Schematic showing the dependence of the third line-luminosity factor on n_e, A, and ϒ. Lines with the same A values (red and green) will approach the same luminosity in the high n_e (LTE) limit, lines with the same ϒ values (blue and red) show the same luminosity in the low n_e limit, and lines with the same A/ϒ (blue and green) show the same value of n_crit, while n_crit for the red line is a factor of x larger.