To illustrate the material flow in process models (EPC (material flow), PCD (material flow)), material types are allocated to individual functions of the business process in the form of function input or output. Similar to the allocation of information objects to functions (representation of information transformation by functions), this allocation represents the transformation of input material types to output material types.

In the material diagram, you can define material types, arrange them in a hierarchy, and assign them to material classes.

A material type typifies individual materials with identical material properties.

Similar material types can be combined to form a material class. The similarity can be based on different classification criteria. Thus, a material type can be assigned to multiple material classes.

Material types can be assigned to packaging material types. This indicates that certain material types can only be transported in specific packaging material types.

Packaging material types can also be arranged in hierarchies and classified. This enables the structure and restrictions of complex bulk packaging to be illustrated, for example.

A packaging material type typifies individual packaging materials with identical properties (for example, material properties).

Similar packaging material types can be combined to form a packaging material class. The similarity can be based on different classification criteria. Thus, a packaging material type can be assigned to multiple packaging material classes.

The following figure illustrates an example of a materials diagram with its hierarchy levels and classifications.