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Re: [ISO8601] Re: Double leap seconds.

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  • Tex Texin
    Ian, thanks for the detailed reply. I was going to make a couple wisecracks in return, but you took my cesium comment seriously and it wasn t intended to be. I
    Message 1 of 6 , Nov 30, 2001
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      Ian, thanks for the detailed reply.

      I was going to make a couple wisecracks in return, but you took my
      cesium comment seriously and it wasn't intended to be. I should have
      thrown in a smiley. 10 hours of googling must have your eyes glazing
      over though. So I'll just say thanks.

      Cheers,
      tex


      g1smd@... wrote:
      >
      > On 2001-Nov-30 Tex wrote(>):
      >
      > [2001-Nov-30]
      >
      > > A question was put to me based on something I wrote:
      >
      > > "This says seconds can be from 00-60, allowing for leap
      > > seconds. However, in XPG's strftime(), seconds can range
      > > from 00-61 because there occasionally have been double
      > > leap seconds. Is 8601 really limited to 00-60?"
      >
      > ISO 8601 is limited to this. And the '60' second can only
      > be at XXXX-12-31 23:59:60 and/or XXXX-06-30 23:59:60 UTC.
      >
      > I assume that you know that the Leap Second is applied
      > simultaneously across the entire planet, so appearing
      > in mid-morning in Japan, and early-evening in the US,
      > reference Local Times in those places.
      >
      > I also assume that you know that Time Zones are best
      > expressed with +HH:MM rather than just +HH because
      > there are several with 15, 30 and 45 minute offsets.
      >
      > There was some discussion that I found concerning one
      > country that for a long time had some really wierd
      > offset like 42 minutes and 38 seconds. It would not
      > be possible to insert a second between nos 38 and 39
      > without having to renumber the rest of the minute or
      > the rest of the hour. I don't remember the actual offset
      > in the discussion, and I no longer have the link to it.
      >
      > > So my questions to the list are:
      >
      > > a) Have there ever been double leap seconds?
      >
      > Not as far as I know. The current definitions for UTC
      > are that UTC must not differ by more than 0.9 sec from
      > TAI (Atomic Time). A leap second is inserted at the end
      > of June and/or December when required. If needed, it is
      > also possible for a leap second to be added at the end
      > of March or September as well. The Earth is slowing down
      > very gradually. Leap Seconds have always been inserted.
      > It is possible for a second to be removed, but this has
      > never happened, and is unlikely to happen.
      >
      > > b) Is it possible there will ever be a double leap second
      > > added? If so, how would 8601 deal with it?
      >
      > It is unlikely that the Earth would slow to such an extent
      > to require two seconds within six months, but I believe
      > that provision is built in by allowing a leap second at the
      > end of March and/or September if required. I have not looked
      > to confirm this fact. Please do so if it is important.
      >
      > > c) Can anyone comment on XPG strftime supporting 61
      > > second/minute and why?
      >
      > I cannot. Outside my knowledge. There must be an answer
      > on a web site somewhere.
      >
      > There are several very good Calendar FAQs and several
      > Astronomy FAQs. All of your other questions, with much
      > other background material will be comprehensively
      > covered in there.
      >
      > > d) How come we can put a man on the moon and we can't keep
      > > a few Caesium atoms in sync with the earth?
      >
      > The problem ain't the Caesium atoms, it's the Earth. The
      > Earth does not spin uniformly on it's axis during 24 hours.
      > Winds and storms on the surface minutely speed and slow it.
      > The interaction with the solar wind, and the gravity of the
      > Moon play a part, as do the tides sloshing round the globe.
      >
      > In addition, in going around the sun some 2.5 million km
      > every day, the gravitational pull of the other planets,
      > combined with the fact that the Earth's orbit around the
      > Sun is not circular also has some very small effect.
      >
      > In fact a Sun Dial is extremely primitive. You would think
      > that the Sun would be due South at mid-day every day, would
      > you not. Nothing could be further from the truth. Look up
      > the stuff about 'The Equation of Time' to see what I mean.
      > It can be up to a quarter of an hour 'early' or 'late' for
      > some parts of the year, and exactly due South at midday
      > only on 4 precise dates.
      >
      > Hope you find some more answers on the web, or someone else
      > here comes up with the required information.
      >
      > I have just spent over 10 hours following up a huge list of
      > links, and compiling a list of sites for the ODP. I really
      > couldn't face revisting Google or NorthernLight again today.
      >
      > Cheers,
      >
      > Ian.
      >
      > <mail://g1smd@...>
      >
      > <http://www.qsl.net/g1smd/>
      > <http://home.freeuk.net/g1smd/>
      > <http://ourworld.compuserve.com/homepages/dstrange/y2k.htm>
      > <http://dmoz.org/Science/Reference/Standards/Individual_Standards/ISO_8601/>
      >
      > <ftp://ftp.funet.fi/pub/ham/misc/g1smd.zip>
      > <ftp://ftp.qsl.net/pub/g1smd/>
      >
      > [2001-11-30]
      >
      > .end
      >
      >
      >
      >
      > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

      --
      -------------------------------------------------------------
      Tex Texin Director, International Business
      mailto:Texin@... Tel: +1-781-280-4271
      the Progress Company Fax: +1-781-280-4655
      -------------------------------------------------------------
      For a compelling demonstration for Unicode:
      http://www.geocities.com/i18nguy/unicode-example.html
    • g1smd@amsat.org
      ... [2001-Dec-06] I came across some comments and answers in another (very long) discussion that I found. I hope this solves it. I think these messages do it:
      Message 2 of 6 , Dec 5, 2001
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        On 2001-Nov-30 Tex wrote(>):


        > A question was put to me based on something I wrote:

        > "This says seconds can be from 00-60, allowing for leap
        > seconds. However, in XPG's strftime(), seconds can range
        > from 00-61 because there occasionally have been double
        > leap seconds. Is 8601 really limited to 00-60?"



        [2001-Dec-06]


        I came across some comments and answers in another
        (very long) discussion that I found. I hope this
        solves it. I think these messages do it:

        <http://www.landfield.com/usefor/2000/May/0052.html>
        <http://www.landfield.com/usefor/2000/May/0077.html>
        <http://www.landfield.com/usefor/2000/May/0078.html>
        <http://www.landfield.com/usefor/2000/May/0090.html>

        There are a few comments that I want to throw into that
        discussion, but unfortunately it is an archive site, is
        about 18 months old, and for a list that I cannot now
        access. Ho hum.



        Cheers,

        Ian.


        <mail://g1smd@...>

        <http://www.qsl.net/g1smd/>
        <http://home.freeuk.net/g1smd/>
        <http://ourworld.compuserve.com/homepages/dstrange/y2k.htm>
        <http://dmoz.org/Science/Reference/Standards/Individual_Standards/ISO_8601/>

        <ftp://ftp.funet.fi/pub/ham/misc/g1smd.zip>
        <ftp://ftp.qsl.net/pub/g1smd/>


        [2001-12-06]

        .end
      • Tex Texin
        Ian, thanks. The remark in the first mail about myths making their way into standards, makes me think we need an Urban Legends site for standards. I would love
        Message 3 of 6 , Dec 5, 2001
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          Ian, thanks.
          The remark in the first mail about myths making their way into
          standards, makes me think we need an Urban Legends site for standards.
          I would love to see a collection of totally (or partially) unfounded
          concepts that made their way into standards.
          ;-)

          g1smd@... wrote:
          >
          > On 2001-Nov-30 Tex wrote(>):
          >
          > > A question was put to me based on something I wrote:
          >
          > > "This says seconds can be from 00-60, allowing for leap
          > > seconds. However, in XPG's strftime(), seconds can range
          > > from 00-61 because there occasionally have been double
          > > leap seconds. Is 8601 really limited to 00-60?"
          >
          > [2001-Dec-06]
          >
          > I came across some comments and answers in another
          > (very long) discussion that I found. I hope this
          > solves it. I think these messages do it:
          >
          > <http://www.landfield.com/usefor/2000/May/0052.html>
          > <http://www.landfield.com/usefor/2000/May/0077.html>
          > <http://www.landfield.com/usefor/2000/May/0078.html>
          > <http://www.landfield.com/usefor/2000/May/0090.html>
          >
          > There are a few comments that I want to throw into that
          > discussion, but unfortunately it is an archive site, is
          > about 18 months old, and for a list that I cannot now
          > access. Ho hum.
          >
          > Cheers,
          >
          > Ian.
          >
          > <mail://g1smd@...>
          >
          > <http://www.qsl.net/g1smd/>
          > <http://home.freeuk.net/g1smd/>
          > <http://ourworld.compuserve.com/homepages/dstrange/y2k.htm>
          > <http://dmoz.org/Science/Reference/Standards/Individual_Standards/ISO_8601/>
          >
          > <ftp://ftp.funet.fi/pub/ham/misc/g1smd.zip>
          > <ftp://ftp.qsl.net/pub/g1smd/>
          >
          > [2001-12-06]
          >
          > .end
          >
          >
          >
          >
          > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

          --
          -------------------------------------------------------------
          Tex Texin Director, International Business
          mailto:Texin@... Tel: +1-781-280-4271
          the Progress Company Fax: +1-781-280-4655
          -------------------------------------------------------------
          For a compelling demonstration for Unicode:
          http://www.geocities.com/i18nguy/unicode-example.html
        • bam
          The Fortran 90 standard (X3.198) does allow for seconds to reach 61, based on concern that there might be such a thing as a double leap second. I do recall a
          Message 4 of 6 , Dec 5, 2001
          • 0 Attachment
            The Fortran 90 standard (X3.198) does allow for
            seconds to reach 61, based on concern that there
            might be such a thing as a double leap second.
            I do recall a written paper suggesting we modify
            the range of some functions to allow for such a
            possibility, but I don't think there was any
            reference to a document claiming that the second
            value could actually go that high, nor any
            assertion that there was such an assertion
            in any standard. Raising the limit to be
            prudent is not quite the same thing as falling
            for some bogus claim.

            However, I would like to recommend "snopes.com"
            as an excellent website thru which to search
            for urban legends, perhaps to recognize one
            that actually made its way into a standard.

            Offhand, I don't know of any modern urban legend
            that made its way into a standard (other than
            the myth that the "WHILE" keyword is necessary
            and its unnecessary, last-minute insertion into
            the DO/EXIT/ENDDO control construct in ANSI X3.9).

            I also recall, however, a (rather lengthy)
            discussion of the origins of the "standard"
            and "narrow-gague" track widths for railroads,
            and how these arbitrary measurements came from
            the spacing of wagon-wheel ruts in muddy roads,
            which in turn had come to be determined by the
            breadth of bovine behinds!
            (i.e. the wheel spacing dictated by the fact
            that two oxen were yoked side-by-side to pull
            the wagons over the many roads leading to the
            seven hills of Rome.

            I'm inclined to post this ironic & insightful story
            (which arrived as part of an official distribution
            to members of X3J3, several years ago), assuming
            I can still find it. However, I'll refrain if I
            upon receiving appropriately discouraging email.

            Just lurking here, until now,
            Bruce A. Martin
            (former Member of ISO/SC22/WG5,
            ANSC X3J3, X3J3.1, X3J11, X4DSK,
            POSIX.9, SIGAda, plus various and sundry
            other standards groups that I've forgotten)

            P.S. I began writing dates with the year first
            in about 1967, after penning a memo recommending
            this practice while on the staff of the Applied
            Mathematics Department (which ran the computers)
            at Brookhaven National Laboratory. This probably
            does not merit any priority, but YMD order seemed
            as obvious then as it does now, and I've been
            doing so consistently ever since. I'm gratified
            that the rest of the world is finally starting to
            catch up to me.

            bam


            Tex Texin wrote:
            >
            > Ian, thanks.
            > The remark in the first mail about myths making their way into
            > standards, makes me think we need an Urban Legends site for standards.
            > I would love to see a collection of totally (or partially) unfounded
            > concepts that made their way into standards.
            > ;-)
            >
            > g1smd@... wrote:
            > >
            > > On 2001-Nov-30 Tex wrote(>):
            > >
            > > > A question was put to me based on something I wrote:
            > >
            > > > "This says seconds can be from 00-60, allowing for leap
            > > > seconds. However, in XPG's strftime(), seconds can range
            > > > from 00-61 because there occasionally have been double
            > > > leap seconds. Is 8601 really limited to 00-60?"
            > >
            > > [2001-Dec-06]
            > >
            > > I came across some comments and answers in another
            > > (very long) discussion that I found. I hope this
            > > solves it. I think these messages do it:
            > >
            > > <http://www.landfield.com/usefor/2000/May/0052.html>
            > > <http://www.landfield.com/usefor/2000/May/0077.html>
            > > <http://www.landfield.com/usefor/2000/May/0078.html>
            > > <http://www.landfield.com/usefor/2000/May/0090.html>
            > >
            > > There are a few comments that I want to throw into that
            > > discussion, but unfortunately it is an archive site, is
            > > about 18 months old, and for a list that I cannot now
            > > access. Ho hum.
            > >
            > > Cheers,
            > >
            > > Ian.
            > >
            > > <mail://g1smd@...>
            > >
            > > <http://www.qsl.net/g1smd/>
            > > <http://home.freeuk.net/g1smd/>
            > > <http://ourworld.compuserve.com/homepages/dstrange/y2k.htm>
            > > <http://dmoz.org/Science/Reference/Standards/Individual_Standards/ISO_8601/>
            > >
            > > <ftp://ftp.funet.fi/pub/ham/misc/g1smd.zip>
            > > <ftp://ftp.qsl.net/pub/g1smd/>
            > >
            > > [2001-12-06]
            > >
            > > .end
            > >
            > >
            > >
            > >
            > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
            >
            > --
            > -------------------------------------------------------------
            > Tex Texin Director, International Business
            > mailto:Texin@... Tel: +1-781-280-4271
            > the Progress Company Fax: +1-781-280-4655
            > -------------------------------------------------------------
            > For a compelling demonstration for Unicode:
            > http://www.geocities.com/i18nguy/unicode-example.html
            >
            >
            >
            >
            > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
          • Tex Texin
            Bruce, thanks for the notes. Living near Boston, I can relate to the bovine-sized tracks, as our roads are not rectangular, and we often claim that the roads
            Message 5 of 6 , Dec 5, 2001
            • 0 Attachment
              Bruce,
              thanks for the notes.

              Living near Boston, I can relate to the bovine-sized tracks, as our
              roads are not rectangular, and we often claim that the roads were laid
              out according to how the cows roamed here.

              As for the ironic/insightful story I would say go for it!

              tex

              bam wrote:
              >
              > The Fortran 90 standard (X3.198) does allow for
              > seconds to reach 61, based on concern that there
              > might be such a thing as a double leap second.
              > I do recall a written paper suggesting we modify
              > the range of some functions to allow for such a
              > possibility, but I don't think there was any
              > reference to a document claiming that the second
              > value could actually go that high, nor any
              > assertion that there was such an assertion
              > in any standard. Raising the limit to be
              > prudent is not quite the same thing as falling
              > for some bogus claim.
              >
              > However, I would like to recommend "snopes.com"
              > as an excellent website thru which to search
              > for urban legends, perhaps to recognize one
              > that actually made its way into a standard.
              >
              > Offhand, I don't know of any modern urban legend
              > that made its way into a standard (other than
              > the myth that the "WHILE" keyword is necessary
              > and its unnecessary, last-minute insertion into
              > the DO/EXIT/ENDDO control construct in ANSI X3.9).
              >
              > I also recall, however, a (rather lengthy)
              > discussion of the origins of the "standard"
              > and "narrow-gague" track widths for railroads,
              > and how these arbitrary measurements came from
              > the spacing of wagon-wheel ruts in muddy roads,
              > which in turn had come to be determined by the
              > breadth of bovine behinds!
              > (i.e. the wheel spacing dictated by the fact
              > that two oxen were yoked side-by-side to pull
              > the wagons over the many roads leading to the
              > seven hills of Rome.
              >
              > I'm inclined to post this ironic & insightful story
              > (which arrived as part of an official distribution
              > to members of X3J3, several years ago), assuming
              > I can still find it. However, I'll refrain if I
              > upon receiving appropriately discouraging email.
              >
              > Just lurking here, until now,
              > Bruce A. Martin
              > (former Member of ISO/SC22/WG5,
              > ANSC X3J3, X3J3.1, X3J11, X4DSK,
              > POSIX.9, SIGAda, plus various and sundry
              > other standards groups that I've forgotten)
              >
              > P.S. I began writing dates with the year first
              > in about 1967, after penning a memo recommending
              > this practice while on the staff of the Applied
              > Mathematics Department (which ran the computers)
              > at Brookhaven National Laboratory. This probably
              > does not merit any priority, but YMD order seemed
              > as obvious then as it does now, and I've been
              > doing so consistently ever since. I'm gratified
              > that the rest of the world is finally starting to
              > catch up to me.
              >
              > bam
              >
              > Tex Texin wrote:
              > >
              > > Ian, thanks.
              > > The remark in the first mail about myths making their way into
              > > standards, makes me think we need an Urban Legends site for standards.
              > > I would love to see a collection of totally (or partially) unfounded
              > > concepts that made their way into standards.
              > > ;-)
              > >
              > > g1smd@... wrote:
              > > >
              > > > On 2001-Nov-30 Tex wrote(>):
              > > >
              > > > > A question was put to me based on something I wrote:
              > > >
              > > > > "This says seconds can be from 00-60, allowing for leap
              > > > > seconds. However, in XPG's strftime(), seconds can range
              > > > > from 00-61 because there occasionally have been double
              > > > > leap seconds. Is 8601 really limited to 00-60?"
              > > >
              > > > [2001-Dec-06]
              > > >
              > > > I came across some comments and answers in another
              > > > (very long) discussion that I found. I hope this
              > > > solves it. I think these messages do it:
              > > >
              > > > <http://www.landfield.com/usefor/2000/May/0052.html>
              > > > <http://www.landfield.com/usefor/2000/May/0077.html>
              > > > <http://www.landfield.com/usefor/2000/May/0078.html>
              > > > <http://www.landfield.com/usefor/2000/May/0090.html>
              > > >
              > > > There are a few comments that I want to throw into that
              > > > discussion, but unfortunately it is an archive site, is
              > > > about 18 months old, and for a list that I cannot now
              > > > access. Ho hum.
              > > >
              > > > Cheers,
              > > >
              > > > Ian.
              > > >
              > > > <mail://g1smd@...>
              > > >
              > > > <http://www.qsl.net/g1smd/>
              > > > <http://home.freeuk.net/g1smd/>
              > > > <http://ourworld.compuserve.com/homepages/dstrange/y2k.htm>
              > > > <http://dmoz.org/Science/Reference/Standards/Individual_Standards/ISO_8601/>
              > > >
              > > > <ftp://ftp.funet.fi/pub/ham/misc/g1smd.zip>
              > > > <ftp://ftp.qsl.net/pub/g1smd/>
              > > >
              > > > [2001-12-06]
              > > >
              > > > .end
              > > >
              > > >
              > > >
              > > >
              > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
              > >
              > > --
              > > -------------------------------------------------------------
              > > Tex Texin Director, International Business
              > > mailto:Texin@... Tel: +1-781-280-4271
              > > the Progress Company Fax: +1-781-280-4655
              > > -------------------------------------------------------------
              > > For a compelling demonstration for Unicode:
              > > http://www.geocities.com/i18nguy/unicode-example.html
              > >
              > >
              > >
              > >
              > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
              >
              >
              >
              >
              > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

              --
              -------------------------------------------------------------
              Tex Texin Director, International Business
              mailto:Texin@... Tel: +1-781-280-4271
              the Progress Company Fax: +1-781-280-4655
              -------------------------------------------------------------
              For a compelling demonstration for Unicode:
              http://www.geocities.com/i18nguy/unicode-example.html
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