In the UI interface, the only way to pass parameters back to the main script is through a UI_Infield command. This method would only allow the main script to receive change of parameter directly from users. However, in a sophisticated program, there are many built in intelligence devices to help user choosing what they want. This would need the UI interface to pass other AI parameters associated to what users have directly input back to the main script. You can say that one can build a temporary database to pass parameters between UI and main script but this method is very inefficient. I see that there is a new "PARAMETERS" command implanted to the parameter script in AC 6.5. If this "PARAMETERS" command could work in the UI interface as well, this would solve the whole problem.