Existing research has defined a new type of simulation time called Approximate Time, where the simulation's knowledge about the values that represent time is uncertain. The approach is based on temporal uncertainty and uses time intervals rather than precise time values to represent time. Simulation language constructs are necessary to provide a convenient means of exploiting the temporal uncertainty to simulation modelers. To address this problem, a new time advance primitive for process-oriented simulations was developed, termed the Interval Hold construct. Interval Hold is an extension of the well-known hold primitive used in conventional simulation languages. This paper defines the interval time advance primitive and describes an algorithm for implementing it.
Margaret L. Loper, Richard M. Fujimoto