¹²CO, ¹³CO, and CS spectra (inner Galaxy only) collapsed (summed) along the spatial dimensions, in the GRS+UMSB surveys (top left), in the ℓ = 143° field of the EXFC 135–165 (top right), and in the ℓ = 81° field of the EXFC 55–100 survey (bottom). The total spectra are shown in black. The collapsed spectra of “detection” voxels only are shown in red, and the total spectra of “noise” voxels are shown in blue. The dip in the “noise” ¹³CO spectrum in the GRS+UMSB at about 12–15 km s⁻¹ is due to a problem with the off position in the GRS data, which causes an artificial absorption-looking feature in the baseline of the spectrum with main beam temperature values around −1.5 to −1 K at longitudes ℓ = 33°–36°.