Dear all
I confess to not having read what the user guide says (at least, not recently)
and I have copied it below in case others would like to be reminded as well.
This suggests that Nan's extra conventions for oceansites would correctly be
denoted "CF-1.4/OceanSITES-1.0", since oceansites accepts all of CF and adds
some more. We could, for instance, amend the CF convention to recommend this
format for additional conventions that explicitly say they adopt all of CF
and add some more. I am sure the checker could be amended to ignore whatever
follows / in the Conventions attribute.
As a matter of policy, I would hope that subconventions like this would only
be added if the extra conventions were too application-specific to be of
general use. New ideas which could apply in other areas could usefully be
added to the main CF standard.
The user guide doesn't say anything about spaces. It doesn't prohibit them,
but it does talk about conventions names being filenames. Although filenames
containing spaces are possible, they're a nuisance on Unix, and it seems to me
they would be a hazard in this context. People often put in extra spaces, or
leave out spaces, fairly arbitrarily in strings, and if they are significant
that would be an error. Wouldn't it be better to recommend against spaces in
conventions names in the netCDF user guide?
This user guide convention with / is for subconventions. It doesn't deal with
the situation where several separately developed conventions are being used,
and you might want to put them in a blank-separated or comma-separated list.
I don't think we should allow that in the Conventions attribute unless and
until we'd decided how to resolve conflicts between these conventions. (There
are no conflicts with a subconvention that explicitly accepts all the of the
standard to which it is adding.)
Best wishes
Jonathan
>From http://www.unidata.ucar.edu/software/netcdf/docs/netcdf.html#Attribute-Conventions
If present, 'Conventions' is a global attribute that is a character array for
the name of the conventions followed by the dataset, in the form of a string
that is interpreted as a directory name relative to a directory that is a
repository of documents describing sets of discipline-specific
conventions. This permits a hierarchical structure for conventions and
provides a place where descriptions and examples of the conventions may be
maintained by the defining institutions and groups. The conventions directory
name is currently interpreted relative to the directory
pub/netcdf/Conventions/ on the host machine
ftp.unidata.ucar.edu. Alternatively, a full URL specification may be used to
name a WWW site where documents that describe the conventions are maintained.
For example, if a group named NUWG agrees upon a set of conventions for
dimension names, variable names, required attributes, and netCDF
representations for certain discipline-specific data structures, they may
store a document describing the agreed-upon conventions in a dataset in the
NUWG/ subdirectory of the Conventions directory. Datasets that followed these
conventions would contain a global Conventions attribute with value "NUWG".
Later, if the group agrees upon some additional conventions for a specific
subset of NUWG data, for example time series data, the description of the
additional conventions might be stored in the NUWG/Time_series/ subdirectory,
and datasets that adhered to these additional conventions would use the global
Conventions attribute with value "NUWG/Time_series", implying that this
dataset adheres to the NUWG conventions and also to the additional NUWG
time-series conventions.
Received on Thu Sep 03 2009 - 01:18:53 BST
