Due to the current gap in continued funding from the U.S. National Science Foundation (NSF), the NSF Unidata Program Center has temporarily paused most operations. See NSF Unidata Pause in Most Operations for details.
Due to the current gap in continued funding from the U.S. National Science Foundation (NSF), the NSF Unidata Program Center has temporarily paused most operations. See NSF Unidata Pause in Most Operations for details.
Harvey Davies (hld@xxxxxxxxxxxx) writes: > We use both netCDF and CDF and it would be convenient to distinguish > between them using different conventional file extensions. I propose > defining a new recommended file extension for netCDF. I suggest ".nc". I think this is a good suggestion, though I wish we had thought of it earlier. This would lessen the confusion between CDF and netCDF, and would correct the early error of choosing the same file extension. The history of this choice is that we came up with a single-file implementation of the CDF model using the ".cdf" extension when NASA/NSSDC already had a multi-file implementation that required n+2 files for an n-variable dataset, with extensions ".CDF", ".CDH", ".V01", ".V02", ..., ".Vnn". Our single-file implementation on Unix had a lower-case extension ".cdf", but we should have foreseen the conflict this would create with NSSDC's CDF when it was ported to Unix. I don't know of any existing conflicts with the ".nc" extension. However there may be archives of netCDF files for which changing the file extension is impractical. There are by now probably a number of other software packages than ours that makes use of the ".cdf" extension for netCDF files. Hence changing from a ".cdf" extension to ".nc" may be disruptive. Therefor I agree that we should continue to support the old ".cdf" extension while encouraging use of the ".nc" extension for future datasets. > ncgen appends the ".cdf" extension if "-o outputfile" is not specified. > This appears to be the only place where ".cdf" is built into the > standard netCDF software. Yes, of our netCDF software, only ncgen currently makes use of this extension. Applcation packages that use it could be changed to accept either ".cdf" or ".nc" files. > I suggest a new flag (say -N) similar to -n, > except that it would generate the new default file extension. Note that > -n would be retained for compatibility and would still produce ".cdf". Unfortunately the "-N" and "-n" arguments could not easily be distinguished on MSDOS systems, and would be inconvenient on VMS systems. I suggest that ncgen should use a "-b" flag (for binary) to specify the generation of a binary netCDF dataset with the extension ".nc". I agree that the old "-n" action should be supported for backward compatibility, but its use for future datasets should be deprecated, after the next release of the netCDF software. > It would be necessary to modify the "NetCDF User's Guide". I suggest it > should mention both the new recommended extension & the old obsolete > ".cdf". I am willing to make such modifications, and again agree with your suggestion. If anyone knows of an existing conflict with the ".nc" extension, or wants to argue why it is too late to begin changing the netCDF file extension from ".cdf" to ".nc", please let us know. Thanks. ________________________________________________________________________ Russ Rew Unidata Program Center russ@xxxxxxxxxxxxxxxx
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