\begin{table}%T2
\caption{Comparison between present (RM1) and earlier (RM2: Aggarwal \cite{Aggarwal92}) results of effective collision strengths for transitions within the levels of the 
(1s$^2$2s$^2$2p$^2$) ground configuration of Ca XV. ($a\pm b\equiv{a}\times{10}^{{\pm}b}$).}
\label{tab2}
%\centering
\par
\begin{tabular}{llllllll}
\hline 
\hline  
\multicolumn{2}{l}{$\log~ T_{\rm e}$} &   5.0  &  5.0 & 6.0 & 6.0 &  7.0 & 7.0 K \\
\hline
 Transition & I--J & RM1 & RM2 & RM1 & RM2 & RM1 & RM2 \\    
\hline                                                                                               
$^3$P$_0$--$^3$P$_1$  &   1--2 & 2.387-1  & 1.679-1 & 1.258-1   & 1.743-1  & 3.885-2  & 3.872-2 \\
$^3$P$_0$--$^3$P$_2$  &   1--3 & 6.914-2  & 1.211-1 & 5.799-2   & 2.430-1  & 2.780-2  & 5.157-2 \\
$^3$P$_0$--$^1$D$_2$  &   1--4 & 4.855-2  & 4.178-2 & 2.573-2   & 2.187-2  & 1.225-2  & 7.742-3 \\
$^3$P$_0$--$^1$S$_0$  &   1--5 & 8.017-3  & 1.327-2 & 5.628-3   & 7.203-3  & 3.231-3  & 1.493-3 \\
$^3$P$_1$--$^3$P$_2$  &   2--3 & 3.911-1  & 5.386-1 & 4.647-1   & 8.777-1  & 1.372-1  & 1.911-1 \\
$^3$P$_1$--$^1$D$_2$  &   2--4 & 1.665-1  & 1.555-1 & 9.944-2   & 9.186-2  & 4.981-2  & 3.181-2 \\
$^3$P$_1$--$^1$S$_0$  &   2--5 & 2.269-2  & 3.104-2 & 1.822-2   & 1.797-2  & 1.041-2  & 4.974-3 \\
$^3$P$_2$--$^1$D$_2$  &   3--4 & 3.926-1  & 3.899-1 & 2.455-1   & 3.602-1  & 1.102-1  & 1.001-1 \\
$^3$P$_2$--$^1$S$_0$  &   3--5 & 2.339-2  & 4.975-2 & 2.262-2   & 3.220-2  & 1.462-2  & 9.405-3 \\
$^1$D$_2$--$^1$S$_0$  &   4--5 & 2.023-1  & 2.105-1 & 1.052-1   & 9.690-2  & 5.912-2  & 4.982-2 \\
\hline                                                                                               
\end{tabular}
\end{table}