\begin{table}%t9
\caption{\label{TabAbund}Summary of elemental abundance $n_{\rm element}/n_{\rm O}$ values in Cas~A ejecta from various sources.}
%\centerline
 {\small \begin{tabular}{lllllll}
\hline\hline
       & CK78 & CK79        & Wil02 & LH03 & Laz06 & Used in this paper \\
\hline
Method & Optical & Optical   & X-ray & X-ray & X-ray & -- \\
\hline
Ne/O   & 0.025 & $<$0.013    & 0.02  & --    & --  & 0.02  \\
Mg/O   &$<$0.04& $<$0.005    & 0.004 & --  & 0.005$-$0.03 & 0.005 \\
Si/O   & --  & --  & 0.025 & 0.003$-$0.015& 0.008$-$0.06 & 0.05  \\
S/O    & 0.06  & 0.002$-$0.7 & 0.014 & --   & 0.006$-$0.05 & 0.05  \\
Ar/O   & 0.004 & 0.003$-$0.1 & 0.0035& --  & --  & 0.005 \\
Fe/O   & 0.003 & $<$0.001 & 0.006$-$0.02& 0.002$-$0.01 & --  & 0.005 \\
\hline
\end{tabular}}
\medskip
The ``average'' data used in this paper are shown in the last column.  Data source abbreviations: \citet{CheKirCasA} -- CK78,
\citet{CheKirAbund} -- CK79, \citet{CasAXMM2002} -- Wil02,
\citet{LamingHwang03} -- LH03, \citet{CasAChandra} -- Laz06.
\end{table}