Equal-mass-mergers: the fraction of particles on retrograde orbits with apocentres above 30 kpc (P_retro, upper panels), and above 60 kpc (, lower panels) after the merger. The panels on the left show models with retrograde, those on the right prograde spin orientation of the infalling galaxy. See Tables B.3 to B.6 for the values. The symbols reflect the initial velocities, with “050vel” standing for 0.5, “100vel” for 1.0 and “150vel” for 1.5 times the parabolic velocity, calculated assuming the initial galaxies are point masses. Mergers where the infalling disc has a retrograde angular momentum (left panels) lead to the highest fractions of retrograde material in the models computed. There is no simple dependence on the initial relative velocity of the galaxies, but for the subset of far particles, faster interactions tend to lead to higher values in P_retro. Mergers where the infalling disc has a prograde spin angular momentum (right panels) lead to low fractions of retrograde material. Similar to the fly-by interactions, faster initial velocities lead to higher fractions of retrograde material. But in contrast to the fly-by cases, P_retro does not drop when considering only the subset of far particles, because of the more similar radial distribution of particles on pro- and retrograde orbits. See the on-line edition of the article for a colour version of this figure.