[Esip-preserve] Fwd: [CF-metadata] Namespaces & multiple conventions

[Christopher Lynnes]

I thought this message to the CF convention mailing list might be of  
interest to the preservation cluster.

Begin forwarded message:

> From: Stephen Emsley <SEmsley at argans.co.uk>
> Date: July 23, 2009 4:55:01 AM EDT
> To: "cf-metadata at cgd.ucar.edu" <cf-metadata at cgd.ucar.edu>
> Subject: [CF-metadata] Namespaces & multiple conventions
>
> Hi All
>
> I am considering data formats for an ESA Sentinel satellite ground  
> processor. It will be based on netCDF-CF files packaged within  
> SAFE , a common format for archiving to ensure long-term  
> preservation of EO data holdings (earth.esa.int/SAFE). I would like  
> to be able to include SAFE attributes within the netCDF-CF in order  
> to simplify packaging.
>
> I came across CF-Metadata Trac ticket #27 : “Using namespace tags to  
> include other conventions...” which discussed using the Conventions  
> attribute to declare an association between a prefix and namespace  
> or using a ‘namespace’ attribute. Several alternative syntax were  
> proposed. For instance,
>
> Conventions = "CF-1.4";
>   namespaces ="safe=http://earth.esa.int/SAFE/<S3_schema>/"
>
>  or
>
> Conventions = "CF-1.4, safe=http://earth.esa.int/SAFE/<s3_schema>/"
>
> In addition, there was discussion regarding the necessity of not of  
> escaping the additional colon in the use of the namespace prefix e.g.
>
> var:safe\:attrib = "value" ;
>
> or
>
> var:safe:attrib = “value” ;
>
>
> This use of namespaces would enable middleware to ingest netCDF-CF  
> files and easily extract the mandatory SAFE attributes from the  
> headers.
>
> Ticket #27 is a year old and I have found no more recent discussion  
> regarding this proposal. Overloading the Conventions attribute to  
> declare additional namespaces is fine (as was discussed in the Trac  
> ticket). However, the usage of the prefix in netCDF files was  
> undecided. I would be grateful for guidance regarding the  
> recommended use of namespaces with respect to CF Conventions.
>
> Kind Regards
> Steve
>
>
> -------------------------------------------------------------------------------------------------
> Dr Stephen Emsley
>   ARGANS  
> Limited 
>                                                                         Tel 
> : +44 (0)1752 764 289
>     Unit 3 Drake  
> Building                                                    Mobile:  
> +44 (0)7912 515 418
>        Tamar Science  
> Park                                                           Fax:  
> +44 (0)1752 772 227
>           Derriford, Plymouth, PL6  
> 8BY                                          SEmsley at argans.co.uk
>                                                                                                                          Skype 
> ™: archonsme
> --------------------------------------------------------------------------------------------------
>
>

--
Christopher Lynnes             NASA/GSFC, Code 610.2          
301-614-5185

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