Hi Nan,
> I'm certain that this has been discussed, but I can't
> find it anywhere in the email archive, or on the trac site.
>
> Don't we allow a compound (comma separated) string
> in the global attribute 'Conventions'?
>
> Because there are new, complimentary conventions
> available - like the ACDD (discovery attributes) - it would
> be very handy to allow multiple conventions to be specified
> in a single attribute: "CF-1.6, ACDD, OceanSITESv2.1.2".
The recommendation on the Unidata site for multiple conventions
http://www.unidata.ucar.edu/netcdf/conventions.html
is to use spaces rather than commas:
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 (recommended) or commas (if a convention name
contains blanks), for example
:Conventions = "XXX YYY" ;
> Here's the text from the current version of the cf-conventions
> document:
>
> > 2.6.1. Identification of Conventions > > We recommend that netCDF files that follow these
> conventions > indicate this by setting the NUG defined global attribute Conventions > to the string
> value "CF-1.6". The string is interpreted as a > directory name relative to a directory that is a
> repository of > documents describing sets of discipline-specific conventions.
>
> I'm not sure about the use of the directory structure in the
> quoted section of the standard; is that actually used by a
> lot of software? Would a separate attribute providing the
> URL for the convention be more flexible/useful?
We agree and Unidata Conventions web page recommends what you have
described:
... Originally, these conventions were named by a string that was
interpreted as a directory name relative to the directory
/pub/netcdf/Conventions/ on the host ftp.unidata.ucar.edu.
This web page is now the preferred and authoritative location for
registering a URI reference to a set of conventions maintained
elsewhere. The FTP site will be preserved for compatibility with
existing references, but authors of new conventions should submit a
request to support-netcdf at unidata.ucar.edu for listing on this page.
--Russ
Received on Wed Dec 21 2011 - 14:46:15 GMT
