The LockButtonElement defines a button to lock the operation of a number of device devices that no other user can change device settings. The button is in pressed state if at least one of the devices it is assigned to is locked by some user. An operator only may release the button if he set the lock by himself of if he has a privilege level of 150 or more.
Actually, LockButtonElement is not included in the API. If the original screen definition contains instances of this type, they are skipped and not included in the ScreenDefinition reported to the UI.