Mass fraction of H, He, C, N, O, and Ne as a function of the mass coordinate for the nonrotational model S2 and rotational model S8 at different evolutionary points as indicated by the different colors: ZAMS (red solid lines); the end of central hydrogen burning (marked by ECHB; green dashed lines); the end of central helium burning (marked by ECHeB; blue dashed lines); the end of calculation (marked by EOC; purple dashed–dotted lines.)