Definition of the location of the regime transition point (Λ_RTP) for M_* = 0.6 M_⊙, T_eq = 1100 K, R_pl = 5 R_⊕, and F_EUV = 543.3 erg s cm⁻². Grey circles show the atmospheric mass-loss rates against Λ given by the hydrodynamic model. The red asterisks denote points identified as planets in the core-powered or Roche lobe overflow regime (Ṁ ≥ 10¹² g s⁻¹ and R_roche > 1.5; the latter condition excludes points that are too much affected by the lower boundary condition). The blue crosses denote the points in the XUV-driven regime (Ṁ ≤ 10⁹ g s⁻¹). The red and dashed blue lines show the linear fits in the log Ṁ–log Λ space for these two groups of points, as specified in the plot. The yellow star gives the position of the regime transition point.