Left: ESDLA BOSS spectrum (black) with the SDSS composite spectrum (grey) reddened by the SMC extinction-law at z_abs(red) with E(B − V) = 0.02. The orange segments indicate the regions used for the fit. Right: distribution of E(B − V)-values for the corresponding control sample. In this example, the “zero-point” (respectively dispersion) of the distribution is −0.03 (respectively 0.044). The value retained for the DLA here is thus E(B − V) = 0.05 ± 0.05.