D_n(4000) index versus distance from the supercluster center (D_c) for galaxies in long filaments with length ≥20 h⁻¹ Mpc (red crosses). Filled red dots denote galaxies in the straight filament at the extension of the supercluster axis (F1033). Colours code the density of points at a given location in the plot. We note that filaments around the supercluster main body begin at clustercentric distances D_c ≈ 7 h⁻¹ Mpc, and F1033 begins in the supercluster tail at D_c ≈ 28 h⁻¹ Mpc. Line at D_n(4000) = 1.55 separate galaxies with young (D_n(4000)≤1.55) and old stellar populations. The line at D_c = 10.2 h⁻¹ Mpc show the distance from the supercluster centre for galaxies with young stellar populations in long filaments which are the closest to the supercluster centre. The line at D_c = 5 h⁻¹ Mpc shows the borders of the HDC of the supercluster.