Large reference models contain a large number of process models. The inclusion of elements of the organization view in these process models illustrates who communicates with whom during the process. The communications diagram enables you to group all processes according to the communication between organizational units.

Therefore, the communications diagram displays all organizational units that communicate with each other. For example, the Sales organizational unit is linked to the Customer organizational unit via an object of the Communication type. Objects of the Communication type can be arranged in a hierarchy. They can be linked to the Process selection matrix model type. This process selection matrix displays all processes in which the sales department communicates with the customer.