\begin{table}%T4
%\centering
\par
\caption{Sensitivities of abundance ratios to variations in the atmospheric
parameters and to errors in the equivalent widths, as computed for a typical 
program star with $T_{\rm eff} = 4500$~K. 
The total error is computed as the quadratic sum
of the three dominant sources of error,
$T_{\rm eff}$, $v_t$, and errors in the ${\it EW}$s (Col.~8: tot.1) or as the sum
of all contributions (Col. 9: tot.2).}
\begin{tabular}{lrrrrrrrr}
\hline\hline
Ratio    & $\Delta T_{\rm eff}$ & $\Delta$ $\log g$ & $\Delta$ [A/H] & $\Delta v_t$
&$\langle N_{lines}\rangle$& $\Delta$ {\it EW} & tot.1 & tot.2\\
         & (+50 K)    & (+0.2~dex)      & (+0.10~dex)      & (+0.20 km~s$^{-1}$) & & & (dex)& (dex)  \\
 (1) & (2) & (3) & (4) & (5) & (6) & (7) & (8) & (9) \\
\hline
$[$Fe/H$]${\sc  i}  &  +0.047 &   +0.001 &$-$0.001 & $-$0.029 & 38 &+0.021  &0.059 &0.059  \\
$[$Fe/H$]${\sc ii}  &$-$0.040 &   +0.010 &  +0.017 & $-$0.011 &  3 &+0.076  &0.087 &0.089  \\
\hline
$[$O/Fe$]${\sc  i}  &  +0.046 & $-$0.001 &  +0.004 &   +0.009 &  2 &+0.093  &0.104 &0.104  \\
$[$Na/Fe$]${\sc ii} &$-$0.006 & $-$0.006 &$-$0.020 &   +0.005 &  4 &+0.066  &0.066 &0.070  \\
\hline
\end{tabular}
\label{t:sensitivity}
\end{table}