Re: 5 Digit Dates (was RE: Euro currency sign)

 John/David

>I concur with David especially when you expand the scope of dates to
>include that used by applications (not just the system date). I've
>worked on software that had to operate on dates in the middle of the
>next millenium (related to nuclear facility management) and way beyond
>(astronomy software for predicting eclipses and unusual alignments).
>It's a royal pain when the system software doesn't handle this.

ISO 8601 is postulated only on the use of the Christian dating system -
therefore does not need to support anything more than 4 digits. If you want
a more comprehensive dating system then you have to use something more
complex, like the HyTime specfication.

I do not know of any websites that give overviews of the HyTime calendar
features, but can point you to the source data:

For details of the calendar related lexical types defined in HyTime see:
ftp://ftp.ornl.gov/pub/sgml/wg8/document/n1920/html/clause-C.1.1.html

Note particularly that this mechanism is extensible - ERA could have more
entries and fulldate could be updated to have as many numbers as required.

For details of how these lexical types are applied in HyTime see:
ftp://ftp.ornl.gov/pub/sgml/wg8/document/n1920/html/clause-9.9.html