1200832Sedwin@(#)Theory 8.4 2192890SedwinThis file is in the public domain, so clarified as of 3192890Sedwin2009-05-17 by Arthur David Olson. 4192625Sedwin$FreeBSD$ 52702Swollman 642991Swollman----- Outline ----- 742991Swollman 842991Swollman Time and date functions 942991Swollman Names of time zone regions 1042991Swollman Time zone abbreviations 11130777Sstefanf Calendrical issues 12130777Sstefanf Time and time zones on Mars 1342991Swollman 1442991Swollman----- Time and date functions ----- 1542991Swollman 16192625SedwinThese time and date functions are upwards compatible with POSIX, 17130777Sstefanfan international standard for UNIX-like systems. 18192625SedwinAs of this writing, the current edition of POSIX is: 1942991Swollman 20192625Sedwin Standard for Information technology 21192625Sedwin -- Portable Operating System Interface (POSIX (R)) 22192625Sedwin -- System Interfaces 23192625Sedwin IEEE Std 1003.1, 2004 Edition 24192625Sedwin <http://www.opengroup.org/online-pubs?DOC=7999959899> 25192625Sedwin <http://www.opengroup.org/pubs/catalog/t041.htm> 2642991Swollman 27192625SedwinPOSIX has the following properties and limitations. 2842991Swollman 29192625Sedwin* In POSIX, time display in a process is controlled by the 30192625Sedwin environment variable TZ. Unfortunately, the POSIX TZ string takes 3142991Swollman a form that is hard to describe and is error-prone in practice. 32192625Sedwin Also, POSIX TZ strings can't deal with other (for example, Israeli) 3342991Swollman daylight saving time rules, or situations where more than two 342702Swollman time zone abbreviations are used in an area. 352702Swollman 36192625Sedwin The POSIX TZ string takes the following form: 3742991Swollman 3842991Swollman stdoffset[dst[offset],date[/time],date[/time]] 3942991Swollman 4042991Swollman where: 41130777Sstefanf 4242991Swollman std and dst 4342991Swollman are 3 or more characters specifying the standard 4442991Swollman and daylight saving time (DST) zone names. 45192625Sedwin Starting with POSIX.1-2001, std and dst may also be 46192625Sedwin in a quoted form like "<UTC+10>"; this allows 47192625Sedwin "+" and "-" in the names. 4842991Swollman offset 4942991Swollman is of the form `[-]hh:[mm[:ss]]' and specifies the 5042991Swollman offset west of UTC. The default DST offset is one hour 5142991Swollman ahead of standard time. 5242991Swollman date[/time],date[/time] 5342991Swollman specifies the beginning and end of DST. If this is absent, 5442991Swollman the system supplies its own rules for DST, and these can 5542991Swollman differ from year to year; typically US DST rules are used. 5642991Swollman time 5742991Swollman takes the form `hh:[mm[:ss]]' and defaults to 02:00. 5842991Swollman date 5942991Swollman takes one of the following forms: 6042991Swollman Jn (1<=n<=365) 6142991Swollman origin-1 day number not counting February 29 6242991Swollman n (0<=n<=365) 6342991Swollman origin-0 day number counting February 29 if present 6442991Swollman Mm.n.d (0[Sunday]<=d<=6[Saturday], 1<=n<=5, 1<=m<=12) 6542991Swollman for the dth day of week n of month m of the year, 6642991Swollman where week 1 is the first week in which day d appears, 6742991Swollman and `5' stands for the last week in which day d appears 6842991Swollman (which may be either the 4th or 5th week). 6942991Swollman 70192625Sedwin Here is an example POSIX TZ string, for US Pacific time using rules 71192625Sedwin appropriate from 1987 through 2006: 72192625Sedwin 73192625Sedwin TZ='PST8PDT,M4.1.0/02:00,M10.5.0/02:00' 74192625Sedwin 75192625Sedwin This POSIX TZ string is hard to remember, and mishandles time stamps 76192625Sedwin before 1987 and after 2006. With this package you can use this 77192625Sedwin instead: 78192625Sedwin 79192625Sedwin TZ='America/Los_Angeles' 80192625Sedwin 81192625Sedwin* POSIX does not define the exact meaning of TZ values like "EST5EDT". 82192625Sedwin Typically the current US DST rules are used to interpret such values, 8342991Swollman but this means that the US DST rules are compiled into each program 8442991Swollman that does time conversion. This means that when US time conversion 852702Swollman rules change (as in the United States in 1987), all programs that 862702Swollman do time conversion must be recompiled to ensure proper results. 872702Swollman 88192625Sedwin* In POSIX, there's no tamper-proof way for a process to learn the 892702Swollman system's best idea of local wall clock. (This is important for 902702Swollman applications that an administrator wants used only at certain times-- 912702Swollman without regard to whether the user has fiddled the "TZ" environment 9242991Swollman variable. While an administrator can "do everything in UTC" to get 932702Swollman around the problem, doing so is inconvenient and precludes handling 9442991Swollman daylight saving time shifts--as might be required to limit phone 952702Swollman calls to off-peak hours.) 962702Swollman 97192625Sedwin* POSIX requires that systems ignore leap seconds. 982702Swollman 99192625SedwinThese are the extensions that have been made to the POSIX functions: 1002702Swollman 1012702Swollman* The "TZ" environment variable is used in generating the name of a file 1022702Swollman from which time zone information is read (or is interpreted a la 1032702Swollman POSIX); "TZ" is no longer constrained to be a three-letter time zone 1042702Swollman name followed by a number of hours and an optional three-letter 1052702Swollman daylight time zone name. The daylight saving time rules to be used 1062702Swollman for a particular time zone are encoded in the time zone file; 1072702Swollman the format of the file allows U.S., Australian, and other rules to be 1082702Swollman encoded, and allows for situations where more than two time zone 1092702Swollman abbreviations are used. 1102702Swollman 1112702Swollman It was recognized that allowing the "TZ" environment variable to 11217211Swollman take on values such as "America/New_York" might cause "old" programs 1132702Swollman (that expect "TZ" to have a certain form) to operate incorrectly; 1142702Swollman consideration was given to using some other environment variable 1152702Swollman (for example, "TIMEZONE") to hold the string used to generate the 1162702Swollman time zone information file name. In the end, however, it was decided 1172702Swollman to continue using "TZ": it is widely used for time zone purposes; 1182702Swollman separately maintaining both "TZ" and "TIMEZONE" seemed a nuisance; 1192702Swollman and systems where "new" forms of "TZ" might cause problems can simply 1202702Swollman use TZ values such as "EST5EDT" which can be used both by 1212702Swollman "new" programs (a la POSIX) and "old" programs (as zone names and 1222702Swollman offsets). 1232702Swollman 1242702Swollman* To handle places where more than two time zone abbreviations are used, 1252702Swollman the functions "localtime" and "gmtime" set tzname[tmp->tm_isdst] 1262702Swollman (where "tmp" is the value the function returns) to the time zone 127192625Sedwin abbreviation to be used. This differs from POSIX, where the elements 1282702Swollman of tzname are only changed as a result of calls to tzset. 1292702Swollman 1302702Swollman* Since the "TZ" environment variable can now be used to control time 1312702Swollman conversion, the "daylight" and "timezone" variables are no longer 13242991Swollman needed. (These variables are defined and set by "tzset"; however, their 1332702Swollman values will not be used by "localtime.") 1342702Swollman 1352702Swollman* The "localtime" function has been set up to deliver correct results 1362702Swollman for near-minimum or near-maximum time_t values. (A comment in the 1372702Swollman source code tells how to get compatibly wrong results). 1382702Swollman 1392702Swollman* A function "tzsetwall" has been added to arrange for the system's 1402702Swollman best approximation to local wall clock time to be delivered by 1412702Swollman subsequent calls to "localtime." Source code for portable 1422702Swollman applications that "must" run on local wall clock time should call 14317211Swollman "tzsetwall();" if such code is moved to "old" systems that don't 14417211Swollman provide tzsetwall, you won't be able to generate an executable program. 1452702Swollman (These time zone functions also arrange for local wall clock time to be 1462702Swollman used if tzset is called--directly or indirectly--and there's no "TZ" 1472702Swollman environment variable; portable applications should not, however, rely 1482702Swollman on this behavior since it's not the way SVR2 systems behave.) 1492702Swollman 150192625Sedwin* These functions can account for leap seconds, thanks to Bradley White. 1512702Swollman 15242991SwollmanPoints of interest to folks with other systems: 15342991Swollman 15442991Swollman* This package is already part of many POSIX-compliant hosts, 15542991Swollman including BSD, HP, Linux, Network Appliance, SCO, SGI, and Sun. 15642991Swollman On such hosts, the primary use of this package 15742991Swollman is to update obsolete time zone rule tables. 15842991Swollman To do this, you may need to compile the time zone compiler 15942991Swollman `zic' supplied with this package instead of using the system `zic', 16042991Swollman since the format of zic's input changed slightly in late 1994, 16142991Swollman and many vendors still do not support the new input format. 16242991Swollman 163130777Sstefanf* The UNIX Version 7 "timezone" function is not present in this package; 1642702Swollman it's impossible to reliably map timezone's arguments (a "minutes west 1652702Swollman of GMT" value and a "daylight saving time in effect" flag) to a 1662702Swollman time zone abbreviation, and we refuse to guess. 1672702Swollman Programs that in the past used the timezone function may now examine 1682702Swollman tzname[localtime(&clock)->tm_isdst] to learn the correct time 16917211Swollman zone abbreviation to use. Alternatively, use 17017211Swollman localtime(&clock)->tm_zone if this has been enabled. 1712702Swollman 17242991Swollman* The 4.2BSD gettimeofday function is not used in this package. 17342991Swollman This formerly let users obtain the current UTC offset and DST flag, 17442991Swollman but this functionality was removed in later versions of BSD. 1752702Swollman 17642991Swollman* In SVR2, time conversion fails for near-minimum or near-maximum 17742991Swollman time_t values when doing conversions for places that don't use UTC. 17842991Swollman This package takes care to do these conversions correctly. 17942991Swollman 18017211SwollmanThe functions that are conditionally compiled if STD_INSPIRED is defined 18117211Swollmanshould, at this point, be looked on primarily as food for thought. They are 18217211Swollmannot in any sense "standard compatible"--some are not, in fact, specified in 18317211Swollman*any* standard. They do, however, represent responses of various authors to 1842702Swollmanstandardization proposals. 1852702Swollman 1862702SwollmanOther time conversion proposals, in particular the one developed by folks at 1872702SwollmanHewlett Packard, offer a wider selection of functions that provide capabilities 1882702Swollmanbeyond those provided here. The absence of such functions from this package 1892702Swollmanis not meant to discourage the development, standardization, or use of such 1902702Swollmanfunctions. Rather, their absence reflects the decision to make this package 191192625Sedwincontain valid extensions to POSIX, to ensure its broad acceptability. If 192192625Sedwinmore powerful time conversion functions can be standardized, so much the 193192625Sedwinbetter. 19442991Swollman 19542991Swollman 19642991Swollman----- Names of time zone rule files ----- 19742991Swollman 198130777SstefanfThe time zone rule file naming conventions attempt to strike a balance 199130777Sstefanfamong the following goals: 20042991Swollman 201130777Sstefanf * Uniquely identify every national region where clocks have all 202130777Sstefanf agreed since 1970. This is essential for the intended use: static 203130777Sstefanf clocks keeping local civil time. 204130777Sstefanf 205130777Sstefanf * Indicate to humans as to where that region is. This simplifes use. 206130777Sstefanf 207130777Sstefanf * Be robust in the presence of political changes. This reduces the 208130777Sstefanf number of updates and backward-compatibility hacks. For example, 209130777Sstefanf names of countries are ordinarily not used, to avoid 210130777Sstefanf incompatibilities when countries change their name 211130777Sstefanf (e.g. Zaire->Congo) or when locations change countries 212130777Sstefanf (e.g. Hong Kong from UK colony to China). 213130777Sstefanf 214130777Sstefanf * Be portable to a wide variety of implementations. 215130777Sstefanf This promotes use of the technology. 216130777Sstefanf 217130777Sstefanf * Use a consistent naming convention over the entire world. 218130777Sstefanf This simplifies both use and maintenance. 219130777Sstefanf 220130777SstefanfThis naming convention is not intended for use by inexperienced users 221130777Sstefanfto select TZ values by themselves (though they can of course examine 222130777Sstefanfand reuse existing settings). Distributors should provide 223130777Sstefanfdocumentation and/or a simple selection interface that explains the 224130777Sstefanfnames; see the 'tzselect' program supplied with this distribution for 225130777Sstefanfone example. 226130777Sstefanf 22742991SwollmanNames normally have the form AREA/LOCATION, where AREA is the name 22842991Swollmanof a continent or ocean, and LOCATION is the name of a specific 22942991Swollmanlocation within that region. North and South America share the same 23042991Swollmanarea, `America'. Typical names are `Africa/Cairo', `America/New_York', 23142991Swollmanand `Pacific/Honolulu'. 23242991Swollman 23342991SwollmanHere are the general rules used for choosing location names, 23442991Swollmanin decreasing order of importance: 23542991Swollman 236130777Sstefanf Use only valid POSIX file name components (i.e., the parts of 237130777Sstefanf names other than `/'). Within a file name component, 238130777Sstefanf use only ASCII letters, `.', `-' and `_'. Do not use 239130777Sstefanf digits, as that might create an ambiguity with POSIX 240130777Sstefanf TZ strings. A file name component must not exceed 14 241130777Sstefanf characters or start with `-'. E.g., prefer `Brunei' 242130777Sstefanf to `Bandar_Seri_Begawan'. 24342991Swollman Include at least one location per time zone rule set per country. 244130777Sstefanf One such location is enough. Use ISO 3166 (see the file 245130777Sstefanf iso3166.tab) to help decide whether something is a country. 246192625Sedwin However, uninhabited ISO 3166 regions like Bouvet Island 247192625Sedwin do not need locations, since local time is not defined there. 24842991Swollman If all the clocks in a country's region have agreed since 1970, 24942991Swollman don't bother to include more than one location 25042991Swollman even if subregions' clocks disagreed before 1970. 25142991Swollman Otherwise these tables would become annoyingly large. 25242991Swollman If a name is ambiguous, use a less ambiguous alternative; 25342991Swollman e.g. many cities are named San Jose and Georgetown, so 25442991Swollman prefer `Costa_Rica' to `San_Jose' and `Guyana' to `Georgetown'. 25542991Swollman Keep locations compact. Use cities or small islands, not countries 25642991Swollman or regions, so that any future time zone changes do not split 25742991Swollman locations into different time zones. E.g. prefer `Paris' 25842991Swollman to `France', since France has had multiple time zones. 259130777Sstefanf Use mainstream English spelling, e.g. prefer `Rome' to `Roma', and 26042991Swollman prefer `Athens' to the true name (which uses Greek letters). 261130777Sstefanf The POSIX file name restrictions encourage this rule. 26242991Swollman Use the most populous among locations in a country's time zone, 26342991Swollman e.g. prefer `Shanghai' to `Beijing'. Among locations with 26442991Swollman similar populations, pick the best-known location, 26542991Swollman e.g. prefer `Rome' to `Milan'. 26642991Swollman Use the singular form, e.g. prefer `Canary' to `Canaries'. 26742991Swollman Omit common suffixes like `_Islands' and `_City', unless that 26842991Swollman would lead to ambiguity. E.g. prefer `Cayman' to 26942991Swollman `Cayman_Islands' and `Guatemala' to `Guatemala_City', 27042991Swollman but prefer `Mexico_City' to `Mexico' because the country 27142991Swollman of Mexico has several time zones. 27242991Swollman Use `_' to represent a space. 27342991Swollman Omit `.' from abbreviations in names, e.g. prefer `St_Helena' 27442991Swollman to `St._Helena'. 275130777Sstefanf Do not change established names if they only marginally 276130777Sstefanf violate the above rules. For example, don't change 277130777Sstefanf the existing name `Rome' to `Milan' merely because 278130777Sstefanf Milan's population has grown to be somewhat greater 279130777Sstefanf than Rome's. 280130777Sstefanf If a name is changed, put its old spelling in the `backward' file. 28142991Swollman 28242991SwollmanThe file `zone.tab' lists the geographical locations used to name 283192625Sedwintime zone rule files. It is intended to be an exhaustive list 284192625Sedwinof canonical names for geographic regions. 28542991Swollman 28642991SwollmanOlder versions of this package used a different naming scheme, 28742991Swollmanand these older names are still supported. 288130777SstefanfSee the file `backward' for most of these older names 28942991Swollman(e.g. `US/Eastern' instead of `America/New_York'). 29042991SwollmanThe other old-fashioned names still supported are 29142991Swollman`WET', `CET', `MET', `EET' (see the file `europe'), 29242991Swollmanand `Factory' (see the file `factory'). 29342991Swollman 29442991Swollman 29542991Swollman----- Time zone abbreviations ----- 29642991Swollman 29742991SwollmanWhen this package is installed, it generates time zone abbreviations 298192625Sedwinlike `EST' to be compatible with human tradition and POSIX. 29942991SwollmanHere are the general rules used for choosing time zone abbreviations, 30042991Swollmanin decreasing order of importance: 30142991Swollman 302130777Sstefanf Use abbreviations that consist of three or more ASCII letters. 30342991Swollman Previous editions of this database also used characters like 30442991Swollman ' ' and '?', but these characters have a special meaning to 30542991Swollman the shell and cause commands like 30642991Swollman set `date` 307130777Sstefanf to have unexpected effects. 308130777Sstefanf Previous editions of this rule required upper-case letters, 309130777Sstefanf but the Congressman who introduced Chamorro Standard Time 310130777Sstefanf preferred "ChST", so the rule has been relaxed. 311130777Sstefanf 312130777Sstefanf This rule guarantees that all abbreviations could have 313192625Sedwin been specified by a POSIX TZ string. POSIX 314130777Sstefanf requires at least three characters for an 315192625Sedwin abbreviation. POSIX through 2000 says that an abbreviation 316130777Sstefanf cannot start with ':', and cannot contain ',', '-', 317192625Sedwin '+', NUL, or a digit. POSIX from 2001 on changes this 318192625Sedwin rule to say that an abbreviation can contain only '-', '+', 319192625Sedwin and alphanumeric characters from the portable character set 320192625Sedwin in the current locale. To be portable to both sets of 321130777Sstefanf rules, an abbreviation must therefore use only ASCII 322192625Sedwin letters. 323130777Sstefanf 32442991Swollman Use abbreviations that are in common use among English-speakers, 32542991Swollman e.g. `EST' for Eastern Standard Time in North America. 32642991Swollman We assume that applications translate them to other languages 32742991Swollman as part of the normal localization process; for example, 32842991Swollman a French application might translate `EST' to `HNE'. 329130777Sstefanf 33042991Swollman For zones whose times are taken from a city's longitude, use the 33142991Swollman traditional xMT notation, e.g. `PMT' for Paris Mean Time. 33242991Swollman The only name like this in current use is `GMT'. 333130777Sstefanf 33442991Swollman If there is no common English abbreviation, abbreviate the English 33542991Swollman translation of the usual phrase used by native speakers. 33642991Swollman If this is not available or is a phrase mentioning the country 33742991Swollman (e.g. ``Cape Verde Time''), then: 33842991Swollman 33942991Swollman When a country has a single or principal time zone region, 34042991Swollman append `T' to the country's ISO code, e.g. `CVT' for 34142991Swollman Cape Verde Time. For summer time append `ST'; 34242991Swollman for double summer time append `DST'; etc. 34342991Swollman When a country has multiple time zones, take the first three 34442991Swollman letters of an English place name identifying each zone 34542991Swollman and then append `T', `ST', etc. as before; 34642991Swollman e.g. `VLAST' for VLAdivostok Summer Time. 34742991Swollman 348192625Sedwin Use UTC (with time zone abbreviation "zzz") for locations while 349192625Sedwin uninhabited. The "zzz" mnemonic is that these locations are, 350192625Sedwin in some sense, asleep. 351130777Sstefanf 35242991SwollmanApplication writers should note that these abbreviations are ambiguous 35342991Swollmanin practice: e.g. `EST' has a different meaning in Australia than 35442991Swollmanit does in the United States. In new applications, it's often better 35542991Swollmanto use numeric UTC offsets like `-0500' instead of time zone 35642991Swollmanabbreviations like `EST'; this avoids the ambiguity. 357130777Sstefanf 358130777Sstefanf 359130777Sstefanf----- Calendrical issues ----- 360130777Sstefanf 361130777SstefanfCalendrical issues are a bit out of scope for a time zone database, 362130777Sstefanfbut they indicate the sort of problems that we would run into if we 363130777Sstefanfextended the time zone database further into the past. An excellent 364200832Sedwinresource in this area is Nachum Dershowitz and Edward M. Reingold, 365200832Sedwin<a href="http://emr.cs.iit.edu/home/reingold/calendar-book/third-edition/"> 366200832SedwinCalendrical Calculations: Third Edition 367200832Sedwin</a>, Cambridge University Press (2008). Other information and 368130777Sstefanfsources are given below. They sometimes disagree. 369130777Sstefanf 370130777Sstefanf 371130777SstefanfFrance 372130777Sstefanf 373130777SstefanfGregorian calendar adopted 1582-12-20. 374130777SstefanfFrench Revolutionary calendar used 1793-11-24 through 1805-12-31, 375130777Sstefanfand (in Paris only) 1871-05-06 through 1871-05-23. 376130777Sstefanf 377130777Sstefanf 378130777SstefanfRussia 379130777Sstefanf 380192625SedwinFrom Chris Carrier (1996-12-02): 381130777SstefanfOn 1929-10-01 the Soviet Union instituted an ``Eternal Calendar'' 382130777Sstefanfwith 30-day months plus 5 holidays, with a 5-day week. 383130777SstefanfOn 1931-12-01 it changed to a 6-day week; in 1934 it reverted to the 384130777SstefanfGregorian calendar while retaining the 6-day week; on 1940-06-27 it 385130777Sstefanfreverted to the 7-day week. With the 6-day week the usual days 386130777Sstefanfoff were the 6th, 12th, 18th, 24th and 30th of the month. 387130777Sstefanf(Source: Evitiar Zerubavel, _The Seven Day Circle_) 388130777Sstefanf 389130777Sstefanf 390130777SstefanfMark Brader reported a similar story in "The Book of Calendars", edited 391130777Sstefanfby Frank Parise (1982, Facts on File, ISBN 0-8719-6467-8), page 377. But: 392130777Sstefanf 393130777SstefanfFrom: Petteri Sulonen (via Usenet) 394130777SstefanfDate: 14 Jan 1999 00:00:00 GMT 395192625Sedwin... 396130777Sstefanf 397130777SstefanfIf your source is correct, how come documents between 1929 -- 1940 were 398130777Sstefanfstill dated using the conventional, Gregorian calendar? 399130777Sstefanf 400130777SstefanfI can post a scan of a document dated December 1, 1934, signed by 401130777SstefanfYenukidze, the secretary, on behalf of Kalinin, the President of the 402130777SstefanfExecutive Committee of the Supreme Soviet, if you like. 403130777Sstefanf 404130777Sstefanf 405130777Sstefanf 406130777SstefanfSweden (and Finland) 407130777Sstefanf 408192625SedwinFrom: Mark Brader 409130777Sstefanf<a href="news:1996Jul6.012937.29190@sq.com"> 410130777SstefanfSubject: Re: Gregorian reform -- a part of locale? 411130777Sstefanf</a> 412130777SstefanfDate: 1996-07-06 413130777Sstefanf 414130777SstefanfIn 1700, Denmark made the transition from Julian to Gregorian. Sweden 415130777Sstefanfdecided to *start* a transition in 1700 as well, but rather than have one of 416130777Sstefanfthose unsightly calendar gaps :-), they simply decreed that the next leap 417130777Sstefanfyear after 1696 would be in 1744 -- putting the whole country on a calendar 418130777Sstefanfdifferent from both Julian and Gregorian for a period of 40 years. 419130777Sstefanf 420130777SstefanfHowever, in 1704 something went wrong and the plan was not carried through; 421130777Sstefanfthey did, after all, have a leap year that year. And one in 1708. In 1712 422130777Sstefanfthey gave it up and went back to Julian, putting 30 days in February that 423130777Sstefanfyear!... 424130777Sstefanf 425130777SstefanfThen in 1753, Sweden made the transition to Gregorian in the usual manner, 426130777Sstefanfgetting there only 13 years behind the original schedule. 427130777Sstefanf 428130777Sstefanf(A previous posting of this story was challenged, and Swedish readers 429130777Sstefanfproduced the following references to support it: "Tiderakning och historia" 430130777Sstefanfby Natanael Beckman (1924) and "Tid, en bok om tiderakning och 431130777Sstefanfkalendervasen" by Lars-Olof Lode'n (no date was given).) 432130777Sstefanf 433130777Sstefanf 434130777SstefanfGrotefend's data 435130777Sstefanf 436192625SedwinFrom: "Michael Palmer" [with one obvious typo fixed] 437130777SstefanfSubject: Re: Gregorian Calendar (was Re: Another FHC related question 438130777SstefanfNewsgroups: soc.genealogy.german 439130777SstefanfDate: Tue, 9 Feb 1999 02:32:48 -800 440192625Sedwin... 441130777Sstefanf 442130777SstefanfThe following is a(n incomplete) listing, arranged chronologically, of 443130777SstefanfEuropean states, with the date they converted from the Julian to the 444130777SstefanfGregorian calendar: 445130777Sstefanf 446130777Sstefanf04/15 Oct 1582 - Italy (with exceptions), Spain, Portugal, Poland (Roman 447130777Sstefanf Catholics and Danzig only) 448130777Sstefanf09/20 Dec 1582 - France, Lorraine 449130777Sstefanf 450130777Sstefanf21 Dec 1582/ 451130777Sstefanf 01 Jan 1583 - Holland, Brabant, Flanders, Hennegau 452130777Sstefanf10/21 Feb 1583 - bishopric of Liege (L"uttich) 453130777Sstefanf13/24 Feb 1583 - bishopric of Augsburg 454130777Sstefanf04/15 Oct 1583 - electorate of Trier 455130777Sstefanf05/16 Oct 1583 - Bavaria, bishoprics of Freising, Eichstedt, Regensburg, 456130777Sstefanf Salzburg, Brixen 457130777Sstefanf13/24 Oct 1583 - Austrian Oberelsass and Breisgau 458130777Sstefanf20/31 Oct 1583 - bishopric of Basel 459130777Sstefanf02/13 Nov 1583 - duchy of J"ulich-Berg 460130777Sstefanf02/13 Nov 1583 - electorate and city of K"oln 461130777Sstefanf04/15 Nov 1583 - bishopric of W"urzburg 462130777Sstefanf11/22 Nov 1583 - electorate of Mainz 463130777Sstefanf16/27 Nov 1583 - bishopric of Strassburg and the margraviate of Baden 464130777Sstefanf17/28 Nov 1583 - bishopric of M"unster and duchy of Cleve 465130777Sstefanf14/25 Dec 1583 - Steiermark 466130777Sstefanf 467130777Sstefanf06/17 Jan 1584 - Austria and Bohemia 468130777Sstefanf11/22 Jan 1584 - Luzern, Uri, Schwyz, Zug, Freiburg, Solothurn 469130777Sstefanf12/23 Jan 1584 - Silesia and the Lausitz 470130777Sstefanf22 Jan/ 471130777Sstefanf 02 Feb 1584 - Hungary (legally on 21 Oct 1587) 472130777Sstefanf Jun 1584 - Unterwalden 473130777Sstefanf01/12 Jul 1584 - duchy of Westfalen 474130777Sstefanf 475130777Sstefanf16/27 Jun 1585 - bishopric of Paderborn 476130777Sstefanf 477130777Sstefanf14/25 Dec 1590 - Transylvania 478130777Sstefanf 479130777Sstefanf22 Aug/ 480130777Sstefanf 02 Sep 1612 - duchy of Prussia 481130777Sstefanf 482130777Sstefanf13/24 Dec 1614 - Pfalz-Neuburg 483130777Sstefanf 484130777Sstefanf 1617 - duchy of Kurland (reverted to the Julian calendar in 485130777Sstefanf 1796) 486130777Sstefanf 487130777Sstefanf 1624 - bishopric of Osnabr"uck 488130777Sstefanf 489130777Sstefanf 1630 - bishopric of Minden 490130777Sstefanf 491130777Sstefanf15/26 Mar 1631 - bishopric of Hildesheim 492130777Sstefanf 493130777Sstefanf 1655 - Kanton Wallis 494130777Sstefanf 495130777Sstefanf05/16 Feb 1682 - city of Strassburg 496130777Sstefanf 497130777Sstefanf18 Feb/ 498130777Sstefanf 01 Mar 1700 - Protestant Germany (including Swedish possessions in 499130777Sstefanf Germany), Denmark, Norway 500130777Sstefanf30 Jun/ 501130777Sstefanf 12 Jul 1700 - Gelderland, Zutphen 502130777Sstefanf10 Nov/ 503130777Sstefanf 12 Dec 1700 - Utrecht, Overijssel 504130777Sstefanf 505130777Sstefanf31 Dec 1700/ 506130777Sstefanf 12 Jan 1701 - Friesland, Groningen, Z"urich, Bern, Basel, Geneva, 507130777Sstefanf Turgau, and Schaffhausen 508130777Sstefanf 509130777Sstefanf 1724 - Glarus, Appenzell, and the city of St. Gallen 510130777Sstefanf 511130777Sstefanf01 Jan 1750 - Pisa and Florence 512130777Sstefanf 513130777Sstefanf02/14 Sep 1752 - Great Britain 514130777Sstefanf 515130777Sstefanf17 Feb/ 516130777Sstefanf 01 Mar 1753 - Sweden 517130777Sstefanf 518130777Sstefanf1760-1812 - Graub"unden 519130777Sstefanf 520130777SstefanfThe Russian empire (including Finland and the Baltic states) did not 521130777Sstefanfconvert to the Gregorian calendar until the Soviet revolution of 1917. 522130777Sstefanf 523130777SstefanfSource: H. Grotefend, _Taschenbuch der Zeitrechnung des deutschen 524130777SstefanfMittelalters und der Neuzeit_, herausgegeben von Dr. O. Grotefend 525130777Sstefanf(Hannover: Hahnsche Buchhandlung, 1941), pp. 26-28. 526130777Sstefanf 527130777Sstefanf 528130777Sstefanf----- Time and time zones on Mars ----- 529130777Sstefanf 530130777SstefanfSome people have adjusted their work schedules to fit Mars time. 531130777SstefanfDozens of special Mars watches were built for Jet Propulsion 532130777SstefanfLaboratory workers who kept Mars time during the Mars Exploration 533130777SstefanfRovers mission (2004). These timepieces look like normal Seikos and 534130777SstefanfCitizens but use Mars seconds rather than terrestrial seconds. 535130777Sstefanf 536130777SstefanfA Mars solar day is called a "sol" and has a mean period equal to 537130777Sstefanfabout 24 hours 39 minutes 35.244 seconds in terrestrial time. It is 538130777Sstefanfdivided into a conventional 24-hour clock, so each Mars second equals 539130777Sstefanfabout 1.02749125 terrestrial seconds. 540130777Sstefanf 541130777SstefanfThe prime meridian of Mars goes through the center of the crater 542130777SstefanfAiry-0, named in honor of the British astronomer who built the 543130777SstefanfGreenwich telescope that defines Earth's prime meridian. Mean solar 544130777Sstefanftime on the Mars prime meridian is called Mars Coordinated Time (MTC). 545130777Sstefanf 546130777SstefanfEach landed mission on Mars has adopted a different reference for 547130777Sstefanfsolar time keeping, so there is no real standard for Mars time zones. 548130777SstefanfFor example, the Mars Exploration Rover project (2004) defined two 549130777Sstefanftime zones "Local Solar Time A" and "Local Solar Time B" for its two 550130777Sstefanfmissions, each zone designed so that its time equals local true solar 551130777Sstefanftime at approximately the middle of the nominal mission. Such a "time 552130777Sstefanfzone" is not particularly suited for any application other than the 553130777Sstefanfmission itself. 554130777Sstefanf 555130777SstefanfMany calendars have been proposed for Mars, but none have achieved 556130777Sstefanfwide acceptance. Astronomers often use Mars Sol Date (MSD) which is a 557130777Sstefanfsequential count of Mars solar days elapsed since about 1873-12-29 558130777Sstefanf12:00 GMT. 559130777Sstefanf 560130777SstefanfThe tz database does not currently support Mars time, but it is 561130777Sstefanfdocumented here in the hopes that support will be added eventually. 562130777Sstefanf 563130777SstefanfSources: 564130777Sstefanf 565130777SstefanfMichael Allison and Robert Schmunk, 566130777Sstefanf"Technical Notes on Mars Solar Time as Adopted by the Mars24 Sunclock" 567192625Sedwin<http://www.giss.nasa.gov/tools/mars24/help/notes.html> (2004-07-30). 568130777Sstefanf 569130777SstefanfJia-Rui Chong, "Workdays Fit for a Martian", Los Angeles Times 570130777Sstefanf(2004-01-14), pp A1, A20-A21. 571