The spectral model is assumed to apply in the SOURCE frame, and the resulting spectrum is then redshifted before folding through the instrument response for comparison with the data. SPLOT corrects for redshift of the model to plot the spectrum which is observed at Earth, and SFLUX, similarly, gives the Earth-based flux. Absorption:- The AG (galactic absorption) model component represents absorption occurring along the sight-line within our own galaxy. This component is therefore NOT redshifted. The AB (intrinsic absorption model), on the other hand IS redshifted, since it represents absorption local to the source.