Evolution of test particle orbits, taken from the benchmark model simulation, in Ω−a (left panel) and L−a (right panel) plane. The strength of EFE was assumed to be Q₂ = 2. Only particles surviving at least 3 Gyr are taken into account. Evolutionary tracks of the particles are shown in the last Gyr of the simulation every time their orbits met the criteria, i.e. i< 50 deg, q< 80 au. The tracks below a = 400 au are not shown as these are just full-width horizontal lines. Increasing Q₂, the clustering in L sets in at lower semimajor axes, e.g. with Q₂ = 6; similar clustering as in the figure develops for a> 300 au.