Evolutionary models for 20–60 M_⊙ in HRD form, with TAMS positions shown for α_ov = 0.1, 0.5. Evolutionary phases are highlighted by number with RSGs at the red dashed line, BSGs at the blue dashed line, and the MS before the yellow lines, with the HD limit shown in green. Position 1 shows MS objects, and positions 2 and 5 are post-MS BSGs that may be pre or post-RSGs. Position 3 represents the majority of observed RSGs, while position 4 illustrates the most luminous RSGs.