α-ζ plane distribution of RQ (top panel) and RL (bottom panel) fit solutions for the PC (magenta triangles), SG (red circles), OG (blue squares), and OPC (black stars) models. Recall that filled and empty symbols refer to best-fit solutions of the optimum and alternative models, respectively. The optimum-solutions that are better than the other models by more than 1σ are plotted as light-colour-filled symbols.