Position-velocity diagrams at constant declination of C¹⁸O J = 1 → 0 (grey scale and contours) as examples of the typical velocity structure in the NW sub-cluster (top) and the SE sub-cluster (bottom) (Duarte-Cabral et al. 2010). Right ascension varies from 18^h30^m06^s to 18^h29^m46^s for all panels. Declinations are 1°16′48′′ (top panel) and 1°12′38′′ (lower panel). The positions of these cuts in the map are shown as white lines in Fig. 3. The dashed lanes labelled as “dust” represent the regions whose 850 μm emission is above 0.6 Jy beam^-1.