Comparison of the color–color diagrams of the Chandra observation ObsID 3814 using the MEG M1 arm with theoretical tracks with different dependencies of the ionization parameter log ξ on the equivalent hydrogen column density; N_N is expressed in units of 10²² cm⁻², which is shown in solid colored lines. The dashed black line additionally shows the realization of the color–color track for a homogeneously ionized absorber with log ξ = 1.4 as presentedin the right panel of Fig. 3 and it is intended to help direct comparison.