The (I_pcos(Ω_p), I_psin(Ω_p)) surface of section for an example circumbinary system and over a range of initial I_p and Ω_p obtained using our N-body code. The different colours refer to four different types of precession: green orbits are prograde with clockwise precession, blue orbits are retrograde with anticlockwise precession, red orbits are in an island of libration with anticlockwise precession, and magenta orbits are in a second island of libration with anticlockwise precession.