Filament width (Gaussian FWHM) properties for the final SI-sample: a) filament width as a function of field distance; b) same as Fig. 6a, but without the 3σ distance uncertainty constraint (see text); c) width distribution histogram; d) variation of the (accumulated) average FWHM of filaments with distance for the final sample (triangles with error bars) relative to that of the filament sample in Fig. 6b (red triangles). Dash-dotted line in Fig. 6d indicates the median FWHM of the SI sample.