2D representations of the phase-resolved He IIλ4686 and Hβ spectra of J0859 (FWHM 1.6 Å) and the Hα spectra of J0953 (FWHM 6 Å); the flux increases from white to black. The NEL component is prominent over one half of the orbit centered on the superior conjunction of the secondary star. The data are shown twice for better visibility of the orbital structure. The ordinate is spectroscopic phase with ϕ = 0 at the blue-red crossing of the NEL (see Sects. 6 and 7).