Skeleton map with the filament crests identified with DisPerSE overlaid on the ArTéMiS +SPIRE 350 μm map (logarithmic colour scale). The numbers mark filament segments roughly corresponding to the N₂H⁺ fibres discussed by Hacar et al. (2018), as listed in Col. 1 of Table 1. The yellow crest corresponds to the ISF portion referred to as ‘ISF-OMC-2/3’ in the text, and the red one corresponds to ‘ISF-OMC-1’.