The program includes several "intelligent" features. You cannot wire an output to an output or an input to an input. When you are wiring multiple nodes simultaneously the devices that you are wiring to may not be exactly aligned vertically. The program allows the devices to be off by a small amount and will still recognize that you intend to wire to each of these devices. Multiple wires being dragged to a device will automatically be connected to the appropriate nodes starting with the uppermost unused node and going down from there if the mouse pointer is dragged over the device being wired to.