I have just bought a tempus 1 programmer and need help with the wiring please. I have a Live, Neutral and earth with a yellow and white wire coming from the wall. The timer has a slot for the Live, Neutral and earth so I know where these go however I'm not sure about the yellow and white. There are 4 more slots numbered 1, 2, 3 and 4. 1 is COM, 2 is Off and 3 is On and nothing for 4. What do I do please? I am not sure about the yellow and white wires and where they go. Is this standard central heating colours?