N_C¹⁸O vs. /X_C¹⁸O measured in a) the entire region; b) the Orion Bar; c) DLSF, d) OMC-1; e) OMC-2/3; f) OMC-4; and g) bending structure area, respectively. The gray, red, orange, yellow, blue, aqua, and green plots are taken from the entire region, data points in the Orion bar, DLSF, OMC-1, OMC-2/3, OMC-4, and bending structure, respectively. The black lines indicate /X_C¹⁸O = 5.5. The dashed lines indicate /X,_C¹⁸O= 12.3, which is the mean value of /X_C¹⁸O for the entire region. The filled squares show the mean /X_C¹⁸O which is computed by binning the individually calculated ratios into intervals of 2.0 × 10¹⁵ cm^-2. The error bars show the standard deviations in each bin.