¹²CO(2–1) spectra (black line) showing different typical profiles: single component (upper left), multiple components (upper right), simple contamination in the off-position (lower left), and a complex spectrum with all features (lower right). The total fit spectrum is overplotted in blue. Coherent velocity complexes are either marked as black (source position) or red (off position; negative features) horizontal bars below the spectrum. The vertical dashed blue lines indicate the peak positions of the fit Gaussian profiles, whereas the vertical red dashed lines indicate the peak position of the emission found in theoff-position.