An agent can communicate with its outside world using ports. Each port can be used both as an input or an output one. The current role of a port is determined by two factors:

1. Connections to the port in the corresponding communication diagram – e.g. if a port p is used only as an input port for an one-way connection, it cannot be used as an output port.
2. Statements used in the code layer – e.g. if a port p is used only as an argument of the in statement, it is an input port even if all its connections are two-way ones.

Any communication through a port can be a pure communication or a value passing combination.

In case of a pure communication, the out statement sends a signal (without specified value) through the statement port.

In case of a value passing communication, the out statement sends a value of the statement parameter (or a literal) through the statement port.

The out statement is a single-step statement.

out p;
out p x;
out p v;

Listing 1. In statement syntax: p stands for a port name, x stands for a parameter name anv v stands for a literal value

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