How do I make two vocabularies describing places or areas interoperate?
In the geographic case it seems that the common factor so far has been latitude, longitude, and elevation. Describing areas in common terms is difficult – it might be possible to describe the Vatican City with a single latitude/longitude at an appropriate scale, but it doesn’t really make sense for Belgium or France. One useful approach is to adapt vocabularies for describing polygons, using a latitude/longitude based scale. This can be created by using a mercator projection map of the world, which has a linear scale for latitude and longitude (but not for distance between two points), or plotted (after transforming the scale as appropriate) on almost any kind of map. Being able to work with partially overlapping areas is important.
