Fit of the RGS spectrum of Mrk 110. Bottom panel: observed spectrum is overlaid with the best-fitting model (C-stat. = 1038 for 900 deg of freedom, red line). The individual emission line components of the model are plotted in black at the bottom of this panel (with a vertical offset of 3 for visualisation purposes). The data were rebinned for clarity. Top panel: transmissivity of the absorbing components: galactic absorption (dark and light blue) and ionised absorbers in Mrk 110 with log ξ = 0.56 (brown), log ξ = 2.91 (orange).