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Re: catalog schema question: variable element

Hi Darren,

Darren Hardy wrote:
I have a question about the <variable> element in the inventory catalog schema. Suppose that I have the following information on a dataset variable (in DAS format): 

Attributes {
    SST {
        String long_name "OI Cloud-free SST, blah blah blah";
        String standard_name "sea_surface_temperature";
        String units "degC";
    }
    Foobar {
        String long_name "My foobar variable"
        String units "m"
    }
}
As I read the catalog spec, I will lose the "human-readable" long_name attribute (ala CF-1.0): 

  <variables>
<variable name="SST" vocabulary_name="sea_surface_temperature" units="degC"/> 
    <variable name="Foobar" vocabulary_name"Foobar" units="m" />
  </variables>
I think the mismatch is in our goals for the <variables> element. Our goal when designing the <variables> element was to provide a way to describe the variables in a dataset to a search service and allow users to add information that wasn't in the dataset. Since many search services require mapping variables to controlled vocabularies, we provided for a way to map dataset variable names into controlled vocabularies.
In your example, if you wanted to map the variables into the CF standard names, you could change the Foobar vocabulary_name to the appropriate CF standard name. So, if you knew that the Foobar variable mapped to CF standard name "sea_surface_height" you could edit your catalog to show this: 

<variables vocabulary="CF-1.0">
<variable name="SST" vocabulary_name="sea_surface_temperature" units="degC"/> <variable name="Foobar" vocabulary_name="sea_surface_height" units="m" /> 
</variables>
Of course, you could use your "long_name" entries as a controlled vocabulary of sorts like: 

<variables vocabulary="myLongNames">
<variable name="SST" vocabulary_name="OI Cloud-free SST, blah blah blah" units="degC"/> <variable name="Foobar" vocabulary_name="My foobar variable" units="m" /> 
</variables>
But either way you can't map all the information in your dataset. We have talked about allowing multiple mappings: either allowing multiple <variables> elements so that different vocabularies could be used; or moving multiple mappings into each <variable> element. But at this point we don't have that so in our schema.
Am I missing something? Is there a way to retain that human-readable description of the variables?
You can put it in the dataset description or keywords but that isn't quite as structured in terms of being specific to a variable. 

Ethan


Thanks,
-Darren



--
Ethan R. Davis                                Telephone: (303) 497-8155
Software Engineer                             Fax:       (303) 497-8690
UCAR Unidata Program Center                   E-mail:    edavis@xxxxxxxx
P.O. Box 3000
Boulder, CO  80307-3000                       http://www.unidata.ucar.edu/
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