On Tue, 2014-05-06 at 23:50 +0000, Martin Holmes
gtxxgm-xsl-list-2(_at_)m(_dot_)gmane(_dot_)org wrote:
The proleptic Gregorian doesn't, I agree, make much sense when it's
extended this far back, but the project I'm working on is an early
modern one, and most of our date-conversion functions convert between
Julian and Gregorian.
It's worth mentioning for the sake of people thinking the Julian
calendar is convenient in general that different countries adopted the
Gregorian calendar at different times - as late as the 1930s for Greece,
1752 in the UK, 16th Century for much of Roman Catholic Europe, and an
even more complex picture in the Americas.
The other historical form commonly seen is to date events in terms of
people, usually monarchs. E.g. 3 Geo III would be the third year of the
reign of George III, although as far as I can tell the usual year end
was employed, so that the years were measured in England (say) from
April 1st, not from the coronation or accession date.
Older dates tagged as Julian also come in for the
same conversion. You're right that it's ambiguous, though; this page:
<http://en.wikipedia.org/wiki/Proleptic_Gregorian_calendar> shows a
table in which 1BC Julian is equivalent to 1BC Gregorian, but it also
appears to suggest that ISO 8601 is somehow equivalent to proleptic
Gregorian.
It is also overly simplistic, for the reasons I already mentioned. Since
dates don't usually mention the calendar to which they conform, you have
to add context. And, of course, a visitor from France to England writing
home would most likely use the French calendar of the time, perhaps
eventually switching after staying in England more than a year or two.
There's a book on Calendrical Calculations, although I seem to remember
that it's awfully proprietary, in that the author claims ownership of
the algorithms. But it looked as if it might be helpful.
Liam
--
Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
Pictures from old books: http://fromoldbooks.org/
Ankh: irc.sorcery.net irc.gnome.org freenode/#xml
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