$\forall$${\it ds}$:fpf(Id; $x$.Type), ${\it da}$:fpf(Knd; $k$.Type), $x$:ecl(${\it ds}$; ${\it da}$).
\\[0ex]ecl{-}kinds($x$) = ecl{-}trans{-}ks(ecl{-}trans($x$)) $\in$ (Knd List)