Hmmm, interesting point, Rich. The ACDD and OceanSITES conventions both
extend
CF, and both recommend a comma separated list in the Conventions attribute.
There doesn't seem to be an explicit prohibition in the document against
using commas
for extensions of other conventions. It seems to me that the '/' in
conventions.html
refers to the old disk directory and URL scheme, where the documentation
for XXX
would be located at /pub/netcdf/Conventions/XXX and the Time_series
extension
would be at /pub/netcdf/Conventions/XXX/Time_series.
Does the / convey any useful information? As long as both CF and UGRID
are listed,
isn't that enough?
I can't see any reason why unidata chooses to promote 2 versions of
this, except maybe
for profiles, in which some of the requirements of a convention are
dropped, or assumed
to have default values, and not required by the profile.
Cheers - Nan
On 3/13/15 1:59 PM, Signell, Richard wrote:
> David,
>
> I looked at this a bit and I'm not sure that
> http://cf-trac.llnl.gov/trac/ticket/76 actually captures this need, as
> UGRID is intended to *extend* CF, rather than a stand-alone
> alternative.
>
> For situations like CF and UGRID, which *extends* CF, it would appear
> from this guidance
> (http://www.unidata.ucar.edu/software/netcdf/conventions.html)
> that the foward slash separator should be used:
>
> Conventions = "CF-1.6/UGRID-0.9"
>
> This is discussed more in github issue
> (https://github.com/ugrid-conventions/ugrid-conventions/issues/11#issuecomment-79157891)
>
> -Rich
>
> P.S. Chris also points out that the current CF-1.6 document
> http://cfconventions.org/Data/cf-conventions/cf-conventions-1.6/build/cf-conventions.html
> there is an unfortunate error/typo that says the convention should look like
>
> Conventions = " CF-1.6 " (e.g. with spaces on either side of the quotes)
>
> Happily, this is gone in the 1.7 version at:
> http://cfconventions.org/Data/cf-conventions/cf-conventions-1.7/build/cf-conventions.html
>
> But perhaps it would be good to edit the CF-1.6 doc if that is indeed a typo.
>
> On Fri, Mar 6, 2015 at 7:21 AM, David Hassell <d.c.hassell at reading.ac.uk> wrote:
>> Hello Martin,
>>
>> Good news - this is covered by trac ticket #76 "More than one name in
>> Conventions attribute" (http://cf-trac.llnl.gov/trac/ticket/76).
>>
>> This has been accepted and should be in 1.7 (if it wasn't already in
>> 1.6?):
>>
>> 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). This is the Unidata
>> recommended syntax from NetCDF Users Guide, Appendix B. If the
>> string contains any commas, it is assumed to be a comma-separated
>> list.
>>
>> For example:
>>
>> :Conventions = "CF-1.6 ACDD-1.0" ;
>>
>>
>> All the best,
>>
>> David
>>
>> ---- Original message from martin.juckes at stfc.ac.uk (12PM 06 Mar 15)
>>
>>> Date: Fri, 6 Mar 2015 12:02:29 +0000
>>> From: martin.juckes at stfc.ac.uk
>>> To: cf-metadata at cgd.ucar.edu
>>> Subject: [CF-metadata] Applying multiple conventions
>>>
>>> Hello,
>>>
>>> There is a proposal floating around to use the UGRID conventions for unstructured grids in CMIP6 data. One issue is that the CF Convention specifies a specific string for the "Conventions" and the UGRID convention specific a different specific string. Is there any chance of modifying CF to accept, e.g. Conventions = "CF-1.8, UGRID-0.9"?
>>>
>>> regards,
>>> Martin
>>>
>>>
--
*******************************************************
* Nan Galbraith Information Systems Specialist *
* Upper Ocean Processes Group Mail Stop 29 *
* Woods Hole Oceanographic Institution *
* Woods Hole, MA 02543 (508) 289-2444 *
*******************************************************
Received on Fri Mar 13 2015 - 12:28:59 GMT
