Schematic explanation of Fig. 17. Above a critical λ (above the solid line) twin solutions are possible. With increasing α, the mass on the twin branch may be higher than the mass at the phase transition point M_ph (regions above the long-dashed line). The region between the vertical dotted and solid lines corresponds to the “Both” class, described in Alford et al. (2013), which is characterised by a delayed onset of instability with respect to configurations with larger λ.