Silicon region in the low- (upper panel, blue) and high-hardness (middle panel, black) spectra; both panels show combined HEG and MEG ± first order spectra normalized to their respective power-law continua. The solid red line shows the best model fits to the data. Residuals are shown in Fig. 7. The lower panel shows the calibrated and summed NASA/GSFC EBIT Calorimeter Spectrometer (ECS) silicon spectrum used for line identification. These data, as analyzed in Hell et al. (2016), are used as best currently available laboratory reference values for the energies of K-shell transitions in L-shell ions of Si.