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Name | Documentation |
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Action | A non-interruptible function. Note: An action represents an atomic unit of processing or work. Actions may be continuous or discrete. Discrete actions may or may not be assumed to execute in zero time. |
Activation/deactivation event | An event that occurs when a function is activated or deactivated. |
Activation/deactivation requirement | The activation or deactivation that one or more functions must satsify when specified events and conditions occur. |
Activation/deactivation rules | The logic which determines when one or more functions are activated and deactivated. |
Activation time | The interval of time that a function or state is active. |
Activity | One or more related actions. |
Analysis | The process of evaluating elements, properties and associated relationships. |
Analysis model | A model used to analyze the structure, behavior, and/or properties of systems and environments. |
AP-233 | ISO STEP Application Protocol for Systems Engineering Data Interchange Standard |
Arc | An association between two or more nodes. |
Association | Refer to UML specification |
Behavior | The activation/deactivation of one or more functions. Note: This describes how a system interacts with its environment. Reactive behavior includes the stimulus and response. |
Behavior allocation | The allocation of functions and/or states to systems, and the allocation of inputs and outputs to system ports. |
Boolean | Refer to UML specification |
Category | A partitioning of elements based on a classification. |
Complex number | A number which can includes a real and imaginary part. |
Component | A constituent part of an element or system that contributes to the properties and behaviors of the whole (emergent). Note: A leaf component does not have constituent parts. |
Composite function | A function which is decomposed into lower level functions. |
Composite state | A state which includes nested states. |
Concurrent state | A state which is active at the same time as another state that is part of the same composite state. |
Condition | An expression with a discrete output, which is true as long as the expression evaluates true, and is false otherwise. |
Connecting component | A specialized component or system, whose primary function is to connect the outputs from one system to the inputs of another system via its ports. Note: This may be a wire, network, or mechanical coupler that has properties and behaviors, which may transform the inputs and outputs. |
Connection | Identification of which ports connect to one another. |
Connection path | Multiple connections that may represent a single logical connection. |
Continuous time model | A model which is based on properities that vary continuously with time. |
Control input | An input that activates or deactivates a function. |
Control operator | A specialized function that provides logic to transform input events and conditions to discrete values that are supplied as control inputs to functions. |
Data | A component of information. |
Data type | Refer to UML specification |
Decomposition | A description of a whole in terms of its component parts. |
Dependency | A relationship where a change to one entity results in a change to the other. |
Deployment | A allocation of one component to another that is often associated with the utilization of resources across the distributed nodes of a system. |
Design | The process of transforming requirements to an implementation. |
Design constraint | A requirement that one or more components of a system must satisfy. Note: This term is sometimes used to refer to a constraint on the design process versus the system. |
Diagram interchange | The ability to exchange notational information on a diagram, including the layout of the diagram. |
Discrete time model | A model which is based on properities that vary discretely with time. |
Domain | A scope that encompasses a set of entities and relationships that may be addressed by the model. |
Effectiveness measure | A criterion for system optimization that is critcial to the success of the mission. Note: The criterion are often used to support trade studies to select among alternatives, as well as to optimize a given design. |
EIA 632 | A process standard for Engineering a System. |
Element | Anything of interest to the modeler, which is uniquely identifiable and can be characterized by a set of properties. |
Enabling system | Any system which may be needed to support another system throughout its life cycle, and typically includes the development, production, deployment, support, and disposal systems. |
Enumerated value | Refer to UML specification |
Environment | A collection of systems and elements that interact either directly or indirectly with the system of interest. |
Event | A noteworthy occurrence that occurs at the instant of time when a specified expression evaluates true. |
Execution | The state of the system or model when it is running. For a model, this implies that model computation is occuring. |
Expression | Refer to UML specification |
Facility | A physical infrastructure that supports use of equipment and other resources. |
Failure | An inability to satsify a requirement. |
Fork | A control operator which enables all of its outputs, when the input is evaluated true. |
Function | A transformation of inputs to outputs that may include the creation, monitoring, modification or destruction of elements, or a null transformation. |
Function port | A binding of an input to the arguments of a function. |
Function time-line | A representation of the interval of time that one or more functions and/or states are active and inactive. |
Functional requirement | A function a system must perform. |
Generalization | The factoring of common features to characterize a more general concept. |
Geometric model | A model of the geometric relationships associated with one or more elements. |
Hardware | A component of a system that has geometric contstraints. |
IDEF0 | Air Force Standard for process modeling. |
Input/Output | An element that is subject to a transformation by a function. |
Instance | A unique model element in a set that iis defined by the general features of its classifier. |
Integer | A whole number |
Interaction | Emergent behavior that results from two or more dependent behaviors Note: A system or component interacts with other components its environment, to yield an emergent system behavior from the individual component behaviors . |
Interface | The inputs, outputs, ports, connections, connecting components (i.e. harness), and associated information that support one or more interactions between systems. Note: The UML definition of interface also includes the operations that must be performed in response to the inputs or invocations. |
Interface requirement | An interface a system must support. |
ISO 15288 | A process standard for system life cycle processes. |
Issue (technical) | A potential problem, that requires resolution. |
Iteration loop | A specialized loop where the loop repeats a specified number of times. |
Join | A control operator which enables its control output, when all of its inputs are evaluated true. |
Leaf function | A function which is not further decomposed. |
Loop | A control operator which initiates one or more loop functions when the input is evaluated true, and is repeated as long as the loop conditions are evaluated true. |
Manual procedure | A set of operations that provide instructions for a user to perform. |
Mean | The expected value associated with a probability distirbution. |
Merge | A control operator which enables its output, when any of its inputs are evaluated true. |
Mission | The operational context and purpose that the system is intended to support. |
Model (graphical, visual) | A representation of something of interest that includes notation and semantics. |
Model element | A construct that is used to build a model. |
Model interchange | The ability to exchange model information. |
Model view | A subset of model elements and associated relationships, that are of use to the modeler for a particular purpose and context. |
Natural object | An element that is not engineered, and may be part of a system or environment. |
Need | A desired requirement of a stakeholder. |
Nested state | A state which is enabled by its composite state. |
Node | A component of a system that provides resources to support execution. |
Notation | The graphical depiction of a model construct. |
Operational requirement | A requirement which is associated with the operation of a system, and typically includes a combination of functional, interface, and performance requirements. |
Parametric model | An analysis model which defines a set of dependent or logically grouped parametric relationships. |
Parametric relationship | A dependency between properties, such that a change to the value of one property impacts the value of the other property. |
Performance property | A measure of the transformation or response of a function or behavior (i.e response time, etc). |
Performance requirement | A performance property a system must satsify. |
Physical property | A physical characteristic of a system or element (i.e. weight, color). |
Physical requirement | A physical property a system must satsify. |
Port | The part of a system or component that provides access between a system’s behaviors and properties, and its environment. Note: this is sometimes referred to as an interaction point. |
Probability distribution | A mathematical function which defines the likelihood of a paritcular set of outcomes. |
Probe | A component that monitors the values associated with one or more parameters (i.e. properties). |
Problem | A deficiency, limitation, or failure to satisfy a requirement or need, or other undesired outcome. Note: A problem may be associated with the behavior, structure, and/or properties of a system or element at any level of the hierarchy (i.e. system of system level, down to a component/part level). |
Problem cause | The relationship between a problem and its source problems (i.e. cause). Note: This cause affect relationship is often represented in fishbone diagrams, fault trees, etc. |
Process | A set of inter-related functions and their corresponding inputs and outputs, which are activated and deactivated by their control inputs. |
Property | A quantifiable characteristic. |
Property association | The assignment of a property to a model element or set of model elements. |
Property attribute | |
Property value | Unique state of a property. |
Real number | A number which can have any value from negative infinity to infinity. |
Replicate function | A function which represents the same transformation, but is implemented by separate resources. |
Requirement | The capability, behavior, structure, and/or properties that a system, component, or element must satisfy. Note: This is used to establish a contract between the customer (or stakeholder) and implementer. |
Requirement allocation | The assignment of a requirement to an element, component, or system. |
Requirement attribute | An attrirbue fo a requirement, which may include its criticality or weighting, level of uncertainty, verification status, etc. |
Requirement traceability | The relationship between a source requirement and the derived requirements needed to satisfy the source requirement. |
Requirement type | A category of requirement. Note: This includes functional, interface, performance, etc. |
Requirement verification | A comparison between a requirement and the verification results that is intended to satisfy the requirement. |
Resource | Any element that is needed for the execution of a function. |
Role | |
Scalable | A measure of the extent to which the modeling langauge (or methodology, etc), can be adapted to an increase in scope and/or complexity. |
Selection | A control operator which represents a test that enables an output based on the values/conditions of the input. |
Semantics | The meaning of a model element. Note: a precise meaning should be able to be expressed mathematically. |
Sequential state | A state which can only be active when the other sequential states are not active. |
Simple state | A state that does not have nested states. |
Software | A component of a system that specifies instructions which are executed by a computer. |
Source requirement | The requirement which is the basis for deriving one or more other requirements. |
Spatial representation | A geometrical relationship among elements. |
Specialization | A classification of an entity (e.g., element, system, function, requirement, …), which specifies the common features of the more general element, and unique features of the specific element. |
Specialized requirement | A requirement that is not explicitly addressed by the default requirement types. Note: This may include safety, reliabillity, maittianability, producibility, usability, security, etc. |
Specialty engineering | A general term for engineering disciplines associated with some specific aspects of a system, suchas reliability or safety engineering. |
Specification | One or more requirements for a system, component or element. |
Stakeholder | Individuals, groups, and/or institutions which may be impacted by the system throughout its life cycle, including acquisition, development, production, deployment, operations, support, and disposal. |
State (finite) | A condition of a system or element, as defined by some of its properties, which can enable system behaviors and/or structure to occur. Note: The enabled behavior may include no actions, such as associated with a wait state. Also, the condition that defines the state may be dependent on one or more previous states. |
State based behavior | Behavior which is described by states and transitions between states. |
Storage device | A component of a system that is used to store a system store. Note: this may include memory device, a battery, or a tank. |
Store requirement | An element a system must store. |
String | A value represented by alphanumeric characters. |
Structure | The relationships between the components that contribute to the properties of the whole, and enable them to interact (inter-relate). |
Subsystem | A logical or physical partitioning of a system. |
System | An element, with structure, that exhibits observable properties and behaviors. |
System (component) boundary | The set of all ports, which connect the system (component) to its environment. |
System context | A depiction of the inputs and outputs between a system and its environment. |
System hierarchy | A decomposition of a system and its components. |
System interconnection | The connection between systems and between components. |
System role | A subset of its behaviors, properties, and structure. Note: The subset may be associated with specific interactions. |
System store | An input/output element that persists over time, which may be depletable or non-depletable. Note: Non-depletable stores may include data store in computer memory, and depletable stores may include energy in a battery, or fluid in a tank. Physical stores obey the conservation laws (only take out what is put in). A non-depletable store, such as a data store, is not constrained by the conservation laws. The system store should be differentiated from the storage device, which stores the element. |
Test case | The input stimulus, expected output, and associated test criteria which verify that the system satisfies its requirements or needs. |
Test scenario | A scenario which replicates the behavior of the environment that interacts with the system under test. |
Text based requirement | One or more requirements specified in text. |
Thread | A process with no concurrent functions, and represents a single path of execution. |
Time property | A property of the model that represents a local or global time, which other properties may depend on. Note: The property can support continuous or discrete-time models. This variable should not be confused with the measured or computed time that an actual system uses, which depends on a number of implementation specific factors related to clocks, synchronization, etc. |
Topology | A graph of nodes and arcs. |
Trade-off study | An evaluation of alternatives based on a set of evaluation criteria. |
Transition | Response to events/conditions, which triggers a behavior. |
Triggering input | An input which is required for a function to be activated. |
UML | |
User | An individual or group of individuals that use a system. |
Validation | The process for demonstrating that a system or its requirements satisfy the stakeholder needs. |
Variance | A measure of the distribution about the mean of a probability distribution. Refer to the mathematical definition associated with a probability distribution. |
Vector | A data type, which specifies a magnitude and direction. |
Verification | The process for demonstrating a system satisfies its requirements. |
Verification procedure | The functions needed to support execution of a test case. Note. This may include generating an input stimulus and monitoring an output |