ISO 8601 has limited ability to express a lot of types of dates,
especially some needed for cultural heritage objects, like those that are
questionable, approximate, etc. Perhaps we should come up with some PREMIS
conventions. I looked at this a few years ago in the context of some
Dublin Core work and could dig up my notes if needed on the limitations of
8601. There has been little consensus on conventions for these kinds of
uncertain dates. So it may be prudent to establish some for PREMIS perhaps
based on what other efforts may be using.
On Fri, 16 Jun 2006, Matthew Beacom wrote:
> It may be that one simply can't use ISO 8601: 2004 this way. Using
> 9999 and 0000 to represent not "dates in the Gregorian calendar" but
> rather a quality of open-endedness with respect to an end date or a
> start date is logically outside of the domain of ISO 8601. Anything
> we do would be a kluge.
> 9999 may not be the best value to mean "forever" as it would also
> mean the year 9999. A bit far off to worry about, of course. And OOOO
> would mean 1 BCE (or be illegal) as there is no year 0 between the
> first year of the common era (1 CE) and the last year prior to the
> 1st year of the CE (1 BCE).
> I think, though, that 0000 is not needed since a way to represent the
> open-endedness of a start date is not needed. The rights related to
> the object can't pre-date the object itself. So One can simply use a
> practical (albeit) arbitrary start date such as the date of the
> creation of the digital object or, if necessary, the date of the
> original object for which the digital copy is a proxy.
> And then--for about 8000 years anyway--9999 may work perfectly well
> being used to mean endless. But, of course, that would be a
> non-standard use of 9999.
> Matthew Beacom
> p.s. below is the abstract for ISO 8601: 2004 from
> ISO 8601:2004 is applicable whenever representation of dates in the
> Gregorian calendar, times in the 24-hour timekeeping system, time
> intervals and recurring time intervals or of the formats of these
> representations are included in information interchange. It includes
> * calendar dates expressed in terms of calendar year, calendar
> month and calendar day of the month;
> * ordinal dates expressed in terms of calendar year and calendar
> day of the year;
> * week dates expressed in terms of calendar year, calendar week
> number and calendar day of the week;
> * local time based upon the 24-hour timekeeping system;
> * Coordinated Universal Time of day;
> * local time and the difference from Coordinated Universal Time;
> * combination of date and time of day;
> * time intervals;
> * recurring time intervals.
> ISO 8601:2004 does not cover dates and times where words are used in
> the representation and dates and times where characters are not used
> in the representation.
> ISO 8601:2004 does not assign any particular meaning or
> interpretation to any data element that uses representations in
> accordance with ISO 8601:2004. Such meaning will be determined by the
> context of the application.
> Matthew Beacom
> Metadata Librarian
> Yale University Library
> 130 Wall Street P.O. Box 208240
> New Haven, CT 06520-8240
> phone: (203) 432-4947
> fax: (203) 432 7231
> e-mail: [log in to unmask]