F_var spectra of observations U1-U3 (left panel) and O1-O2 (right panel). Black and grey squares refer, respectively, to XMM-Newton and NuSTAR data. Blue and magenta dashed curves show F_var models obtained by letting different parameters (as indicated in the labels) of the continuum or of obscurer #2 vary, while red solid curves are obtained by letting all those parameters vary simultaneously. Red dashed curve in the right panel shows the simple model obtained assuming only variations of the primary continuum and correlated variations of the ionisation parameter of obscurer #2. The main spectral features contributing to the shape of the F_var spectra at different energies are schematically indicated by arrows in the plots.