This Special Notice is to advise interested members of the Training and Readiness Accelerator II (TReX II), as well as other interested members within the U.S. technology base, that a Request for Solutions (RFS) has been issued by Advanced Technology International (ATI) for Modeling , Instrumination and Simulation (MIST) for Live training Systems-Coalition Live Training. The purpose of the Training and Readiness Accelerator II (TReX II} is to spur innovative development, demonstration, and expedited delivery of prototypes to increase Warfighter readiness via modeling, simulation, education/training, experimental validation, and military readiness focused projects. A consortium has been established to develop prototypes directly relevant to enhancing the mission effectiveness of military personnel and the supporting platforms, systems, components, or materials proposed to be acquired or developed by the Department of Defense (DOD), or to improvement of platforms, systems, components, or materials in use by the Armed Forces. Link for TREX II-https://www.trexii.org/ Desired Obejectives: UNCLASSIFIED — Description of Requirement for SAM.gov Posting Title: Modeling, Instrumentation and Simulation (MIST) for Live Training Systems — Coalition Live Training Interoperability Prototype Description: The Government is seeking prototype test solutions to achieve live training system interoperability among coalition partner nations—the United States (US), United Kingdom (UK), Canada (CAN), and Australia (AUS). The objective is to enable seamless integration of Tactical Engagement Simulation Systems (TESS) and associated live training instrumentation during combined coalition training exercises, thereby enhancing the realism, fidelity, and mission effectiveness of collective training. Coalition forces are currently constrained by three interoperability gaps that this requirement seeks to address: 1. Standard Level — Partner nations are acquiring live training equipment based on disparate technical standards, creating significant interoperability gaps. The requirement seeks to assess and align common technical standards and support their adoption in future coalition procurements. 2. Functional Level — The current Universal Laser Engagement Interface Standard (U-LEIS) lacks sufficient stringency, permitting vendor-specific implementations that are not fully interoperable. The requirement seeks to support joint testing of fielded partner-nation equipment to identify interoperability deficiencies, develop a stringent common performance specification for U-LEIS, and establish uniform criteria for Battle Damage Assessment (BDA). Develop and deliver test suite to validate interoperability standard. 3. Network / After-Action Review (AAR) Level (Follow on) — International systems are currently unable to connect to a central Instrumentation System network, preventing the creation of a unified Common Operating Picture (COP) and consolidated AAR. The requirement s…