A functional unit is a logical structure containing all the layers of the architecture (primarily Business, Applications, Platforms, Communications), and which is most often formed around a public administration information system. A typical example of a functional unit may be "document management". In addition to the information system itself, such as the electronic filing service and trusted storage, this unit also includes the processes and procedures in the office (shredding plan, document reception, etc.), the necessary HW and SW, communication interfaces, security requirements, standards, rules, etc. However, just because a functional unit is described through all layers of the architecture does not mean that they are an integral part of it. For example, the HW and SW equipment layer is assumed to be a shared platform that is not directly part of the functional unit but uses its services.