The invention relates to a method of automatically modelling a relationship between a configurable product and a plurality of components of the configurable product as a bill of materials, wherein the configurable product and the plurality of components are related to one another by a plurality of selection conditions. The method comprising: providing a processor device; generating in demand planning a plurality of characteristic value combinations representing the plurality of selection conditions, modelling the bill of materials using the characteristic value combinations, and using the bill of material to control the supply of the product.