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[netCDF #RAN-492926]: Re: [Fwd: Fwd: [Support] opendap netcdf

Hi Benno,

You're correct, comma separated conventions can be used in the global
Conventions attribute.

It says this on the netCDF Conventions web page

  http://www.unidata.ucar.edu/software/netcdf/conventions.html

which includes the following paragraph:

  It is possible for a netCDF file to adhere to more than one set of
  conventions, even when there is no inheritance relationship among the
  conventions. In this case, the value of the `Conventions' attribute
  may be a single text string containing a list of the convention names,
  separated by blank space or commas, such as

      :Conventions = "XXX, YYY" ;

We need to make the User Guide documentation on Conventions match the above,
if it doesn't already.  I'll put that on my list.

I've been following your CF proposal for name spaces and Jonathan's arguments
as well.  I haven't commented yet, because I don't consider myself very
well informed about metadata standards.  However, it seems to me that there
is an issue about where the information about mappings among various metadata
standards should be stored.

On the one hand, you could store the fact that a particular data variable has
associated metadata that conforms to standards X, Y, and Z in each data file
that has such data, repeating the same information many times in many data
files.  Alternatively, you could store the relationships among X, Y, Z, and
perhaps later W metadata conventions as they pertain to that variable in one
place and have the variable metadata use indirection to point to that place.
It's the old argument about redundancy versus maintainability: do you represent
information in one place where it can be maintained easily but requires
indirection, or in lots of places redundantly, where it is close to the data?

Namespaces may offer a sort of middle road that provides short abbreviations
for information uniquely defined somwhere authoritatively.  But that's probably
obvious and not worth saying on the CF-metadata Wiki on issue 27 ...

--Russ



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



Ticket Details
===================
Ticket ID: RAN-492926
Department: Support netCDF
Priority: Normal
Status: Closed