\begin{table}%T8
\par
\caption{\label{t:conf}Literature values for metallicity, and methods used. The two values
given for NGC~2506 by Marconi et~al. correspond to the best reproductions of the
observed CMDs with synthetic ones based on the Padova tracks (Bressan et~al.
\cite{Bressan1993}) at~$Z=0.008$ and~0.02; note that further unpublished analyses with
updated evolutionary tracks have shown that the solar solution should
be excluded. The two solutions for~IC~4651 given by \mbox{Anthony-Twarog}
\& Twarog correspond to two different calibrations of the intrinsic {\it b-y} colour
versus metallicity.}
%\centering
\par
\begin{tabular}{llll}
\hline \hline 
Reference & ${\rm [Fe/H]}$ & $E(B-V)$ & method \\
\hline 
\multicolumn{4}{c}{NGC~2506} \\
This paper          & $-$0.20 & 0.073 & high-res sp.\\
Geisler et~al. (\cite{Geisler1992}) & $-$0.58 &      & Washington ph. \\
Friel \& Janes (\cite{Friel1993}) & $-$0.52 & 0.05 & low-res sp. \\
Marconi et~al. (\cite{Marconi1997}) & $\sim$$-$0.4 to 0.0 & 0.05 to 0 & synthetic CMD\\
Twarog et~al. (\cite{Twarog1997})  & $-$0.38 & 0.05 & low-res sp.+ DDO \\
Friel et~al. (\cite{Friel2002})   & $-$0.44 & 0.05 & low-res sp. \\
\multicolumn{4}{c}{NGC~6134} \\
This paper          & +0.15 & 0.363 & high-res sp.\\
Clari\'a \& Mermilliod (\cite{Clari1992}) & $-$0.05 & 0.35 & Wash. + DDO \\
Twarog et~al. (\cite{Twarog1997})  & +0.18 & $0.35{-}0.39$ & DDO \\
Bruntt et~al. (\cite{Bruntt1999})  & +0.28 & 0.365     & Str\"omgren \\
\multicolumn{4}{c}{IC~4651} \\
This paper          & +0.11 & 0.083 & high-res sp.\\
Twarog et~al. (\cite{Twarog1997})  & +0.09 & $0.11{-}0.12$ & DDO \\
Anthony-Twarog \& Twarog (\cite{Anthony2000}) & +0.077 & 0.086  & Str\"omgren \\
                              & +0.115 & 0.099  & Str\"omgren \\
Meibom et~al. (\cite{Meibom2002})  & $\sim$+0.12   & 0.10  & CMD (Yale) \\
\hline 
\end{tabular}
\end{table}