haptic: Refers to all the physical sensors that provide a sense of touch at the skin level and force feedback information from muscles and joints.

hardware in-the-loop simulation: Simulation and simulators that employ one or more pieces of operational equipment (to include computer hardware) within the simulation/simulator system.

head mounted display: Widely used as a visual device for virtual reality and personal video monitors. Graphic images are displayed on a screen or a pair of screens (one for each eye) in the helmet. A tracking sensor attached to the participant's head tells the computer system where the participant is looking. The computer quickly displays a visual image from the vantage point appropriate to the participant's position. Thus, the participant is able to look about a computer-generated world in a manner similar to the real world.

heterogeneous simulation network: A collection of simulations with partially consistent behaviors and/or partially correlated databases. Examples include simulators of different fidelity, mixed virtual and live simulations, and mixes of virtual and constructive simulations.

hierarchical model: A model of information in which data are represented as trees of records connected by pointers.

hierarchy: Hierarchy is a ranking or ordering of abstractions.

High Level Architecture (HLA): 1. A family of related standards that together describe a unified approach and common architecture to constructing interoperable simulation systems. The HLA provides a general framework within which simulation developers can structure and describe their simulation applications. The use of runtime infrastructure software is required to support operations of a federation execution. The runtime infrastructure software provides a set of services, as defined by the federate interface specification, used by federates to coordinate operations and data exchange during a runtime execution. HLA is composed of three parts: the HLA rules, the HLA interface specification, and the object model template. 2. Major functional elements, interfaces, and design rules, pertaining as feasible to all DoD simulation applications, and providing a common framework within which specific system architectures can be defined.

HLA time axis: A totally ordered sequence of values in which each value typically represents an HLA instant of time in the physical system being modeled. For any two points T1 and T2 on the time axis, if T1 < T2, T1 represents an instant of time that occurs before the instant represented by T2.

high resolution model: High resolution simulations are entity level simulations where singular military objects, i.e., a soldier, a tank, an aircraft, are the primary objects represented. They are typically designed for the lower military echelons such as platoon, company and battalion. They can also be used for operational level exercises. In high resolution models the resolution of terrain data is higher than low resolution models, i.e., sometimes up to the plans of individual buildings.

higher order model: A computer model representing combat elements, their functions and/or the terrain they operate on in an aggregated manner. A higher order model may represent a battalion as a specific entity that is a conglomeration or averaging of the characteristics of its real-world components. "Higher Order" generally refers to echelons battalion and above with greater than 100m terrain resolution (i.e., 3km, and with faster than real-time performance, days compressed into minutes, hours into seconds). See: war game.

highly aggregated model: Highly aggregated simulations are aggregate level simulations where collections of military assets, i.e., units, are the primary objects represented. They are designed for the higher military echelons such as corps level. They typically use lower resolution terrain data but they can simulate in very large areas as large as continents.

homogeneous network: A network of objects with fully consistent behaviors and fully correlated databases.

host computer: A computer that supports one or more simulation applications. All host computers participating in a simulation exercise are connected by network(s) including wide area networks, local area networks, and RF links.

human behavioral model: See: behavioral modeling

human behavior representation: The 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.

human centered modeling and simulation: Simulations with a human in the loop and/or one that models human activity and behavior. Human centered M&S is distinguished from science and process based simulations where human intervention and modeling does not occur.

human factors: 1. 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 psychological, cultural, behavioral, and other human attributes that influence decision-making, the flow of information, and the interpretation of information by individuals or groups.

human-in-the-loop: 1. A model that requires human interaction during runtime. See: interactive model. 2. Simulation and simulators that employ one or more human operators in direct control of the simulation/simulator or in some key support function.

human-machine simulation: A simulation carried out by both human participants and computers, typically with the human participants asked to make decisions and a computer performing processing based on those decisions.

human, social, cultural and behavior models: Designed to help understand the structure, interconnections, dependencies, behavior, and trends associated with any collection of individuals. The human, social, cultural and behavior effort seeks to create models for social behavior from the small unit level, such as tribes, militias, small military units, terrorist cells, etc., to the macro level of nations, religions, cultures, ethnic groups and international organizations, and to integrate the two.

hyper text transfer protocol: An application-level protocol for distributed, collaborative, hypermedia information systems.

hypothesis testing: An algorithm or statistical approach that states the alternative to minimize certain risks.

I

iconic model: A physical model or graphical display that looks like the system being modeled; for example, a non-functional replica of a computer tape drive used for display purposes. See: scale model.

identity simulation: A simulation in which the roles of the participants are investigated or defined; for example, a simulation that identifies aircraft based on their physical profiles, speed, altitude, and acoustic characteristics.

immersion: Sensation of being in an environment; can be a purely mental state or can be accomplished through physical means.

implementation: 1. The means by which a synthetic environment, or portions of a synthetic environment, is realized. 2. To give practical effect to and ensure of actual fulfillment by concrete measures.

in-basket simulation: A simulation in which a set of issues is presented to a participant in the form of documents on which action must be taken; for example, a simulation of an unfolding international crisis as a sequence of memos describing relevant events and outcomes of the participant's actions on previous memos.

independent verification and validation: The conduct of verification and validation of a model or simulation by individuals or agencies that did not develop the model or simulation.

inductive modeling: Finding the rule with the cause and the effect. Inductive modeling combines ideas from many other technologies - including simulations, data modeling, expert systems and object-oriented modeling - to apply artificial intelligence to very complex systems such as data networking environments. Inductive techniques include system identification and parameter estimation.

inertial tracker: Self contained sensors that measure the rate of change in an object's orientation. They may also measure the rate of change of an object's translation velocity.

information: 1. Any communication or reception of knowledge such as facts, data, or opinions, including numerical, graphic, or narrative forms, whether oral or maintained in any medium, including computerized databases, paper, microform, or magnetic tape. 2. Any communication or representation of knowledge such as facts, data, or opinions in any medium or form, including textual, numerical, graphic, cartographic, narrative, or audiovisual forms.

information assurance: Measures that protect and defend information and information systems by ensuring their availability, integrity, authentication, confidentiality, and nonrepudiation. This includes providing for restoration of information systems by incorporating protection, detection, and reaction capabilities.

information enterprise: The DoD information resources, assets, and processes required to achieve an information advantage and share information across the Department of Defense and with mission partners. It includes: (a) The information itself and the Department's management over the information life cycle; (b) the processes, including risk management, associated with managing information to accomplish the DoD mission and functions, (c) activities related to designing, building, populating, acquiring, managing, operating, protecting, and defending the information enterprise; and (d) Related information resources such as personnel, funds, equipment, and IT, including national security systems.

information environment: The aggregate of individuals, organizations, or systems that collect, process, disseminate, or act on information.

information model: A model that represents the processes, entities, information flows, and elements of an organization and all relationships between these factors.

information operations: The integrated employment of the core capabilities of electronic warfare, computer network operations, psychological operations, military deception, and operations security, in concert with specified supporting and related capabilities, to influence, disrupt, corrupt or usurp adversarial human and automated decision making while protecting our own.

information system: 1. The organized collection, processing, maintenance, transmission, and dissemination of information in accordance with defined procedures, whether automated or manual. 2. Any equipment, or interconnected system or subsystem of equipment, that is used in the automatic acquisition, storage, manipulation, management, movement, control, display, switching, interchange, transmission or reception of data or information, and includes computers and computer networks, ancillary equipment, software, firmware and similar procedures, services (including support services) and related resources. Notwithstanding the above, the term information technology does not include any equipment that is acquired by a federal contractor incidental to a federal contract. The term information systems is used synonymously with IT (to include National Security Systems).

information technology: 1. The branch of technology devoted to: a. The study and application of data and the processing thereof; i.e., the automatic acquisition, storage, manipulation (including transformation), management, movement, control, display, switching, interchange, transmission or reception of data and b. The development and use of the hardware, software, firmware, and procedures associated with this processing. 2. Any equipment or interconnected system or subsystem of equipment, used in the automatic acquisition, storage, manipulation, management, movement, control, display, switching, interchange, transmission, or reception of data or information by the executive agency, if the equipment is used by the executive agency directly or is used by a contractor under a contract with the executive agency that requires the use of that equipment; or of that equipment to a significant extent in the performance of a service or the furnishing of a product. Information technology includes computers, ancillary equipment, software, firmware and similar procedures, services (including support services), and related resources; but does not include any equipment acquired by a Federal contractor incidental to a Federal contract.

information warfare: Actions taken to achieve information superiority by affecting adversary information, information-based processes, information systems, and computer-based networks, while defending one's own information, information-based processes, information systems, and computer-based networks.

infrastructure: An underlying base or foundation; the basic facilities, equipment, and installations needed for the functioning of a system.

initial condition: The values assumed by the variables in a system, model, or simulation at the beginning of some specified duration of time. Contrast with: boundary condition; final condition.

initial state: The values assumed by the state variables of a system, component, or simulation at the beginning of some specified duration of time. Contrast with: final state.

input/output trace: Typically a time line associated with each major actor in a scenario. The systems involved are listed across the top of the diagram with the time lines running vertically down the page under each of the systems. The progression of time moves from top to bottom in an input/output trace.

instantiation: To represent an abstraction by a concrete instance (e.g., in object oriented programming the creation of a new object (or instance) of a class is called instantiation).

instructional simulation: A 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.

Integrated Definition 0 (IDEF0) & Integrated Definition 1x (IDEF1x) (Entity Relationship diagrams): Functional modeling language(s) sponsored by the Air Force capable of capturing various organizational enterprise operations/functions (IDEF0), and related information requirements (IDEF1x), such as key elements of an invoice.

intellectual property: 1. Property that can be protected under federal law, including copyrightable works, ideas, discoveries, and inventions. Such property would include novels, sound recordings, a new type of mousetrap, or a cure for a disease. 2. Any product of someone's intellect that has commercial value, especially copyrighted material, patents, and trademarks.

intelligent agent: A software entity that carries out a set of operations on behalf of a user with some degree of independence or autonomy, and in so doing, employs knowledge or representation of the user's goals or desires.

interaction: An explicit action taken by a federate that may have some effect or impact on another federate within a federation execution.

interactive graphics: System that can make and manipulate computer generated images not only of concrete, "real world" objects but also of abstract, synthetic objects, such as mathematical surfaces in 4D, and of data that have no inherent geometry, such as survey results.

interaction parameters: The information associated with an interaction that a federate potentially affected by the interaction may receive to calculate the effects of that interaction on its current state.

interactive model: A model that requires human participation.

interactive speed: Attribute of a virtual reality system that reacts "in time" according to actions taken by a user. Such a system must be fast enough to allow a user to perform a task at hand satisfactorily with no perceived delay.

interface specification: Set of structures and/or classes including properties, methods, and/or events which serve to provide a well-defined agreement for which applications (M&S software and adjunct tools), federations, components and/or services can connect and communicate.

internal schema: An internal schema describes data as it is physically stored and includes all aspects of the environment in which the data is to reside.

Internet protocol: A standard protocol designed for use in interconnected systems of packet-switched computer communication networks. The Internet protocol provides for transmitting blocks of data called datagrams from sources to destinations, where sources and destinations are hosts identified by fixed-length addresses. The Internet protocol also provides for fragmentation and reassembly of long datagrams, if necessary, for transmission through small-packet networks.

Internet Protocol version 6 (IPv6): IP version 6 (IPv6) is a new version of the Internet Protocol, designed as the successor to IP version 4 (IPv4). IPv6 increases the IP address size from 32 bits to 128 bits, to support more levels of addressing hierarchy, a much greater number of addressable nodes, and simpler auto-configuration of addresses. The scalability of multicast routing is improved by adding a "scope" field to multicast addresses. And a new type of address called an "anycast address" is defined, used to send a packet to any one of a group of nodes.

interoperability: 1. Interactions between two or more systems affected by allowing information to be exchanged and used by the receiving system. There is an implied level common understanding that is shared between sender and receiver. See: M&S interoperability. 2. The capability, promoted but not guaranteed by joint conformance with a given set of standards, that enables heterogeneous equipment, generally built by various vendors, to work together in a network environment. 3. The ability of a federate to provide services to and/or accept services from other federates and to use the services so exchanged to enable the federates to operate effectively together. 4. The ability to operate in synergy in the execution of assigned tasks. 5. The condition achieved among communications-electronics systems or items of communications-electronics equipment when information or services can be exchanged directly and satisfactorily between them and/or their users. The degree of interoperability should be defined when referring to specific cases. 6. Interoperability exists when different systems exhibit the "same" behavior (performance) when stimulated by a set of standard procedures. The term "same", above, should be framed for a given task or class, be within a specified tolerance or number of anomalies, and with a predefined number of statistically measurable trials. Standard procedures should be layered and decomposed to include but not limited to areas such as update rate, terrain database, models, etc.

interpolation: Estimation of a value based on an established set of collected data within a given data range.

interval-oriented simulation: A continuous simulation in which simulated time is advanced in increments of a size suitable to make implementation possible on a digital system.

irregular warfare: A violent struggle among state and non-state actors for legitimacy and influence over the relevant population(s). Irregular warfare favors indirect and asymmetric approaches, though it may employ the full range of military and other capacities, in order to erode an adversary's power, influence, and will.

J

Joint Capability Technology Demonstration: A demonstration of the military utility of a significant new technology and an assessment to clearly establish its operational utility and system integrity.

joint modeling and simulation: Representations of joint and Service forces, capabilities, equipment, materiel, and services used by the joint community or by two, or more, Military Services.

Joint Training Enterprise Network: The persistent global network connecting live training sites and ranges, constructive models and simulations, virtual simulators, and experimentation sites.

K

kinesthesia: Is the perception of movement or strain from within the muscle, tendons and joints of the body.

knowledge: The rules, environment, etc. that form the structure humans use to process and relate to information, or the information a computer system must have to behave in an apparently intelligent manner.

knowledge-based system: A system in which the domain knowledge is explicit and separate from the system's operational instructions/information.

L

lag: Delay between the measurement of a position and orientation by a tracking apparatus and the report or output of this information to an output device (i.e., scene generator, force feedback apparatus) requiring the orientation or position values.

lag variable: In a discrete simulation, a variable that is an output of one period and an input for some future period; in an analog simulation, a variable that is a function of an output variable and that is used as input to the simulation to provide a time delay response or feedback.

large volume display: Graphics displays that allow several users located in close proximity to simultaneously view a stereo or monoscopic image of the virtual world.

Lambert conformal conic map projection: A conformal map projection of the so-called conical type, on which all geographic meridians are represented by straight lines which meet in a common point outside the limits of the map, and the geographic parallels are represented by a series of arcs of circles having this common point for a center. Meridians and parallels intersect at right angles, and angles on the Earth are correctly represented on the projection. This projection may have one standard parallel along which the scale is held exact; or there may be two such standard parallels, both maintaining exact scale. At any point on the map, the scale is the same in every direction. It changes along the meridians and is constant along each parallel. Where there are two standard parallels, the scale between those parallels is too small; beyond them, too large.

latency: 1. The time delay between action and result. 2. 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. 3. The time interval required for a device to begin output of data after presented with a stimulus or stimuli (i.e., input of data, occurrence of an event). 4. The time required for a device to begin physical output of a desired piece of data once processing is complete. 5. 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).

latency (network): Refers to time delay between any two simulators, from submitting a message from the sending simulation to receiving this message by the recipient simulation.

layered protocol architecture: The communication task is broken up into subtasks, each of which is implemented separately and arranged in a vertical stack. Each layer in the stack performs a related subset of the functions required to communicate with another system. It relies on the next lower layer to perform more primitive functions and to conceal the details of those functions. In provides services to the next higher layer. Ideally, layers should be defined so that changes in one layer do not require change in the other layers.

lead variable: In a discrete simulation, a variable that is an output of one period and that predicts what the output of some future period will be; in an analog simulation, a variable that is a function of an output variable and that is used as input to the simulation to provide advanced time response or feedback.

learning management system: Software that automates learning event administration through a set of services that launches learning content, keeps track of learner progress, determines the order (sequence) that learning objects are to be delivered, and reports student progress through a learning experience.

learning theories: Explanations regarding human learning processes; how to-be-learned material is perceived, cognitively encoded in short-and long-term memory and retrieved independently or as part of other activities (i.e., decision making, problem solving, etc.).

light emitting diode: Photoelectric emitting device used as a light signal.

linear object: A synthetic environment object that is geometrically anchored to the terrain with one point and has a segment size and orientation.

linear programming: Optimization problems in which the object function and the constraints are all linear.

live entity: A perceptible object that can appear in the virtual battlespace but is unaware and non-responsive (either by intent, lack of capability or circumstance) to the actions of virtual entities. See: field instrumentation.

Live Fire Test & Evaluation: A test that involves the firing of actual munitions at targets to examine user casualty, vulnerability and/or lethality issues, and the evaluation of the results of such tests.

live simulation: Live simulation involves real people operating real systems. Military training events using real equipment are live simulations. They are considered simulations because they are not conducted against a live enemy.

live, virtual, and constructive simulation: A broadly used taxonomy describing a mixture of live simulation, virtual simulation, and constructive simulation. Note that live, virtual, and constructive simulations always includes a real or synthetic person in the simulation as contrasted with a science based simulation which models a phenomenon or process only.

local area network: A class of data network that provides high data rate interconnection between network nodes in close physical proximity.

local scene illumination: Treats the interaction between objects and light sources in isolation, neglecting the interdependences between objects.

local time: Time valid for only a component of a system.

logical data model: A model of the data stores and flows of the organization derived from a conceptual business model.

logical time: 1. A federate's current point on the High Level Architecture time axis. Federates making use of the management services follow restrictions on what time stamps can be sent in timestamp order messages (relative to their logical time) to ensure that federates receiving those messages receive them in timestamp order. 2. Measured by ticks of a clock embedded in a model.

logical verification: The identification of a set of assumptions and interactions for which the M&S correctly produces the intended results. Logical Verification determines the appropriateness of the M&S for a particular application and ensures that all assumptions and algorithms are consistent with the conceptual M&S.

long-haul network: A communications network of devices that are separated by substantial geographical distance. A long-haul network could be any of numerous networks available commercially or through the Government that can accommodate the requirements of the Distributed Interactive Simulation or other virtual battlefield for long-distance network services. Synonym: wide area network.

lookahead: Lookahead is a nonnegative value that establishes a lower value on the timestamps that can be sent in timestamp order messages by time-regulating joined federates. Each time regulating joined federate must provide a lookahead value when becoming time-regulating.

loosely coupled: A condition that exists when simulation entities are not involved in very close interaction such that every action of an entity does not need to be immediately accounted for by the other entities. Two tanks moving over terrain five miles apart from each other is an example of a loosely coupled situation.