Comparison between the [C I] 492 GHz and ¹³CO(21) integrated intensities. All three types (Types 0, 1, and 2; Sect. 4.1.1) are used here, and the 70w, IRw, IRb, H II region groups, and diffuse cloud components are shown in different colors. For the Type 1, upper limits were calculated by N.C([C I]) [C I] 492 GHz 5− −v([C I]) where N.C([C I]) is the number of [C I] channels over which ¹³CO is detected and −v([C I]) is the velocity resolution of the [C I] spectra. A similar calculation was done for the Type 2, but using the number of ¹³CO channels over which [C I] is detected, ¹³CO 5−, and velocity resolution of the ¹³CO spectra instead. These derived upper limits are indicated as the arrows. Left: log scale. The measured minimum, median, and maxium I(¹³CO)-to-I([C I]) ratios (0.2, 1.8, and 5.3) are indicated as the dashed lines in different shades of gray color. Right: linear scale. A linear one-to-one relation is shown as the black dashed line.