$\forall$$a$:Id, $T$:Type, ${\it ds}$:$x$:Id fp$\rightarrow$ Top, $P$:Top, $l$:IdLnk, ${\it tg}$:Id, $L$:Top.
\\[0ex]only $L$ sends on ($l$ with ${\it tg}$) $\Vert\!+$ (with ds: ${\it ds}$ action $a$:$T$ precondition $a$(v) is $P$ s v)