Internal structure of the model with Z = 0.0002, M = 0.78 M_⊙, Λ_e = 0.6, and α_th = 50. Top-left and bottom-left panels are the illustrations at the ±0.5 dex point above and below the RGB-bump luminosity (Lb). The top-right panel is the zoom-in on the structure of log μ at the outer layers, which is marked by the pink band on the top-left panel. The cyan-shaded area indicates the thermohaline instability. The grey-hatched area indicates the envelope overshooting region. The grey-dotted area indicates the H-burning shell. The green lines are the decay timescale of different reactions (in 10⁸ yrs).