F_FeHeK/F_3.5−6 (upper panel; circles) and F_FeHK/F_3.5−6 (lower panel; triangles) at 0−0.03r₁₈₀ (red), 0.03−0.06r₁₈₀ (orange), 0.06−0.1r₁₈₀ (magenta) 0.1−0.2r₁₈₀ (green), 0.2−0.3r₁₈₀ (blue), and 0.3−0.5r₁₈₀ (black), plotted against the ICM temperature. Closed and open symbols indicate cD clusters and non-cD clusters, respectively. Black solid and dotted lines correspond to the theoretical ratios from the APEC model of F_FeHeK/F_3.5−6 and F_FeHK/F_3.5−6, respectively, assuming Fe abundance = 0.3, 0.5, 1.0, 1.5, and 2.0 solar. Here, abundance ratios of elements are assumed to have the solar ratios by Lodders (2003). Those of the MEKAL model assuming Fe abundance = 0.5 solar are plotted as gray lines.