Normalized VLT/X-shooter spectrum of GRB 181020A in velocity space, centered on the strongest component at z = 2.9379. The solid black line shows the spectrum and the associated error is shown in blue. The best-fit Voigt profiles are indicated by the solid red lines. The identified velocity components are marked above each of the absorption profiles. Gray shaded regions were ignored in the fit. These lines are representative of the typical low-ionization metal lines in GRB 181020A, showing most clearly the overall velocity structure.