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Re: location of conventions

Jonathan,

> I wonder if we could have the best of both worlds with regard to the location
> of the conventions. The advantage of the method whereby they are maintained
> under ftp://ftp.unidata.ucar.edu/netcdf/Conventions is that the Conventions
> attribute can be just a plain name without any context, whereas a URL may go
> out of date. It could be a nuisance for someone using old data in which an
> outdated URL was recorded as the Conventions.
> 
> Would it be OK for us to have a GDT file in 
> ftp://ftp.unidata.ucar.edu/netcdf/-
> Conventions saying
> 
> The GDT conventions are available at either of
> http://www-pcmdi.llnl.gov/drach/GDT_convention.html
> http://www.met-office.gov.uk/sec5/CR_div/GDT_convention.html

Yes, that seems like a good idea.  I've created that file and stored the
above in it.

There is also another solution to making sure URL's don't go out of
date, called PURL's (Persistent Uniform Resource Locators).  For
details, see

  http://www.purl.org/

and the FAQ question 1.6, at 

  http://purl.oclc.org/OCLC/PURL/FAQ

> in which case we can put just "GDT" in the Conventions attribute, but we can
> maintain the actual convention on our own sites.
> 
> Is there provision for a standard way of recording the version number of
> the conventions in the Conventions attribute?

No, but there probably should be, unless conventions are required to
support backward compatibility with previous versions indefinitely.
A "Conventions_version" attribute is one possibility, but maybe you can
think of a better mechanism.

--Russ