For summer time append `ST'; - # for double summer time append `DST'; etc. - # When a country has multiple time zones, take the first three - # letters of an English place name identifying each zone - # and then append `T', `ST', etc. as before; - # e.g. `MOSST' for MOScow Summer Time. - # - # # For Africa I invented the following time zone abbreviations. # LMT Local Mean Time # -1:00 AAT Atlantic Africa Time (no longer used) --- 27,32 ---- =================================================================== RCS file: RCS/europe,v retrieving revision 1997.7 retrieving revision 1997.7.0.1 diff -c -r1997.7 -r1997.7.0.1 *** europe 1997/07/19 17:14:57 1997.7 --- europe 1997/08/29 08:34:24 1997.7.0.1 *************** *** 630,647 **** # came into force on 16 November. It restates the dates from the EC # seventh Summer Time Directive.... # ! # From Peter Ilieve <peter(a)aldie.co.uk> (1997-03-28): ! # The [European] Transport Council discussed the proposed Eighth Directive ! # on 11 March and agreed [to] it, so it moves forward to the next stage, ! # from a Commission proposal to a Common Position.... What this means is: ! # ! # - The eighth directive proposal rules have been accepted. ! # These are the same as the current rules (last Sunday in March and last ! # Sunday in October). The rules will run until 2001. ! # ! # - The French have had their request to abandon summer time turned down. ! # They have been promised some sort of review in 1999 which might change ! # the rules for 2000 and 2001. # From Peter Ilieve <peter(a)memex.co.uk> (1994-03-28): # The [GB-Eire] end date of 22 October [1995] conflicts with your current rule --- 630,647 ---- # came into force on 16 November. It restates the dates from the EC # seventh Summer Time Directive.... # ! # From Peter Ilieve <peter(a)aldie.co.uk> (1997-08-06): ! # I now have a copy of the ... Eighth Directive 97/44/EC of the European ! # Parliament and of the Council of 22 July 1997 on summer-time arrangements. ! # It runs for 4 years, 1998--2001, and confirms the current rules of ! # last Sunday in March to last Sunday in October.... ! # The directive does not apply in overseas territories of the Member States. ! # It says the Commission should produce a proposal for 2002 and beyond ! # by 1 Jan 2000 and this should be adopted by 1 Jan 2001. I doubt that ! # this will happen though.... ! # There is no mention of the French desire to abandon the whole idea. ! # France has had a change of government recently so maybe it will ! # be quietly dropped. # From Peter Ilieve <peter(a)memex.co.uk> (1994-03-28): # The [GB-Eire] end date of 22 October [1995] conflicts with your current rule *************** *** 667,678 **** # Also, for lack of other data, we'll follow Shanks for Eire in 1940-1948. # # Given Peter Ilieve's comments, the following claims by Shanks are incorrect: ! # * Wales did not switch from GMT to daylight savings time until # 1921 Apr 3, when they began to conform with the rest of Great Britain. # Actually, Wales was identical after 1880. # * Eire had two transitions on 1916 Oct 1. # It actually just had one transition. ! # * Northern Ireland used single daylight savings time throughout WW II. # Actually, it conformed to Britain. # * GB-Eire changed standard time to 1 hour ahead of GMT on 1968-02-18. # Actually, that date saw the usual switch to summer time. --- 667,678 ---- # Also, for lack of other data, we'll follow Shanks for Eire in 1940-1948. # # Given Peter Ilieve's comments, the following claims by Shanks are incorrect: ! # * Wales did not switch from GMT to daylight saving time until # 1921 Apr 3, when they began to conform with the rest of Great Britain. # Actually, Wales was identical after 1880. # * Eire had two transitions on 1916 Oct 1. # It actually just had one transition. ! # * Northern Ireland used single daylight saving time throughout WW II. # Actually, it conformed to Britain. # * GB-Eire changed standard time to 1 hour ahead of GMT on 1968-02-18. # Actually, that date saw the usual switch to summer time. *************** *** 681,687 **** # The following claims by Shanks are possible though doubtful; # we'll ignore them for now. # * Jersey, Guernsey, and the Isle of Man did not switch from GMT ! # to daylight savings time until 1921 Apr 3, when they began to # conform with Great Britain. # * Dublin's 1971-10-31 switch was at 02:00, even though London's was 03:00. # --- 681,687 ---- # The following claims by Shanks are possible though doubtful; # we'll ignore them for now. # * Jersey, Guernsey, and the Isle of Man did not switch from GMT ! # to daylight saving time until 1921 Apr 3, when they began to # conform with Great Britain. # * Dublin's 1971-10-31 switch was at 02:00, even though London's was 03:00. # *************** *** 1047,1053 **** 1:00 - CET 1941 Apr 18 23:00 1:00 C-Eur CE%sT 1945 May 8 2:00s 1:00 1:00 CEST 1945 Sep 16 2:00s ! 1:00 - CET 1982 Oct 11 1:00 EU CE%sT # Bulgaria --- 1047,1053 ---- 1:00 - CET 1941 Apr 18 23:00 1:00 C-Eur CE%sT 1945 May 8 2:00s 1:00 1:00 CEST 1945 Sep 16 2:00s ! 1:00 - CET 1982 Nov 27 1:00 EU CE%sT # Bulgaria *************** *** 1073,1079 **** 1:00 - CET 1941 Apr 18 23:00 1:00 C-Eur CE%sT 1945 May 8 2:00s 1:00 1:00 CEST 1945 Sep 16 2:00s ! 1:00 - CET 1982 Oct 11 1:00 EU CE%sT # Czech Republic --- 1073,1079 ---- 1:00 - CET 1941 Apr 18 23:00 1:00 C-Eur CE%sT 1945 May 8 2:00s 1:00 1:00 CEST 1945 Sep 16 2:00s ! 1:00 - CET 1982 Nov 27 1:00 EU CE%sT # Czech Republic *************** *** 1572,1578 **** 1:00 - CET 1941 Apr 18 23:00 1:00 C-Eur CE%sT 1945 May 8 2:00s 1:00 1:00 CEST 1945 Sep 16 2:00s ! 1:00 - CET 1982 Oct 11 1:00 EU CE%sT # Malta --- 1572,1578 ---- 1:00 - CET 1941 Apr 18 23:00 1:00 C-Eur CE%sT 1945 May 8 2:00s 1:00 1:00 CEST 1945 Sep 16 2:00s ! 1:00 - CET 1982 Nov 27 1:00 EU CE%sT # Malta *************** *** 1968,1974 **** 1:00 - CET 1941 Apr 18 23:00 1:00 C-Eur CE%sT 1945 May 8 2:00s 1:00 1:00 CEST 1945 Sep 16 2:00s ! 1:00 - CET 1982 Oct 11 1:00 EU CE%sT # Spain --- 1968,1974 ---- 1:00 - CET 1941 Apr 18 23:00 1:00 C-Eur CE%sT 1945 May 8 2:00s 1:00 1:00 CEST 1945 Sep 16 2:00s ! 1:00 - CET 1982 Nov 27 1:00 EU CE%sT # Spain *************** *** 2209,2217 **** 1:00 C-Eur CE%sT 1945 May 8 2:00s 1:00 1:00 CEST 1945 Sep 16 2:00s # Metod Kozelj <metod.kozelj(a)rzs-hm.si> reports that the legal date of ! # transition to EU rules was 1982-10-11, for all of Yugoslavia at the time. # Shanks doesn't give as much detail, so go with Kozelj. ! 1:00 - CET 1982 Oct 11 1:00 EU CE%sT ############################################################################### --- 2209,2217 ---- 1:00 C-Eur CE%sT 1945 May 8 2:00s 1:00 1:00 CEST 1945 Sep 16 2:00s # Metod Kozelj <metod.kozelj(a)rzs-hm.si> reports that the legal date of ! # transition to EU rules was 1982-11-27, for all of Yugoslavia at the time. # Shanks doesn't give as much detail, so go with Kozelj. ! 1:00 - CET 1982 Nov 27 1:00 EU CE%sT ############################################################################### =================================================================== RCS file: RCS/northamerica,v retrieving revision 1997.5 retrieving revision 1997.5.0.1 diff -c -r1997.5 -r1997.5.0.1 *** northamerica 1997/03/29 17:48:52 1997.5 --- northamerica 1997/08/29 08:34:24 1997.5.0.1 *************** *** 1249,1256 **** -4:00 - AST # Montserrat # Zone NAME GMTOFF RULES FORMAT [UNTIL] ! Zone America/Montserrat -4:08:52 - LMT 1911 Jul 1 0:01 # Plymouth -4:00 - AST # Nicaragua --- 1249,1259 ---- -4:00 - AST # Montserrat + # From Paul Eggert (1997-08-29): + # Recent volcanic eruptions have forced evacuation of Plymouth, the capital. + # 4:08 is a guess at the longitude of Olveston, the current de facto capital. # Zone NAME GMTOFF RULES FORMAT [UNTIL] ! Zone America/Montserrat -4:08 - LMT 1911 Jul 1 0:01 # Olveston -4:00 - AST # Nicaragua =================================================================== RCS file: RCS/southamerica,v retrieving revision 1997.5 retrieving revision 1997.5.0.1 diff -c -r1997.5 -r1997.5.0.1 *** southamerica 1997/03/29 17:48:52 1997.5 --- southamerica 1997/08/29 08:34:24 1997.5.0.1 *************** *** 533,539 **** Rule Uruguay 1989 only - Oct 29 0:00 1:00 S Rule Uruguay 1990 1992 - Mar Sun>=1 0:00 0 - Rule Uruguay 1990 1991 - Oct Sun>=21 0:00 1:00 S ! Rule Uruguay 1992 1993 - Oct Sun>=15 0:00 1:00 S Rule Uruguay 1993 only - Feb 28 0:00 0 - # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone America/Montevideo -3:44:44 - LMT 1898 Jun 28 --- 533,541 ---- Rule Uruguay 1989 only - Oct 29 0:00 1:00 S Rule Uruguay 1990 1992 - Mar Sun>=1 0:00 0 - Rule Uruguay 1990 1991 - Oct Sun>=21 0:00 1:00 S ! # Shanks's 4th edition (1995) says no DST was observed in 1990/1 and 1991/2, ! # and that 1992/3's DST was from 10-25 to 03-01. Go with IATA. ! Rule Uruguay 1992 only - Oct 18 0:00 1:00 S Rule Uruguay 1993 only - Feb 28 0:00 0 - # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone America/Montevideo -3:44:44 - LMT 1898 Jun 28

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FW: Error in timezone data
by Olson, Arthur David Aug. 28, 1997

Aug. 28, 1997

---------- From: Lee Steakley[SMTP:lee_steakley@eagle1.turner.com] Sent: Wednesday, August 27, 1997 4:37 PM To: tz(a)elsie.nci.nih.gov Subject: Error in timezone data I believe I found an error in the summer-time rules for Uruguay. The latest version of the data (1997g) has the following as the last few lines of the Uruguay rule: Rule Uruguay 1989 only - Mar 12 0:00 0 - Rule Uruguay 1989 only - Oct 29 0:00 1:00 S Rule Uruguay 1990 1992 - Mar Sun>=1 0:00 0 - Rule Uruguay 1990 1991 - Oct Sun>=21 0:00 1:00 S Rule Uruguay 1992 1993 - Oct Sun>=15 0:00 1:00 S Rule Uruguay 1993 only - Feb 28 0:00 0 - I think the intent is to stop observing summer time after 1993 Feb 28. However, the effect is to keep summer time forever after 1993 Oct. I believe the next-to-last line should read: Rule Uruguay 1992 only - Oct Sun>=15 0:00 1:00 S That way, the change to standard time on 1993 Feb 28 is the last rule executed. On a personal note, I just want to thank you for going to all the trouble of compiling this vast repository of time zone information. I couldn't imagine trying to pull all this together myself. Thanks also for supplying it so freely to the Internet community.

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Error in timezone data
by Lee Steakley Aug. 27, 1997

Aug. 27, 1997

I believe I found an error in the summer-time rules for Uruguay. The latest version of the data (1997g) has the following as the last few lines of the Uruguay rule: Rule Uruguay 1989 only - Mar 12 0:00 0 - Rule Uruguay 1989 only - Oct 29 0:00 1:00 S Rule Uruguay 1990 1992 - Mar Sun>=1 0:00 0 - Rule Uruguay 1990 1991 - Oct Sun>=21 0:00 1:00 S Rule Uruguay 1992 1993 - Oct Sun>=15 0:00 1:00 S Rule Uruguay 1993 only - Feb 28 0:00 0 - I think the intent is to stop observing summer time after 1993 Feb 28. However, the effect is to keep summer time forever after 1993 Oct. I believe the next-to-last line should read: Rule Uruguay 1992 only - Oct Sun>=15 0:00 1:00 S That way, the change to standard time on 1993 Feb 28 is the last rule executed. On a personal note, I just want to thank you for going to all the trouble of compiling this vast repository of time zone information. I couldn't imagine trying to pull all this together myself. Thanks also for supplying it so freely to the Internet community.

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RE: bug in mktime() normalization?
by Olson, Arthur David Aug. 25, 1997

Aug. 25, 1997

Below find changes to localtime.c designed to deal with the situation described by Tom Peterson. The challenge we're faced with is that we don't want to prematurely normalize the tm_sec field in a structure passed to "mktime"--the field might contain a value associated with a leap second. The approach taken below is to first do things without normalizing but, if that fails, to do things using normalization. My check indicates that this approach gives the desired behavior in the example program provided by Tom. --ado *** 7.61/localtime.c Mon Aug 25 13:23:24 1997 --- 7.62/localtime.c Mon Aug 25 13:23:25 1997 *************** *** 5,11 **** #ifndef lint #ifndef NOID ! static char elsieid[] = "@(#)localtime.c 7.61"; #endif /* !defined NOID */ #endif /* !defined lint */ --- 5,11 ---- #ifndef lint #ifndef NOID ! static char elsieid[] = "@(#)localtime.c 7.62"; #endif /* !defined NOID */ #endif /* !defined lint */ *************** *** 134,139 **** --- 134,143 ---- void(*funcp) P((const time_t *, long, struct tm*)), long offset, int * okayp)); + static time_t time2sub P((struct tm *tmp, + void(*funcp) P((const time_t *, + long, struct tm*)), + long offset, int * okayp, int do_norm_secs)); static void timesub P((const time_t * timep, long offset, const struct state * sp, struct tm * tmp)); static int tmcomp P((const struct tm * atmp, *************** *** 1276,1286 **** } static time_t ! time2(tmp, funcp, offset, okayp) struct tm * const tmp; void (* const funcp) P((const time_t*, long, struct tm*)); const long offset; int * const okayp; { register const struct state * sp; register int dir; --- 1280,1291 ---- } static time_t ! time2sub(tmp, funcp, offset, okayp, do_norm_secs) struct tm * const tmp; void (* const funcp) P((const time_t*, long, struct tm*)); const long offset; int * const okayp; + const int do_norm_secs; { register const struct state * sp; register int dir; *************** *** 1293,1298 **** --- 1298,1308 ---- *okayp = FALSE; yourtm = *tmp; + if (do_norm_secs) { + if (normalize_overflow(&yourtm.tm_min, &yourtm.tm_sec, + SECSPERMIN)) + return WRONG; + } if (normalize_overflow(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR)) return WRONG; if (normalize_overflow(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY)) *************** *** 1421,1426 **** --- 1431,1454 ---- return t; } + static time_t + time2(tmp, funcp, offset, okayp) + struct tm * const tmp; + void (* const funcp) P((const time_t*, long, struct tm*)); + const long offset; + int * const okayp; + { + time_t t; + + /* + ** First try without normalization of seconds + ** (in case tm_sec contains a value associated with a leap second). + ** If that fails, try with normalization of seconds. + */ + t = time2sub(tmp, funcp, offset, okayp, FALSE); + return *okayp ? t : time2sub(tmp, funcp, offset, okayp, TRUE); + } + static time_t time1(tmp, funcp, offset) struct tm * const tmp;

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Free Upgrades for Government Travelers
by info＠netexpedite.com Aug. 21, 1997

Aug. 21, 1997

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