Comparison between the individual ACIS-stowed observation spectra and output spectra of mkacispback for ACIS-I0, VFAINT mode. In each case, the spectrum is extracted from the entire CCD. In each panel, the upper and lower panels show the data and model count rates (s⁻¹ keV⁻¹) and their ratios (data/model), respectively. One observation per year from the observation list (Table A.1) is presented. Observations with exposure time of less than 40 ksec are omitted.