\begin{table}%t3
 \caption{Field O stars possibly associated with young clusters. See Tables~\ref{sfreg} and~\ref{runw} for the meaning of the abbreviations used in Cols.~2 and~3. The
 projected distance is with respect to the distance of the field O~star.}\label{runw2}
%\centerline
{
  \begin{tabular}{lcccccc}
\hline
\hline
Name & VM & SM    & Proj. dist.& Cluster     & Age & Ref. \\
     &            &                &   (pc)     &             & (Myr) & \\
\hline
HD~117856&  VB     & SB2:  & 57 & St~16         & 4  & 1\\
HD~125206&  single & SB2:  & 45 & NGC~5606     & 7   & 2\\
HD~154368&  VB     & SBE   & 42 & Bo~13        & 6.3 & 3\\
HD~154643& single  & SB1:  & 44 & Bo~13        & 6.3 & 3\\
HD~158186& single  & SBE   & 30 & NGC~6383     & 1.7 & 4\\
HD~161853& single  & SB1:  & 55 & Col~347      & 6.3 & 3\\
HD~169515& single  & SB2OE & 65 & NGC~6604     & 4   & 3\\
\hline
 \end{tabular}}
 \medskip
1: \citealt{1985ApJ...292..148T}; 2: \citet{1994AetAS..106..339V}; 3: \citet{1994AetAS..104..379B}; 4:~\citet{1978MNRAS.182..607F}.
\end{table}