A standard concept for scheduling production requirements in order to match demand is Material
Requirements Planning (MRP). Several authors report on current industry practice, in
particular in the remanufacturing industry, in using traditional MRP systems to plan recovery
operations (see Thierry (1997) for an overview). A number of conceptual difficulties arise in
the use of traditional MRP in this context. In particular, the dependency between components
simultaneously obtainable by disassembly and the choice between multiple supply sources (e.g.
different returned products) cannot be handled adequately by a simple level—by—level top down
approach as in traditional MRP. Therefore modifications to MRP have recently been proposed to
meet the special requirements involved in product recovery planning. Most of these approaches
make use of a 'reverse' bill of materials (BOM), documenting for every returned product the
content of components and the processing times required to release them. This 'reverse' BOM is
not necessarily a symmetric picture of the original BOM as not all components might, be (fully)
reusable.