Spectra of the CO υ = 1–0 band from the three classes defined in Sect. 3.2 (see Fig. 5) based on the absorption or emission of the P- and R-branches. The top panel shows the spectrum of the nuclear region where both branches are in absorption. The middle panel is the integrated spectrum of the regions where the R-branch is in absorption and the P-branch is in emission (rotating disk). The bottom panel is the integrated spectrum of areas with both branches in emission (outflow region perpendicular to the disk). The wavelengths of the P- and R-branches of the ¹²CO, ¹³CO, and C¹⁸O υ = 1–0 bands are marked by the dashed purple, orange, and blue lines, respectively. Transitions from other atomic and molecular species are marked by the dot-dashed black lines. The D_n-PAH band and the OCN⁻ and CO ices are indicated in the middle and top panels. The rest frame is defined using the wavelength of the higher-J CO υ = 1–0 transitions detected, which for the nucleus are blueshifted with respect to the systemic velocity.