\begin{table}%t5
%\centering
\par
\caption{The measured and calculated oscillator strength ($f$-values) of the 2s2p$^{2}$ $^{4}$P $\to $ 2s2p$n$d $^{4}$P, $^{4}$D 
transitions for N$^{2+}$, O$^{3+}$, and F$^{4+}$. Exp: present experimental data; RM: $R$-matrix calculation by \citet{fer04}; MCDF: Multi-Configuration Dirac-Fock calculations performed as part of the present work (N$^{2+}$ and F$^{4+})$ or by \citet[][ O$^{3+}$]{cha03}.\label{tab5}}
\begin{tabular}{lllllll}
\hline\hline
\multicolumn{2}{c}{Transition} & \multicolumn{3}{c}{Oscillator strength} & \multicolumn{2}{c}{Ratio} \\
ion & $n$ & Exp & RM & MCDF & $\frac{{\rm Exp}}{{\rm RM}}$ & $\frac{{\rm Exp}}{{\rm MCDF}}$ \\
\hline
N$^{2+}$ & 5 & 0.004126 & 0.0740 & 0.08717 & 0.06 & 0.05 \\
&6 & 0.003079 & 0.0238 & 0.05555 & 0.13 & 0.06 \\
&7 & 0.002656 & 0.0205 & 0.02146 & 0.13 & 0.12 \\
& 8 & 0.001437 & 0.0138 & 0.01947 & 0.10 & 0.07 \\
& 9 & 0.001076 & 0.0096 & 0.00925 & 0.11 & 0.12 \\
O$^{3+}$ & 5 & 0.002695 & 0.0704 & 0.06270 & 0.04 & 0.04 \\
& 6 & 0.002388 & 0.0374 & 0.03037 & 0.06 & 0.08 \\
& 7 & 0.002501 & 0.0223 & 0.01630 & 0.11 & 0.15 \\
& 8 & 0.002241 & 0.0145 & 0.00955 & 0.15 & 0.23 \\
& 9 & 0.001998 & 0.0100 & 0.00571 & 0.20 & 0.35 \\
& 10 & 0.001206 & 0.0070 & 0.00566 & 0.17 & 0.21 \\
F$^{4+}$ & 6 & 0.004945 & 0.0724 & 0.04480 & 0.07 & 0.11 \\
& 7 & 0.002717 & 0.0379 & 0.02566 & 0.07 & 0.11 \\
& 8 & 0.002055 & 0.0227 & 0.01642 & 0.09 & 0.13 \\
& 9 & 0.002247 & 0.0151 & 0.03253 & 0.15 & 0.07 \\
	\hline
	\end{tabular}
\end{table}