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[netCDF #VQZ-726653]: data packing

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  • Subject: [netCDF #VQZ-726653]: data packing
  • Date: Fri, 28 Sep 2007 08:47:20 -0600
Sue,

Yes, to be CF-compliant, if both the valid_range and _FillValue
attribute are present, then the _FillValue should be outside the
valid_range.  I don't think that convention recommendation needs to
change.  CF-compliant data is a subset of valid netCDF data.

The _FillValue attribute is handled by the netCDF library and is used
in files that follow other conventions or no conventions at all.  So
netCDF data that has a _FillValue anywhere in the range must be
interpreted correctly by the library, and by generic applications such
as ncdump or the NCO programs that handle packed data.

Our example of packing, writing, reading, and unpacking data that
includes a _FillValue will put the _FillValue at one end of the valid
range, as we consider that a "best practice".  I just don't think we
can change the packing/unpacking formulas to *require* the _FillValue
to be at the bottom or top of values that are considered valid.

--Russ

Russ Rew                                         UCAR Unidata Program
address@hidden                     http://www.unidata.ucar.edu



Ticket Details
===================
Ticket ID: VQZ-726653
Department: Support netCDF
Priority: Normal
Status: Closed