The written invitations are issued by 14 invitation centres, the central offices, which receive data for this purpose from the local citizens’ registration offices (Einwohnermeldeämter) in compliance with the data protection and registration regulations of each federal state in Germany. All acceptance, cancellation and rescheduling of appointments is also undertaken by the invitation centres at women’s requests. Planning the invitations is carried out in close collaboration with the screening units with respect to each unit’s screening capacities and opening times.