\begin{table}%t8
%\centering
\par
\caption{Radiative decay rates for forbidden transitions that
  de-populate the metastable 3s$^2$3p3d ${^3}$F$_4$ level. $i$ is the
  level index of the lower level in the transition. M1 denotes a
  magnetic dipole transition, M2 a magnetic 
  quadrupole transition, and E2 an electric quadrupole
  transition.  M1+E2
  indicates that the M1 and E2 components are comparable in
  strength. The symbols \vtl\ 
and \btl\ indicate that the values are different from those of the
present calculations by amounts greater than 30\% and a factor 2, respectively.} \label{tbl.aval-forbid}
\begin{tabular}{lllll}
\hline
\hline
&&Transition &Kohstall \\
$i$&$A_{ji}$ &type &et~al.~(1998) &CHIANTI \\
\hline
3 &$2.583(+1)$ &M2    &$9.96(-1)$ \btl &$2.477(+1)$\\
4 &$2.222(+1)$ &M2    &$3.97(+1)$ \vtl &$2.327(+1)$ \\
6 &$4.957(+0)$ &E2    &$4.73(+0)$  &$4.309(+0)$\\
8 &$1.176(+1)$ &E2    &$1.10(+1)$  &$1.104(+1)$\\
9 &$1.449(+1)$ &M1+E2 &$1.41(+1)$  &$1.334(+1)$\\
12&$2.179(+1)$ &E2    &$1.95(+1)$  &$2.195(+1)$\\
13&$2.408(-1)$ &E2    &$2.02(-1)$ &$1.981(-1)$\\
16&$1.552(+1)$ &M1    &$1.87(+1)$ &$1.554(+1)$\\
\hline
\end{tabular}
\end{table}