Frame a: 3D position-position-velocity view of the velocity-coherent structures in ¹³CO. The pale colours are projections of the structures onto the plane of the sky, the α − v plane and the δ − v plane. Each colour corresponds to a different structure. The id numbers of the five components tabulated in Table 3 are indicated in the δ − v plane. Frame b: Thermal emission of dust in G202.3+2.5 at 250 μm (Herschel/SPIRE). Coloured regions show the same velocity-coherent structures as in frame a for ¹³CO J = 1–0 (no symbol) and N₂H⁺ J = 1–0 (isolated component, with hatches). The colour scale shows the average radial velocity of each structure. Transparency reveals the overlaps between the structures. Sources 1446, 1449, 1454, and 1457 are indicated in black. The white lines show the arc and the bar. The coloured numbers indicate the five main VCSs.