Seems VERY hard to believe, here's some docs:
> To Leap or Not to Leap?
>
> This was never a question for OpenVMS!
>
For anyone who still wonders whether the year 2000 is a leap year,
> we have dusted off the archives from 13-OCT-1983 to retrieve this reply
> from DIGITAL's Stanley Rabinowitz to a Software Performance
> Report (SPR). The report, filed against VAX/VMS Version 3.2, claimed the
> LIB$DAY Run-Time Library service assumed incorrectly that the year 2000
> was a leap year.
>
> Stan's now famous response demonstrates that OpenVMS has been
> forward thinking in terms of the year 2000 long before the current hoopla
> began!
>
> Enjoy!
>
>
>
> D I G I T A L
>
> SPR ANSWER FORM
>
> SPR NO. 11-60903
>
>
> SYSTEM VERSION PRODUCT VERSION COMPONENT
> SOFTWARE: VAX/VMS V3.2 VAX/VMS V3.2 Run-Time Library
>
>
> PROBLEM:
>
> The LIB$DAY Run-Time Library service "incorrectly" assumes the
> year
> 2000 is a leap year.
>
>
> RESPONSE:
>
> Thank you for your forward-looking SPR.
>
> Various system services, such as SYS$ASCTIM assume that the year
> 2000
> will be a leap year. Although one can never be sure of what
> will
> happen at some future time, there is strong historical precedent
> for
> presuming that the present Gregorian calendar will still be in
> affect
> by the year 2000. Since we also hope that VMS will still be
> around by
> then, we have chosen to adhere to these precedents.
>
> The purpose of a calendar is to reckon time in advance, to show
> how
> many days have to elapse until a certain event takes place in
> the
> future, such as the harvest or the release of VMS V4. The
> earliest
> calendars, naturally, were crude and tended to be based upon
> the
> seasons or the lunar cycle.
>
> The calendar of the Assyrians, for example, was based upon the
> phases
> of the moon. They knew that a lunation (the time from one full
> moon
> to the next) was 29 1/2 days long, so their lunar year had a
> duration
> of 364 days. This fell short of the solar year by about 11
> days.
> (The exact time for the solar year is approximately 365 days, 5
> hours,
> 48 minutes, and 46 seconds.) After 3 years, such a lunar
> calendar
> would be off by a whole month, so the Assyrians added an extra
> month
> from time to time to keep their calendar in synchronization with
> the
> seasons.
>
> The best approximation that was possible in antiquity was a
> 19-year
> period, with 7 of these 19 years having 13 months (leap months).
> This
> scheme was adopted as the basis for the religious calendar used by
> the
> Jews. (The Arabs also used this calendar until Mohammed
> forbade
> shifting from 12 months to 13 months.)
>
> When Rome emerged as a world power, the difficulties of
> making a
> calendar were well known, but the Romans complicated their
> lives
> because of their superstition that even numbers were unlucky.
> Hence
> their months were 29 or 31 days long, with the exception of
> February,
> which had 28 days. Every second year, the Roman calendar included
> an
> extra month called Mercedonius of 22 or 23 days to keep up with
> the
> solar year.
>
> Even this algorithm was very poor, so that in 45 BC, Caesar,
> advised
> by the astronomer Sosigenes, ordered a sweeping reform. By
> imperial
> decree, one year was made 445 days long to bring the calendar back
> in
> step with the seasons. The new calendar, similar to the one we
> now
> use was called the Julian calendar (named after Julius Caesar).
> It's
> months were 30 or 31 days in length and every fourth year was
> made a
> leap year (having 366 days). Caesar also decreed that the year
> would
> start with the first of January, not the vernal equinox in late
> March.
>
> Caesar's year was 11 1/2 minutes short of the calculations
> recommended
> by Sosigenes and eventually the date of the vernal equinox
> began to
> drift. Roger Bacon became alarmed and sent a note to Pope Clement
> IV,
> who apparently was not impressed. Pope Sixtus IV later
> became
> convinced that another reform was needed and called the
> German
> astronomer, Regiomontanus, to Rome to advise him.
> Unfortunately,
> Regiomontanus died of the plague shortly thereafter and the plans
> died
> as well.
>
> In 1545, the Council of Trent authorized Pope Gregory XIII to
> reform
> the calendar once more. Most of the mathematical work was
> done by
> Father Christopher Clavius, S.J. The immediate correction that
> was
> adopted was that Thursday, October 4, 1582 was to be the last
> day of
> the Julian calendar. The next day was Friday, with the date
> of
> October 15. For long range accuracy, a formula suggested by
> the
> Vatican librarian Aloysius Giglio was adopted. It said that
> every
> fourth year is a leap year except for century years that are
> not
> divisible by 400. Thus 1700, 1800 and 1900 would not be leap
> years,
> but 2000 would be a leap year since 2000 is divisible by 400.
> This
> rule eliminates 3 leap years every 4 centuries, making the
> calendar
> sufficiently correct for most ordinary purposes. This
> calendar is
> known as the Gregorian calendar and is the one that we now use
> today.
> (It is interesting to note that in 1582, all the Protestant
> princes
> ignored the papal decree and so many countries continued to use
> the
> Julian calendar until either 1698 or 1752. In Russia, it needed
> the
> revolution to introduce the Gregorian calendar in 1918.)
>
> This explains why VMS chooses to treat the year 2000 as a leap
> year.
>
> Despite the great accuracy of the Gregorian calendar, it still
> falls
> behind very slightly every few years. If you are very concerned
> about
> this problem, we suggest that you tune in short wave radio
> station
> WWV, which broadcasts official time signals for use in the
> United
> States. About once every 3 years, they declare a leap second at
> which
> time you should be careful to adjust your system clock. If you
> have
> trouble picking up their signals, we suggest you purchase an
> atomic
> clock (not manufactured by Digital and not a VAX option at this
> time).
>
> END OF SPR RESPONSE
>
> Return to OpenVMS Year 2000 home page
>
>
> > >From Sydney Uni:
> >
> > >Dear All,
> > >
> > >Today is the first 29th of Feburary on a century year for 400 years,
> > >thanks to the Gregorian Calendar. The DEC machine operating system
> > >licenses can't deal with this, they get the date from the network
> > >time server (suphys). As a result, you won't be able to log on to a
> > >DEC machine today. They will function properly again tomorrow, once
> > >they get the date 1/3/00 from suphys. It may be necessary to reboot
> > >them, we'll know more tomorrow.
> > >
> > >In the meantime, just log on to a sun, or PC running solaris, they are
> all
> > ok.
> > >
> > >I've called Compaq (DEC that was) and blown a big rasberry at them.
> > >
> > >Tony.
> > >
> > >
>
> --
> Andrew Dorrell PhD. Research Engineer
> Canon Information Systems Research Australia Phone: 61 2 9805 2224
> 1 Thomas Holt Drive, North Ryde, NSW 2113. Fax: 61 2 9805 2929
> --
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