\begin{table}%T6
\caption{\label{compo}Chemical composition of \object{$\omega$~Ori} {\revised compared to the mean chemical
composition of B~stars, as derived by \cite{gies} and of local B stars, as derived by \cite{gummersbach}.} 
The logarithmic
abundances $\log$~($\epsilon_N/\epsilon_{\odot}$) are given relatively to the 
solar values compiled by \cite{grevesse}.}
%\centering
\par
\begin{tabular}{c @{\ }c @{\ }c @{\ }c}
\hline
\hline
Ion        & \multicolumn{1}{c}{\object{$\omega$~Ori}} & \multicolumn{1}{c}{Gies \& Lambert} & \multicolumn{1}{c}{Gummersbach} \\
\hline
\ion{C}{ii}     &      0.00  $\pm$ 0.07  &    $-$0.32  $\pm$ 0.16 &    $-$0.32  $\pm$ 0.15 \\
\ion{N}{ii}     &      0.26  $\pm$ 0.10  &    $-$0.11  $\pm$ 0.22 &    $-$0.20  $\pm$ 0.12 \\
\ion{O}{ii}     &   $-$0.09  $\pm$ 0.06  &    $-$0.15  $\pm$ 0.14 &    $-$0.27  $\pm$ 0.09 \\
\hline
\end{tabular}
\end{table}