[Esip-documentation] ACDD 1.3 issue: date & time stamps

[John Graybeal via Esip-documentation]

The issue of date/timestamps is by far the most challenging ACDD issue.

A very short version of the very long 1.3 history:
A) A year-plus ago, several members identified ambiguities in definition, understanding, and use of the originals (date_created, date_modified, date_issued)
B) An extensive analysis/discussion took place starting over a year's time; the opinion of that group was that new terms should be created in place of the old. These terms were date_content_modified, date_values_modified, date_product_generated. A fourth was proposed but not settled on, a la date_product_originally_created. Another request relative to this group was for a publication date (which could be date_issued or something else, depending on definitions.)
C) The broader group's recent (general) decision was that existing terms should be kept, but redefined if necessary.
D Our 10-minute attempt yesterday helped bring out some of the original and ongoing issues.
E) Jim Biard's email this morning ("ACDD date attributes question) takes a back-to-fundamentals approach, laying out some suggested use cases and concepts.

For reference (only!), I've provided below definitions of these terms more or less as they originated or were improved.

From a process perspective I think we might want to have a separate sub-group hash out a recommendation, but I think Jim's idea of gather requirements is a necessary first step anyway. So I propose 
(a) you respond to Jim's email with your inputs to his summary, and 
(b) reply to this email with any other comments or analysis, especially about process.

I do not have any clever ideas to make this topic more easily resolvable, given the constraints in (A) and (C) above. Let's start the discussion and see how it goes.

John

====================

date_created	
	The date on which the data was created.
date_modified	
	The date on which this data was last modified.
date_issued	
	The date on which this data was formally issued.
date_content_modified 
	The date on which any of the provided content, including data, metadata, and presented format, was last changed (including creation)
date_values_modified
	The date on which the provided data values were last changed (including creation); excludes metadata and formatting changes
date_product_generated 
	The date on which this data file or product was produced/distributed. While this date is like a file timestamp, the date_content_modified and date_values_modified should be used to assess the age of the contents of the file or product. 
date_product_originally_created
	The date on which this data file or product first came into existence.

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