Δχ² fitting statistics of an example spectrum in the decay phase, plotted vs. different values of the ionization degree log ξ of the relativistic reflection component relxillCp. The sample points are shown as black dots and are connected by solid lines. There are two local minima in this plot, with distinct ionization degrees. We discarded the solution with higher log ξ because it resulted in a vanishing primary emission originating from the corona.