Long-term mass-accretion rate of millisecond pulsars in the accretion phase, as evaluated by Watts et al. (2008). Accreting-MSPs are plotted as red circles, nuclear MSPs as green squares. Magenta triangles mark the accreting MSPs that showed pulsations only intermittently, and that may have a magnetic field close to the threshold for field burial (Cumming 2008). Blue dashed lines represent the magnetic spin equilibrium lines defined by Eq. (1), evaluated for μ₂₆ = 1 and μ₂₆ = 10. The red shaded region defines the parameter space in which a source enters the radio ejector state for μ₂₆ = 1 (e.g., Burderi et al. 2001).