Spatial coverage of a data set

Hello,

I wonder if there is a best practice or recommendation for expressing 
the spatial coverage of a data set. Expressing the spatial coverage 
seems to me an important thing to do, because

1) It makes it clear that the data set is spatial, i.e., can be related 
to a certain part of the world.
2) It can help in drawing the data on a map. The specification of the 
spatial coverage could be used to get an extent (bounding rectangle) for 
the map.
3) It can help relating the data set with other data sets having the 
same spatial coverage.

The most obvious way to express spatial coverage seems to use 
dcterms:spatial (http://purl.org/dc/terms/spatial). Its range is a 
dcterms:Location. But what is the best way to express such a location? I 
now use a dbpedia link (e.g. http://dbpedia.org/resource/Netherlands to 
specify that a data set is spatially limited to The Netherlands). But is 
this the best way? A map extent can not be easily derived and comparison 
with other data sets only works if they use similar dbpedia links. Maybe 
its best to have two specifications of coverage, one referring to a 
spatial entity (like http://dbpedia.org/resource/Netherlands) and one 
specifying the coordinates of the bounding rectangle?

Regards,
Frans


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