\begin{table}%t6 \caption{\label{tab:means}Mean values and standard deviations of the low and high frequency spectral indices.} \small%\centerline { \begin{tabular}{lrrrr} \hline \hline \noalign{\smallskip} Sample$^{(a)}$ & $\alpha_{\rm L}$ & $\sigma$ & $\alpha_{\rm H}$ & $\sigma$ \\ \hline ATESP & $-0.18$ & (0.11) & $-0.79$ & (0.16) \\ Massardi G & $-0.01$ & (0.08) & $-0.35$ & (0.09) \\ ATESP + Massardi G far & $-0.08$ & (0.07) & $-0.50$ & (0.08) \\ Massardi Q far & $0.21$ & (0.04) & $-0.16$ & (0.03) \\ \hline \end{tabular}} \medskip $^{(a)}$ ``Massardi G'' and ``Massardi Q'' respectively refer to galaxies and stellar identifications of the Massardi \etal\ sample. ``Far''~refers to $z>0.5$~sources (or~unknown redshift for quasar candidates). \end{table}