\begin{table}%T2
\caption{\label{tab:fit_EPIC_31}Best-fit models of the EPIC data (in the $1.5{-}41$~\AA\ band), with~90\% statistical confidence ranges computed for one interesting parameter at
a time; nominal errors on~$T_{i}$ and~{\it EM}$_{i}$ are at the 10\%~level. Element
abundances are relative to the solar ones \citep{Grevesse1992}. Mean
temperatures are calculated as
$<T>~=$\protect$\sum_{i=1}^{3}EM_{i}~T_{i}/\sum_{i=1}^{3}EM_{i}$.}
%\centerline
{
\begin{tabular}{lcc} 
\hline\hline
                           &         pn          &       MOS2~        \\ \hline 
$\log T_{1,2,3}~({\rm K})$         &   6.44, 6.92, 7.28  & 6.70, 6.95, 7.25   \\ 
$\log EM_{1,2,3}~({\rm cm}^{-3})$  &   52.6, 53.1, 53.0  & 52.5, 53.4, 53.2   \\ 
$\log <T>~({\rm K})$               &         7.06        &       7.07         \\ 
   C$^{a}$                    &         0.38        &       0.22         \\ 
   O                          & $0.58~\pm~0.03$   & $0.37~\pm~0.05$  \\ 
   Ne                         & $2.35~\pm~0.14$   & $0.58~\pm~0.09$  \\ 
   Mg                         & $1.95~\pm~0.13$   & $0.96~\pm~0.08$  \\ 
   Si                         & $1.23~\pm~0.11$   & $0.69~\pm~0.06$  \\ 
   S                          & $0.58~\pm~0.20$   & $0.60~\pm~0.13$  \\ 
   Fe                         & $1.54~\pm~0.02$   & $0.87~\pm~0.02$  \\ 
   Ni                         & $4.1~\pm~0.3$     & $1.4~\pm~0.2$    \\ 
$N_{\rm H}~({\rm cm}^{-2})^{b}$        &     $10^{18}$       &     $10^{18}$      \\ \hline
   $\chi^{2}_{\nu} /{\rm d.o.f.}$   &      1.1/367        &      1.2/150       \\ \hline
   \end{tabular}}
   \smallskip
$^{a}$ Fixed to 0.25 times the iron abundance (see text for explanations). \\
$^{b}$ Fixed (see text).
\end{table}