Carbon abundance, A(C), versus [Fe/H] for the two CEMP stars (pink stars) compared to the sample of Spite et al. (2013) (blue solid circles). The dashed (red) horizontal line is the solar photospheric carbon abundance. The solid horizontal (black) lines are the two carbon plateaux for CEMP stars, tentatively identified by Spite et al. (2013). The dashed (blue) tilted line, corresponding to [C/Fe] = +1, separates CEMP stars from C-normal stars.