Abstract: The High Level Architecture (HLA)--Object Model Template (OMT) specification defines the format and syntax (but not content) of HLA object models. Simulations are abstractions of the real world, and no one simulation can solve all of the functional needs for the modeling and simulation community. It is anticipated that advances in technology will allow for new and different modeling and simulation (M & S) implementations within the framework of the HLA. The standards contained in this architecture are interrelated and need to be considered as a product set, as a change in one is likely to have an impact on the others. As such, the HLA is an integrated approach that has been developed to provide a common architecture for simulation. Keywords: architecture, class attribute, data distribution management, federate, federation, federation execution, federation object model, framework, High Level Architecture, instance attribute, instance attribute ownership, interaction class, joined federate, object class, object model template, rules, runtime infrastructure, simulation object model, time-constrained, time-regulating.