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#95: Development of CF 1.5 Data Model
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  Reporter:  markh           |       Owner:  [email protected]
      Type:  task            |      Status:  new                          
  Priority:  medium          |   Milestone:                               
 Component:  cf-conventions  |     Version:                               
Resolution:                  |    Keywords:                               
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Comment (by jonblower):

 I'm late to this conversation, but this seems to be a special case of a
 general problem of aggregation and inheritance of metadata in a hierarchy.
 A file is an aggregation of variables, whose attributes can be specified
 at the file or variable level.  Also, a set of files can be aggregated
 into a dataset.  Then we have ensembles etc etc.

 I'm not sure what the solution is, but other systems (e.g. OGC services)
 have the concept of metadata inheritance, with the behaviour of the
 inheritance dependent on the metadata item in question - metadata can be
 inherited, overridden or aggregated by children in the hierarchy.  Other
 items of metadata are not considered inheritable at all and only exist on
 the parent object.

 For example, if a file has a comment field, and the variable has a comment
 field, these might be aggregated in the data model to produce a resulting
 variable with two comment fields (it doesn't seem unreasonable to me that
 there would be valid use cases for this).  However, in an aggregated
 dataset, each variable can only have one scale/offset pairing, otherwise
 it doesn't make sense (this precise case has just bitten someone in
 THREDDS-land by the way), so the semantics of how these items are derived
 are important (what about valid_range for example)?

-- 
Ticket URL: <https://cf-pcmdi.llnl.gov/trac/ticket/95#comment:85>
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