Merged observational spectra obtained in VFAINT mode and the output spectral models of mkacispback. The spectra were extracted from the entire CCD regions. The S1 and S3 data were taken from the CALDB blank-sky data instead of the CDF-S blank-sky data set. For each CCD, the upper and lower panels represent the count rate and data-to-model ratio, respectively. We note that the background was higher in the period covered by the CALDB blank-sky observations, so offsets between the ACIS-stowed and CALDB blank-sky data are present.