Examples of the fits to DIBs 18621 and λ8648 in four ISM spectra. The black and red lines are the ISM spectra and fit DIB pro-flies, respectively, normalized by the fit linear continuum. The error bars indicate the observational flux uncertainties of the RVS spectra. Orange marks the masked region during the fittings. The Gaίa source ID of these targets, E(BP − RP) from Andrae et al. (2023), the EWs of the two DIBs (EW₈₆₂₁ and EW₈₆₄₈), and the S/N of the ISM spectra are indicated as well.