An empty location element could be used for this, with an appropriate attribute. Or simply for the normed value of location, include the region in the standardized string (Mosel / Mosel-Saar-Ruwer, Rheinpfalz, Rheinhessen, Rheingau etc.). Or assume that from the wikidata identifier of a location, the region, country and continent can be identified.
An empty location element could be used for this, with an appropriate attribute. Or simply for the normed value of location, include the region in the standardized string (Mosel / Mosel-Saar-Ruwer, Rheinpfalz, Rheinhessen, Rheingau etc.). Or assume that from the wikidata identifier of a location, the region, country and continent can be identified.