\begin{table}%ta.10 online
  \caption{\label{pox4abun}Physical conditions and chemical abundances of the ionized gas in POX 4, UM 420, and \mbox{SBS 0926+606.}}
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 {\small   \begin{tabular}{l  rrrrr}
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Object &      POX 4         &     POX 4 Comp$^a$   & UM 420 	   &   SBS 0926+606A	&   SBS 0926+606B$^a$  \\
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\noalign{\smallskip}				 $T_{\rm e}$(O III) (K) & $14~000 \pm  500$  & $12~400 \pm  1000$  &$13~200 \pm  600$  &  $13~600 \pm 700$  &   $11~500 \pm 1000 $ \\
$T_{\rm e}$(O II) (K)  &  $12~800 \pm 400$ & $11~800 \pm 600$ &$12~200 \pm 500$ & $12~500 \pm 500$  &  $11~000 \pm 800$ \\
$n_{\rm e}$ (cm$^{-3}$) & $250 \pm  80$  &  $<$100 & $140 \pm  80$ &  $<$100 &  $<$100 \\
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12+log(O$^{+}$/H$^+$)   &    7.21  $\pm$  0.04  &    7.85  $\pm$  0.14  &	 7.63  $\pm$  0.05   &	7.38  $\pm$  0.10  &	  7.73  $\pm$  0.16   \\
12+log(O$^{++}$/H$^+$)  &    7.96  $\pm$  0.04  &    7.55  $\pm$  0.11  &	 7.67  $\pm$  0.05   &	7.80  $\pm$  0.08  &	  7.04  $\pm$  0.15  \\
12+log(O/H) &    8.03  $\pm$  0.04$^c$&  8.03  $\pm$  0.13  &	 7.95  $\pm$  0.05$^c$&	7.94  $\pm$  0.08$^c$&  8.15  $\pm$  0.16	\\
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log(O$^{++}$/O$^+$)     &    0.74  $\pm$  0.06  & $-$0.30  $\pm$  0.22  &	 0.00  $\pm$  0.08   &	0.42  $\pm$  0.12  &    0.21  $\pm$  0.14	\\
12+log(N$^+$/H$^+$)     &    5.68  $\pm$  0.04  &    6.25  $\pm$  0.18  &	 6.52  $\pm$  0.05   &	5.93  $\pm$  0.05  &	  6.39  $\pm$  0.09   \\
12+log(N/H)             &    6.50  $\pm$  0.06  &    6.43  $\pm$  0.22  &	 6.84  $\pm$  0.06   &	6.48  $\pm$  0.10  &	  6.80  $\pm$  0.13   \\
log(N/O)                & $-$1.54  $\pm$  0.06  & $-$1.60  $\pm$  0.20  & $-$1.11  $\pm$  0.07   & $-$1.45  $\pm$  0.09  & $-$1.35  $\pm$  0.12	\\
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12+log(S$^+$/H$^+$)     &    5.28  $\pm$  0.03  &    5.62  $\pm$  0.20  &	 5.61  $\pm$  0.11   &	5.61  $\pm$  0.04  &	  6.12  $\pm$  0.11   \\
12+log(S$^{++}$/H$^+$)  &    6.03  $\pm$  0.08  & \nodata             &	 6.16  $\pm$  0.09   &	6.17  $\pm$  0.11  & \nodata	      \\
12+log(S/H)             &    6.24  $\pm$  0.07  & \nodata             &	 6.29  $\pm$  0.10   &	6.34  $\pm$  0.10  & \nodata	      \\
log(S/O)                & $-$1.80  $\pm$  0.10  & \nodata             & $-$1.66  $\pm$  0.13   & $-$1.60  $\pm$  0.13  & \nodata	      \\
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12+log(Ne$^{++}$/H$^+$) &    7.18  $\pm$  0.06  &    6.97:            &	 6.96  $\pm$  0.09   &	\nodata 	 & \nodata		  \\
12+log(Ne/H)            &    7.26  $\pm$  0.06  &    7.40:            &	 7.24  $\pm$  0.09   &	\nodata 	 & \nodata		 \\
log(Ne/O)               & $-$0.78  $\pm$  0.10  & $-$0.60:            & $-$0.71  $\pm$  0.13   &	\nodata 	 & \nodata		  \\
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12+log(Ar$^{+2}$/H$^+$) & \nodata             & \nodata             & \nodata		   &	5.52  $\pm$  0.07  &  5.54  $\pm$  0.15  \\
12+log(Ar$^{+3}$/H$^+$) &    5.03  $\pm$  0.07  & \nodata 	        &	\nodata        &	4.61  $\pm$  0.18  & \nodata			\\
12+log(Ar/H)            & \nodata             & \nodata             & \nodata		   &	5.60  $\pm$  0.11  & \nodata	\\
log(Ar/O)               & \nodata             & \nodata             & \nodata		   & $-$2.34  $\pm$  0.13  & \nodata	\\
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12+log(Cl$^{++}$/H$^+$) &    3.83  $\pm$  0.14  & \nodata 	        &	 4.18  $\pm$  0.26   & \nodata		     & \nodata        \\
12+log(Fe$^{++}$/H$^+$) &    5.14  $\pm$  0.10  &	\nodata             &	 5.52  $\pm$  0.12&	5.47  $\pm$  0.14  & \nodata	      \\
12+log(Fe/H)            &    5.86  $\pm$  0.10  &	\nodata             &	 5.79  $\pm$  0.13&	5.95  $\pm$  0.15  & \nodata	      \\
log(Fe/O)               & $-$2.17  $\pm$  0.11  & \nodata             & $-$2.16  $\pm$  0.13& $-$1.99  $\pm$  0.16  & \nodata	      \\
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12+log(He$^+$/H$^+$)    &   10.91  $\pm$  0.03  & \nodata             &	10.88  $\pm$  0.04  &   10.94  $\pm$  0.04  & 11.0:\\
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[O/H]$^b$               &   $-$0.63  $\pm$  0.09 & $-$0.63   &  $-$0.71 $\pm$ 0.10   &   $-$0.72  $\pm$  0.13   & $-$0.51 \\
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  \end{tabular}}
  \medskip
  $^a$ Electron temperatures estimated using empirical relations; $^b$~[O/H]~=~$\log$(O/H)-log(O/H)$_{\odot}$, using 12+log(O/H)$_{\odot} = 8.66 \pm 0.05$ \citep{ASP05};   $^c$~considering the existence of O$^{+3}$ because of the detection of \ion{He}{ii} $\lambda$4686, this value should be $\sim$0.01--0.02~dex higher.
\end{table}