\begin{tabbing}
consistent{-}updates(${\it es}$;${\it In}$;${\it Out}$;${\it Cmd}$;${\it isupdate}$;${\it expl}$)
\\[0ex]$\,\equiv$$_{\mbox{\scriptsize def}}$$\;\;$\=$\forall$$e_{1}$, $e_{2}$:E(${\it Out}$).\+
\\[0ex]updates(${\it expl}$($e_{1}$)) $\leq$ updates(${\it expl}$($e_{2}$)) $\vee$ updates(${\it expl}$($e_{2}$)) $\leq$ updates(${\it expl}$($e_{1}$))
\-
\end{tabbing}