Kiel diagram illustrating model atmospheres in log g–T_eff space. The 1807 MARCS nodes (grey circles) are regularly spaced in effective temperature, so model atmospheres with the same T_eff label and log g label but different [Fe/H] labels overlap in this figure. However the 164 STAGGER nodes (blue diamonds) are not regularly space in effective temperature: thus, model atmospheres with different [Fe/H] labels are apparent as a horizontal scatter of the STAGGER nodes around nearby  MARCS nodes. The 3D LTE and 3D non-LTE calculations for C I and O I were only performed on a subset of the full STAGGER-grid (74 red squares), covering dwarfs and sub-giants.