PV diagrams along PA = 155°. Dashed lines indicate the reference position (VLA 4B) and the systemic velocity V_sys = 8.5 km s^-1 (from SO). Contours start at 3σ with steps of 14σ for SiO(5–4), 7σ for SO(6₅ − 5₄) and 21σ for CO(2–1). The color scale displays the intensity in K. Vertical dotted lines indicate the position of the H₂ features of HC14 as labeled in Fig. 2. Red and black crosses show velocities for which the molecules peak on arcs (b) and (c), respectively. The orange arrows indicate contamination by complex organic molecules (COMs).