Example of a velocity plot (a relative velocity vs normalised absorption profile plot) of H i and associated C iv detected in the z = 2.352743 absorber in the spectrum of HE1122−1648. The strongest C iv component is set to be at the zero velocity. The observed spectra are plotted as a histogram, while Voigt-profile fits are as a smooth curve. Thick red curves are the combined fit from individual components. The heavy tick marks above the profiles indicate the velocity centroid of each component. Non-negligible blends by other ions are indicated in gray. The b value (in km s^-1) and log  N_H i with the VPFIT fitting errors are displayed next a tick mark indicating the center of the component.