The vector data set is based on the FAO-UNESCO soil map of the world. The digitized soil map of the world, at 1:5.000.000 scale, is in the geographic projection (latitude longitude) intersected with a template containing water related features (coastlines, lakes, glaciers and double-lined rivers). The digital soil map of the world (except for the continent of Africa) was intersected with the country boundaries map from the world data bank ii (with country boundaries updated to January 1994 at 1:3 000 000 scale), obtained from the US government. For Africa, the country boundaries are derived from the FAO country boundaries on the original FAO/UNESCO soil map of the world. Country boundaries in both cases were checked and adjusted in certain places on the basis of FAO and UN conventions.
