Observed spectra toward the IF and MP2 position. The blue dashed line shows the velocity of 10 km s^-1 relative to the rest frequency of the transition. Two different velocity components can be distinguished at each position. Left: transitions of H₂CO (211.211 and 218.222 GHz), H¹³CN at 259.011 GHz and HNC at 90.663 GHz (from top to bottom) at the IF and MP2 positions. Right: observed spectra for the deuterated species DCO⁺, C₂D, DCN and DNC transitions toward the IF and MP2 positions. The velocities are relative to the frequencies 144.077, 144.241, 144.828, and 152.609 GHz (from top to bottom).