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Ask Slashdot: How Many Time Standards Are There? 214

Posted by timothy
from the didn't-suffer-slept-right-through-it dept.
jjoelc writes "Being one of those 'suffering' through the time change last night, the optimist in me reminded me that it could be much worse. That's when I started wondering how many different time/date standards there really are. Wikipedia is a good starting point, but is sorely lacking in the various formats used by e.g. Unix, Windows, TRS-80, etc. And that is without even getting into the various calendars that have been in and out of use throughout the ages. So how about it? How many different time/date 'standards' can we come up with? I'm betting there are more than a few horror stories of having to translate between them..."
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Ask Slashdot: How Many Time Standards Are There?

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  • For questions like this, my dad would always say something cheesy, like "Does it matter, son? There's no time like the present, and that's all that matters".

    Of course, he didn't think going into the business world as an employee was a good professional choice, either.
  • by girlinatrainingbra (2738457) on Sunday March 10, 2013 @04:51PM (#43133389)
    IMHO, Time Standards would be "standards/standardizations for time keeping", such as say when the railroads crossed the US and decided that local high-noon was not so useful when you translate yourself geographically so swiftly, and thus "time zones" in the US were set up. Some countries (India, and China, maybe others i don't know of...) keep a signle time zone for the entirety of their contiguous expanse for "standardization".
    .
    Time Formats, again IMHO, would be the "standard" (ha, I heard it [that word] both ways!) used for displaying, communicating, or storing "time data values" on paper, verbally, or in a computerized (or book-keeping) record. One example: "yYYYY-MM-DD-HH-mm-ss.{fractional value of second}" [note I added an extra "y" digit to allow for the Y-10K problem!!!). Floppy disks and TRS-DOS and Apple DOS and MS-DOS and CPM and UNIX and so many others use different formats for this. They also use different "loci" for the "origin point" of time (the "epoch", e.g. time elapsed since point $x$ in time. Gregorian year 1904 for old macs, 1970 for the unix epoch, etc.
    • Re: (Score:2, Insightful)

      by eneville (745111)
      Isn't that somewhat close to ISO 8601? I generally find it good and sensihle, helps with sorting and reading.
      • by Chrisq (894406)

        Isn't that somewhat close to ISO 8601? I generally find it good and sensihle, helps with sorting and reading.

        However it is a bit short-termist. I prefer RFC2550 [ietf.org] as a long-term solution

    • You could've saved some time just saying you use ISO 8601...

  • by Anonymous Coward on Sunday March 10, 2013 @04:53PM (#43133397)

    1. How many different date/time standards has the human race come up with

    2. How many different data structures and APIs have tech companies invented in trying to model the present-day Gregorian calendar (with time zones and DST, etc) used by most Western countries?

    It's anyone's guess which one would produce a higher number.

  • by Anonymous Coward

    It was absolutely awful trying to convert between the game-time and real-time.
    I took the easy route and still based everything on seconds, and built it up from there.

    The main reason for doing it was because the game was based on real time, so even being away caused events to pass.
    And given a typical person, they'd play games more or less at the same time every day for a certain period of time.
    This is why I settled on what would effectively be 7 hour days.
    Out of sync with a normal day so a typical person wou

    • by Shavano (2541114) on Sunday March 10, 2013 @05:48PM (#43133749)

      It was absolutely awful trying to convert between the game-time and real-time. I took the easy route and still based everything on seconds, and built it up from there.

      The main reason for doing it was because the game was based on real time, so even being away caused events to pass. And given a typical person, they'd play games more or less at the same time every day for a certain period of time. This is why I settled on what would effectively be 7 hour days. Out of sync with a normal day so a typical person would almost certainly come across every time period at some point. And 7 is short enough to experience in a day, but still long enough to feel "right". I can't remember how I done minutes or hours again, it was way back in 2005.

      That project never got completed due to health reasons. I might come back to it one day, but it isn't a priority.

      At least I never decided to make a language for it as well.

      We're sorry about what this did to your sanity. Glad to see you've recovered.

  • Critical Dates (Score:5, Informative)

    by Sebastopol (189276) on Sunday March 10, 2013 @05:02PM (#43133451) Homepage

    on a side note, i love this website:

    http://www.merlyn.demon.co.uk/critdate.htm [demon.co.uk]

    it is a huge list of important dates relevant to computer programs, algorithms, and O/Ses.

  • Total (Score:5, Funny)

    by fph il quozientatore (971015) on Sunday March 10, 2013 @05:04PM (#43133463) Homepage

    There are in total 863 different time standard, including historical ones. That's the good thing about standards, there are so many to choose from.

    Now, please someone post a link to that xkcd comic and we can move on to the next question.

    • Re:Total (Score:5, Informative)

      by ericloewe (2129490) on Sunday March 10, 2013 @05:20PM (#43133575)

      http://xkcd.com/1179/ [xkcd.com]

      ISO 8601

      But, since you mention the overabundance of standards...

      http://xkcd.com/927/ [xkcd.com]

      • xkcd comics are like standards. You think there's only one that applies, but...
    • 864. I always count time units since the big bang, but I refuse to let anyone know when the big bang was nor what unit of time I use.

    • Actually, we're down to 862. We're deprecating the Mayan method since the world didn't end at the end of their time...
      • by arth1 (260657)

        Actually, we're down to 862. We're deprecating the Mayan method since the world didn't end at the end of their time...

        It didn't? You're just a computer simulation that runs a "what if" scenario of what could have happened if the world hadn't ended.

        Back to topic - I see no problems with all the different methods of counting elapsed time. All of them that I can think of are well defined, so conversion is easy enough.

      • We're deprecating the Mayan method since the world didn't end at the end of their time...

        The Mayan calendar doesn't end just because one cycle (and not even the longest cycle) in their calendar system ended. Its like saying that Gregorian calendar ended just because we reached the end of a month (say, August), even though the Gregorian calendar has longer cycles than months (e.g., years), and doesn't have any particular end-of-world prophecy associated with the end of the cycle at issue.

        The whole "end of th

  • by Blaskowicz (634489) on Sunday March 10, 2013 @05:04PM (#43133465)

    Excel is known for considering year 1900 as a leap year even though it's not, but I don't know if this historical bug (carried over from Lotus 1-2-3 according to wikipedia) is still respected. So consider Excel usable to year 1901 to a date I don't know.
    Likewise the Y2K38 problem with Unix is that time, if represented with 32 bits, doesn't go before a certain 20th century date as well as ending abruptingly on a certain date and time in 2038 - causing the end of the world. Both examples mean that you have to pay attention to the usable time range - be it usable length, absolute minimum date, absolute maximum date, with hopefully some time standards offering infinite range (like A.D. / C.E. year numbering?)

    Leap seconds is another infuriating problem and relativity in general and I have to wonder if we have to consider Mars's time, Earth's time, Sun's time, Voyager 2's time etc. in any relevant way. Have fun!

    • by Xoc-S (645831)
      Excel does not treat 1900 as a leap year. Excel's epoch, though, is December 30th, 1899 instead of the 31st to be compatible with 1-2-3 for all dates from March 1st, 1900 onward, allowing for 1-2-3's bug. Excel and Word, and all other Microsoft products that use VBA as a macro language, use the OLE Automation date format that works just fine on all dates from January 1, year 100 to December 31st 9999. Dates are treated as a double with the integer part being days and fractions being the fraction of a day. N
    • by Shavano (2541114)
      But the problem is easy enough to fix by adding another 32-bit epoch with the default being zero corresponding to our current epoch. And add a 64-bit precision timing field when you need precision much better than a second.
    • by jrumney (197329)

      Excel is known for considering year 1900 as a leap year even though it's not, but I don't know if this historical bug (carried over from Lotus 1-2-3 according to wikipedia) is still respected. So consider Excel usable to year 1901 to a date I don't know.

      2099 if their bugs are consistent.

    • by soldack (48581)

      VBA within excel does not consider 1900 a leap year...getting the two to work together is fun.

  • GPS Time (Score:5, Interesting)

    by Anonymous Coward on Sunday March 10, 2013 @05:11PM (#43133499)

    Another interesting one is GPS-Time, which is basically UTC without the leap seconds.

    https://en.wikipedia.org/wiki/GPS_time#Timekeeping [wikipedia.org]

    • by mbone (558574)

      Or, it is TAI with an arbitrary offset (the UTC offset at the time the system was set up), because the Air Force couldn't be bothered to ask either NIST or the USNO what time standard they should use, and they just set their clocks to the then UTC.

    • Re:GPS Time (Score:5, Informative)

      by fuzzyfuzzyfungus (1223518) on Sunday March 10, 2013 @05:17PM (#43133551) Journal

      What is rather annoying is that GPS time is UTC without leap seconds; but(for some reason) is different than TAI, which is also UTC without leap seconds.

  • ISO 8601 (Score:4, Informative)

    by Anonymous Coward on Sunday March 10, 2013 @05:12PM (#43133501)

    http://xkcd.com/1179/

    This subject has already been discussed.

  • There is but one time, TAI. Everything else is just a TAI with an asterisk.

  • by AbRASiON (589899) * on Sunday March 10, 2013 @05:14PM (#43133521) Journal

    However this particular topic has me wishing I could moderate the actual news posts themselves.
    We get it, Americans don't like DST - good for you, please stop posting hundreds of goddamned articles on it.

    Some of us like getting home from work with more free daylight to spend with the kids, excercise, do gardening or whatever. No, we can't change the time we start work, no we're NOT going to see business's move to an 8-4 model.

    My only complaint is it's not an all round time thing, if society isn't going to move to the 8-4 model then damnit just change the zones forward.

    Furthermore I've been told by several American pals in the last 2 or 3 days, they actually like DST, they dislike when it's not DST infact and it's just common misuse of the term, don't know if this is true or not.
    In conclusion, just deal with it and for fucks sake stop posting these articles every year.

    • by Teun (17872)
      Oh it's not just Americans that claim they have physical discomfort due to this one hr. change twice a year.
      I honestly think they are moaners for the sake of moaning, it's sixty minutes and it's for the vast majority of people during a two-day weekend they have off from work and other pressing engagements.
      Many of them have no problem going out Friday and Saturday night till the break of dawn but those sixty minutes is going to cause them oh so much grief.
      Come on, some nights there's something special on
      • by 0123456 (636235)

        You change time twice a year?

        You're kidding, right? That's the funniest idea I've heard today.

        • You change time twice a year?

          You're kidding, right? That's the funniest idea I've heard today.

          Please tell me you change your time a non-zero, odd number of times per year. Because that would be really cool . . .

      • I arrived in NZ to live on Oct 1, 2006. That happened to be the first Sunday in October, and according to the rules was the day that Daylight Time started in 2006. During 2007 there was rather intense lobbying to have the start date of Daylight Time be moved earlier so the extra daylight could be enjoyed sooner.

        The change happened, and for 2007 the changeover date was set to be the last Sunday in September going forward. My what an outcry there was from many people protesting the awful disruption that ch
    • No, we can't change the time we start work, no we're NOT going to see business's move to an 8-4 model.

      Why, because that would make sense?

    • by Shavano (2541114)

      You know what's even more annoying than that? People who complain about what other people want to discuss. If you don't want to discuss it, then shut the fuck up and let those who care about it discuss it to their heart's content.

      We weren't even discussing DST. Just time formats and timekeeping. Is that not nerd-fodder?

  • by Dracos (107777) on Sunday March 10, 2013 @05:16PM (#43133543)

    Worse than suffering through the actual daylight/standard time changeovers, are dealing with timezones themselves in code. Most timezones are full hour offsets from UTC, but there are a few that are N:30 or N:45. There are even offsets which are greater than 12.

    Then you have to deal with differing dates of when the changeovers actually happen over the years in a given timezone.

    If you ever write an iCal-related application and have to deal with recurring events, you'll soon realize that Outlook's iCal support is comparatively even worse than IE's web standards support.

    Also, relevant xkcd [xkcd.com].

    • I'd mod you up, if only I had the points today...

      I'm a bit surprised there hasn't been a single "everyone should be on UTC" post yet. Maybe they wore themselves out posting so vociferously a couple days ago. Or maybe they forgot to set their clocks forward last night.

    • It's worse than that. There are N:10, N:15, as well as N:30 and N:45. The offset for DST can change on a yearly basis, and some timezones follow DST partially, and different areas will use different dates to change to DST that varies by year as well.

      • by DrVxD (184537)

        It's worse that that; there are regions which observe DST within regions that don't (and vice versa).

        But my favourite spot of Time Zone Weirdness is probably Cameron Corner [wikipedia.org], which actually sits on three time zones.

  • I always push for the ISO 8601 time formats. I like seeing YYYY-MM-DD on my time stamps. Wish this was the industry standard for logging, file systems, etc.

    What I hate how the US has Saturday/Sunday split on the weekend. Who really thinks, Oh its Sunday start of the week!
    Monday is really the start of the week, right after the WEEK END, and that's how I like my calendars displayed. Monday thru Sunday.

    http://en.wikipedia.org/wiki/ISO_8601 [wikipedia.org]

    • by mooingyak (720677)

      What I hate how the US has Saturday/Sunday split on the weekend. Who really thinks, Oh its Sunday start of the week!
      Monday is really the start of the week, right after the WEEK END, and that's how I like my calendars displayed. Monday thru Sunday.

      Or alternately, much like 'bookends', you have one at each end of the week.

    • by rk (6314)

      Then Saturday wouldn't be part of the week-END, now would it?

    • Monday is really the start of the week, right after the WEEK END

      Well, if the first day of the week is Sunday, and the last day is Saturday, what days mark the ends of the week? Thinking of the last day of the week as the end only works when you think of time being one directional.

      • what days mark the ends of the week?

        The problem with you line of thought is that the weekend is singular, not plural.

    • Well, in Portuguese Monday is literally "The second market day".
    • What I hate how the US has Saturday/Sunday split on the weekend. Who really thinks, Oh its Sunday start of the week! Monday is really the start of the week, right after the WEEK END, and that's how I like my calendars displayed. Monday thru Sunday.

      I had always thought that this was a holdover from the Jewish calendar, where Saturday is the last day of the week. In Hebrew, Sunday is "first day", Monday is "second day", etc.

    • I always push for the ISO 8601 time formats. I like seeing YYYY-MM-DD on my time stamps. Wish this was the industry standard for logging, file systems, etc.

      What I hate how the US has Saturday/Sunday split on the weekend. Who really thinks, Oh its Sunday start of the week! Monday is really the start of the week, right after the WEEK END, and that's how I like my calendars displayed. Monday thru Sunday.

      http://en.wikipedia.org/wiki/ISO_8601 [wikipedia.org]

      Except a week has two ends and they fall at the ends of the week, Sunday being the first day of the week and Saturday the last according to the Greco-Roman tradition. There are/were Monday starters in most of Eastern Europe, China and Mongolia. Swahilli start on Saturday as they base a day on sunrise and not sunset.

      • Except a week has two ends and they fall at the ends of the week

        It's always been "the weekend". Singular, not plural.

        Sunday being the first day of the week and Saturday the last according to the Greco-Roman tradition

        No. The Romans had the concept of Saturday and Sunday being the weekend. Not Sunday being the start of the week.

        The whole concept of a week having an end, rather than it's reality as being a continuous cycle, comes from the bible, where The sabbath was the 7th day. So Saturday being the end of the week is a Jewish tradition, and Sunday being the end of the week is a christian one.

        In things that have a natural direction, start comes before end. Sunday is p

  • Time to make the move to fix the 2038 bug

    • by thogard (43403)

      Much fun can be had by convincing a Solaris machine that the date is in the 1800s since it appears that dynamic libraries don't work then due to a bug in the dynamic linker. I'm guessing that bug will show up sometime in the future too. The interesting part is there doesn't appear to be a way to put the kernel into the 1800s via any standard API. The FORTH boot loader can be told to play games with the hardware clocks on some machines which can then be used to simulate these time travelling machines.

  • Standards for Date/Time are one thing, I've had a lot of trouble trying to standardize on adding Dates. What's August 31st + 1 Month?

    See: http://stackoverflow.com/q/7614361/37462 [stackoverflow.com]

    • Well, since "1 Month" isn't a fixed time period, so it could be anything from 28-31 days, and if you need a more precise measurement, you need to use a more precise operand. However, I suspect that most people would assume that August 31 + 1 Month would be either September 30, or October 1 depending which benefited you the most. Then again, in some fields (financial), a "month" is always defined to be 30 days regardless of which month you are referring to.

  • Jesus fucking Christ on a crackery cross, do any of you code monkeys have any idea just how many possible years today is? No, I know you don't. You know how I know this? Because you myopic fucktards have been the reason my phone has been ringing and my mail client actually crashed from overload today. So fuck you, and thank you, because I get to look super-smart and that pays the bills here in the DogPound.

    Even in the fucking "Western World" we live with the Mexican stand-off of Gregorian vs. Julian cale
    • by xaxa (988988)

      Most, possibly all, of Europe starts the week on a Monday.

      I was taught an old rhyme when I was a child:
      Solomon Grundy,
      Born on a Monday,
      Christened on Tuesday,
      Married on Wednesday,
      Took ill on Thursday,
      Grew worse on Friday,
      Died on Saturday,
      Buried on Sunday.
      That was the end,
      Of Solomon Grundy.

      (It annoys me slightly if an American calendar shows the weekend split. I often have events across Saturday and Sunday; displaying them is clearer when Saturday and Sunday are adjacent.)

    • by qwak23 (1862090)

      It could be worse, while Japan will generally work on the same year as everyone else, sometimes they like to throw in the traditional dates where the year is based on the current emperor, which means if you want to convert from one to the other you need a few history books.

  • RFC2550 Compliance (Score:5, Interesting)

    by Mr. Sketch (111112) <mister DOT sketch AT gmail DOT com> on Sunday March 10, 2013 @05:22PM (#43133585)

    We have quite a lot of them, but we don't have many systems that are fully RFC2550 Compliant:
    https://tools.ietf.org/html/rfc2550 [ietf.org]

  • by Scorpinox (479613) on Sunday March 10, 2013 @05:43PM (#43133707)

    Swatch Internet Time is truly the savior to all of this trouble. http://en.wikipedia.org/wiki/Swatch_Internet_Time [wikipedia.org]

    The whole time zone thing is just ridiculous in this age of information. When I'm too busy cruising the information super highway, I don't want to worry about whether the person I'm on IRC with is in London or Sydney. And for that matter, seconds? minutes? Relics of the past. Just divide the day into 1,000 beats and you're good to go.

    So what if no one has any sense of what 10 beats is (14 minutes 4 seconds), and so what if it was created by a watch maker probably to sell more watches. Swatch Internet Time is the wave of the future, man! Throw your grandfather clocks away and dial-up to greatness on your 56k. You don't want to be left behind in the Swatch revolution!

    • by bloodhawk (813939)
      Where someone is in the world and time and date are now more important than ever with the information age. Getting items shipped to you, expectations of response times are hugely dependent on the time of day and date. e.g. it is no use me getting pissed off that the American company I am trying to contact from Australia on a Monday is not answering as it is the middle of sunday evening for them, or perhaps a public holiday. It becomes even more important with delivery times as public holidays and weekends a
      • by rtaylor (70602)

        I've found running a 24/7 website, that day or week and time of day really don't matter. Either someone is working or you risk losing business regardless of the date, holiday, or time of day.

    • It might be good idea for people who spend a lot of time in different time zones and such, but let's face it, the vast majority of people rarely leave their own timezone, and many people never leave it. What's the point?
  • by Shavano (2541114)

    There are quite a number. There are a number of completely different CATEGORIES of time formats.

    For time presentation, there are analog and digital formats. Analog presentation format we are familiar with on watches and clocks is one of them. There is also an analog time presentation format where the hour hand turns once a day instead of once per 12 hours, and seemingly endless variations on these. There are time strip recording charts, timeline graphs, etc. Digital time presentation formats include

  • Although this doesn't answer the article's question, I think it is relevant to the topic.

    One of my peeves (that sometimes has been the cause of actual problems and misunderstandings) is the ambiguous dates that result from the American tradition of using the month,day,year order vs. most of the rest of the world's day,month,year.

    Most people here would probably agree that year,month,day is the best standard because it's logical, sorts easily, and virtually no one writes year,day,month. However, the rest

    • by qwak23 (1862090)

      Just to add confusion, I'm going to start pimping the following date format:
      %YYY!MM@DD#YY:HH(MM)^SS"SSS&ZZZZZ=
      Where YYY is the first 3 digits of a 5 digit year (and it will start fresh from July 19th this year being the first day of the year). MM will be the 2 digit month in a 13 month year (with 00 reserved for new years day, the only day of the year that is month less). DD will range from 01 to 28, except for the new year day which will be 00. HH and MM will be standard hours and minutes as we use t

    • by wvmarle (1070040)

      China uses year-month-day as format. They are very consistent in that, as they always start "largest first". Addresses (country-province-town-street-number) and names (last name - first name) the same.

      However when not using the year when writing a date it becomes ambiguous. They often write month/day. But not always. Especially in Hong Kong where the British standard day/month/year is also commonly followed, that is also how for example you have to write a date on a bank cheque.

      The only reliable workaround:

    • I'm British. We most commonly do dd/mm/yy. with a small minority of people doing dd-mm-yy.

      The French also use dd/mm/yy. Not sure about the rest of Europe.

      So your proposal won't work.

  • Not sure if this is what the OP is looking for, but my favorite is the Ethiopian calendar (no, I'm not Ethiopian). It's about seven years behind us, which meant that they avoided the Y2K catastrophe until 2007.

    Oh, there wasn't any catastrophe?

  • http://www.amazon.com/Calendrical-Calculations-Millennium-Edward-Reingold/dp/0521777526 [amazon.com] while it doesn't necessarily answer the question posed, people interested in computing calendars shouldn't miss this book.

    I have no vested interest, it's not my name on the cover ;>

  • Sorry, I wrote my own in 1992. It's unintentionally similar to the ISO standard. My only goal was to make timestamps easy to sort using alphanumeric methods available to a BASIC interpreter on a barcode scanner while still being mostly human-readable .

    My unintentional and unauthorized contribution to the proliferation. I assume plenty more examples also exist.

    Again, sorry. At least I never submitted it to any legitimate standardization body.

  • Bwahahahahaha.

    Day starts at sundown.
    Months are lunar and vary year to year.
    Some years have more than one month with the same name. Sometimes the calendar is adjusted to account for natural events.
    Sometimes extra months (leap month) are added.

    There are variations on this theme as well,
    Tannaitic
    Amoraic
    Maimonides the Mishneh Torah in the 12th century (starts the AM era)

    Oh wait there is more (from Wikipedia)

    There are additional rules in the Hebrew calendar to prevent certain holidays from falling on certain day

  • The fundamental problem is this: There are 4 naturally occurring measurements of time, all of which are in common use, and none of them are consistently expressible in terms of the other.

    The 4 are:
    - Years (Based on Earth's revolutions of the sun)
    - Lunar months (Based on the moon's revolutions of the Earth)
    - Days (Based on Earth's rotation)
    - Periods of the radiation of ground state cesium 133 (which form the official SI definition of a second)
    And of course you have lots of artificial units of time measuremen

  • As much as I like the UNIX time format, it is very limited on 32 bit systems.

    I store mine in the YYYYMMDDhhmmss format. I stick to GMT/UTC for the timezone. Stor it as a CHAR(14) and you're set for another 7986 years.

    The beauty of this is it fits in fixed character space, entirely numeric, is easily sortable, and easy to select by range. It is still fairly easy to manipulate, just not as easy as UNIX. It is also just as easy to break out and reformat using regex's.

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