WFC: Year-2000 issue

[Preben Grosbol]

sla at ucolick.org wrote:

> It does not make sense to mandate that the time be UTC without also
> mandating that the calendar date be expressed in the Gregorian
> calendar.  There is currently no FITS specification of the calendar
> system.  UTC and TAI are often expressed in counts of seconds and MJD
> counts of 86400 seconds; if there is any specification for the use of
> Gregorian calendar for either timescale it is not widely enough known
> that it can be presumed.

Maybe I should not respond to the 'wfc at nrao.edu' discussion but then
again clarification is never bad.

On the Calender issue, ISO 8601 (and therefore the proposal) clearly
specifies the Gregorian calender (see section 3.8).  Actually, we
may have to detail the ISO 8601 standard with respect to leap
seconds which are not discussed!  In the European discussion a
main argument for the suggestion was that "preferred" in reality
means that the time system is undefined since you can not assume
any by default.  The ISO 8601 format does not either allow for
a 'Z' after the date to specify UTC.

Best regards,
Preben Grosbol