\begin{table}%t13 \par \caption{\label{table13}{\tsq} parameter.} \small%\centering \par \begin{tabular}{lccccc} \hline\hline Method & PB8 & NGC~2867--1 & NGC~2867--2 & PB6--1 & PB6--2 \\ \hline O$^{\rm ++}$ (R/C) & 0.037~$\pm$~0.005 & 0.045~$\pm$~0.009 & 0.061~$\pm$~0.010 & \nodata & \nodata \\ Ne$^{\rm ++}$ (R/C) & 0.016~$\pm$~0.012 & \nodata & \nodata & \nodata & \nodata \\ He$^{\rm +}$ & 0.008$^{+0.020}_{-0.028}$ & 0.039~$\pm$~0.019 & 0.053~$\pm$~0.022 & 0.102:: & 0.139:: \\ Bac--CELs & 0.038$^{+0.013}_{-0.016}$ & 0.061$^{+0.041}_{-0.061}$ & 0.056$^{+0.050}_{-0.056}$ & \nodata & \nodata \\ Adopted & {\bf 0.033~$\pm$~0.005} & {\bf 0.044~$\pm$~0.008} & {\bf 0.060~$\pm$~0.010} & \nodata & \nodata \\ \hline \end{tabular} \end{table}