P–Age relations for O24_ML4h_RA models (f_H = 0.02, f_env = 0.04, η_R = 0.4) without rotation (top panels) and with the highest initial rotation rate of W₀ = 0.65 (bottom panels), for MW, LMC, and SMC metallicities (Z = 0.014, 0.006, and 0.002 in the left, middle, and right panels, respectively). Relations are plotted for each crossing; the upper and lower envelopes of the bands correspond to the red and blue edges of the IS, respectively.