$\forall$$l$, $l_{2}$:IdLnk, ${\it dt}$:${\it tg}$:Id fp$\rightarrow$ Type, ${\it tg}$:Id. rcv($l_{2}$,${\it tg}$) $\in$ dom(lnk{-}decl($l$;${\it dt}$)) $\Rightarrow$ $l_{2}$ $=$ $l$