\begin{table}%t6
\par
\caption{Relative gradients, observed and calculated: $\Delta_{BV}$ is taken 
as~unit. \label{tab6}}
%\centerline
 {
\begin{tabular}{llllllll}
\hline \hline
 Source& $U-B$  & $B-V$  & $B-R$  & $V-I$  & $V-J$  & $V-K$  & $J-K$ \\ 
 Obs.  & 2.38 & 1.00 & 1.24 & 0.92 & 2.06 & 3.44 & 1.41 \\
\hline  
 W94   & 2.45 & 1.00 & 1.48 & 1.17 & 4.24 & 5.14 & 0.90 \\  
 Bal94 & 2.57 & 1.00 & 1.86 & 1.68 & 5.36 & 6.68 & 1.32 \\ 
 BC04  & 2.03 & 1.00 & 1.58 & 1.18 & 3.36 & 3.76 & 1.18 \\  
\hline
 Wal92 & 0.32 & 1.00 & 2.17 & 3.17 & 5.25 & 8.11 & 2.86 \\ 
 id    & 0.92 & 1.00 & 2.45 & 3.83 & 6.31 & 9.75 & 3.44 \\ 
\hline
\end{tabular}}
\smallskip
Sources: Obs. Mean observed gradients from Table~\ref{tab4}; W94 calculated  
from Worthey  (\cite{Worthey94}), range [Fe/H] --0.25 to 0.25, age 12~Gyr; Bal94 calculated from 
Bressan et~al. (\cite{Bressan94}), range $Z=0.008$ to 0.05, age 12.56~Gyr; BC03 calculated from 
Bruzual \& Charlot (\cite{Bruzual03}) $Z=0.008$ to 0.05, age 12~Gyr; Wal92 dust induced colour 
gradients calculated from Witt et~al.  (\cite{Witt92}), Table~3E, Tau($V$)~=~4 (1st. line) and 
Tau($V$)~=~1 (2nd. line). The following columns
show the relative gradients $\Delta_{UB}$/$\Delta_{UV}$ for $U-B$, $B-V$, .... 
\end{table}