All switches in this area are shown with red and green wires leading to the "common" terminals on the switch.  When the switch's position causes other terminals on the switch to make a contact with the "common" terminal, these other terminals are identified by changing their color to the match the color of the wire they are making contact with (either red or green).

This common 3 way switch has 2 sets of terminals.  The unusual design makes a contact from both "common" terminals to other teminals when the switch is in the middle position.  An additional terminal is provided to ground the switch.

In frame 1 below, the contact made from the red "common" terminal is broken, leaving only the green "common" terminal making contact with another terminal.

Both green and red "common" terminals make contact withother terminals on the switch.

In figure 3 below, the contact made from the green "common" terminal is broken, leaving only the red "common" terminal making contact with another terminal.