How does Playstation Move interface it's accessories?

The Playstation Move gun and rifle accessories have their own buttons/triggers. They connect to Move using the extension connector at the bottom (marked J15), next to mini-B USB connector.

What is pin description of this connector, and what type of connector is it?

The connector has 8 pins, while Move controller has 8 buttons (Move, O, ☐, ∆, X, Select, Start and PS) and one analog trigger (255 values). As I understand, two official accessories have mechanical coupling with Move's trigger, so maybe EXT connector supports only buttons, with one button per pin?