Grey filled histograms show spectra converted to brightness temperature (T_b) scale: spectrum extracted towards the central position, the B-shock position, and an average within a radius of 0.′′ 5 around the peak of the dust continuum emission, which is multiplied by a factor of 4 for a better visibility. The blue labels show the species listed in Table 1, pink labels show transitions of CH₃OH (and its isotopologue) discussed in Paper I. The spectra have been shifted along the y-axis for a better visibility.