$\forall$$A$, $B$, $T$:Type, $x$:Id, $a$:Knd, ${\it tg}$:Id, $l$:IdLnk, $f$:($A$$\rightarrow$$B$$\rightarrow$($T$ List)).
\\[0ex]($a$ $=$ rcv($l$,${\it tg}$) $\Rightarrow$ $T$ $=$ $B$) $\Rightarrow$ $a$(v) sends [${\it tg}$,   $f$($x$, v)] on link $l$   $\in$ MsgA