Methanol lines observed in absorption or self-absorption in one or more of the selected regions (Table 1). Red and blue lines are synthetic spectra for methanol A- and E- type, respectively (see Sect. 4.2). Line frequencies are labeled in the top of the figure, while the velocity range (in km s⁻¹, after applying the radio convention (https://web-archives.iram.fr/IRAMFR/ARN/may95/node4.html) and subtracting the v_LSR velocities from Table 1) is indicated in the bottom-left corner. Regions 1–10 are ordered from top to bottom as indicated in the leftmost panel (y-axis: R from “Region” plus the corresponding number). For the location of the regions, see Fig. 1 and Table 1.