Top panel: combined low-background (bottom panel of Fig. 2) background-subtracted RGS spectrum of NGC 6543 overplotted by histograms of optically thin plasma emission models: black – model with nebular abundances and a temperature of 0.147 keV, blue – model with nebular abundances and a temperature of 0.19 keV, and red – model with enhanced Ne and depleted N abundances and temperature 0.147 keV. The intensity of each model has been normalized to that of the O vii triplet at 22 Å. Bottom panel: residuals of the models. The colors correspond to the same models as in the top panel.