The material master record 4711 contains the material 4712 as a planning
material. The planning material contains the BOM with the non-variant
parts. You create planned independent requirements for material 4712.
When creating a sales order for material 4711, the system realizes that
material 4712 is the planning material for material 4711. Then the sales
order for material 4711 consumes the planned independent requirements of
material 4712.