72-696: The North American Central Time Zone ( CT ) is a time zone in parts of Canada , the United States , Mexico , Central America , and some Caribbean islands . In parts of that zone (20 states in the US, three provinces or territories in Canada, and several border municipalities in Mexico), the Central Time Zone is affected by two time designations yearly: Central Standard Time (CST) is observed from
144-426: A 30-minute offset. Nepal was the last country to adopt a standard offset, shifting slightly to UTC+05:45 in 1986. All nations currently use standard time zones for secular purposes, but not all of them apply the concept as originally conceived. Several countries and subdivisions use half-hour or quarter-hour deviations from standard time. Some countries, such as China and India , use a single time zone even though
216-564: A C library based on the BSD C library, or the System V Release 4 C library, can make use of this database. Windows -based computer systems prior to Windows 95 and Windows NT used local time, but Windows 95 and later, and Windows NT, base system time on UTC. They allow a program to fetch the system time as UTC, represented as a year, month, day, hour, minute, second, and millisecond; Windows 95 and later, and Windows NT 3.5 and later, also allow
288-574: A May 1915 ordinance settled on EST and was ratified by popular vote in August 1916. The confusion of times came to an end when standard time zones were formally adopted by the U.S. Congress in the Standard Time Act of March 19, 1918. Italian mathematician Quirico Filopanti introduced the idea of a worldwide system of time zones in his book Miranda! , published in 1858. He proposed 24 hourly time zones, which he called "longitudinal days",
360-647: A city whose borders overlap both Alberta and Saskatchewan. The city charter stipulates that it shall observe Mountain Time and DST, putting the community on the same time as all of Alberta (UTC−7) in the winter, and in time with Saskatchewan (UTC−6) during the summer. Ten states are contained entirely in the Central Time Zone: Five states are split between the Central Time Zone and the Mountain Time Zone : Five states are split between
432-480: A clock for each railroad, each showing a different time. Because of this a number of accidents occurred when trains from different companies using the same tracks mistimed their passings. Around 1863, Charles F. Dowd proposed a system of hourly standard time zones for North American railroads, although he published nothing on the matter at that time and did not consult railroad officials until 1869. In 1870 he proposed four ideal time zones having north–south borders,
504-444: A convenient time, usually at night, not exactly when they cross a certain longitude. Some ships simply remain on the time of the departing port during the whole trip. Ideal time zones, such as nautical time zones, are based on the mean solar time of a particular meridian in the middle of that zone with boundaries located 7.5 degrees east and west of the meridian. In practice, however, many time zone boundaries are drawn much farther to
576-702: A potential deduction of $ 1.80 per sq/ft. Interior lighting may also be improved using the Interim Lighting Rule, which provides a simplified process to earn the Deduction, capped at $ 0.30-$ 0.60/square foot. Improvements are compared to a baseline of ASHRAE 2001 standards. To obtain these benefits the facilities/energy division of a business, its tax department, and a firm specializing in EPAct 179D deductions needed to cooperate. IRS mandated software had to be used and an independent 3rd party had to certify
648-744: A standard reference time while each location in England kept a different time. In the 19th century, as transportation and telecommunications improved, it became increasingly inconvenient for each location to observe its own solar time. In November 1840, the British Great Western Railway started using GMT kept by portable chronometers . This practice was soon followed by other railway companies in Great Britain and became known as railway time . Around August 23, 1852, time signals were first transmitted by telegraph from
720-479: A standard time zone, but only some of them used an hourly offset from GMT. Many applied the time at a local astronomical observatory to an entire country, without any reference to GMT. It took many decades before all time zones were based on some standard offset from GMT or Coordinated Universal Time (UTC). By 1929, the majority of countries had adopted hourly time zones, though some countries such as Iran , India , Myanmar and parts of Australia had time zones with
792-444: A uniform standard time for legal , commercial and social purposes. Time zones tend to follow the boundaries between countries and their subdivisions instead of strictly following longitude , because it is convenient for areas in frequent communication to keep the same time. Each time zone is defined by a standard offset from Coordinated Universal Time (UTC). The offsets range from UTC−12:00 to UTC+14:00 , and are usually
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#1732772961817864-461: A whole number of hours, but a few zones are offset by an additional 30 or 45 minutes, such as in India and Nepal . Some areas in a time zone may use a different offset for part of the year, typically one hour ahead during spring and summer , a practice known as daylight saving time (DST). In the table below, the locations that use daylight saving time (DST) are listed in their UTC offset when DST
936-567: Is not in effect. When DST is in effect, approximately during spring and summer, their UTC offset is increased by one hour (except for Lord Howe Island , where it is increased by 30 minutes). For example, during the DST period California observes UTC−07:00 and the United Kingdom observes UTC+01:00 . The apparent position of the Sun in the sky, and thus solar time , varies by location due to
1008-407: Is 11 hours 30 minutes ahead of GMT. This standard was known as New Zealand Mean Time . Timekeeping on North American railroads in the 19th century was complex. Each railroad used its own standard time, usually based on the local time of its headquarters or most important terminus, and the railroad's train schedules were published using its own time. Some junctions served by several railroads had
1080-628: Is a standard established by the International Organization for Standardization defining methods of representing dates and times in textual form, including specifications for representing time zones. If a time is in Coordinated Universal Time (UTC), a "Z" is added directly after the time without a separating space. "Z" is the zone designator for the zero UTC offset. "09:30 UTC" is therefore represented as "09:30Z" or "0930Z". Likewise, "14:45:15 UTC"
1152-629: Is appended to local times in the same way that alphabetic time zone abbreviations (or "Z", as above) are appended. The offset from UTC changes with daylight saving time , e.g. a time offset in Chicago , which is in the North American Central Time Zone , is " −06:00 " for the winter (Central Standard Time) and " −05:00 " for the summer (Central Daylight Time). Time zones are often represented by alphabetic abbreviations such as "EST", "WST", and "CST", but these are not part of
1224-646: Is called "Central Daylight Time" (CDT) and is UTC−05:00 . In the United States, all time zones that observe DST were effectively changed by the Energy Policy Act of 2005 . Beginning in 2007, DST would now begin at 2 a.m. (02:00) on the second Sunday in March instead of the first Sunday in April, moving the time from 2 to 3 a.m. (i.e., from 02:00 to 03:00). Additionally, DST would end at 2 a.m. (02:00) on
1296-543: Is extended beyond December 31, 2013, is also effective (except as otherwise provided in an amendment of §179D or the guidance thereunder) during the period of the extension. The Congressional Budget Office (CBO) review of the conference version of the bill estimated the Act would increase direct spending by $ 2.2 billion over the 2006–2010 period, and by $ 1.6 billion over the 2006–2015 period. The CBO did not attempt to estimate additional effects on discretionary spending. The CBO and
1368-545: Is known locally as the Zona Centro . The federal entities of Mexico that observe Central Time: Out of the seven countries comprising Central America , all but one use Central Standard Time year-round: Panama , which recognizes Eastern Standard Time (UTC−5) year round, is the exception. Daylight saving time (DST) is in effect in much of the Central time zone between mid-March and early November. The modified time
1440-400: Is the only province or territory in Canada that observes Central Time in all areas. The following Canadian provinces and territories observe Central Time in the areas noted, while their other areas observe Eastern Time : Also, most of the province of Saskatchewan is on Central Standard Time year-round, never adjusting for Daylight Saving Time. One major exception includes Lloydminster ,
1512-467: Is to allow the more efficient use of afternoon sunlight. Some of these locations also use daylight saving time (DST), further increasing the difference to local solar time. As a result, in summer, solar noon in the Spanish city of Vigo occurs at 14:41 clock time. This westernmost area of continental Spain never experiences sunset before 18:00 clock time, even in winter, despite lying 42 degrees north of
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#17327729618171584-599: Is updated whenever time zone or daylight saving time rules change. Oracle provides an updater tool for this purpose. As an alternative to the information bundled with the Java Platform, programmers may choose to use the Joda-Time library. This library includes its own data based on the IANA time zone database. As of Java 8 there is a new date and time API that can help with converting times. Traditionally, there
1656-403: Is usually converted to local time when displayed to the user, and times specified by the user in local time are converted to Unix time. The conversion takes into account the time zone and daylight saving time rules; by default the time zone and daylight saving time rules are set up when the system is configured, though individual processes can specify time zones and daylight saving time rules using
1728-533: Is written as "14:45:15Z" or "144515Z". UTC time is also known as "Zulu" time, since "Zulu" is a phonetic alphabet code word for the letter "Z". Offsets from UTC are written in the format ±hh:mm, ±hhmm, or ±hh (either hours ahead or behind UTC). For example, if the time being described is one hour ahead of UTC (such as the time in Germany during the winter), the zone designator would be " +01:00 ", "+0100", or simply "+01". This numeric representation of time zones
1800-544: The IANA time zone database and includes the ability to get, set and convert between time zones. The DateTime objects and related functions have been compiled into the PHP core since 5.2. This includes the ability to get and set the default script time zone, and DateTime is aware of its own time zone internally. PHP.net provides extensive documentation on this. As noted there, the most current time zone database can be implemented via
1872-617: The PECL timezonedb. Energy Policy Act of 2005 The Energy Policy Act of 2005 ( Pub. L. 109–58 (text) (PDF) ) is a federal law signed by President George W. Bush on August 8, 2005, at Sandia National Laboratories in Albuquerque, New Mexico . The act, described by proponents as an attempt to combat growing energy problems, changed US energy policy by providing tax incentives and loan guarantees for energy production of various types. The most consequential aspect of
1944-513: The TZ environment variable . This allows users in multiple time zones, or in the same time zone but with different daylight saving time rules, to use the same computer, with their respective local times displayed correctly to each user. Time zone and daylight saving time rule information most commonly comes from the IANA time zone database . In fact, many systems, including anything using the GNU C Library ,
2016-645: The bill . John McCain , the Republican Party nominee for President of the United States in the 2008 election voted against the bill. Democrat Barack Obama , President of the United States from January 2009 to January 2017, voted in favor of the bill. To remove from 18 CFR Part 366.1 the definitions of "electric utility company" and exempt wholesale generator (EWG), that an EWG is not an electric utility company. June 28, 2005, 10:00 a.m. Yeas - 85, Nays - 12 The bill's conference committee included 14 Senators and 51 House members. The senators on
2088-416: The high seas . As an ideal form of the terrestrial time zone system, nautical time zones consist of gores of 15° offset from GMT by a whole number of hours. A nautical date line follows the 180th meridian, bisecting one 15° gore into two 7.5° gores that differ from GMT by ±12 hours. However, in practice each ship may choose what time to observe at each location. Ships may decide to adjust their clocks at
2160-624: The spherical shape of the Earth. This variation corresponds to four minutes of time for every degree of longitude , so for example when it is solar noon in London , it is about 10 minutes before solar noon in Bristol , which is about 2.5 degrees to the west. The Royal Observatory, Greenwich , founded in 1675, established Greenwich Mean Time (GMT), the mean solar time at that location, as an aid to mariners to determine longitude at sea, providing
2232-533: The Central Time Zone and the Eastern Time Zone : Additionally, Phenix City, Alabama , and several nearby communities in Russell County, Alabama , unofficially observe Eastern Time. This is due to their close proximity to Columbus, Georgia , which is on Eastern Time. Although legally located within the Central Time Zone, Kenton, Oklahoma —located to the adjacent east of the defined border of
Central Time Zone - Misplaced Pages Continue
2304-541: The Central and Mountain time zones (at the Oklahoma− New Mexico state line)—unofficially observes Mountain Time. This is reportedly because most people who interact with the town reside in either New Mexico or Colorado . Most of Mexico—roughly the eastern three-fourths—lies in the Central Time Zone, except for five northwestern states ( Baja California , Baja California Sur , Sinaloa , Sonora , and most of Nayarit ) and one southeastern state ( Quintana Roo ). It
2376-651: The Energy Efficient Commercial Buildings Tax Deduction , a special financial incentive designed to reduce the initial cost of investing in energy-efficient building systems via an accelerated tax deduction under section §179D of the Internal Revenue Code (IRC) [1] Many building owners are unaware that the [Policy Act of 2005] includes a tax deduction (§179D) for investments in "energy efficient commercial building property" designed to significantly reduce
2448-635: The Joint Committee on Taxation estimated that the legislation would reduce revenues by $ 7.9 billion over the 2005–2010 period and by $ 12.3 billion over the 2005–2015 period. The collective reduction in national consumption of energy (gas and electricity) is significant for home heating. The Act provided gible financial incentives (tax credits) for average homeowners to make environmentally positive changes to their homes. It made improvements to home energy use more affordable for walls, doors, windows, roofs, water heaters, etc. Consumer spending, and hence
2520-993: The National Retinitis Pigmentosa Foundation Fighting Blindness. Lobbyists against this provision included the U.S. Conference of Catholic Bishops , the United Synagogue of Conservative Judaism , the National Parent-Teacher Association , the Calendaring and Scheduling Consortium, the Edison Electric Institute , and the Air Transport Association . This section of the act is controversial; some have questioned whether daylight saving results in net energy savings. The Act created
2592-578: The Royal Observatory. By 1855, 98% of Great Britain's public clocks were using GMT, but it was not made the island's legal time until August 2, 1880. Some British clocks from this period have two minute hands, one for the local time and one for GMT. On November 2, 1868, the British Colony of New Zealand officially adopted a standard time to be observed throughout the colony. It was based on longitude 172°30′ east of Greenwich , that
2664-595: The Terminal Server so that users see the correct time for their time zone in their desktop/application sessions. Terminal Services uses the server base time on the Terminal Server and the client time zone information to calculate the time in the session. While most application software will use the underlying operating system for time zone and daylight saving time rule information, the Java Platform , from version 1.3.1, has maintained its own database of time zone and daylight saving time rule information. This database
2736-536: The US daylight time schedule effective in 2010. In October 2022, however, CDT was used in Mexico for the last time after DST was abolished. The US is also seeing traction in the same direction, with the Sunshine Protection Act that proposes legislation that would permanently end the switching of times and make daylight saving time permanent. Time zone A time zone is an area which observes
2808-486: The US version shows Eastern Time . US Eastern Time and Pacific Time are also used fairly commonly on many US-based English-language websites with global readership. The format is typically based in the W3C Note "datetime". Email systems and other messaging systems ( IRC chat , etc.) time-stamp messages using UTC, or else include the sender's time zone as part of the message, allowing the receiving program to display
2880-506: The area becomes a function of UTC time. The time differences may also result in different dates. For example, when it is 22:00 on Monday in Egypt (UTC+02:00), it is 01:00 on Tuesday in Pakistan (UTC+05:00). The table "Time of day by zone" gives an overview on the time relations between different zones. Since the 1920s, a nautical standard time system has been in operation for ships on
2952-513: The article on daylight saving time for more details on this aspect.) Web servers presenting web pages primarily for an audience in a single time zone or a limited range of time zones typically show times as a local time, perhaps with UTC time in brackets. More internationally oriented websites may show times in UTC only or using an arbitrary time zone. For example, the international English-language version of CNN includes GMT and Hong Kong Time, whereas
Central Time Zone - Misplaced Pages Continue
3024-469: The begin and end dates of daylight saving time are changed, calendar entries should stay the same in local time, even though they may shift in UTC time. Unix-like systems, including Linux and macOS , keep system time in Unix time format, representing the number of seconds (excluding leap seconds ) that have elapsed since 00:00:00 Coordinated Universal Time (UTC) on Thursday, January 1, 1970. Unix time
3096-549: The calendar events are assumed to take place in the time zone the computer or smartphone was on when creating the event. The event can be shown at the wrong time. For example, if a New Yorker plans to meet someone in Los Angeles at 9 am, and makes a calendar entry at 9 am (which the computer assumes is New York time), the calendar entry will be at 6 am if taking the computer's time zone. Calendaring software must also deal with daylight saving time (DST). If, for political reasons,
3168-564: The equation is equivalent to UTC. The conversion equation can be rearranged to For example, the New York Stock Exchange opens at 09:30 ( EST , UTC offset= −05:00). In California ( PST , UTC offset= −08:00) and India ( IST , UTC offset= +05:30), the New York Stock Exchange opens at These calculations become more complicated near the time switch to or from daylight saving time, as the UTC offset for
3240-469: The equator. Near the summer solstice , Vigo has sunset times after 22:00, similar to those of Stockholm , which is in the same time zone and 17 degrees farther north. Stockholm has much earlier sunrises, though. In the United States, the reasons were more historical and business-related. In Midwestern states, like Indiana and Michigan , those living in Indianapolis and Detroit wanted to be on
3312-535: The extent of their territory far exceeds the ideal 15° of longitude for one hour; other countries, such as Spain and Argentina , use standard hour-based offsets, but not necessarily those that would be determined by their geographical location. The consequences, in some areas, can affect the lives of local citizens, and in extreme cases contribute to larger political issues, such as in the western reaches of China. In Russia, which has 11 time zones , two time zones were removed in 2010 and reinstated in 2014. ISO 8601
3384-626: The first Sunday in November instead of the last Sunday in October, moving the time from 2 to 1 a.m. (i.e., from 02:00 to 01:00). At the time, Mexico decided not to go along with this change and observed their horario de verano ("summer schedule") from the first Sunday in April to the last Sunday in October. In December 2009, the Mexican Congress allowed ten border cities, eight of which are in states that observe Central Time, to adopt
3456-432: The first Sunday in November to the second Sunday in March. It is six hours behind Coordinated Universal Time (UTC) and designated internationally as UTC−6. From the second Sunday in March to the first Sunday in November the same areas observe daylight saving time (DST), creating the designation of Central Daylight Time (CDT) which is five hours behind UTC and known internationally as UTC−5. The province of Manitoba
3528-582: The first Sunday of April (April 1, 2007). Clocks were set back one hour on the first Sunday of November (November 4, 2007), rather than on the last Sunday of October (October 28, 2007). This had the net effect of slightly lengthening the duration of daylight saving time. Lobbyists for this provision included the Sporting Goods Manufacturers Association, the National Association of Convenience Stores , and
3600-573: The first centered on Washington, D.C. , but by 1872 the first was centered on meridian 75° west of Greenwich , with natural borders such as sections of the Appalachian Mountains . Dowd's system was never accepted by North American railroads. Chief meteorologist at the United States Weather Bureau Cleveland Abbe divided the United States into four standard time zones for consistency among
3672-532: The first centred on the meridian of Rome . He also proposed a universal time to be used in astronomy and telegraphy. However, his book attracted no attention until long after his death. Scottish -born Canadian Sir Sandford Fleming proposed a worldwide system of time zones in 1876 - see Sandford Fleming § Inventor of worldwide standard time . The proposal divided the world into twenty-four time zones labeled A-Y (skipping J), each one covering 15 degrees of longitude. All clocks within each zone would be set to
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#17327729618173744-449: The greatest terrestrial time zone difference on Earth, with a 3.5 hour difference between Afghanistan's UTC+4:30 and China's UTC+08:00 . Many countries, and sometimes just certain regions of countries, adopt daylight saving time (DST), also known as summer time, during part of the year. This typically involves advancing clocks by an hour near the start of spring and adjusting back in autumn ("spring forward", "fall back"). Modern DST
3816-428: The heating, cooling, water heating and interior lighting cost of new or existing commercial buildings placed into service between January 1, 2006 and December 31, 2013. §179D includes full and partial tax deductions for investments in energy efficient commercial building that are designed to increase the efficiency of energy-consuming functions. Up to $ .60 for lighting, $ .60 for HVAC and $ .60 for building envelope, creating
3888-416: The international time and date standard ISO 8601 . Such designations can be ambiguous; for example, "CST" can mean (North American) Central Standard Time (UTC−06:00), Cuba Standard Time (UTC−05:00) and China Standard Time (UTC+08:00), and it is also a widely used variant of ACST ( Australian Central Standard Time , UTC+09:30). Conversion between time zones obeys the relationship in which each side of
3960-558: The law was to greatly increase ethanol production to be blended with gasoline. The law also repealed the Public Utility Holding Company Act of 1935 , effective February 2006. The law amended the Uniform Time Act of 1966 by changing the start and end dates of daylight saving time , beginning in 2007. Clocks were set ahead one hour on the second Sunday of March (March 11, 2007) instead of on
4032-653: The message's date and time of sending in the recipient's local time. Database records that include a time stamp typically use UTC, especially when the database is part of a system that spans multiple time zones. The use of local time for time-stamping records is not recommended for time zones that implement daylight saving time because once a year there is a one-hour period when local times are ambiguous. Calendar systems nowadays usually tie their time stamps to UTC, and show them differently on computers that are in different time zones. That works when having telephone or internet meetings. It works less well when travelling, because
4104-524: The national economy, was abetted. Dependence on imported oil was reduced. The national trade deficit was improved. Industry grew for manufacture of these environmentally positive improvements. These positive improvements have been near and long-term in effect. The Act was voted on and passed twice by the United States Senate , once prior to conference committee , and once after. In both cases, there were numerous senators who voted against
4176-506: The national economy, was abetted. Industry grew for manufacture of these environmentally positive improvements. These positive improvements have been near and long-term in effect. The collective reduction in national consumption of oil is significant for automotive vehicles. The Act provided tangible financial incentives (tax credits) for operators of hybrid vehicles. It helped fuel competition among auto makers to meet rising demands for fuel-efficient vehicles . Consumer spending, and hence
4248-416: The necessary support for working with all (or almost all) possible local times based on the various time zones. Internally, operating systems typically use UTC as their basic time-keeping standard , while providing services for converting local times to and from UTC, and also the ability to automatically change local time conversions at the start and end of daylight saving time in the various time zones. (See
4320-716: The payback period of a prospective energy improvement investment. The deductions could be combined by participating in demand response programs where building owners agree to curtail usage at peak times for a premium. The most common qualifying projects were in the area of lighting. Summary of Energy Savings Percentages Provided by IRS Guidance Percentages permitted under Notice 2006-52 (Effective for property placed in service January 1, 2006 – December 31, 2008) Percentages permitted under Notice 2008-40 (Effective for property placed in service January 1, 2006 – December 31, 2013) Percentages permitted under Notice 2012-22 Effective date of Notice 2012-22 – December 31, 2013; if §179D
4392-599: The qualification. For municipal buildings, benefits were passed through to the primary designers/architects in an attempt to encourage innovative municipal design. The Commercial Buildings Tax Deduction expiration date had been extended twice, last by the Energy Improvement and Extension Act of 2008 . With this extension, the CBTD could be claimed for qualifying projects completed before January 1, 2014. The commercial building tax deductions could be used to improve
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#17327729618174464-493: The same meridian but north of the Arctic Circle, has two sunsets on the same day in early August, one shortly after midnight at the start of the day, and the other shortly before midnight at the end of the day. China extends as far west as 73°E , but all parts of it use UTC+08:00 ( 120°E ), so solar "noon" can occur as late as 15:00 in western portions of China such as Xinjiang . The Afghanistan-China border marks
4536-548: The same time as the others, but differed by one hour from those in the neighboring zones. He advocated his system at several international conferences, including the International Meridian Conference , where it received some consideration. The system has not been directly adopted, but some maps divide the world into 24 time zones and assign letters to them, similarly to Fleming's system. By about 1900, almost all inhabited places on Earth had adopted
4608-419: The same time zone as New York to simplify communications and transactions. A more extreme example is Nome, Alaska , which is at 165°24′W longitude – just west of center of the idealized Samoa Time Zone ( 165°W ). Nevertheless, Nome observes Alaska Time ( 135°W ) with DST so it is slightly more than two hours ahead of the sun in winter and over three in summer. Kotzebue, Alaska , also near
4680-465: The system time to be fetched as a count of 100 ns units since 1601-01-01 00:00:00 UTC. The system registry contains time zone information that includes the offset from UTC and rules that indicate the start and end dates for daylight saving in each zone. Interaction with the user normally uses local time, and application software is able to calculate the time in various zones. Terminal Servers allow remote computers to redirect their time zone settings to
4752-527: The time-zone system. It was a version proposed by William F. Allen, the editor of the Traveler's Official Railway Guide . The borders of its time zones ran through railroad stations, often in major cities. For example, the border between its Eastern and Central time zones ran through Detroit , Buffalo , Pittsburgh , Atlanta , and Charleston . It was inaugurated on Sunday, November 18, 1883, also called "The Day of Two Noons", when each railroad station clock
4824-471: The war. Similarly, prior to World War II, the Netherlands observed "Amsterdam Time", which was twenty minutes ahead of Greenwich Mean Time. They were obliged to follow German time during the war, and kept it thereafter. In the mid-1970s the Netherlands, as other European states, began observing daylight saving (summer) time. One reason to draw time zone boundaries far to the west of their ideal meridians
4896-472: The weather stations. In 1879, he published a paper titled Report on Standard Time . In 1883, he convinced North American railroad companies to adopt his time-zone system. In 1884, Britain, which had already adopted its own standard time system for England, Scotland, and Wales, helped gather international consent for global time. In time, the American government, influenced in part by Abbe's 1879 paper, adopted
4968-576: The west, and some countries are located entirely outside their ideal time zones. For example, even though the Prime Meridian (0°) passes through Spain and France , they use the mean solar time of 15 degrees east ( Central European Time ) rather than 0 degrees (Greenwich Mean Time). France previously used GMT, but was switched to CET (Central European Time) during the German occupation of the country during World War II and did not switch back after
5040-415: Was first proposed in 1907 and was in widespread use in 1916 as a wartime measure aimed at conserving coal . Despite controversy , many countries have used it off and on since then; details vary by location and change occasionally. Countries around the equator usually do not observe daylight saving time, since the seasonal difference in sunlight there is minimal. Many computer operating systems include
5112-502: Was reset as standard-time noon was reached within each time zone. The North American zones were named Intercolonial, Eastern, Central, Mountain, and Pacific. Within a year 85% of all cities with populations over 10,000 (about 200 cities) were using standard time. A notable exception was Detroit (located about halfway between the meridians of Eastern and Central time), which kept local time until 1900, then tried Central Standard Time, local mean time , and Eastern Standard Time (EST) before
5184-669: Was very little in the way of time zone support for JavaScript . Essentially the programmer had to extract the UTC offset by instantiating a time object, getting a GMT time from it, and differencing the two. This does not provide a solution for more complex daylight saving variations, such as divergent DST directions between northern and southern hemispheres. ECMA-402, the standard on Internationalization API for JavaScript, provides ways of formatting Time Zones. However, due to size constraint, some implementations or distributions do not include it. The DateTime object in Perl supports all entries in
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