Same as Fig. 1, but comparing the prediction of GALSEVN and Schaerer (2003) Pop III models. The solid- and dashed-orange and red curves represent the same GALSEVN Z = 10⁻¹¹ and 10⁻⁶ models as in Fig. 1, with a Chabrier (2003) IMF truncated at 0.1 and 300 M_⊙ for primary stars, combined with a Sana et al. (2012) distribution of secondary-to-primary mass ratios at age zero (with single stars modeled as noninteracting binaries). The green- and red-shaded regions indicate the areas covered by models with the same three top-heavy IMFs with characteristic masses of 50 M_⊙, 100 M_⊙ and 200 M_⊙ as in Fig. 1. The solid purple, solid blue and dot-dashed blue curves show the zero-metallicity, single-star models of Schaerer (2003) for three Salpeter (1955) IMFs with different lower- and upper-mass cut-offs.