\begin{tabbing}
valid{-}sys{-}dcdr\=\{i:l\}\+
\\[0ex](${\it es}$; ${\it Config}$; ${\it Cmd}$; ${\it Sys}$)
\-\\[0ex]$\,\equiv$$_{\mbox{\scriptsize def}}$$\;\;$TERMOF\{decidable\_\_valid{-}sys:ObjectId, 1:l, i:l\}(${\it es}$,${\it Config}$,${\it Cmd}$,${\it Sys}$)
\end{tabbing}