Calibration-induced shifts of the observed profiles illustrated by spectral lines from different absorption systems. The velocity structure is estimated on the basis of lines from the high-resolution (Keck/HIRES) part of the HS 1103+6416 spectrum and then applied to calculate the profiles from low-resolution (HST) parts. The synthetic profiles are shown by red, the vertical ticks mark positions of sub-components. ΔV indicates the velocity shift applied to the observed profile to align it with a reference line from the Keck spectrum.