I do see that you're working with genealogy, I don't even follow your
calendar reasoning.

However, assuming the simple bits that I thought was the Julian
calendar (leapyears every 4th year, except those ending in 00 which is
not divisible by 400), I think the calendar should repeat itself every
2800 years. Hence, if you add 5600 years to each and every value, you
should be able to store dates from before the beginning of
'Astronomical calculations' (1 January 4713 BC) to about 2395 years
from now. Before then, I expect Firebird 5 to have been released, and
I'm certain a solution to your date problem will have been found.

Set

> The QUOTED minimum is January 1, 100AD ( page 945 of the book )
> which would correspond to a correct/incorrect leap year in the
> Gregorian calendar, which is one reason for asking the question.
> *I* currently have dates back to 1000 AD, which are on the Julian
> calendar, and can be converted to Gregorian day counts for
> comparison purposes, with the period from 1500 to 1900 needing to
> converted depending on the country and date, to provide a normalised
> day count. While we do not probably need day accuracy in roman
> times, despite the mess that Old Julius sorted out in 45BC there are
> documented dates back into that period, and Astronomical
> calculations go back to a day 0 of 1 January 4713 BC ( Midday since
> astronomers work nights ;) )
>
> Working from this basis, all of the other calendars used world wide
> can be overlayed with matching days. If you were Jewish you would
> know that the world was created in 3761 BC somewhat after day 0 so
> can still be calculated, and Jewish records preceed the birth of
> Jesus.
>
> *SO* Do I use a simple DATE or TIMESTAMP and adjust for variations,
> or do I throw them in the bin and start again with a REAL date
> element as an integer starting on day 0 :)