A single material or a material class may be stated in the drawing. The material class is considered as a statement on the material(s). It covers different materials with similar chemical composition and similar attainable mechanical characteristics.The specified delivery condition contains more information to the material selection, if a material class is entered, e.g. ZFN 413.A single material can also be stated with a heat treatment specification corresponding to a ZF Company Standard for material classes (ZFN 41X), see Figure 1. All specifications of the ZF Company Standard are then valid for the indicated single material.