•Insures that each
message in the expression is sent after the
previous message has been processed. It
also allows that the return value of one message
invocation may be used as an argument for a
later invocation in the expression.
–Example:
•a1<-m1() @ a2<-m2( token
);
•Send m1 to a1 and then after m1 finishes, send the result with m2 to a2.