Definition of angles and vectors used, following the DT92 convention (Damour & Taylor 1992). All markers in boldface denote vector quantities. Let K be the line-of-sight vector defined to be from the observer to the pulsar. The plane perpendicular to this vector forms the sky plane, defined by unit vectors I₀ and J₀. The orbital angular momentum (L_orb) is in the direction of k and is inclined from K by the orbital inclination angle, i. The plane perpendicular to this, defined by unit vectors i and j, is the orbital plane. Ω_asc is the angle of rotation of the sky plane with respect to the orbital plane when the pulsar passes through the ascending node. The spin of the pulsar and the companion, defined by vectors S_p and S_c, respectively, are misaligned with L_orb by the spin-misalignment angles δ_p and δ_c, respectively. S_p and S_c and L_orb all precess around the total angular momentum of the system, L_tot, which is the vector sum of all the individual angular momenta. However, since the magnitude of L_orb is orders of magnitude more than S_p and S_c, L_tot = L_orb is assumed in the figure for clarity. Hence, S_p and S_c precess around k, forming precession cones as shown. The projection of S_p and S_c on to the sky plane subtends an angle η_p and η_c, respectively – for clarity, only the pulsar’s complementary angle is shown. The pulsar’s magnetic axis (μ) subtends an angle α with respect to S_p. δ denotes the opening angle of the emission cone of the pulsar. As the pulsar rotates, μ sweeps across the sky; the angle suspended by μ during its closest approach with respect to our line of sight is the impact angle β. λ_p is the angle between K and S_p. Hence, by definition, λ_p ≡ 180 − ζ ≡ 180 − (α + β), which are the angles used by the RVM.