All gas N-PDF of GMF20.0-17.9. The PDF is derived by adding the column densities of H I, HISA, and H₂. The plot shows the derived N-PDF of the whole filament marked by both the red polygons in Fig. 11. The red vertical dashed and solid line marks the column density threshold (last closed contour) at 4.5 × 10²¹ cm⁻² and mean column density, respectively. The red solid line indicates the power-law fit to the high column density tail of the distribution.