Superseded. Revision was redesignated 1278.1. Data messages, called protocol data units (PDUs), that are exchanged between simulation applications are defined. These PDUs provide information concerning simulated entity states and the types of entity interactions that take place in a distributed interactive simulation (DIS). The messages defined are for interactions that are primarily within visual range. Future versions of this standard will contain additional PDUs required to exchange information about interactions and functions not currently supported.