\begin{table}%t2
\caption{High-contrast absorption line systems.}
%\centerline
{\begin{tabular}{@{}ccrcl@{}}
\hline
\hline
\noalign{\smallskip}
QSO & $\zabs$ & $\Daova$(10$^{-5}$)  & $\log\NHI$ & Ref. \\
\noalign{\smallskip}
\hline
\noalign{\smallskip}
0100+13  & 2.310 & --$3.941\pm1.368$ & 21.40 & (PW99) \\
0149+33  & 2.140 & --$5.112\pm2.118$ & 20.50 & (PW99) \\
0201+37  & 1.955 &   $1.989\pm1.048$ & 20.20 & (PW96) \\
0201+37  & 2.462 &   $0.572\pm1.719$ & 20.40 & (PW96) \\
0528--25 & 2.141 & --$0.853\pm0.880$ & 20.70 & (L96) \\
0528--25 & 2.811 &   $0.850\pm0.846$ & 21.20 & (L96) \\
0841+12  & 2.374 &   $2.277\pm3.816$ & 20.95 & (PW99) \\
0841+12  & 2.374 &   $1.435\pm1.227$ & 20.95 & (PW99) \\
0841+12  & 2.476 & --$4.304\pm1.944$ & 20.78 & (PW99) \\
1011+43  & 2.959 &   $2.475\pm1.706$ & ..... & (C02) \\
1215+33  & 1.999 &   $5.648\pm3.131$ & 20.95 & (PW99) \\
1759+75  & 2.625 & --$0.750\pm1.387$ & 20.80 & (P01) \\
1759+75  & 2.910 & --$0.492\pm1.645$ & 19.80 & (O99) \\
1850+40  & 1.990 & --$1.663\pm0.859$ & ..... & (C02) \\
2206--20 & 1.920 &   $1.878\pm0.702$ & 20.65 & (PW97) \\
2230+02  & 1.859 & --$5.407\pm1.179$ &$<$20.85 & (PW99) \\
2230+02  & 1.864 & --$0.998\pm0.492$ & 20.85 & (PW99) \\
2231--00 & 2.065 & --$2.604\pm1.015$ & 20.56 & (PW99) \\
2231--00 & 2.065 &   $1.707\pm1.249$ & 20.56 & (PW99) \\
2231--00 & 2.653 & --$3.348\pm1.904$ &$<$20.30 & (L91)\\
2343+12  & 2.430 & --$1.224\pm0.389$ & 20.34 & (L98) \\
2359--02 & 2.095 & --$0.068\pm0.722$ & 20.70 & (PW99) \\
\noalign{\smallskip}
\hline
\end{tabular}}
\par
\smallskip
(L91) \citet{LWT91};
(L96) \citet*{LSB96};
(L98) \citet*{LSB98};
(O99) \citet{OCC99};
(PW96) \citet{PW96};
(PW97) \citet{PW97};
(PW99) \citet{PW99};
(P01) \citet{PWT01};
(C02) \citet{CFK02}.
\label{table2}
\end{table}