the Zn abundance derivation from the 6362 [Å]{} line. Oxygen was also derived for the two most metal-poor stars of the sample BW-f4 and BW-f8, for which no previous derivation was available.

The derivation of C, N, and O abundances was carried out by fitting the Swan C$_2$ (0,1) A$^3$$\Pi$-X$^3$$\Pi$ bandhead at 5635 [Å]{}, the red CN (5,1) A$^2$$\Pi$-X$^2$$\Sigma$ bandhead at 6332.18 [Å]{}, and the forbidden oxygen \[OI\]6300.311 [Å]{} line. Fits to these C,N,O abundance indicators are illustrated in Fig. \[cno\] for star B6-b6. These features have to be fitted iteratively, given that a change in the abundance of any of them has an impact on the molecule dissociative equilibrium. A further check of the CN line intensity was done for the asymmetry of the 6362 [Å]{} line.

In Table \[cncorrected\] we report the Lecureur et al. (2007) C, N, O abundances, and in the next column, we assign the letter [**c**]{} when the abundance is confirmed; otherwise, we give the newly revised abundances. A few comments on individual stars are given in the last column of Table \[cncorrected\]: Telluric means that such lines mask the \[OI\]6300 and \[OI\]6363 lines, thus preventing any possibility of deriving its oxygen abundance, such 