Left: the distribution of orientation differences between the B field (from Planck 353 GHz dust polarization map) and the filament skeletons (extracted on our original column-density map with a resolution of 18.4″). This distribution seems to show a perpendicular preference between the two entities. Right: the distribution of orientation differences in 3D shown as a function of 1 - cos(θ_3D), where θ_3D is the orientation difference angle in 3D as derived by correcting for a random inclination from θ_2D, the observed orientation difference in 2D.