Radial variation of filament M∕L (red) and the number of filaments crossing annular circles (black). Red dots show the actual data points for all skeletons longer than 0.4 pc. The red line represents the average M∕L in each 0.2 pc bin and the error bars are their standard deviations. The black line shows the number of filaments that intersect thecircumference of concentric circles drawn around the HFS as displayed in Fig. A.2.