Rest-frame spectral energy distribution, from the radio to the X-ray band, of VIK J2318−31. Radio data are reported as green squares together with the best-fit curved radio spectrum derived (dashed black line); optical and IR data from the literature are reported as brown inverted triangles, while the photometric points used for the AD model are reported as cyan circles; the X-ray Chandra data are reported as red diamonds together with the expected X-ray emission from the L_X−L_2500 Å relation derived in Lusso & Risaliti (2016) (assuming Γ = 2; blue shaded region). The shaded yellow area represents the range of optical frequencies where the Lyα absorption from the intergalactic medium takes place.