Snippets (text quotes and extracts from authoritative sources)

A Snippet is a short quote or extract (typically a phrase, a sentence, or at most a few sentences) from an authoritative source document such as a specification, technical manual, or design manual. Throughout this site, content is often related to supporting Snippets and each Snippet page links back to the content pages that reference it! The Snippet and Note concepts are very closely related and they support each other.

The Snippet concept is also at the heart of the Parsing Analysis recipe for UML® and SysML®

Kind Snippet quote/extract Source UML keywords SysML keywords Keywords
INFO Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency of approximately 30 PHz) to 400 nm (750 THz), shorter than that of visible light but longer than X-rays. Wikipedia UV radiation, electromagnetic radiation, ultraviolet
INFO Typical examples of across variables, that we will be discussing shortly, are temperature, voltage and pressure. Differences in these quantities typically lead to dynamic behavior in the system. Modelica By Example Modelica, acausal connection
CONSTRAINT two_input_parameters If the DecisionNode has a decisionInputFlow and a second incoming ObjectFlow, then any decisionInput has two in Parameters ... Unified Modeling Language 2.5.1 DecisionNode, ObjectFlow, ObjectNode, ActivityNode::incoming, ActivityEdge, DecisionNode::decisionInputFlow, TypedElement, object token, token, TypedElement::type, Type
CONSTRAINT, INFO Two UseCases specifying the same subject cannot be associated as each of them individually describes a complete usage of the subject. Unified Modeling Language 2.5.1 UseCase, UseCase::subject, Behavior, BehavioredClassifier, Association
INFO Two types of history Pseudostates are provided. Unified Modeling Language 2.5.1 State, StateMachine, Vertex, Pseudostate, history, PseudostateKind::deepHistory, PseudostateKind::shallowHistory
INFO Two such InstanceSpecifications represent the same "measurement unit" if and only if their definitionURIs have values and their values are equal. OMG Systems Modeling Language (SysML) 1.6 InstanceSpecification QuantityKind, Unit, Unit::quantityKind, ValueType::quantityKind, Unit::definitionURI, QuantityKind::definitionURI scientific unit system, VIM3
INFO Two such InstanceSpecifications represent the same "kind-of-quantity" if and only if their definitionURIs have values and their values are equal. OMG Systems Modeling Language (SysML) 1.6 InstanceSpecification QuantityKind, Unit, Unit::quantityKind, ValueType::quantityKind, Unit::definitionURI, QuantityKind::definitionURI scientific unit system, VIM3
INFO Two quarks can have their spins aligned, in which case the two spin vectors add to make a vector of length S = 1 and three spin projections (Sz = +1, Sz = 0, and Sz = −1). Wikipedia
INFO Two main classes of leptons exist, charged leptons (also known as the electron-like leptons), and neutral leptons (better known as neutrinos). Wikipedia
INFO Turning the key on starts two behaviors, Driving and Braking. These behaviors execute until the key is turned off, using streaming parameters to communicate with other behaviors. OMG Systems Modeling Language (SysML) 1.6 Behavior, Parameter::isStreaming SysML specification figure
INFO Turning the key on has a duration constraint specifying that this action lasts no more than 0.1 seconds. OMG Systems Modeling Language (SysML) 1.6 DurationConstraint SysML specification figure
CONSTRAINT trigger_with_ports: If a Trigger specifies one or more ports, the event of the Trigger must be a MessageEvent. Unified Modeling Language 2.5.1 Event, Trigger, Trigger::event, Port, Trigger::port, MessageEvent
INFO Trigger::port : Port [0..*] A optional Port of through which the given effect is detected. Unified Modeling Language 2.5.1 Trigger::port, Trigger, Port
INFO Trigger::event : Event [1..1] The Event that detected by the Trigger. Unified Modeling Language 2.5.1 Trigger, Trigger::event
CONSTRAINT Transitions terminating on an exit point within any Region of the composite State or a StateMachine referenced by a submachine State implies exiting of this composite State or submachine State (with execution of its associated exit Behavior). Unified Modeling Language 2.5.1 State, Pseudostate, PseudostateKind::exitPoint, StateMachine, composite State, Region, State::exit, Behavior
CONSTRAINT Transitions terminating on a join Pseudostate cannot have a guard or a trigger. Unified Modeling Language 2.5.1 Pseudostate, PseudostateKind::join, Transition, Transition::guard, Transition::trigger
NOTATION Transitions of the kind internal are not shown explicitly in diagrams. Unified Modeling Language 2.5.1 State, StateMachine, Transition, Vertex, TransitionKind, Transition::kind, TransitionKind::internal, Internal Transition compartment
INFO Transitions are executed as part of a more complex compound transition that takes a StateMachine execution from one stable state configuration to another. Unified Modeling Language 2.5.1 State, StateMachine, Transition, compound transition
INFO TransitionKind is an Enumeration type used to differentiate the various kinds of Transitions. Unified Modeling Language 2.5.1 Transition, TransitionKind, Transition::kind, Enumeration, TransitionKind::internal, TransitionKind::local, TransitionKind::external
INFO Transition::trigger : Trigger [0..*] ... Specifies the Triggers that may fire the transition Unified Modeling Language 2.5.1 State, StateMachine, Transition, Transition::trigger, Trigger
INFO Transition::target : Vertex [1..1] ... Designates the target Vertex that is reached when the Transition is taken. Unified Modeling Language 2.5.1 State, StateMachine, Transition, Vertex, Transition::target
INFO Transition::source : Vertex [1..1] ... Designates the originating Vertex (State or Pseudostate) of the Transition. Unified Modeling Language 2.5.1 State, StateMachine, Transition, Transition::source, Vertex
INFO Transition::redefinedTransition : Transition [0..1] ... The Transition that is redefined by this Transition. Unified Modeling Language 2.5.1 State, StateMachine, Transition, Transition::redefinedTransition
INFO Transition::kind : TransitionKind [1..1] = external Indicates the precise type of the Transition. Unified Modeling Language 2.5.1 State, StateMachine, Transition, Vertex, compound transition, Transition::kind, kind : TransitionKind [1..1] = external
INFO Transition::guard : Constraint [0..1] ... If the guard is true at that time, the Transition may be enabled, otherwise, it is disabled. Guards should be pure expressions without side effects. Guard expressions with side effects are ill formed. Unified Modeling Language 2.5.1 State, StateMachine, Transition, Transition::guard, Constraint, Event, Event occurrence
INFO Transition::guard : Constraint [0..1] ... A guard is a Constraint that provides a fine-grained control over the firing of the Transition. The guard is evaluated when an Event occurrence is dispatched by the StateMachine. ... Unified Modeling Language 2.5.1 State, StateMachine, Transition, Transition::guard, Constraint, Event, Event occurrence
INFO Transition::effect : Behavior [0..1] ... Specifies an optional behavior to be performed when the Transition fires. Unified Modeling Language 2.5.1 State, StateMachine, Transition, Transition::effect, Behavior
INFO Transition::container : Region [1..1] ... Designates the Region that owns this Transition. Unified Modeling Language 2.5.1 State, StateMachine, Transition, Transition::container, Region
INFO Transition::/redefinitionContext : Classifier [1..1] ... References the Classifier in which context this element may be redefined. Unified Modeling Language 2.5.1 State, StateMachine, Transition, Transition::/redefinitionContext
INFO Traditionally, industry has created digital twins by retrospectively mapping, scanning, surveying, digitising or developing a digital copy of a real world object. ANZLIC 2019 - Principles for Spatially Enabled Digital Twins of the Built and Natural Environment in Australia digital twin
INFO Trade studies are commonly used in the design of aerospace and automotive vehicles and the software selection process ... to find the configuration that best meets conflicting performance requirements. Wikipedia trade study, trade-off study
INFO Trace::getTracedFrom (in ref : NamedElement) : AbstractRequirement [0..*] The query getTracedFrom() gives all the requirements that are clients ("from" end of the concrete syntax) of a «Trace» relationship whose supplier is the element in parameter ... OMG Systems Modeling Language (SysML) 1.6 «trace», NamedElement Trace, Trace::getTracedFrom(in ref), AbstractRequirement
INFO Top: The formation of a virtual image using a diverging lens. Bottom: The formation of a virtual image using a convex mirror. In both diagrams, f is the focal point, O is the object and I is the image, shown in grey ... Wikipedia optics, focal point, virtual image, convex mirror
INFO Top: The formation of a real image using a convex lens. Bottom: The formation of a real image using a concave mirror. In both diagrams, f is the focal point, O is the object, and I is the image. Wikipedia real image, optics, convex lens, lens, focal point
INFO Tokens offered to a ForkNode are offered to all outgoing ActivityEdges of the node. If at least one of these offers is accepted, the offered tokens are removed from their original source and the acceptor receives a copy of the tokens. Unified Modeling Language 2.5.1 Activity, Activity Diagram, ControlNode, ForkNode, ActivityNode::outgoing, ActivityEdge
INFO Tokens consumed by an Action are immediately removed from its InputPins when the action begins an execution (except in some cases for StructuredActivityNodes, where tokens may remain on InputPins during the Action execution ...) Unified Modeling Language 2.5.1 Activity, Activity Diagram, Action, Pin, InputPin, Action::/input, MultiplicityElement::/lower, execution, StructuredActivityNode, token, control token, object token
INFO Tokens arriving at a full object node with the Overwrite stereotype applied take up their positions in the ordering as normal, if any. The arriving tokens do not take the positions of the removed tokens. OMG Systems Modeling Language (SysML) 1.6 ObjectNode, MultiplicityElement::/upper, InputPin, Action::/input, token Overwrite, «overwrite»
INFO Tokens arriving at a control InputPin have the same semantics as control tokens arriving at the Action, except that control tokens can be buffered in control Pins. Unified Modeling Language 2.5.1 InputPin, control Pin, Pin::isControl, ObjectNode::isControlType, control token, Action
INFO Tokens are placed on control OutputPins according to the same semantics as tokens placed on ControlFlows coming out of an Actions. Unified Modeling Language 2.5.1 OutputPin, control Pin, Pin::isControl, ObjectNode::isControlType, control token, Action
INFO Today this process can occur in reverse, with the digital model developed first followed by the physical asset. ANZLIC 2019 - Principles for Spatially Enabled Digital Twins of the Built and Natural Environment in Australia digital twin
INFO To signify that only water flows between the pump and the tank, we can specify an ItemFlow of type Water on the connector. OMG Systems Modeling Language (SysML) 1.6 InformationFlow ItemFlow, FlowProperty, FlowDirectionKind::in, FlowDirectionKind::out, FlowDirectionKind
EXAMPLE, INFO To manage the complexity, a hierarchical sequence diagram is used which refers to other interactions that further elaborate the system behavior (“ref StartVehicleBlackBox”). OMG Systems Modeling Language (SysML) 1.6 interactionOperator ref SysML Sequence Diagram
INFO Timing diagrams, while included in UML 2, are not directly supported by SysML. OMG Systems Modeling Language (SysML) 1.6 Timing Diagram
INFO Thus electrons are stable and the most common charged lepton in the universe, whereas muons and taus can only be produced in high energy collisions (such as those involving cosmic rays and those carried out in particle accelerators). Wikipedia
INFO This value type has no unit, reflecting that the signals are not measurements of physical quantities and do not follow conservation laws. SysPhS-1.1 Port Real, Unit, ValueType::unit, ValueType SysPhS, signal processing
INFO This supports linking the execution of the activity with items that are flowing through the activity or assigned to variables or parameters, and happen to be contained by an object node or assigned to a variable or parameter at the time the link exists. OMG Systems Modeling Language (SysML) 1.6 Association, Classifier, ObjectNode, Variable, Parameter Block, ValueType, SysML Block Definition Diagram
EXAMPLE This single signal carries the temperature, rpm, and knockSensor information of the engine. OMG Systems Modeling Language (SysML) 1.6 Signal
INFO This radioactive decay, known as beta decay, is possible because the mass of the neutron is slightly greater than the proton. Wikipedia neutron
INFO This provides a means for representing activity decomposition in a way that is similar to classical functional decomposition hierarchies. OMG Systems Modeling Language (SysML) 1.6 Activity «activity», SysML Block Definition Diagram, Block functional allocation, functional decomposition
INFO This portion of concrete syntax is the same as may be shown for values within the UML instance specification notation, but this is the only element of UML InstanceSpecification notation that may be shown in an initial values compartment. OMG Systems Modeling Language (SysML) 1.6 compartment initial values, initialValues compartment, context-specific values
INFO, NOTATION This notation is purely a notational shorthand for a property that could otherwise be shown within a structure of nested property boxes, with the names in the dotted string taken from the name that would appear at each level of nesting OMG Systems Modeling Language (SysML) 1.6 Property multi-level property path, pathname dot notation, nested Property
EXAMPLE, INFO This non-normative extension includes stereotypes for an objective function and a measure of effectiveness. The objective function is a stereotype of a ConstraintBlock and the measure of effectiveness is a stereotype of a block property. OMG Systems Modeling Language (SysML) 1.6 custom Stereotype, user defined Stereotype «moe», ConstraintBlock, Block, «objectiveFunction» Measure of Effectiveness, objective function, non-normative
EXAMPLE, INFO This means the provided features of ICE are provided by the ctrl port of InternalCombustionEngine, and required by the ice port of PowerControlUnit, while the required features of ICE are required by the ctrl port of InternalCombustionEngine, and provided OMG Systems Modeling Language (SysML) 1.6 Port HSUV sample problem, provided Feature, required Feature, part property, Block
INFO This means that: Not all words appearing between guillemets are necessarily keywords, and words appearing in guillemets do not necessarily represent stereotypes. Unified Modeling Language 2.5.1 «keyword», Stereotype, guillemets UML, MagicDraw UML
INFO This means that the complete semantics of the client Element(s) are either semantically or structurally dependent on the definition of the supplier Element(s). Unified Modeling Language 2.5.1 Dependency, Dependency::client, Dependency::supplier, DirectedRelationship, NamedElement
INFO This means that an Activity model in which non-determinacy occurs may be subject to timing issues and race conditions. It is the responsibility of the modeler to avoid such conditions in the construction of the Activity model, if they are not desired. Unified Modeling Language 2.5.1 ActivityEdge, ActivityNode::outgoing, ActivityNode, token
INFO This is why we want to work with across variables that have not been overly differentiated. Modelica By Example Modelica, acausal connection
INFO This is typically used with fast or continuously flowing data values, to prevent buffer overrun, or to model transient values, such as electrical signals. OMG Systems Modeling Language (SysML) 1.6 ObjectNode, ActivityNode::outgoing, InputPin, Action::/input «noBuffer», NoBuffer
INFO This is typically used on an input pin with an upper bound of 1 to ensure that stale data is overridden at an input pin. OMG Systems Modeling Language (SysML) 1.6 ObjectNode, MultiplicityElement::/upper, InputPin, Action::/input, token Overwrite, «overwrite»
INFO This is a Transition that originates in the history Pseudostate and terminates on a specific Vertex (the default history state) of the Region containing the history Pseudostate. This Transition is only taken if execution leads to the history Pseudostate a Unified Modeling Language 2.5.1 State, StateMachine, Vertex, Transition, Pseudostate, history, PseudostateKind::deepHistory, PseudostateKind::shallowHistory, default history mechanism
INFO This is a major advantage for solar telescopes, where a field stop (Gregorian stop) can reduce the amount of heat reaching the secondary mirror and subsequent optical components. Wikipedia telescope, Gregorian reflector, field stop, optics, primary mirror, secondary mirror
INFO This includes the direction of flow properties on nested ports, and if the port is full and its type is unencapsulated, ports on parts of the port, recursively. The arrows are perpendicular to the boundary lines they overlap. OMG Systems Modeling Language (SysML) 1.6 Port ProxyPort, FullPort, FlowProperty, FlowProperty::direction, FlowDirectionKind::in, FlowDirectionKind::out
INFO This important distinction enables blocks to be interconnected in different ways depending on its usage context. OMG Systems Modeling Language (SysML) 1.6 ItemFlow
INFO This image may be recorded or viewed through an eyepiece, which acts like a magnifying glass. The eye then sees an inverted [DISPUTED] magnified virtual image of the object. Wikipedia optical telescope, telescope, light, image, lens, mirror
INFO This image may be ... viewed through an eyepiece, which acts like a magnifying glass. The eye then sees an inverted magnified virtual image of the object. Wikipedia optical telescope, telescope, light, image, lens, mirror
INFO This image may be ... viewed through an eyepiece, which acts like a magnifying glass. The eye then sees a ... magnified virtual image of the object. Wikipedia optical telescope, telescope, light, image, lens, mirror
EXAMPLE, INFO This diagram expresses only the nominal states. Exception states, like “acceleratorFailure,” are not expressed on this diagram. OMG Systems Modeling Language (SysML) 1.6 State, StateMachine, StateMachine Diagram HSUV sample problem black box, Object Constraint Language
INFO This can be achieved in several ways. For instance by making it behavioral, by binding it to a fully specified internal part or by having all its properties individually bound to internal parts. OMG Systems Modeling Language (SysML) 1.6 Port::isBehavior ProxyPort
INFO This allows a value property (such as an engine displacement) that may be deeply nested within a containing hierarchy (such as vehicle, power system, engine) to be referenced at the outer containing level (such as vehicle-level equations). OMG Systems Modeling Language (SysML) 1.6 Constraint ConstraintBlock, SysML Parametric Diagram, block property, NestedConnectorEnd, pathname dot notation, nested Property mathematics, equation
CONSTRAINT, INFO This aggregate is not a separate element of the system, and only groups the internal parts for purposes of binding to the proxy port. OMG Systems Modeling Language (SysML) 1.6 Port, part, Feature ProxyPort, part property, MD:PartProperty, BindingConnector
INFO They were used for both terrestrial applications and astronomy. Wikipedia telescope, optical telescope, astronomy
INFO They encompass potential or actual physical assets, processes, people, places, systems, devices and the natural environment. ANZLIC 2019 - Principles for Spatially Enabled Digital Twins of the Built and Natural Environment in Australia
INFO They cannot be behavioral ports, or [be] linked to internal parts by binding connectors, because these constructs imply identity with the owning block or internal parts. OMG Systems Modeling Language (SysML) 1.6 Port::isBehavior, Port, Element::owner, internal part FullPort, Block, part property, MD:PartProperty, BindingConnector, owning Block
INFO They are also classified as fermions, i.e., they have half-integer spin. Wikipedia
INFO These viable solutions are judged by their satisfaction of a series of measures or cost functions. These measures describe the desirable characteristics of a solution. They may be conflicting or even mutually exclusive. Wikipedia trade study, trade-off study
INFO These two extensions are useful for ensuring that the most recent information is available to actions by indicating when old values should not be kept in object nodes, and for preventing fast or continuously flowing values from collecting ... OMG Systems Modeling Language (SysML) 1.6 ObjectNode, Pin NoBuffer, «noBuffer», Overwrite, «overwrite»
INFO These specify that the voltage v across the component is equal to the difference between the voltage at the positive and negative pins. The current i through the component is equal to the current going through the positive pin. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock, Block SysPhS
EXAMPLE, INFO These multiplicities may be assumed if not shown on a diagram. To avoid confusion, any multiplicity other than the default should always be shown on a diagram. OMG Systems Modeling Language (SysML) 1.7beta1 Association, AggregationKind, multiplicity, AggregationKind::composite, AggregationKind::shared, MultiplicityElement::upperValue, MultiplicityElement::lowerValue, MultiplicityElement, MultiplicityElement::/lower, MultiplicityElement::/upper, Property::isNavigable(), DirectedRelationship::/target
INFO These include relationships for defining a requirements hierarchy, deriving requirements, satisfying requirements, verifying requirements, and refining requirements. OMG Systems Modeling Language (SysML) 1.6 Requirement, SysML Requirements Diagram, Satisfy, DeriveReqt, Copy, Verify requirements engineering
INFO These include modeling either the logical or physical decomposition of a system, and the specification of software, hardware, or human elements. OMG Systems Modeling Language (SysML) 1.6 Block systems engineering, Model-Based Systems Engineering, SysML, Systems Modeling Language, logical decomposition, physical decomposition, functional decomposition, software, hardware, human, human resource
INFO These flows are usually the result of some difference in the across variables across a component model. For example, current flowing through a resistor is in response to a voltage difference across the two sides of the resistor. Modelica By Example Modelica, acausal connection
INFO These connectors specify instances of the association block created within the instances of the block that owns the connector. OMG Systems Modeling Language (SysML) 1.6 ConnectorProperty, Connector, AssociationClass AssociationBlock, ParticipantProperty
INFO Therefore, the digit "1" may easily be confused with the letter "l". In some computer typefaces, the two characters are barely distinguishable. As a result, L (uppercase letter L) was adopted by the CIPM as an alternative symbol for litre in 1979. Wikipedia litre, units, scientific unit system, volume, SI unit, SI alternative unit, ISO-80000
CONSTRAINT There can be at most one initial Vertex in a Region. Unified Modeling Language 2.5.1 PseudostateKind::initial, Region, Vertex
SEMANTIC There are two kinds of ActivityEdges: Unified Modeling Language 2.5.1 Activity, ActivityEdge, ControlEdge, ObjectFlow
SEMANTIC There are three kinds of ActivityNodes: Unified Modeling Language 2.5.1 Activity, ActivityNode, ControlNode, ObjectNode, ExecutableNode
INFO There are telescope designs that do not present an inverted image such as the Galilean refractor and the Gregorian reflector. These are referred to as erecting telescopes. Wikipedia optical telescope, telescope, light, image, lens, mirror, erecting telescope
INFO There are six types, known as flavors, of quarks: up, down, strange, charm, bottom, and top. Wikipedia
INFO There are six types of leptons, known as flavours, grouped in three generations. Wikipedia
INFO There are several large modern telescopes that use a Gregorian configuration such as the Vatican Advanced Technology Telescope, the Magellan telescopes, the Large Binocular Telescope, and the Giant Magellan Telescope. Wikipedia Gregorian reflector, reflecting telescope, reflector, optical telescope, telescope
INFO there are only two possible values for a spin-1/2 particle: sz = +1/2 and sz = -1/2. These correspond to quantum states in which the spin component is pointing in the +z or −z directions respectively, and are often referred to as "spin up" and "spin down" Wikipedia
INFO There are no precisely defined boundaries between the bands of the electromagnetic spectrum; rather they fade into each other like the bands in a rainbow (which is the sub-spectrum of visible light). Wikipedia electromagnetic radiation, electromagnetic spectrum, visible light, light
INFO Then that set shall be included in (or the same as) a set calculated by eliminating duplicates from the collection of values denoted by the subsettedProperty in the same context. Unified Modeling Language 2.5.1 Property, Property::subsettedProperty
INFO Then it is delivered to a factory, reclassified from a warehouse item to a factory resource (while still being a machine), and records the percentage of time it is operating. OMG Systems Modeling Language (SysML) 1.6 Classifier, Stereotype, Property PropertySpecificType
EXAMPLE, INFO The “refine” relation, introduced in Figure D.12, shows how the Acceleration requirement is refined by a similarly named use case. OMG Systems Modeling Language (SysML) 1.6 UseCase HSUV sample problem, Requirement, Refine
EXAMPLE, INFO The “hybridSUV” lifeline represents another interaction which further elaborates what happens inside the “hybridSUV” when the vehicle is started. OMG Systems Modeling Language (SysML) 1.6 Interaction, Event, Message, Lifeline SysML Sequence Diagram
INFO The Δ baryons have ... a spin of ​3⁄2 ... Wikipedia
EXAMPLE, INFO The «system» and «external» stereotypes are user defined, not specified in SysML, but help the modeler to identify the system of interest relative to its environment. OMG Systems Modeling Language (SysML) 1.6 context diagram, «system», «external»
INFO The «rate» stereotype has a rate property of type InstanceSpecification. The values of this property shall be instances of classifiers stereotyped by «valueType» or «distributionDefinition» ... OMG Systems Modeling Language (SysML) 1.6 InstanceSpecification Rate, «rate», Rate::rate
INFO The ~InterfaceBlock stereotype (shall be pronounced: "conjugated interface block") is a specialization of InterfaceBlock that has the same features as its original InterfaceBlock except that its DirectedFeatures and FlowProperties are reversed (conjugated OMG Systems Modeling Language (SysML) 1.6 InterfaceBlock, ~InterfaceBlock, conjugation, ~InterfaceBlock::original, DirectedFeature, FlowProperty, FlowProperty::direction, FlowDirectionKind, DirectedFeature::featureDirection, FeatureDirectionKind