Defined connection point of a functional unit which can be connected to other functional units
Note 1: “Defined” means that the requirements and the assured properties of this connection point are described.
Note 2: The connection between the interfaces of function units is also called an interface.
Note 3: In an information system, the defined exchange of information takes place at this point.
Note 4: Interface places certain requirements on the connection that is to be made.
Note 5: Interface demands certain features.
Source: Industrie 4.0 – Begriffe/Terms, VDI Statusreport Industrie 4.0 (April 2017)