$\forall$${\it es}$:ES, ${\it Cmd}$:Type, ${\it isupdate}$:(${\it Cmd}$$\rightarrow\mathbb{B}$), ${\it In}$:AbsInterface(${\it Cmd}$), $L$:(E(${\it In}$) List).
\\[0ex]updates($L$) $\in$ (\{$e$:E(${\it In}$)$\mid$ $\uparrow$(${\it isupdate}$(${\it In}$($e$)))\}  List)