The WRB is an international soil classification system. It is edited by the Working Group WRB of the International Union of Soil Sciences (IUSS). The third edition 2014, update 2015, is the currently valid version (IUSS Working Group WRB 2015). The first edition stems from 1998 (FAO 1998) and the second from 2006 (IUSS Working Group WRB 2006). The WRB has its roots in the Soil Map of the World (FAO/UNESCO 1971-1981), the respective Legend and the Revised Legend (FAO 1988).