[Bug 1967] [F+O] Year Zero

http://www.w3.org/Bugs/Public/show_bug.cgi?id=1967





------- Additional Comments From liam@w3.org  2005-09-03 17:25 -------
Actually the date calculations start going pear-shaped if you
go before 1753 (when Sweden adopted the Gregorian calendar;
England moved in 1752, so that the correct answer for
1752-09-15 - 1752-09-01 is 4.  Any other answer is incorrect,
and since it is not possible to talk about invalid dates with
Schema, you can't mention that 1752-09-10 (for example) does
not exist and should be every bit as invalid as allowing a
leap second or leap day (29th Feb) when there wasn't one.

There was, of course, a 10th of September 1752 in most other
European countries, since they had already switched and had
their lacunæ -- in some cases there were riots as people felt
days were being taken away from them.  So you cannot do
calculations involving historical dates without knowing,
date in which country, and from whose perspective?

A spaniard, for example, could write "the 14th of September,
which the English called the 2nd of September".

When we project the Gregorian calendar backwards boyond the
date of its adoption, we get progressively less accurate.

It would not be unreasonable to forbid dates earlier than 1754.

However, requiring that an implementation check that no
intermediate values in a calculation be less than 1754, or
less than 1, may be an unreasonable burden.

Until such time as Schema supports non-Gregorian calendars,
anyone working with historical dates will surely

(1) avoid the date/time type, if they know what they are doing,
or
(2) quickly find life full of surprises...

What is the use case for making reference to 0BC an error?

Liam

Received on Saturday, 3 September 2005 17:25:17 UTC