Random Security Function : This mode prevents the disclosure of the PIN Code by entering the PIN Code after authenticating 2 arbitrarily selected numbers. When the buttons for 2 arbitrarily selected numbers are illuminated, pressing the 2 illuminated buttons illuminates the whole touchscreen. You can enable or disable the Random Security function. This function is enabled by default. Registration Button : This button is used to change Master PIN Code/User PIN Codes/User Cards or the lock settings. It is found below the battery cover of the Interior Unit. The length of time the [Registration] button is pressed varies depending on the function. Resetting : Deletes all registered information and restores the factory default. After resetting, change the Master PIN Code for security.