Dependence of the CRSF and NPEX parameters on the 3–50 keV luminosity, obtained from the 34 date‐sorted data sets and the 8 intensity‐sorted data sets. The circles and triangles represent those spectra that are described by the double and single CRSF factor(s), respectively. (a) The ﹩W/ E_{a}﹩ ratio for the fundamental and second harmonic resonances. (b) NPEX kT. (c) Fundamental resonance depth, ﹩\tau _{1}﹩. (d) Second harmonic depth, ﹩\tau _{2}﹩.