This European Standard is part 3-1 of the series of standards EN 50090 on Home and Building Electronic Systems (HBES). It gives an overview of the application related user process as defined in EN 50090-3-2 and the Application Layer(see ENV 50090-3-3). Is founded on the general structure defined in EN 50090-2-1, which is based on the basic reference model for the interconnection of open systems (OSI).