Configurable material is useful if you have a large number of combination of parts that go into a product. It means different permutations and combinations of the parts for same material. If you maintain a unique material code for each combination , you require a large number of material numbers. KMAT may be used in such a case where you maintain just one generic product code. A super BOM is maintained for such a material consisting of all possible alternatives. A routing is also maintained consisting of all possible operations that could be used. Typically configurable material is used in Made To Order (MTO) environment. However frequently ordered configurations may be planned with a material variant which needs to have a material master record. Thus Material variants may have stock and value. Depending upon characteristic values chosen at sales order entry Sales Order BOM is created. Routing operations are also chosen depending upon which BOM components are assigned to them.