{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,22]],"date-time":"2026-06-22T04:49:18Z","timestamp":1782103758168,"version":"3.54.5"},"reference-count":44,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2026,6,16]],"date-time":"2026-06-16T00:00:00Z","timestamp":1781568000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Systems"],"abstract":"<jats:p>Engineering programs increasingly rely on simulation for early design decisions, yet a simulation\u2019s obligations\u2014the specific questions it must answer and observations it must provide\u2014are often left implicit until late in development. The Experimental Frame\u2013System Under Test (EFSUT) methodology addresses this gap by requiring these commitments to be specified explicitly early in system design. EFSUT organizes simulation around four core elements\u2014questions, experimental conditions, models, and results\u2014and defines formal relations that clarify how tests are derived and which models can meaningfully be evaluated. We demonstrate the methodology in two contrasting domains, showing how an informally stated motivating question leads to a structured sequence of experimental conditions and guides model selection and interpretation. Compared with existing approaches to model adequacy and digital-engineering traceability, EFSUT provides a clear, question-driven foundation that links stakeholder intent to model evaluation in a transparent, defensible manner. This approach is particularly valuable for aligning simulation practice in multi-model and system-of-systems contexts. Future work includes the automated derivation of Experimental Frames, integration with digital-thread toolchains, and more broadly, development of a lifecycle-spanning, formalized question-driven framework to support evaluation, optimization, and adaptation where traditional requirement-based methods fall short.<\/jats:p>","DOI":"10.3390\/systems14060691","type":"journal-article","created":{"date-parts":[[2026,6,17]],"date-time":"2026-06-17T03:27:21Z","timestamp":1781666841000},"page":"691","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Specifying Simulation Commitments Early in System Design: Introduction to the EFSUT Methodology"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0636-1352","authenticated-orcid":false,"given":"Bernard P.","family":"Zeigler","sequence":"first","affiliation":[{"name":"RTSync Corp., 6909 W. Ray Road, Chandler, AZ 85226, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,6,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Zeigler, B.P., Muzy, A., and Kofman, E. (2018). Theory of Modeling and Simulation, Academic Press. [3rd ed.].","DOI":"10.1016\/B978-0-12-813370-5.00010-9"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"\u00d6ren, T., Zeigler, B.P., and Tolk, A. (2023). Reliability and Quality Assurance of M&S. Body of Knowledge for Modeling and Simulation: A Handbook by the Society for Modeling and Simulation International, Springer.","DOI":"10.1007\/978-3-031-11085-6"},{"key":"ref_3","unstructured":"Chreyh, R., and Wainer, G.A. (2009). CD++ Repository: An Internet-Based Searchable Database of DEVS Models and Their Experimental Frames. 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