Panel a: histogram of the values of the band width FWHM (Å) of the DIBs detected in the lines of sight of HD 183143 or HD 204827 (Hobbs et al. 2009, 2008) that have recently been confirmed in the Apache Point catalogue of Fan et al. (2019) for an FWHM < 3Å (out of 509 DIBs, there are 19 with FWHM > 3Å). Panel b: histogram of the values of the band width of the DIBs, identified as C₂ (black), ζ (red), and σ (green) (Table 1), detected in the lines of sight of HD 183143 or HD 204827, for FWHM < 3Å (out of 12 σ DIBs, there are 4 with FWHM > 3Å). The vertical arrows show the adopted limit, 1.1 Å, for the separation between “narrow” and “broad” DIBs.