Nan's email was spt on re current recommendations. CF of course does not call for the standard_name_vocabulary to be filled out, because if you are using CF, you ARE using their standard name vocabulary.
My recommendation to Ajay is that if your file is CF, don't specify the standard_name_vocabulary. If that makes you feel too non-compliant, use one of the following:
- "CF-23"
- "
http://cf-pcmdi.llnl.gov/documents/cf-standard-names/standard-name-table/23/"
- "
http://mmisw.org/ont/cf/parameter" [1] or
"
http://mmisw.org/orr/#http://mmisw.org/ont/cf/20130603T200127/parameter"
- the current NERC URL, which I don't have in hand
I already don't like the recommendation in the ACDD working document (full disclosure: I wrote it); this question highlighted all sorts of issues. So I'm glad it will get some discussion. :-)
This thread suggests CF should definitize this practice. Since CF vocabularies have versions, it is useful to say how to specify them. Using the URL is a little tricky, especially for versions, but also for URLs whose name might change. The one in the original guidance table was to an HTML page and no longer resolves; and now there are two semantic representations (in NERC, and in MMI's ORR). And I wouldn't mind if CF adopted a multi-vocabulary model along the way?.
I'd be willing to write up a TRAC ticket, but I doubt I could do a good job of moderating it, alas.
John
[1] Given the state of the practice, I'm not worried (yet) about the version if you're using CF. CF standard names are never redefined to mean something entirely different; there are plenty of cues about when you created the metadata to provide a time/version reference point (assuming you haven't accidentally used an old version, in which case you might get the ID wrong anyway); and guidance being what it is, almost no one will use a version number in a consistent way. Semantically speaking,though, it will be good to have a standard practice of versions.
On Jun 14, 2013, at 05:53, Jim Biard <Jim.Biard at noaa.gov> wrote:
> Ajay,
>
> As best as I understand, the standard_name_vocabulary attribute should contain the name and version of the actual standard name table - most likely the one current to when you designed the file contents. It should be something along the lines of
>
> CF Standard Name Table (v16, 11 October 2010)
>
> Grace and peace,
>
> Jim
>
> Jim Biard
> Research Scholar
> Cooperative Institute for Climate and Satellites
> Remote Sensing and Applications Division
> National Climatic Data Center
> 151 Patton Ave, Asheville, NC 28801-5001
>
> jim.biard at noaa.gov
> 828-271-4900
>
>
> <CicsLogoTiny.png>
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>
> On Jun 14, 2013, at 8:48 AM, Ajay Krishnan - NOAA Affiliate <ajay.krishnan at noaa.gov> wrote:
>
>> Hello Roy,
>>
>> Thanks for that bit of information. So is it safe to leave out the version number till the issues with the reference to multiple URI's have been sorted out?
>>
>> Thanks,
>> Ajay
>>
>>
>> Message: 2
>> Date: Thu, 13 Jun 2013 08:44:25 -0400
>> From: Ajay Krishnan - NOAA Affiliate <ajay.krishnan at noaa.gov>
>> To: cf-metadata at cgd.ucar.edu
>> Subject: [CF-metadata] standard_name_vocabulary attribute
>> Message-ID:
>> <CAA9eyS49D1bzGpQE5dcxTd9gzEnkX9aUMFjZQbiT_uLmL7EpZA at mail.gmail.com>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Hi,
>>
>> There seems to be some ambiguity about the usage of the
>> standard_name_vocabulary attribute. Based on the link below, the right
>> value would be to use something like CF 1.6
>> http://www.unidata.ucar.edu/software/netcdf-java/formats/DataDiscoveryAttConvention.html#standard_name_vocabulary_Attribute
>>
>> Is that the right usage or should we reference the version of the
>> cf-standard-name-table like v1..v23 etc.?
>>
>> Any info on this would be much appreciated.
>>
>> Thanks,
>> Ajay
>> -------------- next part --------------
>> An HTML attachment was scrubbed...
>> URL: <http://mailman.cgd.ucar.edu/pipermail/cf-metadata/attachments/20130613/2313776c/attachment-0001.html>
>>
>> ------------------------------
>>
>> Message: 3
>> Date: Thu, 13 Jun 2013 14:50:04 +0100
>> From: "Lowry, Roy K." <rkl at bodc.ac.uk>
>> To: Ajay Krishnan - NOAA Affiliate <ajay.krishnan at noaa.gov>,
>> "cf-metadata at cgd.ucar.edu" <cf-metadata at cgd.ucar.edu>
>> Subject: Re: [CF-metadata] standard_name_vocabulary attribute
>> Message-ID:
>> <40829B0E077C1145A6DE44D39B3830A922C46DC0B0 at nerckwmb1.ad.nerc.ac.uk>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Hello Ajay,
>>
>> If I've got it right, your example is a URL for a single standard name. The version numbers refer to versions of the whole list and so including the version number in a reference to a single standard name causes the standard name to inherit the version number of the list of which it is a member. Trouble is that most standard names are members of more than one list version but the standard name is exactly the same in each of these versions. Consequently, a given standard name ends up with multiple URIs. In version 1 of the vocabulary server we run (NERC Vocabulary Server or NVS) we made the mistake of list members inheriting the version numbers of their parent lists and learned the hard way the problems it causes for operational systems. Versioning in the current version of NVS (V2)has been done differently with list member and list versioning totally decoupled and the versioning information explicitly excluded from list member URIs.
>>
>> I am aware of work underway by Mark Hedley at the UK Met Office to provide URLs for Standard Names in a CF namespace that follow linked data principles by resolving into usable XML (SKOS RDF) documents. I'm not sure how far this work has progressed, so I'll leave it Mark to say more on the list if he feels he's ready.
>>
>> Cheers, Roy.
>>
>> ________________________________
>> From: CF-metadata [cf-metadata-bounces at cgd.ucar.edu] On Behalf Of Ajay Krishnan - NOAA Affiliate [ajay.krishnan at noaa.gov]
>> Sent: 13 June 2013 13:44
>> To: cf-metadata at cgd.ucar.edu
>> Subject: [CF-metadata] standard_name_vocabulary attribute
>>
>>
>> Hi,
>>
>> There seems to be some ambiguity about the usage of the standard_name_vocabulary attribute. Based on the link below, the right value would be to use something like CF 1.6
>> http://www.unidata.ucar.edu/software/netcdf-java/formats/DataDiscoveryAttConvention.html#standard_name_vocabulary_Attribute
>>
>> Is that the right usage or should we reference the version of the cf-standard-name-table like v1..v23 etc.?
>>
>> Any info on this would be much appreciated.
>>
>> Thanks,
>> Ajay
>>
>> ________________________________
>> ________________________________
>> From: CF-metadata [cf-metadata-bounces at cgd.ucar.edu] on behalf of Lowry, Roy K. [rkl at bodc.ac.uk]
>> Sent: 13 June 2013 14:50
>> To: Ajay Krishnan - NOAA Affiliate; cf-metadata at cgd.ucar.edu
>> Subject: Re: [CF-metadata] standard_name_vocabulary attribute
>>
>> Hello Ajay,
>>
>> If I've got it right, your example is a URL for a single standard name. The version numbers refer to versions of the whole list and so including the version number in a reference to a single standard name causes the standard name to inherit the version number of the list of which it is a member. Trouble is that most standard names are members of more than one list version but the standard name is exactly the same in each of these versions. Consequently, a given standard name ends up with multiple URIs. In version 1 of the vocabulary server we run (NERC Vocabulary Server or NVS) we made the mistake of list members inheriting the version numbers of their parent lists and learned the hard way the problems it causes for operational systems. Versioning in the current version of NVS (V2)has been done differently with list member and list versioning totally decoupled and the versioning information explicitly excluded from list member URIs.
>>
>> I am aware of work underway by Mark Hedley at the UK Met Office to provide URLs for Standard Names in a CF namespace that follow linked data principles by resolving into usable XML (SKOS RDF) documents. I'm not sure how far this work has progressed, so I'll leave it Mark to say more on the list if he feels he's ready.
>>
>> Cheers, Roy.
>>
>>
>>
>> ________________________________
>> From: CF-metadata [cf-metadata-bounces at cgd.ucar.edu] on behalf of Ajay Krishnan - NOAA Affiliate [ajay.krishnan at noaa.gov]
>> Sent: 13 June 2013 13:44
>> To: cf-metadata at cgd.ucar.edu
>> Subject: [CF-metadata] standard_name_vocabulary attribute
>>
>>
>> Hi,
>>
>> There seems to be some ambiguity about the usage of the standard_name_vocabulary attribute. Based on the link below, the right value would be to use something like CF 1.6
>> http://www.unidata.ucar.edu/software/netcdf-java/formats/DataDiscoveryAttConvention.html#standard_name_vocabulary_Attribute
>>
>> Is that the right usage or should we reference the version of the cf-standard-name-table like v1..v23 etc.?
>>
>> Any info on this would be much appreciated.
>>
>> Thanks,
>> Ajay
>> -------------- next part --------------
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>>
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>>
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