ALMA continuum-subtracted spectra of the [CII] emission line of J1015+0020 and its companion [CII] emitters, extracted from an area of 1.5 to 2 beam areas, according to the source. The continuum-subtracted [CII] flux density is shown as a function of the relative velocity with respect to the QSO redshift z_[CII], indicated by the dashed vertical line. The plotted channel width corresponds to 60 km s⁻¹. The red curve represents the best fit to the data of one or two Gaussians model.