Stokes I and Q/I profiles of the Mg ii h and k lines calculated in the FAL-F atmospheric model taking PRD and J-state interference into account. Panel a) intensity profile of the radiation emergent at μ = 0.3 across the two lines (expressed in erg cm^-2 s^-1 Hz^-1 sr^-1). The intensity profile calculated by Uitenbroek’s (2001) code is overplotted with dotted line, but it cannot be distinguished from that obtained with our two-term atom polarization transfer code. Panel b) same as panel a), but for a smaller wavelength interval in order to better visualize the line-core region of the two lines. Panel c) Q/I profile. The reference direction for positive Q is the parallel to the nearest limb. Panel d) same as panel c) but for a smaller wavelength interval.