H–R diagram for instability. Pulsationally stable in F–p4 modes (small dotted) and unstable in F (circles), p1 (open triangles), p2 (open inverse triangles), p3 (open squares) and p4 (plus signs) on the evolutionary tracks calculated for M = 0.6–3.0 M_ȯ. Panel (a): models in complete anisotropic equilibrium models; Panel (b): models in quasi-anisotropic equilibrium models. The dashed and solid lines are, respectively, the theoretical blue and red edges of instability strip for complete anisotropic models.