Comparison of the linewidth as defined by Molnar et al. (2019; upper panel), by Leenaarts et al. (2012; middle panel) and as defined as the FWHM (lower panel). The red, black and green lines show normalised spectra for the VAL C model, Bifrost QS and the observed spectrum for α Cen A (Porto de Mello et al. 2008), respectively. The solid blue lines in the top panel mark ± 1 Å, while the dotted lines show the considered maxima and the dashed lines show the calculated linewidths in all three cases.