\begin{table}%t2
\caption{\label{tab:clas}Classification of the optical sources detected in the 2XMMi catalog.}
%\centerline
{
\begin{tabular}{l c c c}
\hline\hline
Quality flag & O stars & B stars & WR stars \\     
\hline                        
0 & 35 (16) & 91 (22) & 7 (6)\\ 
$\neq$0 & 98 (62) & 70 (28) & 9 (8)\\ 
\hline                                   
\end{tabular}}
\medskip
The number in parentheses yields the number of sources with available EPIC spectra.
\end{table}