- DIS defines an infrastructure for linking simulations of various types at multiple locations to create realistic virtual worlds for the simulation of highly interactive activities. This infrastructure brings together systems built for separate purposes, heterogeneous technologies, and products from different vendors and permits them to interoperate. DIS exercises are intended to support a mixture of virtual entities (human-in-the-loop simulators), live entities (operational platforms and test and evaluation systems), and constructive entities (CGF computer generated forces wargames and other automated simulations). Most of the DIS standard definitions are focused on the flow of information between simulations in order to make them interoperable. These definitions include an identification of data items, a common representation of these data items, the assembly of these data items into networked messages called Protocol Data Units (PDU), the processing that must be done before emitting and after receiving PDUs, and the key algorithms and representations that must be known and shared by all DIS participants. STANAG 4482 1995 covers these IEEE standards.