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Date:      Tue, 28 Oct 1997 00:39:25 +0100 (MET)
From:      Wolfgang Helbig <helbig@Informatik.BA-Stuttgart.DE>
To:        jack@diamond.xtalwind.net (jack)
Cc:        steve@visint.co.uk, freebsd-questions@FreeBSD.ORG
Subject:   Re: 2000 Compliance / dates / time libs
Message-ID:  <199710272340.AAA21304@rvc1.informatik.ba-stuttgart.de>
In-Reply-To: <Pine.BSF.3.96.971027130748.23256A-100000@zeus.xtalwind.net> from jack at "Oct 27, 97 01:09:34 pm"

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> On Tue, 29 Feb 2000, Stephen Roome wrote:
> 
> > 
> > So when (or if) does the julian/gregorian switch take place
> 
> It already happened, in the 1500s.  The exact year varied by country.

The switch took place October 4th 1582, which was followed by the
October 15th 1582. At least that's what the catholic church
determined. The switch was necassary, because the calendar and the
revolution of the earth around the sun (or the sun around the earth
:-) got out of synch. Especially April 21st was not the start of
spring anymore which confused the calculation of easter.

The old Julian calendar defines a leap year as every year divisible
by four.
The new Gregorian calendar defines a leap year as every year
divisible by four and not divisible by hundred or divisible by 400.

Hence for the year 2000 it does not matter: Since it's divisible
by four it's a leap year according to Julius Caesar and since it's
divisible by 400 it's a leap year according to Pope Gregor.

BTW. The usr/src/share/zoneinfo files contain the switch date
for some countries.

Wolfgang



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