Left-hand panels: scatter plots showing the ratio of the effective collision strength Υ with Auger-plus-radiation damping (Υ_A + R) or radiation damping (Υ_R) to without damping (Υ_U) or with radiation damping alone, as a function of line strength for dipole core-excitation of O⁵⁺a), Ar¹⁵⁺c), Fe²³⁺e) and Kr³³⁺g) at temperature of 10⁴(z + 1)² K, where z is the ionic charge. Right-hand panels: percentage of the corresponding transitions where the effect of damping exceeds 10%, 20% and 30%. [ Colour online]