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From: kessler%cons.utah.edu@wasatch.utah.edu (Robert R. Kessler)
Newsgroups: comp.sys.mac
Subject: Re: why 1904?  ms excel
Message-ID: <3270@wasatch.utah.edu>
Date: 6 Sep 89 19:44:10 GMT
References: <457a7553.1285f@maize.engin.umich.edu> <30291@srcsip.UUCP>
Sender: news@wasatch.utah.edu
Organization: University of Utah CS Dept
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In article <30291@srcsip.UUCP> mnkonar@src.honeywell.com (Murat N. Konar) writes:
>In article <457a7553.1285f@maize.engin.umich.edu> edt@caen.engin.umich.edu () writes:
>-Excel stores dates and times as serial numbers from 0 to 49710, where
>-0 is the number for January 1, 1904, and 49710 is the number for February 6,
>[stuff deleted]
>-Why 1904?  I don't see why they chose that year rather than 1900 (which makes

My guess is that January 1900 is special, because of it being a leap
year, which would add a day in February, but since it is not a
multiple of 400 years, then the day is taken away, so it isn't really
a leap year.  The year 2000 will be a leap year (aren't we lucky that
we won't have to rewrite all that date software for the year 2000 ;-).
So, you don't have to special case the software to know about
centuries that aren't multiples of 400.  I suspect that it will
think Feb 29, 2100 is a legal date (just a guess).

B.