vs. N_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 dashed lines indicate /X_C¹⁸O = 5.5 and 12.3. In panels b)–g), black lines denote the best fitting lines to measure the abundance ratio /X_C¹⁸O for each region (see Table 4).