In most situations, information is transferred between elements (via links) continuously in time. For example, if Expression element X is defined as being equal to A + B, the values of A and B are continuously sent to X (i.e., the information is "broadcast" through the link throughout the simulation). Conceptually, at any given time in the simulation, X is receiving a signal from A and B.
In order to propagate discrete events (and their consequences) between elements in a model, however, it is necessary to send information between elements intermittently as a "spike" or discrete "packet" of information. To facilitate this, GoldSim allows certain elements to emit and receive (i.e., produce as outputs and/or accept as inputs) discrete signals. Discrete signals are a special category of outputs which emit information discretely, rather than continuously.
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