The "A" COM at the top is the single-pole. Just the way it was marked. The "B" at the bottom is the 3-way. One is marked "COM" and the other two are marked "3W" to designate the 3-way switch.

The break off tab allows you to use a single power feed for the single-pole and the 3-way in the case where you are the "head" of the circuit. In your case, looking at the wires, coming in, you want to remove the tab to isolate the switches from each other.

deleted

This post was edited by amateurplumber on Thu, Jan 30, 14 at 20:07