Approximated value of the equivalent width for each line calculated in the generation of a synthetic spectra at T_eff = 6000 K, log g = 4.0 dex and [Fe/H] = −1 dex using the SYNSPEC code (Hubeny et al. 1985; http://nova.astro.umd.edu/Synspec49/synspec.html).

This quantity indicates the percentage of the selected spectral region used in calculating the χ² parameter, in order to mostly include lines that belong to the element whose abundance is desired to be measured, and avoid features due to other elements.