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#107: CF Data Model 1.7
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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):

 Hi Mark, Jim,

 My reading of the standard is that `grid_mapping` points to something that
 looks like a CRS definition, and the "true latitude and longitude"
 coordinates are supplied by the `coordinates` attribute. Even though it's
 redundant, both of these may be used for the convenience of clients.

 I'm not sure what is meant in Mark's document by a "derived" coordinate.
 This seems to be an association of coordinates in one CRS with a defined
 formula to transform into another one. I would argue that vertical sigma
 coordinates '''do''' fall into this definition, but horizontal coordinates
 '''do not''', because CF does not (currently) supply the formula to
 translate to another system (it describes the CRS instead, which is
 different, leaving the application to figure out the transformation).

 Cheers,
 Jon

-- 
Ticket URL: <https://cf-pcmdi.llnl.gov/trac/ticket/107#comment:33>
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