A Function receives inputs and delivers outputs via Function Ports. Each Input Port describes an expected input (Exchange Items), each Output Port describes an available output.

A Function Port is usually identified by its name (e.g. ‘tuning parameters’, ‘equalized signal’).

Function Ports can be given non functional properties characterizing the input needs or output capabilities of the Function it belongs to: e.g. specifying that a sampling function can deliver x samples per second, and compare it to a playback function needing y samples per second at input. Such non-functional properties allow securing the external use of the Function w.r.t. input and output flows: no consistency check would be possible when reusing it elsewhere in the system or from one system to another.