The WRB homepage has been moved to https://wrb.isric.org
The direct link to the fourth edition of the WRB can be found here: WRB_fourth_edition_2022-12-18.pdf
World Reference Base for Soil Resources (WRB) is a Working Group of the International Union of Soil Sciences (IUSS). It belongs to IUSS Division 1 (Soils in Space and Time), Commission 1.4. (Soil Classification).
The WRB is an international soil classification system for naming soils and creating legends for soil maps. The task of the Working Group is to test and further develop the WRB.