$\forall$${\it es}$:ES, ${\it Fail}$:AbsInterface(Top).
\\[0ex]fail{-}dcdr\{i:l\}(${\it es}$;${\it Fail}$) $\in$ $e$:E$\rightarrow$Dec($\exists$${\it e'}$:E. ((${\it e'}$ $<$loc $e$) \& ($\uparrow$(${\it e'}$ $\in_{b}$ ${\it Fail}$))))