Terms and Definitions

This glossary provides an authoritative source of definitions for digital engineering, modeling, and simulation terms relevant to the DoD engineering community.

Many but not all of the definitions are identical to those maintained on the Defense Acquisition University website.

abstraction1. The process of selecting the essential aspects of a simuland to be represented in a model or simulation while excluding those aspects that are not relevant to the purpose of the model or simulation. The set of elements produced by this process.
2. A view of an object that focuses on the information relevant to a particular purpose and ignores the remainder of the information.
2. ISO/IEC 2010
accept event actionThe element you use in an activity to convey that the activity must wait for an asynchronous event occurrence before it can continue its execution. Typically, that asynchronous event occurrence is the receipt of a signal instance.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
accreditationThe official certification that a model or simulation and its associated data are acceptable for use for a specific purpose.DoDI 5000.61, Change 1, 15 Oct 2018
accreditation agentThe organization designated by the M&S Application Sponsor (user) to conduct an accreditation assessment for an M&S application.VV&A Best Practices Guide
accreditation authorityThe organization or individual responsible to approve the use of models, simulations, and their associated data for a particular application.DoDI 5000.61, Change 1, 15 Oct 2018
accreditation criteriaA set of standards that a particular model, simulation, or federation must meet to be accredited for a specific purpose.  Also known as acceptability criteria.DoDI 5000.61, Change 1, 15 Oct 2018
accreditation planThe plan of action for certifying a model, simulation, or simulation federation as acceptable for specific purposes. The accreditation plan specifies the reviews, testing, and other accreditation assessment processes, as appropriate, needed to certify that the model or simulation has met the acceptability criteria.VV&A Best Practices Guide
accuracyThe degree to which a parameter or variable, or set of parameters or variables, within a model or simulation conforms to the true value, or a standard or referent value.D. C. Gross, "Report from the Fidelity Implementation Study Group," Simulation Interoperability Standards Organization (SISO), Orlando, 1999 Spring Simulation Interoperability Workshop
activity modelA process model that describes the functional activity under examination in terms of inputs, transforms, outputs, and controls.
activity parameterA specialized kind of object node. Attached to the frame of an activity diagram to represent an input or an output of the activity as a whole.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
activity-based simulationA discrete simulation that represents the components of a system as they proceed from activity to activity; for example, a simulation in which a manufactured product moves from station to station in an assembly line.IEEE 610.3-1989
actor A representation of someone or something that has an external interface with your system.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
adaptive systemA system that is able to adapt its behavior according to changes in its external environment or internal components of the system itself.DoD M&S Human Capital Strategy
agentA computer system capable of autonomous action - of deciding for itself what behaviors are needed to satisfy its design objectives, and is capable of interacting with other agents (e.g., a 3D character that exhibits human or human-like behavior).Wooldridge, Michael J. An Introduction to Multiagent Systems
agent-based simulationA simulation that focuses on the implementation of agents and the sequence of actions and interactions of the agents over periods of time.DoD M&S Human Capital Strategy
aggregate (unit)A group of entities or a  group of other aggregates considered as a single unit. The substitution of the word "unit" is used to avoid phrases like "aggregate aggregate."IEEE 1278.1-2012
Aggregate Level Simulation ProtocolA family of simulation interface protocols and supporting infrastructure software that permit the integration of distinct simulations and war games. Combined, the interface protocols and software enable large-scale, distributed simulations and war games of different domains to interact at the combat object and event level.
aggregationThe process of grouping entities while preserving the salient effects of entity behavior and interaction while grouped. Contrast with: Disaggregation.DoDD 5000.59-P
agile approachA software development process where end user(s) team with developers in order to make instant decisions on user functionality. High level requirements are initially prioritized and developed quickly by small teams in order to get a working product quickly to the customer. Multiple, rapidly executed increments are developed and capabilities are released to the customer as soon as possible. Prototypes may be used as a starting place and utilize a modular, open-systems approach. Agile methods are typically used for small, low risk projects.DAU Glossary of Defense Acquisition Acronyms and Terms
agile project managementAn iterative process, where feedback is continuously gathered from users and stakeholders to create the right user experience. Different methods can be used to perform an Agile process.en.wikipedia.org
agile software developmentA set of methods and practices where solutions evolve through collaboration between self-organizing, cross-functional teams. Requirements, plans, and results are evaluated continuously so teams have a mechanism for responding to change quickly.www.agilealliance.org
algorithmA finite sequence of well-defined instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing calculations, data processing, automated reasoning, automated decision-making and other tasks.en.wikipedia.org
aliasing1. Displayed data having jagged edges, as a result of a discrete approach to scan conversion in which each pixel either is replaced with the primitive's color or is left unchanged.
2. A distortion or artifact that results when reconstructing a signal from samples rather than the original, continuous signal (e.g., graphics appearing having jagged, rather than smooth, edges).
1. Foley, James D., Andries Van Dam, Steven K. Feiner, and John F. Hughes. Computer Graphics Principles and Practice
analysis1. The systematic, thoughtful, and rigorous employment of the scientific method to examine a problem, scenario, or issue in order to gain insights into relationships between constituent components, understand underlying principles, or answer a specific set of pre-identified questions.
2. (verification and validation) An element of verification that uses established technical or mathematical models or simulations, algorithms, charts, graphs, circuit diagrams, or other scientific principles and procedures to provide evidence that stated requirements were met.
3. (verification and validation) The use of recognized analytic techniques (including computer models) to interpret or explain the behavior/performance of the system or element. Analysis of test data or review and analysis of design data should be used as appropriate to verify requirements.
1. Jahnke, H. N. A History of Analysis
2. MIL-STD-961E, Change 4, July 16, 2020 w/ Change 4
3. Defense Acquisition Guidebook
analytical modelA model consisting of a set of mathematical equations or logical connections / representation; e.g., a system of solvable equations or logical links that represent a specific behavior of the real world to be simulated. NAFEMS Glossary
anchoringA validation process that compares model or simulation output to test or real world data using similar input and environment conditions. The validation must consider input differences and explain comparison discrepancies.VV&A Recommended Practices Guide
application lifecycle managementThe product lifecycle management (governance, development, and maintenance) of computer programs. It encompasses requirements management, software architecture, computer programming, software testing, software maintenance, change management, continuous integration, project management, and release management. (Wikipedia.org)NAFEMS Glossary
architecture dataFacts, characteristics, and concepts that define the structure of a system and the interrelationships between its parts and its environment. The data is created in a manner suitable for communication, interpretation, or processing by humans or by automatic means. For complex systems, a framework of conventions, principles and practices is used for organizing and presenting the architecture data within a specific domain of application or community of stakeholders. The Department of Defense Architecture Framework (DoDAF) is one example.DAU Glossary
architecture designA Systems Engineering technical process by which the Program Manager and Systems Engineer, often through system modeling, trade-offs, and decision analyses, capture the functional requirements and interdependencies in the system architecture. Trade-offs and analyses are also used to mature and realize the design of the system and system elements during the Implementation process, generating the product baseline. Architecture Design translates the outputs of the Stakeholder Requirements Definition and Requirements Analysis processes into alternative design solutions and establishes the architectural design of candidate solutions that may be found in a system model. The Architecture Design process, combined with Stakeholder Requirements Definition and Requirements Analysis, provides key insights into technical risks early in the acquisition life cycle, allowing for early development of mitigation strategies.DAU Glossary
architecture frameworkConventions, principles and practices for the description of architectures established within a specific domain of application and/or community of stakeholders.ISO/IEC/IEEE 2011
architecture viewpoints and modelsVisualizing architectural data is accomplished through models. Department of Defense Architecture Framework (DoDAF) described models are grouped into viewpoints. Models can be documents, spreadsheets, dashboards, or other graphical representations and serve as a template for organizing and displaying data in a more easily understood format. When data are collected and presented as a "filled-in" model, the result is called a view. Organized collections of views (often representing processes, systems, services, standards, etc.) are referred to as viewpoints and, with appropriate definitions, are collectively called the Architectural Description. Department of Defense Architecture Framework (DoDAF) Viewpoints are: All, Capability, Data and Information, Operational, Project, Services, Standards, and Systems.DAU Glossary
architectures1. The structure of components in a program/system, their interrelationships, and the principles and guidelines governing their design and evolution over time.
2. Fundamental concepts or properties of a system in its environment embodied in its elements, relationships, and in the principles of its design and evolution
1. DoDI 5000.70, Change 3, 15 Oct 2018
2. ISO/IEC/IEEE 2015, Section 4.5
articulated partA visible part of a simulated entity that is able to move relative to the entity or relative to other articulated parts. Note: Articulated Parts have been a perpetual discrepancy with regard to interoperability between distributed simulations. Care should be taken to ensure proper handling of articulated parts across simulations.IEEE 1278.1-2012
artificial intelligence1. The ability of machines to perform tasks that normally require human intelligence; concept to create intelligent machines that can simulate human thinking capability and behavior.
2. Intelligence demonstrated by machines, as opposed to natural intelligence displayed by animals including humans.
2. en.wikipedia.org
assumptionA specific supposition of the operational environment that is assumed to be true, in the absence of positive proof, essential for the continuation of planning.JP 5-0
attached partA visible part of a simulated entity that may not move relative to the entity, but that may be present. For example, a bomb on an aircraft wing station. IEEE 1278.1-2012
attribute1. An attribute is any distinctive feature, characteristic, or property of an object that can be identified or isolated quantitatively or qualitatively by either human or automated means. For example: color, weight, sex, time of occurrence.
2. (High Level Architecture) A named characteristic of an object class or object instance.
1. ISO/IEC 27000
2. IEEE 1516-2010
attribute ownershipThe property of an instance attribute that gives another federate the capability to supply values for that instance attribute during simulation execution.IEEE 1516-2000
augmented realityA type of virtual reality in which synthetic stimuli are registered with and superimposed on real world objects; often used to make information otherwise imperceptible to human senses perceptible.Sherman, William R., and Alan Craig. Understanding Virtual Reality Interface, Application, and Design
authoritative data sourceA recognized or official data production source with a designated mission statement, source, or product that publishes reliable and accurate data for subsequent use by customers. An authoritative data source may be the functional combination of multiple separate data sources. DoDI 8320.03, Change 3, 25 Oct 2021, DoDI 8320.05, Change 1, 22 Nov 2017
authoritative source of truth1. An entity such as a person, governing body, or system that applies expert judgement and rules to proclaim a digital artifact is valid and originates from a legitimate source
2. captures the current state and the history of the technical baseline. It serves as the central reference point for models and data across the lifecycle. The authoritative source of truth will provide traceability as the system of interest evolves, capturing historical knowledge, and connecting authoritative versions of the models and data.
1. https://www.omgwiki.org/MBSE/doku.php?id=mbse:authoritative_source_of_truth
2. DoD Digital Engineering Strategy
authoritative visualizationA digital model of a system that renders its inputs, operational environments, and internal functions and behaviors - along with all subsystems necessary to capture them -  such that outputs can be certified as predictiveBending the Spoon, W. Roper, 2021
autonomousAn entity that can operate independently - without input or guidance from another entity - to achieve objectives within the intended operational environment, being simulated or other.
avatarA virtual object used to represent a participant or physical object in a simulation; the (typically visual) representation may take any form.Sherman, William R., and Alan Craig. Understanding Virtual Reality Interface, Application, and Design
battlespaceThe physical environment in which the simulated warfare will take place and the forces that will conduct the simulated warfare. All elements that support the front line forces (i.e., logistics, intelligence) are included. 
behavior1. For a given object, how attribute value changes affect or are affected by the attribute value changes of itself, other objects, or the simulation environment.
2. Systems behavior is a change which leads to events in itself or other systems. Thus, action, reaction or response may constitute behavior in some cases.
1. VV&A Best Practices Guide
2. SEBoK
benchmarkAn accepted representation or standard of a process being modeled or simulated against which the results of other models or simulations are compared or judged. SISO-REF-002-1999
benchmarking1. The comparison between the output of a model or simulation and the benchmark.
2. Comparison of an internal process or practice to those employed by one or more external organizations to determine how the existing process or practice can and should be improved. Ideally, one of those external organizations being evaluated should be recognized as having an industry “best practice” for the process or practice.
1. Barfield, Woodrow, and Thomas Caudell. Fundamentals of Wearable Computers and Augmented Reality
2. CIMdata PLM Glossary https://www.cimdata.com/en/resources/about-plm/cimdata-plm-glossary
binding connectorRepresents an equality relationship between the two elements attached at either end. One of those two bound elements must be a constraint parameter. The other bound element can be either a value property or another constraint parameter (in a different constraint expression). A binding connector can appear only on a parametric diagram.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
black box modelA model whose inputs, outputs, and functional performance are known, but whose internal implementation is unknown or irrelevant. Also see white box model. IEEE 610.3-1989
blockRepresents a system component, a modular structural unit that encapsulates its contents (Properties, Behaviors, Constraints) and supports first-class (i.e., can be drawn and directly manipulated in the model repository)
block definition diagramUsed to display elements such as blocks and value types (elements that define the types of things that can exist in an operational system) and the relationships between those elements.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
body of knowledgeComplete set of concepts, terms, and activities pertaining to a discipline as identified by a community of practice and includes an interactive environment for stakeholders (e.g., specified pathways, user roles, etc.) to digitally navigate pathways of content within an enterprise or on a program.OUSD R&E
boundary conditionThe values assumed by the variables in a system, model, or simulation when one or more of them is at a limiting value or a value at the edge of the domain of interest. Also see: Final Condition; Initial Condition.IEEE 610.3-1989
bridgeA type of computer network device that provides interconnection with other bridge networks that use the same protocol.https://www.techopedia.com/definition/3160/bridge
calibrationThe process of adjusting numerical or modeling parameters in the model to improve agreement with a simuland (reference system).
call behavior actionA specialized action that invokes another behavior when it becomes enabled. Call behavior actions let you decompose a higher-level behavior into a set of lower-level behaviors.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
capabilityThe ability to achieve a Desired Effect under specified [performance] standards and conditions through combinations of ways and means [activities and resources] to perform a set of activities.DoDAF 2.02
Capability Maturity Model IntegrationA proven industry framework to improve product quality and development efficiency for both hardware and software. Capability Maturity Model Integration describes an evolutionary improvement path from ad hoc, immature processes to disciplined, mature processes with improved quality and effectiveness. NAFEMS Glossary
Cave Automatic Virtual EnvironmentA mechanism for manifesting a virtual reality experience that involves placing the participant within a room like space that is surrounded by computer generated imagery.Sherman, William R., and Alan Craig. Understanding Virtual Reality Interface, Application, and Design
certificationAn agency or organization endorsement of a model. Certification is typically used when formal validation or accreditation is not sought or not yet achieved.
chaotic systemA system whose long-term behavior is unpredictable, tiny changes in the accuracy of the starting value can rapidly diverge to anywhere in its possible state space. There can, however, be a finite number of available states, so statistical prediction can still be useful.
characterizationThe process of defining the systems capabilities. The result of the system characterization effort is a description of actual system capability at a particular point in time. Characterization relies on test data supplemented by analysis to establish confidence in estimates across the threat space.United States Strategic Command Joint Functional Component Command For Integrated Missile Defense (JFCC IMD), "Ballistic Missile Defense System (BMDS) Warfighter Capability Acceptance," September 20, 2012.
closed-form solutionA method in which the states or status of resources are described as explicit and computationally tractable functions. (e.g., in a dynamic model, the status of a resource at time "t" can be found by evaluating the appropriate function at "t" without having to simulate combat from the start of that combat through time "t".)Military Operations Research Society (MORS) Report: A Taxonomy for Warfare Simulation (SIMTAX)
cloud computingOn-demand availability of computer system resources, e.g., data storage and computing power, without direct active management by the useren.wikipedia.org
cloud-based simulationExecuting simulation from or distributing simulation through cloud computingSimulation Interoperability Standards Organization
collaborative communityConsists of two or more people from different groups or companies that are working jointly on a project.CIMdata AD PLM AG
collaborative environmentAn environment enabling multiple users to interact (e.g., simulation, design activities, test activities)
combat modelingAny structural activity that is undertaken to represent higher level strategic guidance, doctrine operational concepts, concepts of operation and combat.NATO MSG MS Glossary and Acronym List 1.2 - 22Apr2008
combined fragmentA mechanism that allows you to add control logic (such as decisions, loops, parallel behaviors) to an interaction.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
command post exerciseAn exercise in which the forces are simulated, involving the commander, the staff, and communications within and between headquarters. CJCSM 3500.03E, April 20, 2015
commercial off-the- shelf Commercial items that require no unique acquirer modifications or maintenance over the life cycle of the product to meet the needs of the procuring agency NAFEMS Glossary
Common Training Instrumentation ArchitectureThe foundation architecture of the U.S. Army Live Training Transformation Family of Training Systems (LT2-FTS) strategy.“Common Training Instrumentation Architecture (CTIA).” US ARMY PEO STRI
common useServices, materiel, or facilities provided by a DoD agency or a Military Department on a common basis for two or more DoD agencies, elements, or other organizations as directed. DoDI 5000.61, Change 1, 15 Oct 2018
common virtual environmentA condition where virtual simulations portray the same image and interact within the same virtual environment, sufficient to achieve fair fight interoperability Abbreviated-Capability Development Document (A-CDD) Draft – For (U) Synthetic Training Environment – Next Generation Constructive (STE-NGC) Sponsoring Agency: US Army
commonalityA quality that applies to materiel or systems possessing like and interchangeable characteristics enabling each to be utilized or operated and maintained by personnel trained on the others without additional specialized training, and/or having interchangeable repair parts and/or components. Applies to consumable items interchangeable without adjustment.DAU Glossary
common-use M&SM&S applications, services, or materials provided by a DoD component to two or more DoD components.VV&A Best Practices Guide
community of practiceA group of people who share a concern or a passion for something they do and learn how to do it better as they interact regularly."Introduction to communities of practice - A brief overview of the concept and its uses". Etienne and Beverly Wenger-Trayner
complex dataData that cannot be characterized as single concepts including highly derived data; objects utilizing the concepts of multiple inheritance, multiple root hierarchies, and polymorphic attributes; compositions such as command hierarchies, road networks, images, compound documents; and artifacts of legacy systems and physical constraints. 
Component Subsystem, assembly, subassembly, or other major element of an end item.ISO/IEC/IEEE Standard 24765:2010
composability1. The capability to select and assemble reusable modeling and simulation components in various combinations into simulation systems to meet user requirements.
2. A system design principle that deals with the interrelationships of components, each of which are considered self-contained and stateless, and that can be (re-)combined to test/satisfy specific user requirements.
1. Morse, K. L., M. D. Petty, P. F. Reynolds, W. F. Waite, and P. M. Zimmerman. “Findings and Recommendations from the 2003 Composable Mission Space Environments Workshop."
2. DoD M&S Human Capital Strategy
composite associationA composite association between two blocks conveys structural decomposition. An instance of the block at the composite end is made up of some number of instances of the block at the part end.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
computational dataThe data is maintained and formatted such that it can be used by the tools within the organization and its external partners. This concept is role specific, i.e. not all data must be compatible or consumable by all tools. An example could be that requirements are received in a spreadsheet and imported into a requirements management tool. The compatibility of certain data and tools may be addressed with plugins as necessary if applicable.
computational modelA model consisting of defined procedures that can be executed by a computer.IEEE 610.3-2009
computer aided engineeringThe use of computer-based tools to assist in analyzing one or more aspects of a product design such as structural and mechanism analysis.CIMdata PLM Glossary https://www.cimdata.com/en/resources/about-plm/cimdata-plm-glossary
computer aided software engineeringThe use of computers to aid in the software engineering process. Computer aided software engineering tools may include the application of software tools to software design, requirements tracing, code production, testing, document generation, and other software engineering activities. Assemblers and compilers are CASE tools.DAU Glossary
computer assisted exerciseA command post exercise where computers simulate the operational environment and provide event resolution that may be used in a distributed or non-distributed form or a combination of both.
computer simulationA simulation that is executed on a computer, with some combination of executing code, control/display interface hardware, and, in some cases, interfaces to real-world equipment.
computer war gameSee: war game
computer-aided designThe use of computers to aid in the creation, modification, analysis, or optimization of a design.en.wikipedia.org
computer-generated forcesA generic term used to refer to computer representations of forces in models and simulations that attempts to model human behavior sufficiently so that the forces will take some actions automatically (without requiring human-in-the-loop interaction). Types of CGF include: automated forces - computer-generated forces that require little or no human interaction. Semi-automated forces - computer-generated forces in which the individual platform simulation is operated by computer simulation of the platform crew and command hierarchy. IEEE 1278.3-1996
concept of operationsA verbal and graphic statement, in broad outline, of an enterprise’s assumptions or intent in regard to an operation or series of operations. The concept of operations frequently is embodied in long-range strategic plans and annual operational plans. In the latter case, the concept of operations in the plan covers a series of connected operations to be carried out simultaneously or in succession. The concept is designed to give an overall picture of the enterprise operations.United States Strategic Command Joint Functional Component Command For Integrated Missile Defense (JFCC IMD), "Ballistic Missile Defense System (BMDS) Warfighter Capability Acceptance," September 20, 2012.
concept selection rationaleDocumented demonstration of how (process) and why (results) the Concept Selection process arrived at the Recommended System Concept.NAFEMS Glossary
conceptual data modelA model that documents the business information requirements and structural business process rules of the architecture, and describes the information that is associated with the information of the architecture. Included are information items, their attributes or characteristics, and their inter-relationships.  
conceptual modelAn abstraction of what is intended to be represented within a simulation environment, which serves as a frame of reference for communicating simulation-neutral views of important entities and their key actions and interactions. The conceptual model describes what the simulation environment will represent, the assumptions limiting those representations, and other capabilities needed to satisfy the user’s requirements. Conceptual models are bridges between the real world, requirements, and design.IEEE 1730-2010
configurationThe grouping of a component or product as defined by the number, nature, and interconnections of its constituent parts.CIMdata PLM Glossary https://www.cimdata.com/en/resources/about-plm/cimdata-plm-glossary
configuration controlThe configuration management activity concerning: the systematic proposal, justification, evaluation, coordination, and disposition of proposed changes; and the implementation of all approved and released changes into (a) the applicable configurations of a product, (b) associated product information, and (c) supporting and interfacing products and their associated product information. DoD, "Military Handbook: Configuration Management Guidance," MIL-HDBK-61A(SE), 7 February 2001.MIL-HDBK-61A(SE), 7 February 2001.
configuration managementA management process for establishing and maintaining consistency of a product's performance, functional, and physical attributes with its requirements, design and operational information throughout its life MIL-HDBK-61A(SE), 7 February 2001.
conservative event simulationA simulation in which events are processed in a manner that never violates the correct chronology. Pooch, Udo W. Discrete event simulation a practical approach
consistencyData maintained so that it is free from variation or contradiction. SISO-REF-020-Draft DIS Plain and Simple-20131107SISO-REF-020-Draft DIS Plain and Simple-20131107
constant1. A quantity or data item whose value cannot change.
2. A parameter, variable or data item within a model or simulation whose value cannot change during the course of the execution.
1. IEEE 610.3-1989
constrained simulationA simulation where time advances are paced to have a specific relationship to wall clock time; real-time or scaled-real-time simulations (e.g., human-in-the-loop (e.g., training exercises), hardware-in-the-loop (e.g., test and evaluation simulations)). SISO-REF-002-1999
constraintAn externally imposed limitation on a process, model, or dataset. (e.g., An equation (equality or inequality) that must be satisfied in order for a possible solution to be determined feasible.)
constraint blockProvide a mechanism that allows the representation of mathematical expressions that constrain the physical properties of a system.A Practical Guide to SysML: The Systems Modeling Language / Sanford Friedenthal, 2014
constructive simulationA constructive simulation includes simulated people operating simulated systems. Real people stimulate (make inputs) to such simulations, but are not involved in determining the outcomes. A constructive simulation is a computer program. For example, a military user may input data instructing a unit to move and to engage an enemy target. The constructive simulation determines the speed of movement, the effect of the engagement with the enemy and any battle damage that may occur.DoD Human Capital Strategy
constructive simulationSimulations involving simulated people operating simulated systems. Real people can be allowed to stimulate (make inputs) to such simulations, but are not involved in determining the outcomes. Modified from DoD M&S Human Capital Strategy
Context DiagramA model of a function at the highest level of inputs, controls, outputs, and mechanisms NAFEMS Glossary
continuous modelA mathematical or computational model whose output variables change in a continuous manner; that is, state (dependent) variables change in a continuous manner. Contrast with: discrete modelIEEE 610.3-1989
control flowUsed to convey sequencing constraints among a set of actions when the object flows in your activity do not by themselves convey the intended sequence.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
control loadingA system that produces feel forces, on the simulators controls, which accurately reflect those felt by the operator in real world conditions (i.e., pilot in actual flight).Flight Simulation (Cambridge Aerospace Series).
control nodesUsed to steer the execution of an activity along paths other than a simple sequence of actions. Control nodes can direct the flow of control tokens as well as object tokens within an activity. There are seven kinds of control nodes: initial nodes, activity final nodes, flow final nodes, decision nodes, merge nodes, fork nodes, and join nodes.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
correlation1. A convergent relationship between parallel representations of the same data. 2. A causal, complementary, parallel, or reciprocal relationship, especially a structural, functional, or qualitative correspondence between comparable entities.SISO-REF-020-Draft DIS Plain and Simple-20131107
Co-SimulationThe different subsystems which form a coupled problem are modeled and simulated in a distributed manner NAFEMS Glossary
CredibilityThe relevance the user sees in a model or simulation and the confidence the user has that a model or simulation can serve their purpose.U.S. Army Test and Evaluation Command, "Modeling and Simulation Verification, Validation, and Accreditation Methodology; ATEC Pamphlet 73-21," April 13, 2007.
critical assessment conditionsSpecifies the conditions for test data collection necessary to accurately assess the performance [how well] of the fielded Elements and an integrated system.Missile Defense Agency DTD, "Ballistic Missile Defense System Integrated Master Test Plan (IMTP); vol. 14.1 Signature Draft v7," March 17, 2014.
critical engagement conditionA defined set of test points that provide data to efficiently resolve a known modeling and simulation uncertainty that limits performance prediction accuracy. The test data collected is used to improve existing models of System or Element behaviors. Critical engagement conditions impose conditions on test events that focus data collection efforts with the goal of improving existing models and simulations. The set of test points that define a critical engagement condition are the condition(s) under which there is uncertainty in the model’s ability to accurately reflect the operational system.Missile Defense System Engineering Team (MDSET), "Critical Engagement Condition and Empirical Measurement Event Description Document; S-2391-4.0," Missile Defense Agency, Huntsville , July 6, 2012
cultural featureFeature of the environment that has been constructed by man. Included are such items as roads, buildings, canals, marker buoys; boundary lines, and, in a broad sense, all names and legends on a map.SISO-REF-002-1999
dataInformation in a specific representation, usually as a sequence of symbols that have meaning.DoDI 8320.02, Change 1, 24 June 2020
data asset1. Any entity that is comprised of data. For example, a database is a data asset that is comprised of data records. A data asset may be a system or application output file, database, document, or web page. A data asset also includes a service that may be provided to access data from an application. For example, a service that returns individual records from a database would be a data asset. Similarly, a web site that returns data in response to specific queries (e.g., www.weather.com) would be a data asset.
2. An information-based resource.
1-2. DoDI 8320.02, Change 1, 24 June 2020
data centerThe data center is the department in an enterprise that houses and maintains back-end information technology (IT) systems and data stores—its mainframes, servers and databases. SEBoK
data certificationThe determination that data have been verified and validated. Data user certification is the determination by the application sponsor or designated agent that data have been verified and validated as appropriate for the specific M&S usage. Data producer certification is the determination by the data producer that data have been verified and validated against documented standards or criteria. IEEE 1278.3-1996
data curationThe active and ongoing management of data through its life cycle of interest and usefulness to scholarship, science, and education. Data curation activities enable data discovery and retrieval, maintain its quality, add value, and provide for reuse over time, and this new field includes authentication, archiving, management, preservation, retrieval, and representation.University of Illinois’ Graduate School of Library and Information Science
data dictionaryA repository for the definition of data elements: their attributes, representations, and descriptions.CIMdata PLM Glossary https://www.cimdata.com/en/resources/about-plm/cimdata-plm-glossary
data elementA basic unit of information having a meaning and subcategories (data items) of distinct units and values (e.g., address).SISO-REF-020-Draft DIS Plain and Simple-20131107
data item descriptionA document that specifically defines the data required of a contractor in terms of content, format, and intended use.DAU Glossary
data lineageThe trace and history of the data from an authoritative data source to its current state. Data lineage is data pedigree without the accountability for quality. Also referred to as data provenance.
data loggerA device that accepts data outputs from a simulation or federation and stores them for processing and replay. IEEE 610.3-1989
data model1. In a database, the user's logical view of the data in contrast to the physically stored data, or storage structure. A description of the organization of data in a manner that reflects the information structure of an enterprise. 
2. The definition of all data elements (and their relationships) to be maintained within a product data management system. The data model defines the database schema for the product data management system.
1. SISO-REF-002-1999
2. CIMdata PLM Glossary https://www.cimdata.com/en/resources/about-plm/cimdata-plm-glossary
data pedigreeIncludes both the history and quality of the data. The data history starts with and includes an authoritative data source and extends to the current state of the data. The quality of the data is a result of proper Configuration Management.
data qualityThe correctness, timeliness, accuracy, completeness, relevance, and accessibility that make data appropriate for use. Quality statements are required for source, accuracy (positional and attribute), currency, logical consistency, completeness (feature and attribute), clipping indicator, security classification, and releasability.SISO-REF-020-Draft DIS Plain and Simple-20131107
data repositoryA specialized database containing information about data, such as meaning, relationships to other data, origin, usage, and format, including the information resources needed by an organization.SISO-REF-020-Draft DIS Plain and Simple-20131107
data verification and validationThe process of verifying the internal consistency and correctness of data and validating that it represents real-world entities appropriate for its intended purpose or an expected range of purposes.DoDI 5000.61, Change 1, 15 Oct 2018
dead reckoningA method for the estimation of the position/orientation of an entity based on a previously known position/orientation and estimates of the passage of simulation time and motion. IEEE 1278.1-2012
decision gateA decision gate is an approval event (often associated with a review meeting). Entry and exit criteria are established for each decision gate; continuation beyond the decision gate is contingent on the agreement of decision-makers. NAFEMS Glossary
decision treeThe basic analytic tool for decision analysis. The construction of the decision tree helps display the logical sequences involved in the decision process, with decision nodes representing cases where behavior/action/path is based on a piece of information and chance nodes representing cases where the outcome is ruled by chance.https://www.ncbi.nlm.nih.gov/books/NBK127478/ ’Decision and Simulation Modeling Alongside Systematic Reviews’
degrees of freedomThe number of degrees of freedom for a system is equal to the number of coordinates which are used to specify the configuration of a system minus the number of constraints. In rigid body motion with no constraints, there are 6 degrees of freedom: translation along X, translation along Y, translation along Z; rotation around X, rotation around Y, rotation around Z.Barfield, Woodrow, and Thomas Caudell. Fundamentals of Wearable Computers and Augmented Reality
democratization of simulationExpanding significantly the user community of Engineering Simulation capabilities that result in benefits of reduced time and cost, and more reliable product lifecycle studies.NAFEMS Glossary
demonstration1. An element of verification that involves the actual operation of an item to provide evidence that the required functions were accomplished under specific scenarios. The items may be instrumented and performance monitored.
2. Demonstration is the performance of operations at the system or element-level where visual observations are the primary means of verification. Demonstration is used when quantitative assurance is not required for verification of the requirements.
1. MIL-STD-961E, Change 4, July 16, 2020
2. Defense Acquisition Guidebook
dependencyOne element in the model, the client, depends on another element in the model, the supplier. More precisely, a dependency conveys that when the supplier element changes, the client element may also have to change.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
dependent variableA variable whose value is a function of one or more independent variables.  Contrast with: independent variableSISO-REF-002-1999
Derived Requirements A requirement that arises from constraints, consideration of issues implied but not explicitly stated in the requirements baseline, factors introduced by the selected architecture, Information Assurance (IA) requirements and the design. Derived requirements are definitized through requirements analysis as part of the overall Systems Engineering Process (SEP) and are part of the allocated baseline.DAU Glossary
descriptive modelA model used to depict the behavior or properties of an existing system or type of system.SISO-REF-020-2007
design constraintsThe boundary conditions, externally or internally imposed, for the system-of-interest within which the organization must remain when executing the processes during the concept and development stage NAFEMS Glossary
deterministic modelA model in which the results are determined through known relationships among the states and events and in which a given input will always produce the same output; for example, a model depicting a known chemical reaction. Contrast with: Stochastic Model.  SISO-REF-020-2007
deviationDeparture from a specified requirement, standard, or norm.ISO/IEC/IEEE 24765:2017[E]
development referentThe development referent is the information upon which development of the M&S is based. That information determines the entities, processes, and interactions that should be included in the M&S to represent the simuland (the thing being simulated).That information determines the algorithms and data that should be used in the M&S.Modeling and Simulation Verification, Validation and Accreditation Recommended Practices Guide - Special Topic: Developing the Referent https://vva.msco.mil
developmental test and evaluation1. Any testing used to assist in the development and maturation of products, product elements, or manufacturing or support processes.
2. Any engineering-type test used to verify status of technical progress, verify that design risks are minimized, substantiate achievement of contract technical performance, and certify readiness for initial operational testing. Development tests generally require instrumentation and measurements and are accomplished by engineers, technicians, or soldier operator-maintainer test personnel in a controlled environment to facilitate failure analysis.
1. DAU Glossary
2. DAU Glossary
DevSecOpsAn organizational software engineering culture and practice that aims at unifying software development (Dev), security (Sec) and operations (Ops). The main characteristic of DevSecOps is to automate, monitor, and apply security at all phases of the software lifecycle: plan, develop, build, test, release, deliver, deploy, operate, and monitor. In DevSecOps, testing and security are shifted to the left through automated unit, functional, integration, and security testing - this is a key DevSecOps differentiator since security and functional capabilities are tested and built simultaneouslyhttps://dodcio.defense.gov/Portals/0/Documents/DoD%20Enterprise%20DevSecOps%20Reference%20Design%20v1.0_Public%20Release.pdf?ver=2019-09-26-115824-583
diagram namespaceThe container element within the model hierarchy. model element type and model element name shown in the diagram header indicate where the elements on the diagram can be found within the model.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
digital artifactAn artifact produced within, or generated from, the digital engineering ecosystem. These artifacts provide data for alternative views to visualize, communicate, and deliver data, information, and knowledge to stakeholders.DAU Glossary
digital curationDigital curation involves maintaining, preserving and adding value to digital research data throughout its lifecycle. The active management of research data reduces threats to their long-term research value and mitigates the risk of digital obsolescence.Digital Curation Centre in the UK
digital elevation modelA numerical model of the elevations of points on the earth's surface. Digital records of terrain elevations for ground positions at regularly spaced horizontal intervals.DoD Mil Handbook 850-1994
digital engineeringAn integrated digital approach that uses authoritative sources of systems' data and models as a continuum across disciplines to support lifecycle activities from concept through disposal.
DAU Glossary
Digital Engineering Acquisition Technology Hub Simulation, Training, Analysis & ResearchProvides an in-house cadre with experience on tools similar to the ones used by their contractor counterparts that will enable USAF engineers to better evaluate contractors’ claims and analyseshttps://usaf.dps.mil/teams/20496/SitePages/Home.aspx
digital engineering ecosystemThe interconnected infrastructure, environment, and methodology (process, methods, and tools) used to store, access, analyze, and visualize evolving systems' data and models to address the needs of the stakeholders.DAU Glossary
digital feature analysis dataA database of selected natural and manmade planimetric features classified as point, line, or area features as a function of their size and composition.DoD Mil Handbook 850-1994
digital feature dataDigital data of all natural feature, man's alteration to those features, and the measurement and description of physical features of the oceans, lakes, rivers and other waters and their adjoining coastal areas.DoD Mil Handbook 850-1994
digital modelingIs the use of digital tools to create a digital representation of a system including but not limited to architectural structures, mathematical terms, logical expressions, or simulations. In concert with the other facets of DE, the premise for digital modeling efforts is that the data created be consumable (computational) to other sources, i.e. modeling efforts should be useful not just visual representations.
digital prototypingDigital Prototyping gives conceptual design, engineering, manufacturing, and sales and marketing departments the ability to virtually explore a complete product before it's built. Industrial designers, manufacturers, and engineers use Digital Prototyping to design, iterate, optimize, validate, and visualize their products digitally throughout the product development process. Innovative digital prototypes can be created via CAutoD through intelligent and near-optimal iterations, meeting multiple design objectives (such as maximised output, energy efficiency, highest speed and cost-effectiveness), identifying multiple figures of merit, and reducing development gearing and time-to-market. Marketers also use Digital Prototyping to create photorealistic renderings and animations of products prior to manufacturing. Companies often adopt Digital Prototyping with the goal of improving communication between product development stakeholders, getting products to market faster, and facilitating product innovation.Wikipedia
digital representation1. The use of discrete impulses or quantities arranged in coded patterns to represent variables or other data in the form of numbers or characters.
2. A computer software-based representation of a real physical system, phenomena, or their features, attributes, functions, etc.
1. McGraw-Hill Dictionary of Scientific & Technical Terms, 6E. (2003).
digital simulationA simulation that is designed to be executed on a digital system. IEEE 610.3-1989
digital system modelA digital representation of a defense system, generated by all stakeholders, that integrates the authoritative technical data and associated artifacts, which defines all aspects of the system for the specific activities throughout the system life cycle.DAU Glossary
digital terrain elevation dataA uniform matrix of terrain elevation values which provides basic quantitative data for all military systems that require terrain elevation, slope, and/or surface roughness information.DoD Mil Handbook 850-1994
digital thread1. An extensible, configurable and component enterprise-level analytical framework that seamlessly expedites the controlled interplay of authoritative technical data, software, information, and knowledge in the enterprise data-information-knowledge systems, based on the Digital System Model template, to inform decision makers throughout a system's life cycle by providing the capability to access, integrate and transform disparate data into actionable information.
2. A mechanism for correlating information across multiple dimensions of the virtual representation, where the dimensions include (but are not limited to) time or lifecycle stage (including design intent), kind-of-model, and configuration history.
3. An extensible analytic frameworks to *connect* models - and all associated data, software, and functional support that govern system lifecycle phases - to create an authoritative, digital source of truth with one-to-one real-word traceability.
1. DAU Glossary
2. OMG Digital Twin Consortium
3. "Bending the Spoon", W. Roper, 2021
digital twin1. An integrated multi physics, multiscale, probabilistic simulation of an as-built system, enabled by Digital Thread, that uses the best available models, sensor information, and input data to mirror and predict activities/performance over the life of its corresponding physical twin.
2. The electronic representation—the digital representation—of a real-world entity, concept, or notion, either physical or perceived.
3. A virtual representation of real-world entities and processes, synchronized at a specified frequency and fidelity.
4. A physics-based description of a system resulting from the generation, management, and application of data, models, and information from authoritative sources across the system’s lifecycle. The Digital Twin must be more than just a descriptive model or collection of related digital information (e.g., a SysML model). It is a complete physical description including all behaviors.
1. DAU Glossary
2. NISTIR 8356
3. OMG Digital Twin Consortium
4. CIMdata PLM Glossary
digital viewA digital view is a visual presentation on an electronic display device of one or more processed digital artifacts, enabling the consumption of digital artifact content according to stakeholders’ unique activities at any phase or step in the system life cycle.DEIXPedia
digital viewpointA design of a digital view that uses conventions, formalisms and standards to define the systematic procedures to select, compile, layout, and present digital artifacts in a digital ecosystem such that it meets stakeholders’ unique needs.DEIXPedia
digitalizationThe process of moving information from paper to digital forms (e.g., computer files, connected data elements representing a product, managing a configuration and all its dependencies) to transform business; moving to a digital business.CIMdata PLM Glossary https://www.cimdata.com/en/resources/about-plm/cimdata-plm-glossary
disaggregationThe process of replacing a single aggregate with two or more aggregates or entities at a higher level of detail. Contrast with: aggregation
discovery metadataA type of metadata that describes or summarizes key attributes and concepts, and allows assets (e.g., a model, simulation, or data) to be found using enterprise-level search capabilities.DoDI 5000.70, Change 3, 15 Oct 2018
discrete event simulationA simulation where the dependent variables (i.e., state indicators) change at discrete points in time referred to as events.IEEE 610.3-1989
discrete event simulation specificationA modeling formalism, methodology and specification framework that provides a theoretical foundation independent of programming languages and hardware platforms. SISO-RPT-009-2008
discrete modelA mathematical or computational model whose output variables take on only discrete values; that is, in changing from one value to another, they do not take on the intermediate values. Contrast with: continuous model.SISO-REF-020-2007
distributed exerciseAn exercise enabled by distributed simulation where the training participants are at different locations (i.e., different cities, countries or continents).
Distributed Interactive SimulationA time and space coherent synthetic representation of world environments designed for linking the interactive, free-play activities of people in operational exercises. The synthetic environment is created through real-time exchange of data units between distributed, computationally autonomous simulation applications in the form of simulations, simulators, and instrumented equipment interconnected through standard computer communicative services. The computational simulation entities may be present in one location or may be distributed geographically.IEEE 1278.1-2012
distributed simulationA simulation that has multiple modules, which can be run on multiple processors. The processors can be co-located in the same room or located in remote sites.
Distributed Simulation Engineering and Execution Process1. A seven-step process used to develop and execute distributed simulation events as standardized in IEEE 1730-2010.
2. A high-level process framework into which the lower-level systems engineering practices native to any distributed simulation user can be easily integrated
1-2. IEEE 1730-2010
DoD Architecture FrameworkThe Department of Defense Architecture Framework (DoDAF), Version 2.0 is the overarching, comprehensive framework and conceptual model enabling the development of architectures to facilitate the ability of Department of Defense (DoD) managers at all levels to make key decisions more effectively through organized information sharing across the Department, Joint Capability Areas (JCAs), Mission, Component, and Program boundaries. DoD, “DoD Architecture Framework Version 2.02, Introduction,” DoD Chief Information Officer, accessed 7 December 2021, https://dodcio.defense.gov/Library/DoD-Architecture-Framework/dodaf20_background/
DoD CommunityA DoD activity area, enabled by M&S, that has an established executive-level management structure.  Examples of such activities that meet these criteria include acquisition, training, and analysis.DoDD 5000.59, Change 1, 15 October 2018
DoD Community M&S Strategic PlanA high-level DoD plan created and published by a DoD Community to facilitate and achieve the DoD M&S Strategic Vision, goals, and objectives for that DoD Community.DoDI 5000.70, Change 3, 15 Oct 2018
DoD Community Specified Models and SimulationsModels and simulations designated by a Community to focus Community management of M&S and to limit the scope of the Components' responsibility to develop, manage, and provide Component data, and support the development of tools and services.DoDD 5000.59, Change 1, 15 October 2018
DoD M&S discovery metadata search capabilityAn enterprise-level capability that enables the discovery of metadata about M&S assets to facilitate visibility into the resources available across the DoD and within other Federal and non-Federal agencies engaged in M&S, and federated with DoD M&S. Sources of the M&S assets described by the discovery metadata are maintained by DoD Components and other authoritative data and software repositories. Visibility into the discovery metadata enables a user or developer of M&S assets to identify potential reuse opportunities relative to their requirements.DoDI 5000.70, Change 3, 15 Oct 2018
Dynamic Analysis An analysis that includes the effect of the variables changing with time as well as space.NAFEMS Glossary
dynamic modelA model of a system in which there is change, such as the occurrence of events over time or the movement of objects through space; for example, a model of a bridge that is subjected to a moving load to determine characteristics of the bridge under changing stress.SISO-REF-020-2007
dynamic natural environmentAn environment that can be constantly changing as a result of man-made activities (battlefield smoke) and natural phenomena (weather).Army Model and Simulation Master Plan.
ecosystemSee digital engineering ecosystem
electronic data interchangeStructured way of transmitting data held electronically from database to database, usually using telecommunications networks.DAU Glossary
emergent behaviorA behavior or property that appears when a number of simple entities (agents) operate in an environment, forming more complex behaviors as a collective. SEBoK
empirical measurement eventA defined set of test points that provide data for a condition that is not modeled or not modeled to sufficient fidelity. EME data characterize System or Element behavior in previously unexplored conditions, and are used to develop new models. EMEs may also be test points in addition to those defined for the Critical Engagement Conditions (CECs) that extend the operational conditions of previously explored models.Missile Defense System Engineering Team (MDSET), "Critical Engagement Condition and Empirical Measurement Event Description Document; S-2391-4.0,"
empirical modelA model based on observed and measured phenomena obtained from one or more reference systems under controlled conditions.
emulationA model that accepts the same inputs and produces the same outputs as a given system.SISO-REF-002-1999
emulatorA device, computer program, or system that performs emulation.SISO-REF-002-1999
enabling systemA system that supports a system-of-interest during its life cycle stages but does not necessarily contribute directly to its function during operation.NAFEMS Glossary
engineeringThe creative application of scientific principles to design or develop structures, machines, apparatus, or manufacturing processes, or works utilizing them singly or in combination; or to construct or operate the same with full cognizance of their design; or to forecast their behaviour under specific operating conditions; all as respects an intended function, economics of operation and safety to life and property.Engineering Council for Professional Development
engineering simulationThe use of physics-based mathematical (numerical) models and/or logical models, including relevant data derived from their physical model counterparts, as representations of a conceptual or real-world system, phenomenon, or process in studying its technical requirements and operational behavior.NAFEMS Glossary
enterpriseAn arbitrarily defined functional and administrative entity that exists to perform a specific, integrated set of missions and achieve associated goals and objectives, encompassing all of the primary functions necessary to perform those missions.DoDI 5000.70, Change 3, 15 Oct 2018
enterprise information modelThe core metadata and supporting services which DoD Organizations (i.e. SAF/CO) will use for enterprise data management.
enterprise modelInformation model(s) that presents an integrated top-level representation of processes, information flows, and data.DoD 8320.1-M
enterprise simulation managementIntegrates and manages simulation and analysis data and processes across the product development processes. ESM’s primary components include knowledge capture and replication and integrated simulation management. Also called Simulation Data Management or Simulation Lifecycle Management.CIMdata PLM Glossary https://www.cimdata.com/en/resources/about-plm/cimdata-plm-glossary
entityA distinguishable person, place, unit, thing, event, or concept about which information is kept.SISO-REF-020-2007
entity perspectiveThe perception of the synthetic environment held by a simulation entity based on its knowledge of itself and its interactions with the other simulation entities. This includes not only its own view of the simulated physical environment, but also its own view of itself, the other entities in the synthetic environment, and of the effects of the other entities on itself and the synthetic environment. Syn: World View.SISO-REF-020-2007
environment1. The aggregate of all external and internal conditions that influence the form, performance of an item.
2. The surroundings (natural or man-made) in which the system-of-interest is utilized and supported; or in which the system is being developed, produced or retired.
1. DAU Glossary
2. NAFEMS Glossary
environmental effect modelA numerical model, parametric model, or database for simulating a natural environmental effect on an entity of a simulation exercise, such as a sensor or platform.SISO Fidelity ISG Glossary
environmental featureAn individual element of the physical environment.SISO Fidelity ISG Glossary
environmental representationA model, simulation, or database designed to produce an accurate and consistent data set for one or more parameters that characterize the state of the physical environment. 
error modelA model used to estimate or predict the extent of deviation of the behavior of an actual system from the desired behavior of the system.SISO-REF-020-2007
eventA change of object attribute value, an interaction between objects, an instantiation of a new object, or a deletion of an existing object that is associated with a particular point on the federation time axis. Each event contains a time stamp indicating when it is said to occur.http://www.ms.army.mil/library/glossary.html
event listAn ordered list that contains the time all events will occur or have occurred.Law, Averill M. Simulation modeling and analysis.
event-driven simulationA simulation in which attention is focused on the occurrence of events and the times at which those events occur. IEEE 610.3-1989
examination1. An element of verification that is generally nondestructive and typically includes the use of sight, hearing, smell, touch, and taste; simple physical manipulation; and mechanical and electrical gauging and measurement.
2. Visual inspection of equipment and evaluation of drawings and other pertinent design data and processes should be used to verify conformance with characteristics such as physical, material, part, and product marking and workmanship.
1. MIL-STD-961E, Change 4, July 16, 2020
2. Defense Acquisition Guidebook
executable modelA model intended to simulate the simuland as detailed in the conceptual model, so the conceptual model is thereby a design specification for the executable model.Sokolowski, John A. Principles of modeling and simulation a multidisciplinary approach.
exerciseA military maneuver or simulated wartime operation normally involving planning, preparation, execution, and after-action review.  Also see simulation exercise.AFP 16-10 2006
experimentationA process using simulation to identify, develop, assess and recommend changes to doctrine, organizational structure, training, materiel, leadership and education, people, and facilities required to achieve advances in operational capabilities.
expert systemA knowledge collection combined with an inference engine capable of interpreting queries and chaining together separate items of knowledge to develop new inferences.Defense Science Board Report: Report of the Defense Science Board Task Force on Computer Applications to Training and Wargaming.
extensibilityThe ability of a model, simulation, or data structure to accommodate additional values or iterations of data over time without impacting the initial design.SISO Fidelity ISG Glossary
face validationThe process of determining whether a model or simulation seems reasonable to people who are knowledgeable about the system under study, based on the model's performance. This process does not review the software code or logic, but rather reviews the inputs and outputs to ensure they appear realistic or representative.SISO-REF-020-2007
facilityThe physical means or equipment for facilitating the performance of an action, e.g. buildings, instruments, tools NAFEMS Glossary
fair fightA condition when the differences between the performance characteristics of two or more interoperating simulations have significantly less effect on the outcome of a simulated situation than the actions taken by or resources available to the simulation participants.SISO-REF-020-2007
family of systemsA set of systems that provides similar capabilities through different approaches to achieve similar or complementary effects. For example, the warfighter may need the capability to track moving targets. The FoS that provides this capability could include manned or unmanned aerial vehicles (UAVs) with appropriate sensors, a space-based platform, or a special operations capability. Each can provide the ability to track moving targets, but with differing characteristics of persistence, accuracy, timeliness, etc.DAU Glossary
faster than real-timeSimulated time advances at a rate greater than actual time.IEEE 1278.2-1995
featureA static element of the synthetic environment that exists but does not actively participate in synthetic environment interactions. Entities can interact with features (building them, destroying them, colliding with them, etc.), but features are passive in that they do not initiate action.Barfield, Woodrow, and Thomas Caudell. Fundamentals of Wearable Computers and Augmented Reality
federate(High Level Architecture) An application that may be or is currently coupled with other software applications under a Federation Object Model (FOM) Document Data (FDD) and a runtime infrastructure (RTI).IEEE 1516.2-2010
federatedThe ability to search across multiple archives, data collections, or multiple content aggregator services.DoDI 5000.70, Change 3, 15 Oct 2018
federation1. An architecture made up of multiple independent M&S applications and products that were designed and developed separately and then brought together through interfaces and frameworks.
2. In High Level Architecture, a named set of federate applications and a common federation object model (FOM) that are used as a whole to achieve some specific objective.  (IEEE 1516-2000) More generally, a system of interacting models, simulations, and a supporting infrastructure that are based on a common understanding of the objects portrayed in the system. In High Level Architecture, a named set of federate applications and a common federation object model (FOM) that are used as a whole to achieve some specific objective.
1. MDA M&S Intended Uses Document, 20-Apr-2015, Admin Change 1, 01-Jul-2020
2. IEEE 1516-2000
Federation Development and Execution ProcessA seven-step process used to develop and execute High Level Architecture (HLA) federations as standardized in IEEE 1516.3-2003.  This standard has been superseded by the Distributed Simulation Engineering and Execution Process.IEEE 1730-2010
federation object modelA specification defining the information exchanged at runtime to achieve a given set of federation objectives. This information includes object classes, object class attributes, interaction classes, interaction parameters, and other relevant information. The federation object model (FOM) is specified to the runtime infrastructure (RTI) using one or more FOM modules. The RTI assembles a FOM using these FOM modules and one Management Object Model (MOM) and Initialization Module (MIM), which is provided automatically by the RTI or, optionally, provided to the RTI when the federation execution is created.IEEE 1516.2-2010
federation of models and simulationsA system of interacting models, simulations, and supporting infrastructure that are based on a common understanding of the objects portrayed in the system.MIL-STD-3022, Change 1, 5 April 2012
fidelity1. The degree to which a model or simulation reproduces the state and behavior of a real world object or the perception of a real world object, feature, condition, or chosen standard in a measurable or perceivable manner; a measure of the realism of a model or simulation; faithfulness. Fidelity should generally be described with respect to the measures, standards or perceptions used in assessing or stating it.
2. The methods, metrics, and descriptions of models or simulations used to compare those models or simulations to their real world referents or to other simulations in terms of measures, standards or perceptions. Fidelity measures, standards or perceptions include: Accuracy; Precision; Repeatability; Resolution; Scope; Sensitivity
1-2. D. C. Gross, "Report from the Fidelity Implementation Study Group"
field-of-viewThe angular extent of the observable world that is seen at any given moment.DoD M&S Human Capital Strategy
field training exerciseA military exercise conducted in the field under simulated operational conditions in which troops and armament of one side are actually present while those of the other side are imaginary or simulated.CJCSM 3500.03E, April 20, 2015
final conditionThe values assumed by the variables in a system, model, or simulation at the completion of some specified duration of time; final state.IEEE 610.3-1989
finite differencesA numerical method for solving partial differential equations by expressing them in a difference form rather than an integral form. Finite difference methods are very similar to finite element methods and in some cases are identical.NAFEMS Glossary
fitness (for use)Providing the capabilities needed or being suitable for some purpose, function, situation or application.D. C. Gross, "Report from the Fidelity Implementation Study Group"
flow portSpecifies an interaction point with a focus on the types of matter, energy, or data that can flow in and out of a block.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
flow specification1. An element of definition—one that defines a set of flow properties that can flow in or out of a nonatomic flow port.
2. Defines the set of input and/or output flows for a non-composite flow port. may be one of: in, out, or inout.
1. SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
2. A Practical Guide to SysML: The Systems Modeling Language / Sanford Friedenthal, 2014
follow-on operational test and evaluationThe Test and Evaluation (T&E) that may be necessary after the Full-Rate Production Decision Review (FRPDR) to refine the estimates made during Operational Test and Evaluation (OT&E), to evaluate changes, and to reevaluate the system to ensure that it continues to meet operational needs and retains its effectiveness in a new environment or against a new threat.DAU Glossary
forced responseThe dynamic motion results from a time varying forcing function or from the constraining of an internal/external variable.NAFEMS Glossary
frame rateThe rate at which a complete image is displayed on a display device.Sherman, William R., and Alan Craig. Understanding Virtual Reality Interface, Application, and Design
FrameworkProvides the mechanizes and environment necessary to federate combinations of models and simulations that: initializes those models and simulations, controls and coordinates their execution, facilitates communications among them, collects the results of their operation, and provides them with a common and consistent backdrop against which to operate, but generally does not model or simulate anything by itself.MDA M&S Intended Uses Document, 20-Apr-2015, Admin Change 1, 01-Jul-2020
full portEquivalent to a part on the boundary of the parent block that is made available as an access point to and from the block. Is typed by a block and can have nested parts and behaviors, and can modify incoming and outgoing flows like any other part.A Practical Guide to SysML: The Systems Modeling Language / Sanford Friedenthal, 2014
functionAn action, a task, or an activity performed to achieve a desired outcome.SEBoK
functional architectureSet of functions and their sub-functions that defines the transformations of input flows into output flows performed by the system to achieve its mission.SEBoK
functional mock-up interfaceA tool independent (open) standard to support both model exchange and co-simulation of dynamic models using a combination of xml-files and compiled C-code.NAFEMS Glossary
functional mock-up unitThe instantiation, initialization and/or execution of an individual executable (or C code) model representation performed within a simulation environment. The FMU contains a concrete mathematical model described by differential, algebraic and discrete equations with possible events of a dynamic physical system transformed into explicit form and represented as C code or machine code.NAFEMS Glossary
game theoryThe study of situations involving competing interests, modeled in terms of the strategies, probabilities, actions, gains, and losses of opposing players in a game.IEEE 610.3-1989
gatewayA device that connects two or more systems, especially if the systems use different protocols. For example, a gateway might be needed to connect two independent local networks, or to connect a local network to a long-haul network.M&S Educational Training Tool (MSETT) Navy Air Weapons Center Training Systems Division Glossary
general use M&SSpecific representations used by, or common to, many models and simulations (e.g., physical environment or environmental effects such as terrain, atmospheric, or hydrographic effects).DoDI 5000.61, Change 1, 15 Oct 2018
generalizationA generalization is another kind of relationship you typically display on Block Definition Diagrams. This relationship conveys inheritance between two elements: a more generalized element, called the supertype, and a more specialized element, the subtype.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
generative designThe use of algorithmic methods to create feasible designs of assemblies and components or outcomes from a set of performance requirements, objectives, constraints and specified use cases.NAFEMS Glossary
genetic algorithmsStochastic algorithms whose search methods model some natural phenomena.Michalewicz, Zbigniew. Genetic Algorithms Data Structures = Evolution Programs.
geo-specific terrain modelTerrain modeled is an actual location STE-NGC A-CDD (draft)
geo-typical terrain modelTerrain modeled is a representative fictional terrain of a specific region of the world. STE-NGC A-CDD (draft)
glass box modelSee: white box model.
government reference modelProvides the architecture views used to support business case development and investment decisions, monitor capability development, and service improvements. The government reference model can be provided to potential bidders for contracted efforts to further the acquisition, development and sustainment.Aerospace Corporation
graphical modelA symbolic model whose properties are expressed in diagrams.  (e.g., a decision tree used to express a complex procedure.) SISO-REF-020-2007
ground truthThe actual facts of a situation, without errors introduced by sensors or human perception and judgment.SISO-REF-020-2007
hapticRefers to all the physical sensors that provide a sense of touch at the skin level and force feedback information from muscles and joints.Sherman, William R., and Alan Craig. Understanding Virtual Reality Interface, Application, and Design
hardware in-the-loop simulation1. Simulation and simulators that employ one or more pieces of operational equipment (to include computer hardware) within the simulation/simulator system.
2. A closed loop simulation with actual mission components in a laboratory environment where the physical environment is simulated and controlled by computer equipment.
1. DoD M&S Human Capital Strategy
2. Missile Defense Agency, "Ballistic Missile Defense System (BMDS) Integrated Master Assessment Plan (IMAP) Volume 2, Version 14.1," March 1, 2014.
hardware-in-the-loop – distributedTesting that involves operational assets and labs.MDA Instruction 3200.09, June 3, 2020
hardware-in-the-loop – integratedIntegrated lab testing that does not involve operational assets and involves a broad spectrum of objectives.MDA Instruction 3200.09, June 3, 2020
hardware-in-the-loop testingA type of dynamic simulation that includes one or more actual system components operating in conjunction with simulated components.SEBoK
hierarchical modelA model in which superior/subordinate relationships are represented, often as trees of records connected by pointers.
hierarchical modelA model of information in which data are represented as trees of records connected by pointers.Singh, S. K. Database Systems Concepts, Design & Applications.
High Level ArchitectureA family of related standards that describe a unified approach and common functional architecture used to construct interoperable simulation systems as standardized in IEEE 1516.IEEE 1516.1-2000
high performance computingMost generally refers to the practice of aggregating computing power in a way that delivers much higher performance than one could get out of a typical desktop computer or workstation in order to solve large problems in science, engineering, or business.https://www.usgs.gov/core-science-systems/sas/arc/about/what-high-performance-computing
human behaviorThe classical cognitive functions, as well as the effects of moderators such as stress, injury, fatigue, discomfort, motivation, and emotions. Any form of human representation, including individuals, aggregates of individuals and organizations.
human behavior representationThe use of a computer based model within a simulation that mimics either the action of a single human or the collective action of a team of humans. Human behavior representation models aspects of the complicated facets of human behavior including ability to reason, ability to change the environment, reaction to comfort or discomfort, susceptibility to injury and illness, emotional response, communication with others, ability to sense the environment and physical capabilities and limitations.DoD M&S Human Capital Strategy
human behavioral modelModel of a human activity in which individual or group behaviors are derived from the psychological or social aspects of humans. Behavioral models include a diversity of approaches; however, computational approaches to human behavior modeling that are most prevalent are social network models and multi-agent systems.Sokolowski, John A. Principles of modeling and simulation a multidisciplinary approach.
human factors1. The discipline or science of studying man-machine relationships and interactions. The term covers all biomedical and psychological considerations; it includes, but is not limited to, principles and applications in the areas of human engineering, personnel selection, training, life support, job performance aids, and human performance evaluation.
2. The physical, cultural, psychological, and behavioral attributes of an individual or group that influence perceptions, understanding, and interactions.
1. SISO Fidelity ISG Glossary
2. JP 2-0
human, social, cultural and behavior representationA model of the structure, interconnections, dependencies, behavior, and trends associated with any collection of individuals ranging from the small unit level (e.g., tribes, militias, small military units, terrorist cells) to the macro level (e.g., of nations, religions, cultures, ethnic groups and international organizations), and the integrated relationships between and among them.
human-in-the-loop simulationSimulation and simulators that employ one or more human operators in direct control of the simulation/simulator or in some key support function.DoD M&S Human Capital Strategy
hybrid simulation1. A simulation that combines constructive, live, and/or virtual simulations, typically in a distributed environment.
2. A simulation, portions of which are designed to be executed on an analogue system and portions on a digital system.
AMSP-02 NATO MS Glossary of Terms
immersionThe placing of a human in a synthetic environment through physical and/or emotional means.
implementationThe means by which a model or simulation or portions of a model or simulation is realized.SISO-REF-020-2007
incrementOne of a series of regular consecutive additions.Merriam-Webster Dictionary, Merriam-Webster, https://www.merriam-webster.com/
incremental approachDetermines user needs and defines the overall architecture, but then delivers the system in a series of increments (“software builds”). The first build incorporates a part of the total planned capabilities, the next build adds more capabilities, and so on, until the entire system is complete.DAU Glossary
independent variableA variable whose value is not dependent on the values of other variables. Contrast with: dependent variable. IEEE 610.3-1989
independent verification and validationThe conduct of verification and validation of a model or simulation by individuals or agencies that did not develop the model or simulation.  IV&V does not require complete organizational independence, but does imply a reasonable degree of organizational separation to assure unbiased analysis.VV&A Recommended Practices Guide
information modelA model that represents the processes, entities, information flows, and elements of an organization and all relationships between these factors.
infrastructureThe supporting hardware, software, communication, and information security services that a system requires to operate but can be shared by multiple systems for scalabilityDAU Glossary (derived from Information Technology Infrastructure)
initial conditionThe values assumed by the variables in a component, system, model, or simulation at the beginning of some specified duration of time; initial state.SISO-REF-002-1999
initial operational test and evaluationDedicated Operational Test and Evaluation (OT&E) conducted on production, or production representative articles, to determine whether systems are operationally effective and suitable to support a Full-Rate Production (FRP) decision.DAU Glossary
inputThe externally supplied data to which a simulation responds and from which it calculates its output (e.g., operator controls, weapon detonation, wind speed, and direction).SISO-REF-002-1999
instructional simulationA simulation intended to provide a simulation equivalent of a real or hypothesized stimulus that could occur in the synthetic environment for the purpose of training. Barfield, Woodrow, and Thomas Caudell. Fundamentals of Wearable Computers and Augmented Reality
integrated testingThe collaborative planning and collaborative execution of test phases and events to provide shared data in support of independent analysis, evaluation, and reporting by all stakeholders, particularly the development and operational test and evaluation communitiesOffice of the Secretary of Defense, Definition of Integrated Testing
integration A process that combines system elements to form complete or partial system configurations in order to create a product specified in the system requirements.ISO/IEEE 12207:2008
Integration DEFinition for Functional ModelingA multiple page (view) model of a system that depicts functions and information or product flow. Boxes illustrate functions and arrows illustrate information and product flow. Alphanumeric coding is used to denote the view. IDEF0 - functional modeling method IDEF1 - information modeling method IDEF1X - data modeling method; IDEF3 - process description capture method IDEF4 - object oriented design method IDEF5 - ontology description capture method NAFEMS Glossary
intellectual property1. Intangible property that is the result of creativity, such as patents, trademarks, or copyrights.
2. Includes inventions, trademarks, patents, industrial designs, copyrights, and technical information including software, data designs, technical know-how, manufacturing information and know-how, techniques, Technical Data Packages (TDPs), manufacturing data packages, and trade secrets.
1. DoDI 5000.70, Change 3, 15 Oct 2018
2. DAU Glossary
intelligence mission dataDoD intelligence used for programming platform mission systems in development, testing, operations, and sustainment including, but not limited to, the functional areas of signatures, electronic warfare integrated reprogramming, order of battle, characteristics and performance, and geospatial intelligence.DAU Glossary
intelligent agentSee: agent.
intended useA description of the problem to be addressed by a model or simulation and its associated data, including the system or process being represented and the role it plays in the overall program.MIL-STD-3022, Change 1, 5 April 2012
interfaceThe functional and physical characteristics required to exist at a common boundary or connection between persons, between systems, or between persons and systems.DAU Glossary
interface blockA special type of block used for typing proxy ports that has no behaviors or internal parts. Typically contains flow properties.A Practical Guide to SysML: The Systems Modeling Language / Sanford Friedenthal, 2014
interface requirementConstraint which defines how the system is required to interact with external systems (external interface), or how system elements within the system, including human elements, interact with each other (internal interface).SEBoK
internal & external interface requirementSee Interface RequirementSEBoK
internal block diagramUsed to specify the internal structure of a single block; shows the connections between the internal parts of a block and the interfaces between them.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
interoperability1. The ability of a model or simulation to provide services to and accept services from other models and simulations, and to use these exchanged services to operate effectively together.
2. The ability of two or more systems or components to exchange information and to use the information that has been exchanged. For example, interoperable tools have access to and use the original data, not translated data or copies of the data.
1. SISO-REF-002-1999
2. CIMdata PLM Glossaryhttps://www.cimdata.com/en/resources/about-plm/cimdata-plm-glossary
issueAn event or condition with negative effect that has occurred (such as a realized risk) or is certain to occur (probability of 1) that should be addressed.DoD, “Risk, Issue, and Opportunity Management Guide for Defense Acquisition Programs,” Office of the Deputy Assistant Secretary of Defense for Systems Engineering, January 2017
issue managementIn the context of the DoD Risk, Issue and Opportunity Management Process, the process for identifying and addressing events or conditions that have already occurred, are occurring, or are certain to occur in the future and which have a potential negative impact on the program.DAU Glossary
item flowRepresents a type of matter, energy, or data that flows between two structures within a system.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
iterationA procedure in which repetition of a sequence of operations yields results successively closer to a desired result.Merriam-Webster Dictionary, https://www.merriam-webster.com/
key modeling and simulation assetAn M&S tool, data set, or service, including models, simulations, or data assets, that either exceeds $5M in annual expenditures, or is less than $5M but determined by the DoD Component to be "key." The total annual expenditure will be determined using standard justification documentation for DoD appropriations, such as RDT&E (R-docs), Procurement (P-docs), and O&M (O&M exhibits), which are provided to Congress pursuant to DoD 7000.14-R DoDI 5000.70, Change 3, 15 Oct 2018
key test pointsUsed by Critical Engagement Conditions (CEC’s), Empirical Measurement Events (EME’s), and Critical Assessment Conditions (CAC’s) to establish where, for associated conditions and condition ranges, data must be collected to sufficiently satisfy the requirement that originally led to the creation of each CEC, EME, or CAC.Ballistic Missile Defense System (BMDS) Integrated Master Assessment Plan (IMAP) Volume 2, Version 14.1, March 1, 2014
knowledgeAcquaintance with facts, truths, or principles, as from study or investigation; general erudition: knowledge of many things. acquaintance or familiarity gained by sight, experience, or report: a knowledge of human nature. the fact or state of knowing; the perception of fact or truth; clear and certain mental apprehension.SEBoK
knowledge assetExplicit knowledge content that belongs to the enterprise and can be used and/or reused to further enterprise goals.American Productivity & Quality Center
knowledge managementThe process of enabling knowledge flow to enhance shared understanding, learning, and decision-making. Knowledge flow refers to the ease of movement of knowledge within and among organizations CJCSI 5124.01, 12 April 2013
lagThe difference between real time and the simulation time; an architectural level error in the operation of the model or simulation itself; excessive lag is an undesirable condition. WHITE PAPER;ON M&S LAG AND LATENCY, Ron VanIwaarden, MDA/MDA/DES/M&S OPSL, November 16, 2011
latency1. The time delay between action and result.
2. The time delay between any two simulators, from submitting a message from the sending simulation to receiving this message by the recipient simulation.
3. The time interval required for a simulation to begin its response to a stimulus after it has been presented with a stimulus or stimuli (e.g., input of data, occurrence of an event).
4. The time interval required by a simulation to respond to a stimulus in excess of the time interval required for the corresponding real world or standard event. 
1. Burdea, Grigore. Virtual reality technology
2. IEEE Std. 1278.2-1995
3. SISO Fidelity ISG Glossary
4. SISO Fidelity ISG Glossary
legacy model; legacy simulation; legacy modeling and simulationAny model or simulation that was developed either in the past or for a different purpose.
legacy system1. A system that has been in operation for a long time, and whose functions are too essential to be disrupted by upgrading or integration with another system.
2. A legacy system is an old method, technology, computer system, or application program that continues to be used, typically because it still functions for the users' needs, even though newer technology or more efficient methods of performing a task are now available. A legacy system may include procedures or terminology which are no longer relevant in the current context, and may hinder or confuse understanding of the methods or technologies used.
3. In-place computing and application systems that are currently being used within an organization to perform defined functions and tasks.
1. SEBoK
2. SEBoK
3. CIMdata PLM Glossary https://www.cimdata.com/en/resources/about-plm/cimdata-plm-glossary
life cycle costThe total cost to the organization of acquisition and ownership of a system over its entire life. It includes all costs associated with the system and its use in the concept, development, production, utilization, support and retirement stages.
life cycle modelA framework of processes and activities concerned with the life cycle that may be organized into stages, which also acts as a common reference for communication and understanding.NAFEMS Glossary
lifecycleDescription of the distinct phases through which each product passes during its product life. This includes phases such as requirements definition, concept design, production, etc.CIMdata PLM Glossary https://www.cimdata.com/en/resources/about-plm/cimdata-plm-glossary
lifelineElement that represents a participant in an interaction; More precisely, a lifeline represents a single instance that participates in an interaction by exchanging messages with other lifelines.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
live fire test and evaluationA test process that provides a timely assessment of the survivability and/or lethality of a conventional weapon or conventional weapon system as it progresses through its design and development. LFT&E is a statutory requirement (Title 10 U.S.C. § 2366) for covered systems, major munitions programs, missile programs, or product improvements to a covered system, major munitions programs, or missile programs before they can proceed beyond Low-Rate Initial Production (LRIP).DAU Glossary
live simulationA simulation involving real people operating real systems.DoD M&S Human Capital Strategy
live, virtual, and constructive simulationA broadly used taxonomy describing a mixture of live simulation, virtual simulation, and constructive simulation.LVCAR Final Report
logical architectureThe logical architecture of a system is composed of a set of related technical concepts and principles that support the logical operation of the system. It includes a functional architecture, a behavioral architecture, and a temporal architecture.SEBoK
logical data modelA model that provides a common dictionary of data definitions to consistently express models wherever logical-level data elements are included in the descriptions.  
logical timeA federate’s current point on the High Level Architecture (HLA) time axis. Federates making use of the time management services follow restrictions on what timestamps can be sent in timestamp order (TSO) messages (relative to their logical time) to ensure that federates receiving those messages receive them in TSO.IEEE 1516.2-2010
machine learning1. An application or subset of Artificial Intelligence that allows machines to learn from data without being programmed explicitly.
2. A class of computer algorithms that automatically optimize parameters to process a given input and yield a desired output.
3. The study of computer algorithms that can improve automatically through experience and by the use of data.
2. STE-NGC A-CDD (draft)
3. en.wikipedia.org
maintainabilityThe ability of an item to be retained in, or restored to, a specified condition when maintenance is performed by personnel having specified skill levels, using prescribed procedures and resources, at each prescribed level of maintenance and repair.DAU Glossary
management gameA simulation game in which participants seek to achieve a specified management objective given pre-established resources and constraints; for example, a simulation in which participants make decisions designed to maximize profit in a given business situation and a computer determines the results of those decisions.IEEE 610.3-1989
Markov Chain ModelA discrete, stochastic model in which the probability that the model is in a given state at a certain time depends only on the value of the immediately preceding state.IEEE 610.3-1989
master scenario events listA chronological list that supplements the exercise scenario with event synopses; expected participant responses; capabilities, tasks, and objectives to be addressed; and responsible personnel. It includes specific scenario events (or injects) that prompt players to implement the plans, policies, and procedures that require testing during the exercise, as identified in the capabilities-based planning process. It also records the methods that will be used to provide the injects (i.e., phone call, facsimile, radio call, e-mail).Homeland Security. Security Exercise and Evaluation Program (HSEEP).
mathematical modelA symbolic model whose properties are expressed in mathematical symbols and relationships.IEEE 610.3-1989
measure of effectiveness1. A qualitative or quantitative measure of aggregate performance or a characteristic of a model, simulation or system that indicates the degree to which it performs the task or meets an operational objective or requirement under specified conditions. 
2. The data used to measure the military effect (mission accomplishment) that comes from using the system in its expected environment. That environment includes the system under test and all interrelated systems, that is, the planned or expected environment in terms of weapons, sensors, command and control, and platforms, as appropriate, needed to accomplish an end-to-end mission in combat.
1. VV&A Recommended Practices Guide
2. DAU Glossary
measure of outcomeA qualitative or quantitative measure that defines how operational requirements contribute to end results at higher levels, such as campaign or national strategic outcomes.Piplani. Systems Acquisition Managers Guide for the Use of Models and Simulations
measure of performance1. A qualitative or quantitative measure of how the system/individual performs its functions in a given environment (i.e., number of targets detected, reaction time, number of targets nominated, susceptibility of deception, task completion time). It is closely related to inherent parameters (physical and structural) but measures attributes of system behavior. 
2. System-particular performance parameters such as speed, payload, range, time-on-station, frequency, or other distinctly quantifiable performance features. Several MOPs may be related to achieving a particular Measure of Effectiveness (MOE).
1. IEEE 610.3-1989
2. DAU Glossary
measure of suitabilityMeasure of an item's ability to be supported in its intended operational environment. Measures of suitability typically relate to readiness or operational availability and, hence, reliability, maintainability, and the item's support structure.DAU Glossary
measures of effectiveness needsThe “operational” measures of success that are closely related to the achievement of the mission or operational objective being evaluated, in the intended operational environment under a specified set of conditions (i.e., how well the solution achieves the intended purpose).NAFEMS Glossary
measures of performance needsKey performance characteristics the system should have when fielded and operated in its intended operating environment.NAFEMS Glossary
medical modeling and simulationThe medical discipline that comprises the development or use of medical modeling and simulations. It involves the equipment, including hardware, and the software that implements a model or simulation or an adjunct tool. The hardware or software that is either used to provide part of a simulation environment (e.g., to manage the execution of the environment) or to transform and manage data used by or produced by a model or simulation.DODI 6000.18, August 22, 2018
messageRepresents a communication between a sending lifeline and a receiving lifeline. That communication may be an invocation of a behavior, a reply at the end of a behavior, the creation of a lifeline, or the destruction of a lifeline. There are four types of messages that commonly appear in interactions: asynchronous messages, synchronous messages, reply messages, and create messages.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
metadata Information describing the characteristics of data, data or information about data, or descriptive information about an entity’s data, data activities, systems, and holdings. For example, discovery metadata is a type of metadata that allows data assets to be found using enterprise search capabilities. Metadata can be structural (specifying the format structure), semantic (specifying the meaning), or descriptive (providing amplifying or interpretive information) for data, information, or IT services.DoDI 8320.02, Change 1, 24 June 2020
metamodelA model of a model or simulation. Metamodels are abstractions which use functional decomposition to show relationships, paths of data and algorithms, ordering, and interactions between model components and subcomponents. Metamodels allow the developer to abstract details to a level that subject matter experts can validate.M&S Educational Training Tool (MSETT) Navy Air Weapons Center Training Systems Division Glossary
methodConsists of techniques for performing a task, in other words, it defines the “HOW” of each task. (In this context, the words “method,” “technique,” “practice,” and “procedure” are often used interchangeably.) At any level, process tasks (the “WHAT”) are performed using methods. See also: process.Estefan, Jeff A., Survey of Model-Based Systems Engineering (MBSE) Methodologies Rev. B, INCOSE, 23 May 2008
metric1. A measure of the extent or degree to which a product possesses and exhibits a certain quality, property, or attribute.
2. Quantitative measurement of a system, component, or process to determine the degree to which it possesses a given attribute. Metrics are often used to measure quality and process improvement.
1. SISO-REF-002-1999
2. CIMdata PLM Glossary https://www.cimdata.com/en/resources/about-plm/cimdata-plm-glossary
mission engineeringDescribes the application of systems engineering to the planning, analysis, and designing of missions, where the mission is the system of interest.SEBoK
mission spaceThe collection of entities, actions, and interactions comprising the set of interrelated processes used by individuals and/or organizations to accomplish assigned tasks.  
Mock-upA full-sized model, but not necessarily functional, built accurately to scale, used chiefly for study, testing, or display.IEEE 610.3-1989
modelA physical, mathematical, or otherwise logical representation of a system, entity, phenomenon, or process.DoDI 5000.61, Change 1, 15 Oct 2018, DoDI 5000.70, Change 3, 15 Oct 2018
model accessionThe formal process of accepting and recording a model as a collection object in the enterprise level model portfolio. Accessioning addresses the legal, IP and ethical issues in model acquisition and developmentSERC-2018-TR 104
model curationThe lifecycle management, control, preservation and active enhancement of models and associated information to ensure value for current and future use, as well as repurposing beyond initial purpose and context. SERC-2018-TR 104
model libraryContains a set of elements intended to reuse in multiple models. The notation for a model library is the same as the one for a package—a folder symbol—but it must have the keyword «modelLibrary» displayed above the name.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
model pedigreeModel-associated information that describes model origin, development process, originators and developers, assumptions, expert knowledge, model enhancements, investment costs, versions, change history, etc.SERC-2018-TR 104
model-based definitionThe practice of using 3D solid models to document additional information about a design, such as PMI (product manufacturing information) and associated metadata. The PMI information is embedded directly in the solid models and is associated with the geometric elements of the design.CIMdata PLM Glossary https://www.cimdata.com/en/resources/about-plm/cimdata-plm-glossary
model-based designThe use of models and modeling techniques as an integral part of the design phase of a development process.NAFEMS Glossary
model-based developmentThe systematic use of models and modeling techniques as an integral part of the overall development engineering process.NAFEMS Glossary
model-based engineeringAn approach to engineering that uses models as an integral part of the engineering processes that includes the requirements, design, analysis, implementation, and the verification and validation of a capability, system, and/or product throughout its life cycle.NAFEMS Glossary
model-based enterpriseAn organization where models serve as the authoritative information source for processes beyond engineering.Derived from Wikipedia
model-based safety analysisAn approach in which the system and safety engineers share a common system model created using a model-based development process. By extending the system model with a fault model as well as relevant portions of the physical system to be controlled, automated support can be provided for much of the safety analysis.NAFEMS Glossary
model-based systems engineering The formalized application of modeling to support system requirements, design, analysis, verification, and validation activities beginning in the conceptual design phase and continuing throughout development and later life cycle phases.https://www.incose.org/
modeling and simulation1. The discipline that comprises the development and/or use of models and simulations.
2. The use of models and simulations, either statically or over time, to develop data as a basis for making managerial or technical decisions. This includes but is not limited to emulators, prototypes, simulators and stimulators.
1. DoDD 5000.59, Change 1, 15 October 2018, DoDI 5000.61, Change 1, 15 Oct 2018
2. MIL-STD-3022, Change 1, 5 April 2012
modeling and simulation applicationExecuting software on a host computer that models or simulates one or more entities. The M&S Application represents real-world entities for the purpose of training, analysis, or experimentation and requires an accreditation assessment for a specific intended use.IEEE Computer Society, "IEEE Standard of Distributed Interactive Simulation - Application Protocols," IEEE 1278.1-2012.
modeling and simulation assetsM&S tools, data, and services, including models and simulations and data assets.DoDI 5000.70, Change 3, 15 Oct 2018
modeling and simulation assumptionA simplification due to the complex nature of reality a real world object. Expressions can take the form of mathematical, logical, or symbolic relationships between entities.
modeling and simulation capabilityThe model or simulation contains the needed behavior of a real world object.
Modeling and Simulation Community of Interest A collaborative group of users that must exchange modeling and simulation information in pursuit of its shared goals, interests, missions, or business processes and therefore must have shared vocabulary for the information it exchanges.
modeling and simulation constraintThe model or simulation lacks the needed behavior of a real world object; an unsatisfied M&S capability. An M&S capability that is outside the scope or vision of a model or simulation. See M&S Capability.
modeling and simulation dataData used to develop models or simulations, data used as input to models and simulations, and data produced by models and simulations.DoDD 5000.59, Change 1, 15 October 2018
modeling and simulation developerThe individual, group or organization responsible for developing or modifying a simulation in accordance with a set of design requirements and specifications.
modeling and simulation limitationThe model or simulation contains aspects of the needed behavior of a real world object but does not completely satisfy functionality and/or faithfulness requirements; a partial implementation of an M&S capability available for use. See M&S Capability. MIL-STD-3022, Change 1, 5 April 2012
modeling and simulation productA composition of M&S applications into a configuration that represents the system suitable or tailored to meet objectives of a venue or event. See M&S Applications MDA M&S Intended Uses Document, 20-Apr-2015, Admin Change 1, 01-Jul-2020
modeling and simulation proponentThe DoD component organization that has primary responsibility to initiate development and life-cycle management of the reference version of one or more models and/or simulations.MIL-STD-3022, Change 1, 5 April 2012
modeling and simulation services1. An activity that enhances the ability to effectively and efficiently use M&S to accomplish a mission.
2. Examples include M&S standards development and promulgation, interoperability, Verification, Validation, and Accreditation (VV&A) process development, and workforce development.
1. DoDD 5000.59, Change 1, 15 October 2018
2. DoDI 5000.70, Change 3, 15 Oct 2018 addition
modeling and simulation toolsSoftware that implements a model or simulation or an adjunct tool, i.e., software and/or hardware that is either used to provide part of a simulation environment (e.g., to manage the execution of the environment) or to transform and manage data used by or produced by a model or simulation. Adjunct tools are differentiated from simulation software in that they do not provide a virtual or constructive representation as part of a simulation environment.DoDD 5000.59, Change 1, 15 October 2018
modeling and simulation userM&S User is the term used to represent the organization, group, or person responsible for the overall application. The M&S User needs to solve a problem or make a decision and wants to use modeling or simulation to do so. The M&S User defines the requirements, establishes the criteria by which model or simulation fitness will be assessed, determines what method or methods to use, makes the accreditation decision, and ultimately accepts the results.MIL-STD-3022, Change 1, 5 April 2012
modeling languageA semiformal language that defines the kinds of elements allowed into the model, the allowable relationships between them, and—in the case of a graphical modeling language—the set of notations you can use to display the elements and relationships on diagrams.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
modeling methodA documented set of design tasks that a modeling team performs to create a system model; a documented set of design tasks that ensures that everyone on the team is building the system model consistently and working toward a common end point.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
model-in-the-loopThe simulation of an embedded system in an early development stage for designing control strategies using a representative system model. Extremely fast development occurs at this stage as you can make small changes to the control model and immediately test the system. NAFEMS Glossary
model-test-modelAn integrated approach to using models and simulations supporting pretest analysis and planning; conducting the actual test and collecting data; and supporting post-test analysis of test results along with further validation of the models using the test data.Piplani. Systems Acquisition Managers Guide for the Use of Models and Simulations
Monte Carlo simulationA simulation in which random statistical sampling techniques are employed to determine estimates for unknown values; i.e., making a random draw.SISO-REF-020-2007
multi-domain operationsOperations conducted across multiple domains and contested spaces to overcome an adversary’s (or enemy’s) strengths by presenting them with several operational and/or tactical dilemmas through the combined application of calibrated force posture; employment of multi-domain formations; and convergence of capabilities across domains, environments, and functions in time and spaces to achieve operational and tactical objectives.TRADOC Pamphlet 525-3-1
multi-resolution modelingRepresents aspects of the real world at more than one level of detail.NATO M&S Standards Profile
natural modelA model that represents a system by another system that already exists in the real world; for example, a model that uses one body of water to represent another.IEEE 610.3-1989
needAn operational capability description that describes what the system will accomplish and how well.Defense Acquisition Guidebook; Chapter 3 - System Engineering
net-centricRelating to or representing the attributes of a robust, globally interconnected network environment (including infrastructure, systems, processes, and people) in which data are shared timely and seamlessly among users, applications, and platforms.DAU Glossary
numerical modelA mathematical model in which a set of mathematical operations is reduced to a form suitable for solution by simpler methods such as numerical analysis or automation; for example, a model in which a single equation representing a nation's economy is replaced by a large set of simple averages based on empirical observations of inflation rate, unemployment rate, gross national product, and other indicators;  A model whose properties are expressed by numbers.IEEE 610.3-1989
objectA fundamental element of a conceptual representation that reflects the "real world" at levels of abstraction and resolution appropriate for interoperability.  A representation of a real-world physical item or phenomenon in the synthetic environment.  High Level Architecture Glossary
object codeComputer instructions and data definitions in a form that is output by an assembler or compiler. Typically machine language.DAU Glossary
object flowConvey instances of matter, energy, or data flow through an activity from one node to another when the activity executes during system operation.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
object model templateThe format and syntax (but not content) of High Level Architecture object models as standardized in IEEE 1516.2. IEEE 1516.2
object nodeAnother kind of node that can exist within an activity, models the flow of object tokens through an activity (where each object token, again, represents an instance of matter, energy, or data). An object node most often appears between two actions to convey that the first action produces object tokens as outputs, and the second action consumes those object tokens as inputs.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
objectiveThe clearly-defined, decisive, specific, and attainable statements that describe the desired outcomes allocated to an event. M&S efforts or actions intended to attain or accomplish a purpose.
ontology1. The formal definition of the types, properties, and relationships of entities that exist in a particular domain.
2. The philosophical study of being. More broadly, it studies concepts that directly relate to being, in particular becoming, existence, reality, as well as the basic categories of being and their relations.
1. American Productivity & Quality Center
2. Merriam-Webster Dictionary, https://www.merriam-webster.com/
open architectureA technical architecture that adopts open standards supporting a modular, loosely coupled and highly cohesive system structure that includes publishing of key interfaces within the system and full design disclosure.DAU Glossary
open standardsWidely accepted and supported standards set by recognized standards organizations or the marketplace. These standards support interoperability, portability, and scalability and are equally available to the public at no cost or with a moderate license fee.DAU Glossary
open systemA system whose technical architecture adopts open standards and supports a modular, loosely coupled, and highly cohesive system structure. This modular open architecture includes publishing of key interfaces within the system and relevant design disclosure.DAU Glossary
operationRepresents a behavior that a block performs when a client calls it.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
operational conceptA verbal and graphic statement of an enterprise’s assumptions or intent in regard to an operation or series of operations of a system or a related set of systems. The operational concept is frequently developed as part of a system development or acquisition program. The operational concept is designed to give an overall picture of the operations using one or more specific systems, or set of related systems, in the enterprise’s operational environment from the users’ and operators’ perspective.J. R. v. Gaasbeek, "Operational Concept," in 11th Annual Systems Engineering Conference; National Defense Industrial Association, San Diego, October 23, 2008.
operational effectivenessMeasure of the overall ability of a system to accomplish a mission when used by representative personnel in the environment planned or expected for operational employment of the system considering organization, doctrine, tactics, supportability, survivability, vulnerability, and threat.DAU Glossary
operational environmentA composite of the conditions, circumstances, and influences that affect the employment of capabilities and bear on the decisions of the commander JP 3-0
operational test and evaluationThe field test, under realistic conditions, of any item (or key component) of weapons, equipment, or munitions for the purpose of determining the effectiveness and suitability of the weapons, equipment, or munitions for use in combat by typical military users, and the evaluation of the results of such tests.DAU Glossary
operatorRepresents personnel who are the consumers (typically those who will actually operate the system the M&S represents) of the model or simulation and includes a normal operator, maintenance operator, operational support, planner, analyst, trainer, trainee, and integrator.I. F. Alexander, "A Taxonomy or Stakeholders: Human Roles in System Development,"
overlayGeometric-based data with a set of attributes overlaid on terrain, clothing to define/provide a functionality. For example, a camouflage pattern on an agent. IWARS 5.1 Methodology Guide
packageA general-purpose mechanism for organizing model elements and diagrams into groups. Packages define unique namespaces for model elements defined within their scope.
package diagramUsed to display the way a model is organized in the form of a package containment hierarchy. A package diagram may also show the model elements that packages contain and the dependencies between packages and their contained model elements.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
parametric modelA model using parametric equations that may be based on numerical model outputs or fits to semi-empirical data. A Parametric equation is a type of equation that employs an independent variable called a parameter and in which dependent variables are defined as continuous functions of the parameter and are not dependent on another existing variable.M&S Educational Training Tool (MSETT) Navy Air Weapons Center Training Systems Division Glossary
parametric modelingA form of CAD product design in which surfaces, features, and other design elements can be defined by a set of mathematical, geometric, and logical functions that describe the relationships among these elements. This approach enables models that can be semi-automatically updated based on changes to the underlying parameters used in the embedded geometric, logical, or mathematical functions.CIMdata PLM Glossary https://www.cimdata.com/en/resources/about-plm/cimdata-plm-glossary
pedigree of data1. Addresses the accuracy, correctness, completeness, and timeliness of a data element, and its compliance with established standards.
2. (T&E) Accurately documenting the configuration of the test asset and the actual test conditions under which each element of test data were obtained. It indicates whether the test configuration represented operationally realistic or representative conditions.
1. https://financialtechnologytoday.com/data-lineage-pedigree-one/
2. DoDI 5000.89, November 19, 2020
perceived truthAn observer's interpretation of the situation; it may not correspond to actual conditions due to the influences of sensors, human perspective, judgment, and/or other factors.
Petri net modelAn abstract, formal model of information flow, showing static and dynamic properties of a system defined by places, transitions, input function, and output function. It graphically depicts the structure of a distributed system as a directed bipartite graph with annotations.IEEE 610.3-2009
physical data modelA model that defines the structure of the various kinds of system or service data that are utilized by the systems or services in the architecture.  DoDAF 2.02
physical environment An environment that includes both natural and man-made features, and the external objects, conditions, and processes that influence the behavior of a system.
physical immersionSituation of presenting a virtual world to users based on their location and orientation and providing synthetic stimuli to one or more of their senses in response to their position and actions.Burdea, Grigore. Virtual reality technology
physical modelA model whose physical characteristics resemble the physical characteristics of the system being modeled; for example, a plastic or wooden replica of an airplane. A mock-up. See: Mock Up; Scale Model.IEEE 610.3-1989
physics-based modelMathematical models in which the equations that constitute the model are those used in physics to describe or define physical phenomenon being modeled.Committee on Modeling and Simulation Enhancements for 21st Century Manufacturing and Defense Acquisition, and National Research Council. Modeling and Simulation in Manufacturing and Defense Acquisition: Pathways to Success
portRepresents a distinct interaction point at the boundary of a structure through which external entities can interact with that structure—either to provide or request a service or to exchange matter, energy, or data. Can be connected to one another by connectors on an internal block diagram to support the interactions between parts.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
precision1. The quality or state of being clearly depicted, definite, measured or calculated.
2. A quality associated with the spread of data obtained in repetitions of an experiment as measured by variance; the lower the variance, the higher the precision.
3. A measure of how meticulously or rigorously computational processes are described or performed by a model or simulation.
1-3. D. C. Gross, "Report from the Fidelity Implementation Study Group,"
predictive modelA model in which the values of future states can be predicted or are hypothesized; for example, a model that predicts weather patterns based on the current value of temperature, humidity, wind speed, and so on at various locations.IEEE 610.3-1989
prescriptive modelA model used to convey the required behavior or properties of a proposed system.IEEE 610.3-1989
probabilistic modelSee: stochastic model.
processA process is a logical sequence of tasks performed to achieve a particular objective. A process defines “WHAT” is to be done, without specifying the method (the “HOW”) by which each task is performed. See also: method.Estefan, Jeff A., Survey of Model-Based Systems Engineering (MBSE) Methodologies Rev. B, INCOSE, 23 May 2008
process modelA model that defines the functional decomposition and the flow of inputs and outputs for a system.Buede, Dennis M. Engineering design of systems models and methods.
product and manufacturing informationData pertinent to manufacturing a product including information such as tolerances, reference dimensions, datum points for quality processes, surface finish, material specifications, etc. This data has historically been included in drawings to be used in manufacturing operations. MCAD solutions may also store the PMI in the 3D CAD model, from where it can be added automatically to drawings or accessed by viewing the 3D CAD model.https://www.cimdata.com/en/resources/about-plm/cimdata-plm-glossary
product lifecycle managementA strategic business approach that applies a consistent set of business solutions in support of the collaborative creation, management, dissemination, and use of product definition information across the extended enterprise, and spanning from product concept to end of life—integrating people, processes, business systems, and informationhttps://www.cimdata.com/en/resources/about-plm/cimdata-plm-glossary
project infrastructure needsInfrastructure needs, including commitments to external stakeholders, derived from and requiring coordination with the organization.NAFEMS Glossary
proprietaryA technological design or architecture that may not be duplicated without permission from the designer or architect.DoDI 5000.70, Change 3, 15 Oct 2018
protocol(modeling and simulation) A set of rules and formats (semantic and syntactic) that define the communication behavior of simulation applicationsIEEE 610.3-1989
Protocol Data Unit (PDU)(Distributed Interactive Simulation) A unit of data that is passed on a network between simulation applications according to a defined protocol. IEEE 1278
prototypeA preliminary type, form, or instance of a system that serves as a model for later stages or for the final, complete version of the system.IEEE 610.3-1989
provided interfaceDisplayed using the ball notation; a block that provides an interface must implement all of the interface’s operations and receptions.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
proxy portProvides external access to and from the features of its parent block or the block’s parts without modifying its inputs or outputs. Typed by an interface block that specifies the features that can be accessed via the port.A Practical Guide to SysML: The Systems Modeling Language / Sanford Friedenthal, 2014
qualitative modelA model that provides results expressed as a non-numeric description of a person, place, thing, event, activity, or concept.
quantitative modelModel that provides answers that are numerical.Buede, Dennis M. Engineering design of systems models and methods.
quality assuranceA planned and systematic pattern of all actions necessary to provide confidence that adequate technical requirements are established, that products and services conform to established technical requirements, and that satisfactory performance is achieved.DAU Glossary
queuing modelA model consisting of service facilities, entities to be served, and entity queues (e.g., a model depicting teller windows and customers at a bank).SISO-REF-002-1999
real time systemPertaining to a system or mode of operation in which computation must be performed during the actual time that an external process occurs in order to allow computational results to respond to external processes.DAU Glossary
Real-timeSimulated time advances at the same rate as actual time.IEEE 1278.2-1995
real-time clockAn electronic device that measures the passage of time. The real-time clock is responsible for the synchronization of real time and simulated time.Cellier, Francois E., and Ernesto Kofman. Continuous System Simulation.
receptionRepresents a behavior that a block performs when a client sends a signal that triggers it.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
reference associationA Reference Association between two blocks means that a connection can exist between instances of those blocks in an operational system. And those instances can access each other for some purpose across the connection.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
referentA codified body of knowledge about a thing being simulated. See also: development referent, and validation referent.SISO-REF-002-1999
refine relationshipA kind of dependency. Conveys that the element at the client end is more concrete (i.e., less abstract) than the element at the supplier end.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
regression testingComparing current and historic test data to determine what data has changed and if a difference in data results is acceptable. Ensure that updates to application software and/or operating systems have not introduced new faults.MDA M&S Intended Uses Document, 20-Apr-2015, Admin Change 1, 01-Jul-2020
reliabilityReliability is a measure of the probability that the system will perform without failure over a specific interval, under specified conditions.DAU Glossary
reliability modelA model used to estimate, measure, or predict the reliability of a system.IEEE 610.3-1989
repeatabilityAbility of a model or simulation to accurately recreate responses under identical stimuli.Barfield, Woodrow, and Thomas Caudell. Fundamentals of Wearable Computers and Augmented Reality
representationModels of the entity or phenomenon associated and its effects. Representations using algorithms and data that have been developed or approved by a source having accurate technical knowledge are often considered authoritative.AFP 16-10 2006
required interfaceDisplayed using the socket notation; A block that requires an interface may invoke one or more—but not necessarily all—of its operations or receptions at some point during system operation.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
requirementA statement that identifies a system, product or process characteristic or constraint, which is unambiguous, clear, unique, consistent, stand-alone (not grouped), and verifiable, and is deemed necessary for stakeholder acceptability.NAFEMS Glossary (https://www.nafems.org/publications/glossary/)
requirements analysisThe process of studying user needs to arrive at a valid definition of system, functional, hardware, and software requirements.Alexander Kossiakoff, "Systems Engineering Principles and Practice, 2nd Edition" May 2011.
requirements creepThe tendency of the user (or developer) to add to the original mission responsibilities and/or performance requirements for a system while it is still in development.DAU Glossary
requirements diagramUsed to display text-based requirements, the relationships between requirements (containment, derive requirement, and copy), and the relationships between requirements and the other model elements that satisfy, verify, and refine them.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
resolution1. The degree of detail used to represent aspects of the real world or a specified standard or referent by a model or simulation.
2. Separation or reduction of something into its constituent parts; granularity.
1. DAU Glossary
2. D. C. Gross, "Report from the Fidelity Implementation Study Group,"
reuse(modeling and simulation) The practice of using again, in whole or part, existing M&S tools, data, or services.DoDD 5000.59, Change 1, 15 October 2018
riskPotential future event or condition that may have a negative effect on achieving program objectives for cost, schedule, and performance. Defined by 1) the probability (greater than 0, less than 1) of an undesired event or condition, and 2) the consequences, impact or severity of the undesired event, were it to occur.DoD, “Risk, Issue, and Opportunity Management Guide for Defense Acquisition Programs,” Office of the Deputy Assistant Secretary of Defense for Systems Engineering, January 2017
runtime infrastructureThe software that provides common interface services during a High Level Architecture (HLA) federation execution for synchronization and data exchange.IEEE 1516.2-2010
satisfy relationshipA kind of dependency. The satisfy relationship is simply a mechanism to allocate a requirement to a structure. The proof of that satisfaction will come from test cases.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
scalabilityThe ability of a simulation to maintain time and spatial consistency as the number of entities and accompanying interactions increase.SISO-REF-002-1999
scale modelA physical model that resembles a given system, with only a change in scale.  Also known as an iconic model.SISO-REF-002-1999
scenario1. Description of an exercise. It is part of the session database that configures the units and platforms and places them in specific locations with specific missions.
2. An initial set of conditions and time line of significant events imposed on trainees or systems to achieve exercise objectives.
IEEE 1730-2010
scene generationThe process of creating electromagnetic representations of the real world in specific bands of interest using physics, behavioral, and phenomenological models. Typical examples of this application include rendering visual imagery for gaming and training and rendering Infrared imagery to stimulate sensors or sensor models.
scene-based simulationA simulation that incorporates scene generation of the environment as detected/viewed by system sensors or seen visually by the human eye.
schemaDescriptive representation of data and/or data requirements that describe conceptual, internal, or external views of information/data needs.SISO-REF-002-1999
scope(modeling and simulation) The range of real or imagined world objects or conditions represented by a particular model, simulation or simulation exercise.SEBoK
semantic interoperabilityThe ability to exchange data in such a way that the precise meaning of the data is readily accessible and the data itself can be translated by any system into a form that it understands.SEBoK
semantics1. The implied meaning of data to define what entities mean with respect to their roles in a system.
2. The relationships of symbols or groups of symbols to their meanings in a given language.
send signal actionA specialized kind of action that asynchronously generates and sends a signal instance to a target when it becomes enabled.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
sensitivityThe ability of a component, model or simulation to respond to a low level stimulus.VV&A Recommended Practices Guide
sensitivity analysisDetermine what model factors have a significant impact on performance measures and, thus, have to be modeled carefully.Simulation-Modeling-and-Analysis-Averill-M.-Law-Edisi-5-2014
sequence diagramUsed to specify a behavior, with a focus on how the parts of a block interact with one another via operation calls and asynchronous signals. Commonly used as a detailed design tool to precisely specify a behavior as an input to the development stage of the life cycle.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
serious gameA game designed for a primary purpose other than pure entertainment
signalDefines a message that can be sent and received by a block. It has a set of attributes that specify the content of the message.A Practical Guide to SysML: The Systems Modeling Language / Sanford Friedenthal, 2014
simulandThe system being simulated by a simulation.SISO-REF-002-1999
simulationA method for implementing a model over time.DoDD 5000.59, Change 1, 15 October 2018, DoDI 5000.61, Change 1, 15 Oct 2018, DoDI 5000.70, Change 3, 15 Oct 2018
simulation data managementA technology which uses database solutions to enable users to manage structures of simulation and process data across the complete product lifecycle. SDM artifacts can be data, models, processes, documents and metadata relevant to modeling, simulation, and analysis.NAFEMS Glossary
simulation environmentThe interconnected infrastructure, software, data, and methodology (process, methods, and tools) used to store, access, analyze, and visualize simulations.DAU Glossary (derived from Digital Engineering Ecosystem)
simulation exerciseAn exercise that consists of a single simulation, or multiple interacting simulation applications.Based on IEEE 1278.1-2012. Rewritten for clarity.
simulation governanceExecutive management policies and procedures assuring that the business benefits of engineering modeling and simulation across the product lines are aligned with the strategic vision and goals of a company.NAFEMS Glossary
simulation managementA process that provides control of the simulation exercise. Functions of simulation management include but are not limited to: start, restart, maintenance, shutdown of the exercise, and collection/distribution of certain types of data.IEEE 1278.1-2012
simulation object modelA specification of the types of information that an individual federate could provide to High Level Architecture (HLA) federations as well as the information that an individual federate can receive from other federates in HLA federations. The simulation object model (SOM) is specified using one or more SOM modules. The standard format in which SOMs are expressed facilitates determination of the suitability of federates for participation in a federation.IEEE 1516.2-2010
simulation timeThe shared time being simulated within a simulation exercise; it may advance faster, slower, or at the same pace as real time.IEEE 1278.1-2012
simulatorA device, computer program, or system that performs simulation.IEEE 610.3-1999
slower than real-timeSimulated time advances at a rate less than actual time.IEEE 1278.2-1995
software engineeringThe application of a systematic, disciplined, quantifiable approach to the development and operations and support (O&S) of software. It is the application of systems engineering (SE) to software, that is, the systematic application of scientific and technical knowledge, methods, and experience to the design, implementation, testing and documentation of software. Typical software engineering tasks include analyzing the system requirements allocated to the software, developing the software requirements, developing the software architecture, designing the software, implementing the software in the code, integrating the software components, and testing the software to verify that the software satisfies the specified requirements allocated to the software component of a system or subsystem. It also may include management issues such as directing program teams, scheduling, and budgeting.DAU Glossary
software maintainabilityThe ease with which a software system, or component, can be modified to correct faults, or improve performance or other attributes.DAU Glossary
software-in-the-loop simulationSimulation and simulators that employ one or more elements of operational software within the simulation/simulator system.Sherman, William R., and Alan Craig. Understanding Virtual Reality Interface, Application, and Design
software-in-the-loop testingIn software-in-the-loop testing, the actual Production Software Code is incorporated into the mathematical simulation that contains the models of the Physical System.  This is done to permit inclusion of software functionality for which no model(s) exists, or to enable faster simulation times.SEBoK
source codeHuman-readable computer instructions and data definitions expressed in a form suitable for input to an assembler, compiler, or other translator.DAU Glossary
specificationA document prepared to support acquisition that describes essential technical requirements for materiel and the criteria for determining whether those requirements are met.MIL-STD-961E, Change 4, July 16, 2020 w/ Change 4
stakeholderA party having a right, share, or claim in a system or in its possession of characteristics that meet that party’s needs and expectations. NOTE: Stakeholder is a broader reference than customer, acquirer, operator, or user and includes those roles as well as others.IEEE 1220-2005
standard portSpecifies an interaction point with a focus on the services that a block provides or requires.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
state1. The internal status of a system, component or simulation as defined by the state variable.
2. Represents a condition or situation during the life of an object during which it satisfies some condition, performs some activity, or waits for some event.
1. Barfield, Woodrow, and Thomas Caudell. Fundamentals of Wearable Computers and Augmented Reality
state invariantA condition that you apply to a specific lifeline at a point preceding (immediately above) a particular event occurrence. That condition must hold true for that lifeline at the moment of that event occurrence in a valid execution of the interaction.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
state machine diagramUsed to specify a behavior, with a focus on the set of states of a block and the possible transitions between those states in response to event occurrences. A precise specification of a block’s behavior that can serve as an input to the development stage of the life cycle.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
static modelA model of a system in which there is no change over time.IEEE 610.3-2009
static variablesVariables that do not change over time.Sokolowski, John A. Principles of modeling and simulation a multidisciplinary approach
steady state(modeling and simulation) A situation in which a model, process, or device exhibits stable behavior independent of time.SISO-REF-002-1999
stealth viewerA component that provides the capabilities for visually observing a simulation exercise without participating in the simulation exercise interaction.Barfield, Woodrow, and Thomas Caudell. Fundamentals of Wearable Computers and Augmented Reality
stereotypeDefines a new kind of model element by adding properties, constraints, or semantics to an existing kind of model element.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
stimulateTo provide input to a real system or subsystem in order to observe or evaluate the response.IEEE 610.3-2009
stimulation(modeling and simulation) The use of simulations to provide an external stimulus to a real system or subsystem.SISO-REF-020-2007
stimulatorA hardware or software device that provides input into an operational system or subsystem.
stochastic modelA model in which the results are determined by using one or more random variables to represent uncertainty about a process or in which a given input will produce an output according to some statistical distribution. Contrast with: Deterministic Model.Reference (Barfield, Woodrow, and Thomas Caudell. Fundamentals of Wearable Computers and Augmented Reality
subsystemA functional grouping of components that combine to perform a major function within an element such as electrical power, attitude control, and propulsion.DAU Glossary
suitabilityThe quality of an entity to provide the capabilities, correctness, accuracy, and usability needed for the intended use or current application. Also referred to as “fitness (for use)”
supportabilityIt includes design, technical support data, and maintenance procedures to facilitate detection, isolation, and timely repair and/or replacement of system anomalies.DAU Glossary
synthetic battlefieldOne type of synthetic environment.
synthetic environmentThe integrated set of data elements that define the environment within which a given simulation application operates. The data elements include information about the initial and subsequent states of the terrain including cultural features, and atmospheric and oceanographic environments throughout an exercise. The data elements include databases of externally observable information about instantiable entities, and are adequately correlated for the type of exercise to be performed.  Also known as virtual world.IEEE 1278.1-2012
synthetic training environmentA capability that will converge current live, virtual, constructive and gaming environments into a single simulation training environment.STAND-TO
systemAn ordered arrangement of components with links to comprise a whole where the components mutually interact together toward achieving a common objective. It can be regarded as a set of interrelated components that perform one or more functions.ISO/IEC 15288
system boundaryRepresents the system that owns and performs the use cases on the diagram.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
system modelRepresents aspects of a system and its environment.https://www.sebokwiki.org/wiki/System_Modeling_Concepts
System Modeling LanguageA general-purpose architecture modeling language for Systems Engineering applications, is a general-purpose graphical modeling language for specifying, analyzing, designing, and verifying complex systems that may include hardware, software, information, personnel, procedures, and facilities.(INCOSE, https://sysml.org/) OMG
system-of-systems1. A collection of independent systems, integrated into a larger system that delivers unique capabilities. The independent constituent systems collaborate to produce global behaviour that they cannot produce alone.
2. Brings together a set of systems for a task that none of the systems can accomplish on its own. Each constituent system keeps its own management, goals, and resources, while coordinating within the SoS and adapting to meet SoS goals.
2. ISO/IEC/IEEE 15288 Annex G (ISO, 2015)
systems engineering1. A transdisciplinary and integrative approach to enable the successful realization, use, and retirement of engineered systems, using systems principles and concepts, and scientific, technological, and management methods.
2. An interdisciplinary approach and process encompassing the entire technical effort to evolve, verify and sustain an integrated and total life cycle balanced set of system, people, and process solutions that satisfy customer needs.
2. DAU Glossary
tailoringThe adaptation of established M&S approaches and processes to improve alignment with complexity, intended purpose, program scope, and program requirements.
taxonomyA kind of metadata that functions as a “common language.” Taxonomy is a hierarchy of categories used to classify content by moving from broad categories to increasingly narrow ones. In the enterprise, taxonomy is used to classify enterprise content to promote consistency across media types, business areas, and/or locations.American Productivity & Quality Center
technical coherenceThe logical traceability of the evolution of a system's data and models, decisions, and solutions throughout the life cycle. DAU Glossary
technical data package1.A description of an item adequate for supporting an acquisition, production, engineering, and logistics support (e.g. Engineering Data for Provisioning, Training, and Technical Manuals
2. Recorded information of scientific or technical nature, regardless of form or character (such as equipment technical manuals and engineering drawings), engineering data, specifications, standards and Data Item Descriptions (DID). Data rights, data delivery, as well as use of any source controlled data as part of this element are included in technical data as are “as maintained” bills of material and system configuration identified by individual configuration item. Technical data does not include computer software or financial, administrative, cost or pricing, or management data or other information incidental to contract administration.
technical debtthe implied cost of additional rework caused by choosing an easy (limited) solution now instead of using a better approach that would take longer.https://en.wikipedia.org/wiki/Technical_debt
terrain databaseA collection of related layers of geospatial data, consisting primarily of terrain elevation data, object geometry, imagery for features and terrain, and feature data and attributes (often in vector form).UK MOD/ Modeling and Simulation Terrain Database Management- USMA 2005
terrain skinThe representation of the terrain database in the model or simulation.
testAn element of verification in which scientific principles and procedures are applied to determine the properties or functional capabilities of items.MIL-STD-961E, Change 4, July 16, 2020 w/ Change 4
Test and Training Enabling ArchitectureA software architecture designed to enhance and enable interoperability, reuse, and composability of software resources among the test and training range and simulation communities. TENA software includes the TENA Middleware and a set of tools and utilities to enable users to create and maintain live-virtual-constructive environments known as logical ranges.TENA Architecture Reference Document
time management(High Level Architecture) Provides a federation execution with the means to order the delivery of messages throughout the federation execution. Use of these mechanisms permits messages sent by different joined federates to be delivered in a consistent order to any joined federate in the federation execution that is to receive those messages.IEEE 1516.1-2010
time stamp (of an event)(modeling and simulation) A value representing a point on the federation time axis that is assigned to an event to indicate when that event is said to occur. Certain message ordering services are based on this time stamp value. In constrained simulations, the time stamp may be viewed as a deadline indicating the latest time at which the message notifying the federate of the event may be processed.SISO-REF-020-2007
time step simulationsSimulations in which simulation time is advanced by a fixed or independently determined amount to a new point in time, and the states or status of some or all resources are updated as of that new point in time. Typically these time steps are of constant size, but they need not be.Military Operations Research Society (MORS) Report: A Taxonomy for Warfare Simulation (SIMTAX)
toolA tool is an instrument that, when applied to a particular method, can enhance the efficiency of the task; provided it is applied properly and by somebody with proper skills and training. The purpose of a tool should be to facilitate the accomplishment of the method (the “HOW”). In a broader sense, a tool enhances the process (the “WHAT”) and the “HOW.” See also: method, and process.Estefan, Jeff A., Survey of Model-Based Systems Engineering (MBSE) Methodologies Rev. B, INCOSE, 23 May 2008
trace relationshipA kind of dependency. conveys nothing more than a basic dependency would: A modification to the supplier element (at the arrowhead end) may result in the need to modify the client element (at the tail end).SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
trackerThe special-purpose hardware used in virtual reality to measure the real-time change in a 3D object position and orientation.Burdea, Grigore. Virtual reality technology
transitionRepresents a change from one state to another. Each transition can specify three optional pieces of information: a trigger, a guard, and an effect.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
Turing testAn informal validation method well suited for validating models of human behavior first proposed as a means to evaluate the intelligence of a computer system.Sokolowski, John A. Principles of modeling and simulation a multidisciplinary approach
uncertainty The degree to which observed or calculated values may differ from their actual values. This estimated difference can be attributed to a variety of factors, such as lack of knowledge (requiring SME estimation), physical/mechanical variation, inherent stochastic behavior, etc.
uncertainty analysisThe process of calculating uncertainty (a.k.a. error) of a value that has been determined from several measured quantities; deals with assessing the uncertainty in a measurement. The error is unavoidable due to the nature of the experiment.NASA-HDBK-8739.19-3," July 13, 2010.
uncertainty quantification The process of identifying and characterizing (e.g., probability distributions) all relevant sources of model uncertainties, experimentally propagating the uncertainties through the model to analyze and characterize the overall impact to model output.
Unified Modeling LanguageA specification defining a graphical language for visualizing, specifying, constructing, and documenting the artifacts of distributed object systems.https://www.omg.org/spec/UML/About-UML/
use caseThe specification of a sequence of actions, including variants, that a system (or other entity) can perform, interacting with actors of the system.ISO/IEC 19501:2005(E)
use case diagramUsed to convey the use cases that a system performs and the actors that invoke and participate in them. A use case diagram is a black-box view of the services that a system performs in collaboration with its actors.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
validation(modeling and simulation) The process of determining the degree to which a model or simulation and its associated data are an accurate representation of the real world from the perspective of the intended uses of the model.DoDI 5000.61, Change 1, 15 Oct 2018
validation referentIn supporting M&S assessment, the referent is concerned with M&S fidelity, validation, and accreditation. The referent provides the information with which M&S results are compared to determine M&S fidelity and validity. That comparison provides factual information to support an accreditation decision. For clarity, when a referent is used in this way, it is helpful to call it an assessment referent or a validation referent.VV&A Recommended Practices Guide
value propertyDescribes the quantitative characteristics of a block.A Practical Guide to SysML: The Systems Modeling Language / Sanford Friedenthal, 2014
varianceA quantifiable deviation, departure, or divergence away from a known baseline or expected value.ISO/IEC/IEEE 24765:2017[E]
venueA live, virtual, and/or constructive environment that employs representations of the Blue Force, Red Force, communication infrastructure, and man-made and natural effects to produce data that services one or more Intended Uses. These representations may include a combination of tactical hardware, tactical software, physical models, simulations, and supporting infrastructure.MDA M&S Intended Uses Document, 20-Apr-2015, Admin Change 1, 01-Jul-2020
verification(modeling and simulation) The process of determining that a model or simulation implementation and its associated data accurately represent the developer's conceptual description and specifications.DoDI 5000.61, Change 1, 15 Oct 2018
verification and validation agent(modeling and simulation) The individual, group, or organization responsible for providing evidence of the simulation's fitness for the intended use by ensuring that all the V&V tasks are properly carried out.VV&A RPG
verification, validation & accreditationThe combined process of performing verification, validation, and accreditation.
viewA representation of a whole system from the perspective of a related set of concerns.ANSI/IEEE 1471-2000
viewpointA viewpoint is a specification of the conventions and rules for constructing and using a view for the purpose of addressing a set of stakeholder concernsSEBoK
virtualAn entity or data that is derived from a modeled or simulated representation of the actual or anticipated system. 
virtual machineA computer file, typically called an image, that behaves like an actual computer. In other words, creating a computer within a computer. It runs in a window, much like any other program, giving the end user the same experience on a virtual machine as they would have on the host operating system itself. The virtual machine is sandboxed from the rest of the system, meaning that the software inside a virtual machine can’t escape or tamper with the computer itself. This produces an ideal environment for testing other operating systems including beta releases, accessing virus-infected data, creating operating system backups, and running software or applications on operating systems they weren’t originally intended for.https://azure.microsoft.com/en-us/overview/what-is-a-virtual-machine/
virtual prototypeA model or simulation of a system placed in a synthetic environment and used to investigate and evaluate requirements, concepts, system design, testing, production, and sustainment of the system throughout its life cycle.SISO-REF-020-2007
virtual realityAn environment represented by models and simulations.  This environment is interactive, allowing the participant to look and navigate about the environment, enhancing the immersion effect. Also known as virtual environment and virtual world.Burdea, Grigore. Virtual reality technology), (Sherman, William R., and Alan Craig. Understanding Virtual Reality Interface, Application, and Design
virtual simulationA simulation involving real people operating simulated systems.DoD M&S Human Capital Strategy
visualizationThe formation of an artificial image that cannot be seen otherwise. Typically, abstract data that would normally appear as text and numbers is graphically displayed as an image. The image can be animated to display time varying data.SISO-REF-020-2007
virtual desktop environment/infrastructureThe hosting of desktop environments on a central server. It is a form of desktop virtualization, as the specific desktop images run within virtual machines (VMs) and are delivered to end clients over a network. Those endpoints may be PCs or other devices, like tablets or thin client terminals.https://www.citrix.com/glossary/vdi.html
wait time actionAn accept event action that waits for a time event occurrence.SysML Distilled : a guide to the systems modeling language / Lenny Delligatti, 2014
wall clock timeTime as determined by a chronometer such as a wristwatch or wall clock.IEEE 1516.2-2010
warfare simulationAny live, virtual or constructive activity in which a warfare model is implemented over time or actual forces conduct scenario-based exercises or training in interaction with symbolic or surrogate opposition forces (OPFOR).
wargameA warfare model or simulation that does not involve the operation of actual forces, and in which the flow of events is shaped by decisions made by a human player or players.Perla, Peter: The Art of Wargaming: A Guide for Professionals and Hobbyists, US Naval Institute Press, 1990, p. 274. Simpson, William: A Compendium of Wargaming Terms, July 2018, pp. 47-48
wargamingThe practice of employing wargame models to simulate warfare for purposes of education, analysis, planning or decision support.Perla, Peter: The Art of Wargaming: A Guide for Professionals and Hobbyists, US Naval Institute Press, 1990, p. 274. Simpson, William: A Compendium of Wargaming Terms, July 2018, pp. 47-48
white box modelA model whose internal implementation is known and fully visible. Also known as a glass box model.IEEE 610.3-1999
white box systemA system where the inner components or logic are available for inspection.SEBoK
workflowThe routine manner in which work gets done by an individual, team, or organization.American Productivity & Quality Center
World Geodetic System 1984Current global reference system expressed as a consistent set of parameters describing the size and shape of the Earth, the positions of a network of points with respect to the center of mass of the Earth, transformations from major geodetic data, and the gravitational potential of the Earth.  Referred to as WGS-84.
world viewThe view each simulation entity maintains of the simulated world from its own vantage point, based on the results of its own simulation and its processing of event messages received from all external entities.  See: entity perspectiveDoD M&S Human Capital Strategy

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