[Esip-documentation] ACDD date attributes question

[Jim Biard via Esip-documentation]

Hi.

I was wondering if it would be useful to back the whole date attribute 
question up a bit.

Without using any existing or proposed attribute name, can each 
stakeholder describe what kinds of date stamps they need and want?

When describing these date stamps, I see three different entities (sort 
of) that they might relate to - and there are probably more. The ones 
that I see are:

  * Granule - An atom of data that is bounded in space and/or time. One
    granule can include multiple variables, and has variable- and
    granule-level metadata. A granule *is not* a netCDF file. It is data
    and metadata floating free in "the cloud".
  * Collection - A group of granules that are treated as a consistent
    whole. A collection may be static, or it may grow over time. As with
    a granule, a collection is a conceptual object in "the cloud".
  * Granule Instance - A granule expressed as one or more netCDF files.


Using these terms, here are date stamps that I find useful/needed. Most 
all of these should have accompanying annotations in history metadata.

  * Date a granule's data was first produced/acquired. This can get
    tricky for a granule consisting of a long time series.
  * Date a granule's metadata was first associated with the data.
  * Date a granule's data was last modified.
  * Date a granule's metadata was last modified.
  * Date a granule instance was created.
  * Date a granule instance was last modified.
  * Date a collection was established. (I say it this way on account of
    growing collections.) I guess this amounts to a version/edition time
    stamp.


There are other entities and date stamps that I have left out because I 
didn't see them as being relevant to a particular granule instance in a 
netCDF file.

Do these make sense? Are there others that you can think of?

Grace and peace,

Jim

CICS-NC <http://www.cicsnc.org/> Visit us on
Facebook <http://www.facebook.com/cicsnc> 	*Jim Biard*
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