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
EXAMPLE, INFO “BlackBox” for the purpose of this example, refers to how the subject system (HybridSUV block) interacts only with outside elements, without revealing any interior detail. OMG Systems Modeling Language (SysML) 1.6 UseCase::subject HSUV sample problem black box
INFO «streaming» Used for activities that can accept inputs or provide outputs after they start and before they finish. The activity has at least one streaming parameter. OMG Systems Modeling Language (SysML) 1.6 Activity «streaming» non-normative
INFO «Refine» Abstraction Specifies a refinement relationship between model elements at different semantic levels, such as analysis and design. The mapping specifies the relationship between the two elements or sets of elements. The mapping ... Unified Modeling Language 2.5.1 Refine, Stereotype, UML StandardProfile
CONSTRAINT «physicalRequirement»: satisfied by a structural element. OMG Systems Modeling Language (SysML) 1.6 ExtendedRequirement, AbstractRequirement, «performanceRequirement», Block, part property, MD:PartProperty requirements engineering
CONSTRAINT «performanceRequirement»: satisfied by a value property. OMG Systems Modeling Language (SysML) 1.6 ExtendedRequirement, AbstractRequirement, «performanceRequirement», value property, MD:ValueProperty requirements engineering
INFO «objectiveFunction» An objective function (aka optimization or cost function) is used to determine the overall value of an alternative in terms of weighted criteria and/or moe's. OMG Systems Modeling Language (SysML) 1.6 custom Stereotype, user defined Stereotype «objectiveFunction», «moe» non-normative, objective function, Measure of Effectiveness
INFO «nonStreaming» Used for activities that accept inputs only when they start, and provide outputs only when they finish. The activity has no streaming parameters. OMG Systems Modeling Language (SysML) 1.6 Activity «nonStreaming» non-normative
INFO «moe» A measure of effectiveness (moe) represents a parameter whose value is critical for achieving the desired mission cost effectiveness. OMG Systems Modeling Language (SysML) 1.6 custom Stereotype, user defined Stereotype «moe» non-normative, Measure of Effectiveness
CONSTRAINT «interfaceRequirement»: satisfied by a port, conector, item flow, and/or constraint property. OMG Systems Modeling Language (SysML) 1.6 Operation, Connector ExtendedRequirement, AbstractRequirement, «interfaceRequirement», ItemFlow, constraint property requirements engineering
CONSTRAINT «functionalRequirement»: satisfied by an operation or behavior OMG Systems Modeling Language (SysML) 1.6 Operation, Behavior «functionalRequirement», ExtendedRequirement, AbstractRequirement requirements engineering
INFO «effbd» Specifies that the activity conforms to the constraints necessary for EFFBD. OMG Systems Modeling Language (SysML) 1.6 Activity «effbd» non-normative
CONSTRAINT «designConstraint»: satisfied by a block or part. OMG Systems Modeling Language (SysML) 1.6 ExtendedRequirement, AbstractRequirement, «performanceRequirement», Block, part property, MD:PartProperty requirements engineering
INFO ~InterfaceBlock::original : InterfaceBlock [1] The InterfaceBlock that this is a conjugation of. OMG Systems Modeling Language (SysML) 1.6 InterfaceBlock, ~InterfaceBlock::original, ~InterfaceBlock
INFO [SysML1.6: PREFER SysML1.7] A DirectedFeature indicates whether the feature is supported by the owning block (provided), or is to be supported by other blocks for the owning block to use (required), or both ... OMG Systems Modeling Language (SysML) 1.6 DirectedFeature, FeatureDirectionKind::provided, FeatureDirectionKind::required, FeatureDirectionKind::providedrequired, FeatureDirectionKind
CONSTRAINT zero_input_parameters If the DecisionNode has no decisionInputFlow and an incoming ControlFlow, then any decisionInput Behavior has no in parameters. Unified Modeling Language 2.5.1 DecisionNode, DecisionNode::decisionInputFlow, ControlFlow, DecisionNode::decisionInput, Behavior, Parameter, ParameterDirectionKind::in, ActivityNode::incoming, Behavior::ownedParameter, Behavior::inputParameters()
INFO You may have seen a similar table before with slightly different choices. For example, you will sometimes see velocity (in ) chosen as the across variable for translational motion. The choices above are guided by two constraints. Modelica By Example Modelica, acausal connection
INFO Within the limits of experimental accuracy, the electron charge is identical to the charge of a proton, but with the opposite sign. Wikipedia
INFO Within an Activity, inputs to and outputs from an Activity are handled using ActivityParameterNodes. Unified Modeling Language 2.5.1 Activity, Behavior, Parameter, ActivityParameterNode
INFO While the monitor is enabled, it outputs a modulation frequency for applying the brakes as determined by the ABS system. OMG Systems Modeling Language (SysML) 1.6 SysML specification figure, ControlOperator, ControlValueKind, ControlValueKind::disable, ControlValueKind::enable
INFO While the ExecutableNode is executing, it is considered to hold a single control [token] indicating it is execution [executing]. Unified Modeling Language 2.5.1 Behavior, Activity, Activity Diagram, ExecutableNode, implicit join, ControlFlow, ActivityNode::incoming, token, control token
INFO While the electron has a negative electric charge, the positron has a positive electric charge, and is produced naturally in certain types of radioactive decay. The opposite is also true: the antiparticle of the positron is the electron. Wikipedia
INFO Whereas flow properties specify what “can” flow in or out of a block, item flows specify what “does” flow between blocks and/or parts in a particular usage context. OMG Systems Modeling Language (SysML) 1.6 ItemFlow
NOTATION Where a subject is a Classifier with a standard stereotype, the keyword for the stereotype shall be shown in guillemets above the name of the subject. Unified Modeling Language 2.5.1 UseCase, UseCase Diagram, UseCase::subject, Classifier, «keyword», Stereotype, guillemets
INFO When the «rate» stereotype is applied to an activity edge, it specifies the expected value of the number of objects and values that traverse the edge per time interval, that is, the expected value rate at which they leave the source node and arrive at ... OMG Systems Modeling Language (SysML) 1.6 ActivityEdge, DirectedRelationship::/source, DirectedRelationship::/target, object token, value, ActivityNode Rate, «rate»
CONSTRAINT, INFO When the «probability» stereotype is applied to output parameter sets, it gives the probability the parameter set will be given values at runtime. These shall be between zero and one inclusive, and add up to one for output parameter sets of the same ... OMG Systems Modeling Language (SysML) 1.6 Parameter::parameterSet, ParameterSet «probability», Probability, Probability::probability
CONSTRAINT, INFO When the «probability» stereotype is applied to edges coming out of decision nodes and object nodes, it provides an expression for the probability that the edge will be traversed. These shall be between zero and one inclusive, and add up to one ... OMG Systems Modeling Language (SysML) 1.6 DecisionNode, ObjectNode, ActivityEdge «probability», Probability, Probability::probability
INFO When the «overwrite» stereotype is applied to object nodes, a token arriving at a full object node removes one that is already there before being added (a full object node has as many tokens as allowed by its upper bound). OMG Systems Modeling Language (SysML) 1.6 ObjectNode, MultiplicityElement::/upper Overwrite, «overwrite»
INFO When the «optional» stereotype is applied to parameters, the lower multiplicity shall be equal to zero. This means the parameter is not required to have a value for the activity or any behavior to begin or end execution ... OMG Systems Modeling Language (SysML) 1.6 Parameter, MultiplicityElement::/lower, multiplicity «optional», Optional, Optional, required
INFO When the «nobuffer» stereotype is applied to object nodes, tokens arriving at the node are discarded if they are refused by outgoing edges, or refused by actions for object nodes that are input pins. OMG Systems Modeling Language (SysML) 1.6 ObjectNode, ActivityNode::outgoing, InputPin, Action::/input «noBuffer», NoBuffer
When the «controlOperator» stereotype is not applied, the behavior may not have a parameter typed by ControlValue. OMG Systems Modeling Language (SysML) 1.6 Behavior, Operation ControlOperator, ControlValueKind
When the «controlOperator» stereotype is applied to behaviors, the behavior takes control values as inputs or provides them as outputs, that is, it treats control as data OMG Systems Modeling Language (SysML) 1.6 Behavior, Operation ControlOperator
INFO When the LoopNode begins executing, the tokens on the loopVariableInput InputPins are moved to the corresponding loopVariable OutputPins before the first iteration of the loop. Unified Modeling Language 2.5.1 Activity, Activity Diagram, LoopNode, LoopNode::loopVariable, ActivityNode::outgoing, ActivityEdge, OutputPin, LoopNode::loopVariableInput, InputPin
INFO When the computer is in StandBy, y.sigsp [ERROR] is set to 8, and when the computer is On, y.sigsp [ERROR] is set to 3. SysPhS-1.1 StateMachine, State, Transition, ChangeEvent, ChangeEvent::changeExpression SysPhS, SysML, Systems Modeling Language
INFO When the brake pressure goes to zero, disable control values are emitted from the control operator. The first one disables the monitor, and the rest have no effect. OMG Systems Modeling Language (SysML) 1.6 SysML specification figure, ControlOperator, ControlValueKind, ControlValueKind::disable, ControlValueKind::enable
INFO When the Activity is invoked, values may be passed into the Activity execution on input Parameters (i.e., those with direction in or inout) and values may be passed out .. on output Parameters (i.e., those with direction inout, out or return). Unified Modeling Language 2.5.1 Activity, Behavior, Parameter, ActivityParameterNode, ParameterDirectionKind::in, ParameterDirectionKind::out, ParameterDirectionKind::inout, ParameterDirectionKind::return, Parameter::direction, execution
INFO When the Action is enabled by other means, values are computed as specified for the ValuePins and ActionInputPins owned by an Action, and the results are provided as inputs to the Action when it begins execution. Unified Modeling Language 2.5.1 Activity, Activity Diagram, Action, Pin, InputPin, ValuePin, ActionInputPin, execution
NOTATION When several item flows having the same direction are represented, only one triangle is shown, and the list of item flows, separated by a comma is presented. OMG Systems Modeling Language (SysML) 1.6 Connector, Association ItemFlow
INFO When multiple triggers are defined for a Transition, they are logically disjunctive, that is, if any of them are enabled, the Transition will be triggered. Unified Modeling Language 2.5.1 State, StateMachine, Transition, Trigger, Transition::trigger, Event, Event occurrence, Trigger::event
EXAMPLE, INFO When Monitor Traction is enabled, it begins listening for signals coming in from the wheel and accelerometer, as indicated by the signal receipt symbols on the left, which begin listening automatically when the activity is enabled. OMG Systems Modeling Language (SysML) 1.6 Signal, accept signal action, SignalEvent, AcceptEventAction, AcceptEventAction::isUnmarshall SysML specification figure
INFO When he sets Sophie down, she begins to plead for her life, believing that the giant will eat her. Wikipedia Webel Parsing Analysis
INFO When exiting from an orthogonal State, each of its Regions is exited. After that, the exit Behavior of the State is executed. Unified Modeling Language 2.5.1 State, StateMachine, Behavior, State::exit, State::/isOrthogonal, orthogonal Region, Region
INFO When exiting from a composite State, exit commences with the innermost State in the active state configuration. This means that exit Behaviors are executed in sequence starting with the innermost active State. Unified Modeling Language 2.5.1 State, StateMachine, Behavior, State::exit, composite State, State::/isComposite, substate, active state configuration
INFO When exiting a State, regardless of whether it is simple or composite, the final step involved in the exit, after all other Behaviors associated with the exit are completed, is the execution of the exit Behavior of that State. Unified Modeling Language 2.5.1 State, StateMachine, Behavior, State::exit
INFO When composition is used with activity blocks, the termination of execution of an activity on the whole end will terminate executions of activities on the part end of the links. OMG Systems Modeling Language (SysML) 1.6 Activity, Association, AggregationKind::composite Block
INFO When completed, an Action execution provides any output data on the OutputPins of the Action, and it terminates. Unified Modeling Language 2.5.1 Activity, Activity Diagram, Action, execution, completion, termination, Action::/output, OutputPin
INFO When calibrated to ITS-90, where one must interpolate between the defining points of gallium and indium, the boiling point of VSMOW water is about 10 mK less, about 99.974 °C. Wikipedia thermodynamics, temperature, celsius, kelvin, Kelvins, water, boiling point
RULE When an offer for an object token held by a DataStoreNode is accepted by a downstream object node, the offered token is removed from the DataStoreNode, per the usual CentralBufferNode semantics. However, a copy is made of the removed object token ... Unified Modeling Language 2.5.1 Activity, CentralBufferNode, token, object token, DataStoreNode, token offer
INFO When an ExecutableNode completes an execution, the control token representing that execution is removed from the ExecutableNode and control tokens are offered on all outgoing ControlFlows of the ExecutableNode. That is, there is an implicit fork ... Unified Modeling Language 2.5.1 Behavior, Activity, Activity Diagram, ExecutableNode, implicit join, ControlFlow, ActivityNode::outgoing, token, control token, implicit fork
INFO When an Action in an Activity completes execution, object tokens for output data placed on its OutputPins may be offered on any outgoing ObjectFlows from those Pins ... In addition, control tokens shall be offered on any outgoing ControlFlows ... Unified Modeling Language 2.5.1 Action, Activity, OutputPin, ObjectFlow, ObjectNode, ControlFlow, ExecutableNode, execution, completion, run-to-completion
INFO When a requirement has nested requirements, all the nested requirements apply as part of the container requirement. Deleting the container requirement deleted [deletes] the nested requirements, a functionality inherited from UML. OMG Systems Modeling Language (SysML) 1.6 Requirement, composite (compound) requirement, subrequirement requirements engineering
SEMANTIC When a Region of the submachine StateMachine reaches the corresponding exit point, the submachine state is exited via this exit point. Unified Modeling Language 2.5.1 State, StateMachine, submachine, ConnectionPointReference, exit point, PseudostateKind::exitPoint, Region
CONSTRAINT, INFO When a proxy port is connected to multiple internal parts, the connectors have the same semantics as a single binding connector to an aggregate of those parts, supporting all their features, and treating flows and invocations from outside the aggregate... OMG Systems Modeling Language (SysML) 1.6 Port, part, Feature ProxyPort, part property, MD:PartProperty, BindingConnector
CONSTRAINT, INFO When a proxy port is connected to a single internal part [or port or internal part], the connector shall be a binding connector, or have the same semantics as a binding connector ... OMG Systems Modeling Language (SysML) 1.6 Port, part ProxyPort, part property, MD:PartProperty, BindingConnector
RULE When a DataStoreNode accepts an object token, if that token contains an object with the same identity as an object contained in a token already held by the node, then the duplicate object token shall not be placed on the DataStoreNode. Unified Modeling Language 2.5.1 Activity, token, object token, DataStoreNode, token offer, identity
CONSTRAINT When a Copy dependency exists between two requirements, the requirement text of the client requirement is a read-only copy of the requirement text of the requirement at the supplier end of the dependency. OMG Systems Modeling Language (SysML) 1.6 Dependency, Dependency::client, Dependency::supplier Requirement, Copy, AbstractRequirement::text, AbstractRequirement::id
INFO Viewpoint::stakeholder : Stakeholder [0..*] Set of stakeholders whose concerns are to be addressed by the viewpoint. OMG Systems Modeling Language (SysML) 1.6 Viewpoint, Viewpoint::stakeholder, Stakeholder, Stakeholder::/concern, Viewpoint::/concern
INFO Viewpoint::purpose : String [1] The purpose addresses the stakeholder concerns. OMG Systems Modeling Language (SysML) 1.6 String Viewpoint, Viewpoint::purpose, Stakeholder, Viewpoint::/concern, Stakeholder::/concern
INFO Viewpoint::presentation : String [0..*] The specifications prescribed for formatting and styling the view. OMG Systems Modeling Language (SysML) 1.6 String Viewpoint, Viewpoint::presentation, View
INFO Viewpoint::language : String [0..*] The languages used to express the models that represent content which is represented by the view. The language specification such as its metamodel, profile, or other language specification is referred to by its URI. OMG Systems Modeling Language (SysML) 1.6 Viewpoint, Viewpoint::language URI, URL
INFO Viewpoint::concernList : Comment [0..*] The interests of the stakeholders addressed by this viewpoint. OMG Systems Modeling Language (SysML) 1.6 Comment::body Viewpoint, Stakeholder, Stakeholder::/concern, Viewpoint::/concern, Stakeholder::concernList, Viewpoint::concernList
CONSTRAINT Viewpoint::2_create_view_operation The property ownedOperation shall include at least one operation named "View" with the UML Create stereotype applied. OMG Systems Modeling Language (SysML) 1.6 «Create», constructor, Operation, Class::ownedOperation Viewpoint, View
CONSTRAINT Viewpoint::1_method_derived_from_create_operations The derived values of the method attribute shall be the names of the methods of the operations stereotyped by the UML Create stereotype on the classifier stereotyped by Viewpoint. OMG Systems Modeling Language (SysML) 1.6 «Create», constructor, Operation, BehavioralFeature::method Viewpoint, Viewpoint::/method
INFO Viewpoint::/method : Behavior [0..*] The behavior is derived from the method of the operation with the Create stereotype. (derived) OMG Systems Modeling Language (SysML) 1.6 Behavior, «Create», constructor, Operation, BehavioralFeature::method Viewpoint, Viewpoint::/method URI, URL
INFO Viewpoint::/concern : String [0..*] The interest of the stakeholders displayed as the body of the comments from concernList. (derived) OMG Systems Modeling Language (SysML) 1.6 Comment::body Viewpoint, Stakeholder, Stakeholder::/concern, Viewpoint::/concern, Stakeholder::concernList, Viewpoint::concernList
INFO View::/viewpoint : Viewpoint [1] The viewpoint for this View is derived from the conform relationship. (derived) OMG Systems Modeling Language (SysML) 1.6 View, View::/viewpoint, Conform, Viewpoint
INFO View::/stakeholder : Stakeholder [0..*] The list of stakeholders is derived from the viewpoint the view conforms to. (derived) OMG Systems Modeling Language (SysML) 1.6 View, View::/stakeholder, Stakeholder
INFO Various sources define visible light as narrowly as 420–680 nm to as broadly as 380–800 nm. Wikipedia visible light
EXAMPLE, INFO Various other model elements may be necessary to help develop a derived requirement, and these model element may be related by a «refinedBy» relationship. OMG Systems Modeling Language (SysML) 1.6 Refine HSUV sample problem, Requirement, DeriveReqt, Refine requirements engineering
NOTATION Various notations for properties are available to distinguish these specialized kinds of properties on an internal block diagram. OMG Systems Modeling Language (SysML) 1.6 Property Block, block property, value property, SysML Internal Block Diagram systems engineering, Model-Based Systems Engineering, SysML, Systems Modeling Language
CAVEAT Variables are excluded from fUML because the passing of data between actions can be achieved using object flows. Semantics of a Foundational Subset for Executable UML Models 1.4 Variable
INFO Vapor refers to a gas phase at a temperature where the same substance can also exist in the liquid or solid state, below the critical temperature of the substance. Wikipedia vapour, Psychrometrics, gas, critical temperature, pressure
INFO Values are specified in an initialValues compartment by lines in the form <property-name> = <value-specification> or <property-name> : <type> = <value-specification>, each line of which specifies the initial value for one property owned either by ... OMG Systems Modeling Language (SysML) 1.6 compartment initial values, initialValues compartment, context-specific values
INFO ValuePins and ActionInputPins are InputPins, but are not used in the determination of whether an Action is enabled for execution. If an Action has no other way to start execution, simply having ValuePins or ActionInputPins for its inputs will not enable.. Unified Modeling Language 2.5.1 Activity, Activity Diagram, Action, Pin, InputPin, ValuePin, ActionInputPin, execution
CAVEAT ValuePin – Value pins are excluded from fUML because they are redundant with using value specifications to specify values. Semantics of a Foundational Subset for Executable UML Models 1.4 ValuePin, ValueSpecification fUML, Foundational UML, execution, simulation
INFO Value types may be used to type properties, operation parameters, or potentially other elements within SysML. OMG Systems Modeling Language (SysML) 1.6 DataType, Type, Property, Parameter ValueType
INFO Validation can be expressed by the query "Are you building the right thing?" and verification by "Are you building it right?" Wikipedia validation, verification, V&V, V-model, ISO/IEC/IEEE 15288, ISO/IEC/IEEE 15288-2015, ISO/IEC/IEEE 12207:2017, ISO/IEC/IEEE 12207
INFO Using existing blocks with ports only requires knowing the port types, because they define the features available for linking or communication with those ports via connectors. OMG Systems Modeling Language (SysML) 1.6 Port FullPort, "standard" Port, ProxyPort
INFO Using an InstanceValue in a ValueSpecificationAction is similar to creating an instance using a CreateObjectAction, except that values may be given for the StructuralFeatures of the instance using slots on the InstanceSpecification of the InstanceValue. Unified Modeling Language 2.5.1 Action, ValueSpecificationAction, CreateObjectAction, InstanceValue, InstanceSpecification, Slot, StructuralFeature
INFO UseCases need not be owned by their subject. Unified Modeling Language 2.5.1 UseCase, UseCase::subject
INFO UseCases may have associated Actors, which describe how an instance of the Classifier realizing the UseCase and a user playing one of the roles of the Actor interact. Unified Modeling Language 2.5.1 UseCase, UseCase::subject, Behavior, BehavioredClassifier, Actor, Association
INFO UseCases define the offered Behaviors of the subject without reference to its internal structure. These Behaviors, involving interactions between the Actors and the subject, may result in changes to the state of the subject and communications with its... Unified Modeling Language 2.5.1 UseCase, UseCase::subject, Classifier, Behavior, Actor, BehavioredClassifier black box
INFO UseCases can be used both for specification of the (external) requirements on a subject and for the specification of the functionality offered by a subject. Unified Modeling Language 2.5.1 UseCase, UseCase::subject functional requirement, external requirement
INFO UseCase::subject : Classifier [0..*] ... The subjects to which this UseCase applies. Each subject or its parts realize all the UseCases that apply to it. Unified Modeling Language 2.5.1 UseCase, Classifier, UseCase::subject, Classifier::useCase
INFO UseCase::include : Include [0..*]{subsets A_source_directedRelationship::directedRelationship, subsets Namespace::ownedMember} ... The Include relationships owned by this UseCase. Unified Modeling Language 2.5.1 UseCase, UseCase::include, Include
INFO UseCase::extensionPoint : ExtensionPoint [0..*]{subsets Namespace::ownedMember} ... The ExtensionPoints owned by this UseCase. Unified Modeling Language 2.5.1 UseCase, UseCase::extensionPoint, ExtensionPoint
INFO UseCase::extend : Extend [0..*]{subsets A_source_directedRelationship::directedRelationship, subsets Namespace::ownedMember} ... The Extend relationships owned by this UseCase. Unified Modeling Language 2.5.1 UseCase::extend, UseCase, Extend
INFO Up and down quarks have the lowest masses of all quarks. Wikipedia
INFO Unstereotyped ports have the basic functionality of stereotyped ones, including flow properties and nested ports, so they can be used as long as the modeler is not concerned with the distinction between proxy and full, and the constraints they impose. OMG Systems Modeling Language (SysML) 1.6 Port FullPort, "standard" Port, ProxyPort
INFO Unstereotyped ports do not commit to whether they are proxy or full, and do not prevent or dictate future application of the stereotypes, except for ports that violate constraints of the stereotypes. OMG Systems Modeling Language (SysML) 1.6 Port FullPort, "standard" Port, ProxyPort
INFO Unlike quarks, however, leptons are not subject to the strong interaction, but they are subject to the other three fundamental interactions: gravitation, the weak interaction, and to electromagnetism ... Wikipedia
INFO Unlike leptons, quarks possess color charge, which causes them to engage in the strong interaction. Wikipedia
SEMANTIC Unlike ControlFlows, ObjectFlows also provide additional support for multicast/receive, token selection from ObjectNodes and transformation of tokens Unified Modeling Language 2.5.1 Activity, ActivityEdge, ObjectFlow, object token, token, ObjectFlow::selection, ObjectFlow::transformation, ObjectNode, multicast
INFO Unlike a regular CentralBufferNode, a DataStoreNode contains objects uniquely. Unified Modeling Language 2.5.1 Activity, CentralBufferNode, token, object token, DataStoreNode, token offer
INFO Unit, or a specialization of it, classifies an InstanceSpecification to define a particular "measurement unit" in the sense of a "real scalar quantity, defined and adopted by convention, with which any other quantity of the same kind can be compared ... OMG Systems Modeling Language (SysML) 1.6 QuantityKind, Unit, Unit::quantityKind, ValueType::quantityKind, Unit::definitionURI, QuantityKind::definitionURI scientific unit system, VIM3
INFO Unit is defined as a non-abstract SysML Block defined in the SysML UnitAndQuantityKind model library. OMG Systems Modeling Language (SysML) 1.6 QuantityKind, Unit, Unit::quantityKind, ValueType::quantityKind, Unit::definitionURI, QuantityKind::definitionURI scientific unit system, VIM3
INFO unit : InstanceSpecification [0..1] A unit, represented by an InstanceSpecification classified by a kind of SysML Unit, in terms of which the magnitudes of other quantities that have the same quantity kind can be stated. OMG Systems Modeling Language (SysML) 1.6 ValueType, ValueType::unit, QuantityKind
INFO Under ideal laboratory conditions, people can see infrared up to at least 1050 nm; children and young adults may perceive ultraviolet wavelengths down to about 310–313 nm. Wikipedia visible light, infrared, ultraviolet
INFO Uncharged mesons may decay to photons. Wikipedia
INFO UML 2.5.1: «Trace»: Specifies a trace relationship between model elements or sets of model elements that represent the same concept in different models. Traces are mainly used for tracking requirements and changes across models. Unified Modeling Language 2.5.1 Trace, «trace»
INFO UML 2.5.1: «Trace»: As model changes can occur in both directions, the directionality of the dependency can often be ignored. The mapping specifies the relationship between the two, but it is rarely computable and is usually informal. Unified Modeling Language 2.5.1 Trace, «trace»