Selected integrated intensity [5,15] km s⁻¹ maps. Black contours run from 10 to 90% of the maximum value in steps of 10%, while the white contour shows the 3σ level. The maps highlight some of the molecules typically used as tracers: CO for the bulk of molecular gas, HCO ⁺ as an indicator of high density, N₂H⁺ for cold dense gas, CH₃OH for shocked material, and C₂H associated with UV irradiation. The velocity range used for the maps does not encompass the whole line width (which differs strongly, especially comparing OMC-1 to OMC-3), but covers all central velocities.