RGS spectra of the centre of M 82 in the O VIII (a), (b) and O VII (c)–(e) bands for the three representative position angles. The best-fitting models and the data-to-model ratios for the three methods are plotted: the CIE modelling convolved with local band images (the first row), the shifted-CIEs modelling convolved by the broadband image (the second row), and the CIE+CX modelling convolved with the O VII band image (the third row, only for the O VII lines). The positions of the O VII forbidden and resonance lines are labelled in the 319° panel of c.