[C/N] measurements of HeCB stars as a function of T_eff compared to predictions from isochrones and stellar evolutionary tracks. Isochrones are from Syclist models of solar metallicity (Z = 0.014) and an age of 0.5 Gyr unless otherwise stated. Evolutionary tracks of Solar metallicity are from Lagarde et al. (2012) with the exception of the 2.5 M_⊙, nonrot, β = 0 track, which is from Vincenzo et al. (2021). The different evolutionary stages are located similarly to Fig. 3, but for clarity, many of the tracks and isochrones only show the part from the upper RGB to and including the AGB.