ISO 2692:2006 defines the maximum material requirement, the least material requirement and the reciprocity requirement, and specifies their applications. These requirements are used to control specific functions of workpieces where size and geometry are interdependent, e.g. to fulfil the functions assembly of parts (for maximum material requirement) and minimum wall thickness (for least material requirement). However, the maximum material requirement and least material requirement are also used to fulfil other functional design requirements.