The system to be simulated is seen as a set of subsystems, that exchange information in different ways. The subsystems can store, transform, transmit, create, and eliminate information. Nodes may be of different types according to their functions. Information transformation is described and performed by program code associated to each node. Information exchange among nodes is done by the action of the code on shared variables or files, and also by passing messages from a node to other.
Information is stored in variables, files or in lists of received messages in the nodes.