Top: Surface N abundance versus projected rotational velocity. From left to right, He-low, normal, and rich sample. For reference purposes, we include evolutionary tracks for v_ini/v_crit = 0.2 and 0.4 from GENEC (Ekström et al. 2012, and priv. comm.; dotted and dashed lines; M_ini = 20, 25, 32, and 40 M_⊙) and MESA models, adopting the Mix1 prescription from Keszthelyi et al. (2022) (equivalent to Brott et al. 2011, solid and dashed dotted lines: M_ini = 20, 25, 30, and 40 M_⊙). Model segments with Y_He ≥ 0.12 are highlighted in blue. The same markers as in Fig. 1 are used. Bottom: For the subsets in the upper panels, v sin i distributions separated in low, normal, and high nitrogen (red, green, and blue histograms, respectively).