Relative (left panel) and absolute (right panel) differences of spectral line parameters measured in two slices of the S2D spectra as a function of wavelength, EW, and the distance from the center of the spectral order. The boundary wavelength region (at ~5250 Å) of the blue- and red-arm detectors is indicated by the rectangle. Line parameters were measured with ARES with a S/N that varied as a function of the position of the spectral line in the echelle order.