\begin{table}%t4
  \caption{\label{tab4}The XIS spectra from the second and fifth intervals.}
%\centerline
 {\begin{tabular}{lcccc}
\hline\hline
\noalign{\smallskip}
Interval & $\Gamma $ & log $\xi$\tablefootmark{a}  & $N_{\rm W}^{{b}}$ & \\[5pt]
2 & $1.75\pm 0.07$ & $1.6\pm 0.5$ & $1.1\pm 0.2$ & \\
5 & $1.23\pm 0.07$ & $1.0\pm 0.1$ & $2.4\pm 0.3$ & \\[5pt]
$\Gamma $ & --  & $1.56\pm 0.09$ & $1.47\pm 0.09$ & \\
log $\xi$\tablefootmark{a} & $1.4\pm 0.3$ & --  & $1.1\pm 0.2$ & \\
$N_{\rm W}^{{b}}$ & $2.2\pm 0.5$ & $2.3\pm 0.3$ & --  & \\[5pt]
$\chi^2$/d.o.f. & 281.8/309 & 293.2/309 & 283.4/309 & \\[10pt]
Interval & $\Gamma $ & log $\xi$\tablefootmark{a} & $N_{\rm W}$\tablefootmark{b}  & $\chi^2$/d.o.f. \\[5pt]
2 & $1.65\pm 0.08$ & $1.5\pm 0.2$ & $2.2\pm 0.4$ & 275.0/308 \\
5 & $1.34\pm 0.10$ & $1.0\pm 0.2$ & as above & \\[5pt]
2 & $1.66\pm 0.09$ & $1.3\pm 0.2$ & $1.8\pm 0.2$ & 275.5/308 \\
5 & $1.34\pm 0.09$ & as above & $2.3\pm 0.3$ & \\
\hline
\end{tabular}}
\tablefoot {Results of joint model fitting to the XIS spectra from the
    second and fifth intervals are shown. For the spectral fitting, the procedure is
    the same as that described in Table~\ref{tab3}. The lower part shows the
    results when the spectral slope and the warm absorber parameters
    ($N_{\rm W}$, log $\xi$) are left to vary, but either of the two
    warm absorber parameters is tied between the two spectra.
\tablefoottext{a}{In unit of erg~s$^{-1}$~cm.}
\tablefoottext{b}{In unit of $10^{22}$~cm$^{-2}$.}}
\end{table}