Observed (X-SHOOTER spectrum; ID 5 in Table 1) and synthetic spectra of the region around 3400 Å showing theO IV and N IV lines. The observed spectrum (blue) shows clear indications of ISM absorption lines. The black line isthe synthetic spectrum without a contribution of ISM lines. The spectrum with the modeled ISM lines is shown as red dotted line. The interstellar absorption arise in the Galactic foreground and in the SMC.