the High Level Architecture Federation Development and Execution Process It was soon found that the 1516-2000 standard had APIs that were slightly different for each RTI implementation. SISO produced a standard with alternate, dynamic link compatible (DLC) C++ and Java APIs: SISO-STD-004.1-2004: Standard for Dynamic Link Compatible HLA API Standard for the HLA Interface Specification (IEEE 1516.1 Version) SISO-STD-004-2004: Standard for Dynamic Link Compatible HLA API Standard for the HLA Interface Specification (v1.3) The DLC APIs were later merged into the main standard. HLA 1516-2010 (HLA Evolved) The IEEE 1516-2010 standard was published in August 2010 by IEEE and is commonly known as HLA Evolved. It consists of: IEEE 1516–2010 – Standard for Modeling and Simulation High Level Architecture – Framework and Rules IEEE 1516.1–2010 – Standard for Modeling and Simulation High Level Architecture – Federate Interface Specification IEEE 1516.2-2010 – Standard for Modeling and Simulation High Level Architecture – Object Model Template (OMT) Specification Major improvements in IEEE 1516-2010 include Modular FOMs, incorporation of the DLC APIs in C++ and Java, a Web Services API and Fault Tolerance. Machine-readable parts of this version of HLA, such as XML Schemas, C++, Java and WSDL APIs as well as FOM/SOM samples can be downloaded from the IEEE 1516 download area of the IEEE web site. The full standards texts are available at no cost to SISO members or can be purchased from the IEEE shop. HLA 1516-20XX (HLA 4) The development of a new version of HLA started in January 2016 by SISO and is currently ongoing. Technical overview The HLA standard consists of three parts: Framework and Rules, which specifies ten architectural rules that federates or the entire federation shall adhere to. Federate Interface Specification, which specifies the services that shall be provided by the RTI. The services are provided as C++ and Java APIs as well as Web Services. Object Model Template Specification which specifies the format that HLA object models, such as the FOM, shall use. Common HLA terminology Run-time Infrastructure (RTI): Software that provides a standardized set of services, as specified in the HLA Federate Interface Specification. There are seven service groups. Federate: A system, such as a simulation, a tool or an interface to live systems, that connects to the RTI. Examples of tools are data loggers and management tools. A federate uses the RTI services to exchange data and synchronize with other federates. Federation: A