\begin{table}%t2
\caption{Ionic and total abundances of IPHAS PN-1.
Percentage {{rms}} errors are given within brackets. }
%\centerline
{\small \begin{tabular}{lrrrr}
 \hline \hline
Ion/Element&Abundance&12 + log(X/H)&Type I$^a$&Type I$^b$\\
 \hline
 He$^+$/H &  0.076\ (8)  & & & \\
 He$^{2+}$/H  &  0.054\ (7)  & & & \\
 {\bf He/H } & {\bf 0.130\ (11)} & {\bf 11.11 $\pm$ 0.05} & 11.11[$\pm$0.016] &
11.22[$\pm$0.015] \\
 \hline
 O$^0$/H &   1.06E-05\ (23) & & & \\
 O$^+$/H  &   4.00E-05\ (27) & & & \\
 O$^{2+}$/H  &   6.48E-05\ (49) & & & \\
 {\it icf}(O)  &   1.42\ (13) & & & \\
 {\bf O/H}  &   {\bf 1.49E-04\ (34)} & {\bf 8.17 $\pm$ 0.15} & 8.65[$\pm$0.15] &
8.46[$\pm$0.17] \\
 \hline
 N$^+$/H  &   7.39E-05\ (17) & & & \\
 {\it icf}(N)  &   3.73\ (44) & & & \\
 {\bf N/H} &   {\bf 2.76E-04\ (46)} & {\bf 8.44 $\pm$ 0.20} & 8.72[$\pm$0.15] &
8.50[$\pm$0.12] \\
 \hline
 Ne$^{2+}$/H &   5.68E-05\ (59) & & & \\
 {\it icf}(Ne) &   2.30\ (60) & & & \\
 {\bf Ne/H} &   {\bf 1.31E-04\ (84)} &  {\bf 8.12 $\pm$ 0.36} & 8.09[$\pm$0.15]
&  \\
 \hline
 S$^+$/H  &   8.81E-07\ (18) & & & \\
 S$^{2+}$/H  &   2.57E-06\ (65) & & & \\
 {\it icf}(S) &   1.18\ (39) & & & \\
 {\bf S/H} &   {\bf 4.07E-06\ (62)} &  {\bf 6.61 $\pm$ 0.27} & 6.91[$\pm$0.30]  &
6.55[$\pm$0.25] \\
 \hline
 Ar$^{2+}$/H  &   5.83E-07\ (35) & & & \\
 {\it icf}(Ar) &   1.87\ (21) & & & \\
 {\bf Ar/H} &   {\bf 1.09E-06\ (41)} & {\bf 6.04 $\pm$ 0.18} & 6.42[$\pm$0.30]  &
6.54[$\pm$0.04] \\
\hline
\end{tabular}}\medskip
$^a$ Abundances
for type~I PNe from \cite{kb94}. $^b$ Abundances for the three type~I PNe with $D_{\rm GC}\ge 11$~kpc from \cite{costa}. 1-$\sigma$ dispersions of both samples are given within square brackets.
\end{table}