Correlation between I( [N II]) (205 μm) and I( [C II]) (159 μm). The data points are labeled with their position (in offsets of ′′). The black line corresponds to the best fit line provided by Abel (2006) and the solid gray line shows the fit given by Heiles (1994). The dashed and dot-dashed lines show how the relation by Abel (2006) is affected by an enhanced elemental (N/O) ratio ((1.86 × (N/O)) and by beam size effects (I( [N II] ) × (14″/18″)²), respectively.