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This is not a use case for before/after but for "open ended" intervals.

The expression (using the proposed syntax) "20101010.." we read as "a date 
on or after 10 Oct 2010"--- I have suggested "on or after" versus after as 
per the original af.20101010 as it is more consistent with common usage 
of "..".

The expression (using the proposed syntax) "20101010/" we read, by contast, 
as an undetermined interval (intuitively "infinite" at the knowledge state) 
starting on 10 Oct 2010.

Since permissions are an on-going thing they are clearly defined by an 
interval (many of a series of incremental dates) rather than a single point 
(date) within a continuum.  "publication dates of journals or other serially 
issued resources" that are still being published--- and to which no plans 
have been expressed to cease publication--- are clearly defined too by "open 
ended" intervals.

By most estimates the date at which man will first land on Mars is no 
earlier than 2030. To express this we'd use the notation "2030..". Man 
landing on Mars is an event similar to the date when Neil Armstrong took his 
first steps on the Moon-- 19690721--- but in front of rather than behind us.


On Wed, 16 Mar 2011 16:09:26 -0400, Guenther, Rebecca wrote
> In particular, it was needed in PREMIS (preservation metadata) for the 
case when there are permissions granted in association with the preservation 
of an object that may be time limited. A common case is that there is a 
start date and no end date specified. A repository may want to look for all 
those that are time limited vs. those that are open ended.
> 
> It is also used for publication dates of journals or other serially issued 
resources that have a start date but no end date.
> 
> Rebecca
> 
> Rebecca S. Guenther
> Senior Networking & Standards Specialist
> Network Development & MARC Standards Office
> Library of Congress
> 101 Independence Ave SE
> Washington, DC 20540
> voice: +1.202.707.5092
> fax: +1.202.707.0115
> [log in to unmask]
> 
> -----Original Message-----
> From: Discussion of the Developing Date/Time Standards 
[mailto:[log in to unmask]] On Behalf Of Ray Denenberg, Library of 
Congress
> Sent: Wednesday, March 16, 2011 1:00 PM
> To: [log in to unmask]
> Subject: Re: [DATETIME] Before/after indicator LAST CALL
> 
> > From: [UTF-8?]SaaÅ¡ha Metsärantala
> > > 20040101/ Does anyone see a problem
> > I consider that the notation is OK. But, are such open-ended intervals 
> > really useful?
> 
> Yes, the PREMIS community has cited this as a requirement, for 
preservation data.
> 
> --Ray


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Edward C. Zimmermann, NONMONOTONIC LAB
http://www.nonmonotonic.net
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