[CF-metadata] source, institution, and history

Roy Mendelssohn - NOAA Federal roy.mendelssohn at noaa.gov
Fri Jan 20 19:30:21 MST 2017

> On Jan 20, 2017, at 6:20 PM, John Graybeal <jbgraybeal at mindspring.com> wrote:
> Hi all,
> Over on the ACDD (esip-documentation) list, we started a thread to answer some questions about ACDD attributes. One question related to the 3 CF attribute definitions for source, institution, and history (documented in http://cfconventions.org/Data/cf-conventions/cf-conventions-1.7/build/ch02s06.html#description-of-file-contents); I believe ACDD slavishly follows the CF definitions so this list seems the authority.
> I’ve copied that bit of the ACDD thread below for context. (In that thread JPL provided initial data, and ERD processes those data to create the ‘new’ data set that’s being documented.) But the question boils down to the following.
> Do CF source, institution, and history attributes all document the ‘new’ data set, referred to in CF as the current file? (Please note that in some definitions, like institution, this is called “the original data”.)  This is what the introduction to the section seems to say. But if this ‘new’ data set *is* "the original data”, how can there be any “modifications to the original data” as described in the history definition?
> Thanks very much for your input, and apologies for the cross-posting.
> John
>>> source: Should this be info what JPL did since original data is specified in the definition (below)
>>> 'The method of production of the original data. If it was model-generated, source should name the model and its version, as specifically as could be useful. If it is observational, source should characterize it (e.g., " surface observation " or " radiosonde “)'
>> As ’source’ comes directly from the CF conventions, I went back to those definitions, and I’m still not sure. (See also the next two items.) If no one on this list sounds authoritative, I suggest you send a question to the CF conventions list (mailto:cf-metadata at cgd.ucar.edu, subscribe at http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata). Actually, I’ll do that now, just so the CF folks are aware of the question.
>>> institution: JPL nice original data is specified
>>> 'Specifies where the original data was produced’
>> Will be the same answer as source. I would have agreed with you, but then the history definition (next) seems to suggest otherwise.
>>> history: where we describe modifications to the original data. 
>>> 'Provides an audit trail for modifications to the original data. Well-behaved generic netCDF filters will automatically append their name and the parameters with which they were invoked to the global history attribute of an input netCDF file. We recommend that each line begin with a timestamp indicating the date and time of day that the program was executed’
>> So the relevant CF section for source, institution, and history is http://cfconventions.org/Data/cf-conventions/cf-conventions-1.7/build/ch02s06.html#description-of-file-contents. While the definitions for institution (’Specifies where the original data was produced’) is almost certainly describing the current file’s institution, the  history is ‘an audit trail for modifications to the original data’. If this file _is_ the original data, I don’t see how there can be any modifications to it yet, I would call this a CF issue (and we of ACDD carefully avoided messing with CF definitions, as I recall), so maybe that group needs to weigh in.
> ---------------------------------------
> John Graybeal
> jbgraybeal at mindspring.com
> linkedin: http://www.linkedin.com/in/johngraybeal/
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Roy Mendelssohn
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