Amendment 2: Date range for the 1904 date base?

[Chris Rae]

Hi all - starting another thread for this one as it's a quite separate question. When comparing IS 29500:1 to ECMA-376:1, they differ in a move to promote 1900 to be the primary date base system over 1904. Previously I thought that the extent of this was simply to rename 1904 to be "backward compatibility", and we exchanged some threads on this list concerning that. Gareth and I decided that there was no reason to demote 1904 and, as such, in Amendment 2 we are intending removing the "backward compatibility" in its name.

It's also been pointed out to me that the 1904 date base has a curtailed range - although the 1900 date base can go back to the year -9999, the 1904 date base is stuck at 1904. I propose that, in strict, we allow the 1904 date base to cover the same range as 1900 (years -9999 to 9999). In transitional it should retain the same range as it had in Ecma-376 (and currently has in strict).

Does anyone have any objections to these changes? The 1904 date base is used a lot less than 1900 but there's no technological reason as to why it shouldn't have the same functionality.

Chris

Date base definitions from IS 29500 (18.17.4.1):

Three different bases can be used for converting dates into serial values:
* In the 1900 date base system, the lower limit is January 1, -9999 00:00:00, which has serial value -
4346018. The upper-limit is December 31, 9999, 23:59:59, which has serial value 2,958,465.9999884.
The base date for this date base system is December 30, 1899, which has a serial value of 0.
* In the 1900 backward compatibility date-base system, the lower limit is January 1, 1900, 00:00:00, which
has serial value 1. The upper limit is December 31, 9999, 23:59:59, which has serial value
2,958,465.9999884. The base date for this date base system is December 31, 1899, which has a serial
value of 0.
* In the 1904 backward compatibility date-base system, the lower limit is January 1, 1904, 00:00:00, which
has serial value 0. The upper limit is December 31, 9999, 23:59:59, which has serial value
2,957,003.9999884. The base date for this date base system is January 1, 1904, which has a serial value
of 0.