The part of the code that processes the departing message
(that may be a system generated code or a user's programmed
RELEASE instruction)
is only activated by a departing event that refers to the node.
This event can be only introduced in the FEL by the node itself
when a STAY instruction is executed. The node must not be activated
by an ACT instruction.
The part that controls the entrance of the messages to the IL
is activated during the scanning of the network when the EL is
not empty.