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Re: [Scheme-reports] Date/time package

John Cowan <cowan@x> writes:
> John J Foerch scripsit:
>> The proposal now says that the gregorian and julian chronologies are
>> both proleptic.  Do I interpret correctly that this means that in the
>> gregorian chronology, the day before 1582-10-15 is 1582-10-14, not
>> 1582-10-04?
> Correct.  Note that this is only the transition date for certain
> Catholic countries as well as for the Church itself.  The remaining
> Catholic countries followed within a few years.  But Protestant countries
> transitioned at various times in the 18th century (the English-speaking
> lands in 1752 -- try typing "cal 9 1752" if you are on a non-Windows
> system), and the Orthodox countries not until the 20th century.
> So to interpret historical dates, we must have the correct
> location and then create the appropriate compound chronology.
> http://www.tondering.dk/claus/cal/gregorian.php#country gives
> non-authoritative information about the transition dates in
> various locations.
>> In the julian chronology, is there a gregorian reform after 1582-10-04?
> No.
>> Do the gregorian and julian chronologies have a year zero?
> Also no.

Okay, let's suppose an application working with historical astronomical
data.  The tradition in that field, since Kepler I understand, is to use
a calendar which is Julian up to 1582 has the Gregorian reform in 1582,
and *has* a year zero.  How would this proposal accomodate that

John Foerch

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