The Port Input Functions Panel is used to set dependencies into an input port where multiple functions appear on the net into the input port.
The Automatically Filtered dependencies checkbox must be turned off to edit the input function.
It is primarily used where a bus with many functions on it is modeled and the analyst wants to select only a part or a single function on the net to be seen by the input port. Here we see a Video Switches input that is filtered to see the video only.