Lower side band continuum-subtracted representative spectra of IRAS 17233 at the peak of the 1.3 mm continuum emission. All transitions used to derive the zero-th and first moment maps of Figs. 4–14 are labelled. For reference, we also mark the C¹⁸O(2−1) and SO(5₆−5₅) lines (discussed in Leurini et al. 2009), and the ladder of the CH₃CN (labelled with the corresponding K quantic number) and CHCN(12−11) lines (labelled with the corresponding K quantic number followed by ¹³C).