Comparison of some of the relative abundances of the O I systems/DLAs at high redshift (z >  4.5) found in this work (red dots), in Becker et al. (2012) (blue squares), and Poudel et al. (2018, 2020) (green diamonds). Dotted lines mark the solar abundance values. We report also the predictions of the simulations by Kulkarni et al. (2013) at z = 6, the three models are described in greater detail the text. Model 1 assigns a 1–100 M_⊙ Salpeter IMF to Pop III stars. This is 35–100 M_⊙ Salpeter in case of model 2 and 100–260 M_⊙ Salpeter for model 3. The prediction of model 1 is the light blue dot at the junction of the lines of model 2 and 3.