\begin{table}%t6
\caption{\label{tab:fxfbol}Average $\log f^{\rm unabs}_{\rm X}/f_{\rm BOL}$ ratios, with their dispersions.}
%
\par
%\centering
\par
\begin{tabular}{l c c }
\hline\hline
 & O stars & B stars \\     
\hline                        
\multicolumn{3}{l}{From fits only}\\
\\[-2mm]
0.5--10~keV & $-6.45\pm0.51$ & $-6.27\pm0.98$ \\ 
\\[-2mm]
0.5--1.~keV & $-6.69\pm0.45$ & $-6.73\pm0.69$ \\ 
1.--2.5~keV & $-7.02\pm0.58$ & $-6.82\pm1.07$ \\ 
2.5--10~keV & $-8.03\pm1.32$ & $-7.48\pm1.89$ \\ 
\\[-2mm]
\multicolumn{3}{l}{From fits and conversion of the count rates (0.5--10~keV band)}\\
\\[-2mm]
all     & $-6.66\pm0.50$ & $-6.59\pm0.83$ \\ 
\\[-2mm]
$S$=0   & $-6.80\pm0.35$ & $-6.81\pm0.74$ \\ 
$S\neq$0& $-6.61\pm0.54$ & $-6.34\pm0.87$ \\ 
\\[-2mm]
binaries& $-6.47\pm0.52$ & $-7.34\pm0.62$ \\ 
singles & $-6.72\pm0.49$ & $-6.55\pm0.82$ \\ 
 \\[-2mm]
supergiants  & $-6.75\pm0.36$ & $-6.82\pm0.88$ \\ 
giants       & $-6.74\pm0.33$ & $-7.13\pm0.85$ \\ 
main sequence& $-6.67\pm0.49$ & $-6.33\pm0.77$ \\ 
 \\[-2mm]
Carina  & $-6.54\pm0.56$ &\\ 
NGC6231 & $-6.71\pm0.22$ &\\ 
NGC6604 & $-6.48\pm0.48$ &\\ 
CygOB2  & $-6.97\pm0.40$ &\\ 
\hline                                   
\end{tabular} 
\end{table}