Histograms of the average C¹⁸O(2–1)spectra of the six boxes across cut A with a bin size of 0.1 km s^-1. The black dash-dotted line indicates the 3×rms limit. The values of 3 ×rms and the signal-to-noise ratio S/N are given in the upper right of each plot. The red solid line shows the Gaussian fit to the spectrum. If more than one component was fitted, each of the components is represented by a blue dashed line and the red solid line is their sum. The residuals of the fit are given by the red bars in the small plot below each spectrum. Peak positions v_pi and FWHM Δv_i of each component in one box are given in the upper left of each plot. A summary of all these values can be found in Table 2, where they are denoted by an upper index G.