Quantities, Units, Dimensions and Types (QUDT) Schema - Version 2.1.19
This version: 2.1
Latest published version: http://www.qudt.org/doc/2022/08/DOC_SCHEMA-QUDT-v2.1.html
Previous published version: https://qudt.org/doc/2022/06/DOC_SCHEMA-QUDT-v2.1.html
Editor: Ralph Hodgson, TopQuadrant, Inc
Contributors: Daniel Mekonnen, David Price, Jack Hodges, James E. Masters, Simon J D Cox, Steve Ray
Last Modified: 2022-08-02T09:39:48.263-04:00
Copyright © 2011 - 2022 qudt.org , All Rights Reserved.
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Abstract
The QUDT, or "Quantity, Unit, Dimension and Type" schema defines the base classes properties, and restrictions used for modeling physical quantities, units of measure, and their dimensions in various measurement systems. The goal of the QUDT ontology is to provide a unified model of, measurable quantities, units for measuring different kinds of quantities, the numerical values of quantities in different units of measure and the data structures and data types used to store and manipulate these objects in software.
Except for unit prefixes, all units are specified in separate vocabularies. Descriptions are provided in both HTML and LaTeX formats. A quantity is a measure of an observable phenomenon, that, when associated with something, becomes a property of that thing; a particular object, event, or physical system.
A quantity has meaning in the context of a measurement (i.e. the thing measured, the measured value, the accuracy of measurement, etc.) whereas the underlying quantity kind is independent of any particular measurement. Thus, length is a quantity kind while the height of a rocket is a specific quantity of length; its magnitude that may be expressed in meters, feet, inches, etc. Or, as stated at Wikipedia, in the language of measurement, quantities are quantifiable aspects of the world, such as time, distance, velocity, mass, momentum, energy, and weight, and units are used to describe their measure. Many of these quantities are related to each other by various physical laws, and as a result the units of some of the quantities can be expressed as products (or ratios) of powers of other units (e.g., momentum is mass times velocity and velocity is measured in distance divided by time).
The namespace prefix for resources in this ontology is: qudt
The schema graph is available as:
Turtle
Table of Contents
Imported Graphs
A list of graphs imported by http://qudt.org/2.1/schema/qudt is shown below.
| Graph URI | Intent |
|---|---|
| http://www.linkedmodel.org/schema/dtype | The purpose of DTYPE is to provide, by import, a foundation for data types. |
| http://www.linkedmodel.org/schema/vaem | The purpose of VAEM is to provide, by import, a foundation for commonly needed resources for metadata on an ontology. |
| http://www.w3.org/2004/02/skos/core |
Non-imported Resources
The graph uses 12 resources from other graphs that are not imported, as listed below:
Resource Index
The main namespace for resources in this graph is http://qudt.org/schema/qudt/ with the prefix qudt.
Classes
The graph defines, or extends, 72 classes, as indexed below:
Properties
The graph defines, or extends, 182 properties, as indexed below:
Instances
The graph defines, or extends, 28 instances, as indexed below:
Restricted Datatypes
The graph defines, or extends, 9 restricted datatypes, as indexed below:
qudt:AbstractQuantityKind
qudt:AngleUnit
All units relating to specification of angles.
qudt:AspectClass
qudt:BaseDimensionMagnitude
A Dimension expresses a magnitude for a base quantiy kind such as mass, length and time.
DEPRECATED - each exponent is expressed as a property. Keep until a validaiton of this has been done.
qudt:BinaryPrefix
A Binary Prefix is a prefix for multiples of units in data processing, data transmission, and digital information, notably the bit and the byte, to indicate multiplication by a power of 2.
qudt:BitEncodingType
A bit encoding is a correspondence between the two possible values of a bit, 0 or 1, and some interpretation. For example, in a boolean encoding, a bit denotes a truth value, where 0 corresponds to False and 1 corresponds to True.
qudt:BooleanEncodingType
qudt:ByteEncodingType
This class contains the various ways that information may be encoded into bytes.
qudt:CardinalityType
In mathematics, the cardinality of a set is a measure of the number of elements of the set. For example, the set \(A = {2, 4, 6}\) contains 3 elements, and therefore \(A\) has a cardinality of 3. There are two approaches to cardinality – one which compares sets directly using bijections and injections, and another which uses cardinal numbers.
qudt:CharEncodingType
The class of all character encoding schemes, each of which defines a rule or algorithm for encoding character data as a sequence of bits or bytes.
qudt:Citation
Provides a simple way of making citations.
qudt:Comment
qudt:Concept
The root class for all QUDT concepts.
qudt:ConstantValue
Used to specify the values of a constant.
qudt:CountingUnit
Used for all units that express counts. Examples are Atomic Number, Number, Number per Year, Percent and Sample per Second.
qudt:CurrencyUnit
Used for all units that express currency.
qudt:DataEncoding
Data Encoding expresses the properties that specify how data is represented at the bit and byte level. These properties are applicable to describing raw data.
qudt:Datatype
A data type is a definition of a set of values (for example, "all integers between 0 and 10"), and the allowable operations on those values; the meaning of the data; and the way values of that type can be stored. Some types are primitive - built-in to the language, with no visible internal structure - e.g. Boolean; others are composite - constructed from one or more other types (of either kind) - e.g. lists, arrays, structures, unions. Object-oriented programming extends this with classes which encapsulate both the structure of a type and the operations that can be performed on it. Some languages provide strong typing, others allow implicit type conversion and/or explicit type conversion.
qudt:DateTimeStringEncodingType
Date Time encodings are logical encodings for expressing date/time quantities as strings by applying unambiguous formatting and parsing rules.
qudt:DecimalPrefix
A Decimal Prefix is a prefix for multiples of units that are powers of 10.
qudt:DerivedUnit
A DerivedUnit is a type specification for units that are derived from other units.
qudt:DimensionlessUnit
A Dimensionless Unit is a quantity for which all the exponents of the factors corresponding to the base quantities in its quantity dimension are zero.
qudt:Discipline
qudt:Encoding
An encoding is a rule or algorithm that is used to convert data from a native, or unspecified form into a specific form that satisfies the encoding rules. Examples of encodings include character encodings, such as UTF-8.
qudt:EndianType
qudt:EnumeratedValue
This class is for all enumerated and/or coded values. For example, it contains the dimension objects that are the basis elements in some abstract vector space associated with a quantity kind system. Another use is for the base dimensions for quantity systems. Each quantity kind system that defines a base set has a corresponding ordered enumeration whose elements are the dimension objects for the base quantity kinds. The order of the dimensions in the enumeration determines the canonical order of the basis elements in the corresponding abstract vector space.
An enumeration is a set of literals from which a single value is selected. Each literal can have a tag as an integer within a standard encoding appropriate to the range of integer values. Consistency of enumeration types will allow them, and the enumerated values, to be referred to unambiguously either through symbolic name or encoding. Enumerated values are also controlled vocabularies and as such need to be standardized. Without this consistency enumeration literals can be stated differently and result in data conflicts and misinterpretations.
The tags are a set of positive whole numbers, not necessarily contiguous and having no numerical significance, each corresponding to the associated literal identifier. An order attribute can also be given on the enumeration elements. An enumeration can itself be a member of an enumeration. This allows enumerations to be enumerated in a selection. Enumerations are also subclasses of Scalar Datatype. This allows them to be used as the reference of a datatype specification.
qudt:Enumeration
An enumeration is a set of literals from which a single value is selected. Each literal can have a tag as an integer within a standard encoding appropriate to the range of integer values. Consistency of enumeration types will allow them, and the enumerated values, to be referred to unambiguously either through symbolic name or encoding. Enumerated values are also controlled vocabularies and as such need to be standardized. Without this consistency enumeration literals can be stated differently and result in data conflicts and misinterpretations.
The tags are a set of positive whole numbers, not necessarily contiguous and having no numerical significance, each corresponding to the associated literal identifier. An order attribute can also be given on the enumeration elements. An enumeration can itself be a member of an enumeration. This allows enumerations to be enumerated in a selection. Enumerations are also subclasses of Scalar Datatype. This allows them to be used as the reference of a datatype specification.
qudt:EnumerationScale
qudt:Figure
qudt:FloatingPointEncodingType
A "Encoding" with the following instance(s): "Double Precision Encoding", "Single Precision Real Encoding".
qudt:IntegerEncodingType
The encoding scheme for integer types
qudt:IntervalScale
median, percentile & Monotonic increasing (order (<)) & totally ordered set
qudt:LogarithmicUnit
Logarithmic units are abstract mathematical units that can be used to express any quantities (physical or mathematical) that are defined on a logarithmic scale, that is, as being proportional to the value of a logarithm function. Examples of logarithmic units include common units of information and entropy, such as the bit, and the byte, as well as units of relative signal strength magnitude such as the decibel.
qudt:MathsFunctionType
qudt:NIST_SP811_Comment
qudt:NominalScale
A nominal scale differentiates between items or subjects based only on their names or (meta-)categories and other qualitative classifications they belong to; thus dichotomous data involves the construction of classifications as well as the classification of items. Discovery of an exception to a classification can be viewed as progress. Numbers may be used to represent the variables but the numbers do not have numerical value or relationship: For example, a Globally unique identifier. Examples of these classifications include gender, nationality, ethnicity, language, genre, style, biological species, and form. In a university one could also use hall of affiliation as an example.
qudt:OrderedType
Describes how a data or information structure is ordered.
qudt:OrdinalScale
The ordinal type allows for rank order (1st, 2nd, 3rd, etc.) by which data can be sorted, but still does not allow for relative degree of difference between them. Examples include, on one hand, dichotomous data with dichotomous (or dichotomized) values such as 'sick' vs. 'healthy' when measuring health, 'guilty' vs. 'innocent' when making judgments in courts, 'wrong/false' vs. 'right/true' when measuring truth value, and, on the other hand, non-dichotomous data consisting of a spectrum of values, such as 'completely agree', 'mostly agree', 'mostly disagree', 'completely disagree' when measuring opinion.
qudt:Organization
qudt:PhysicalConstant
A physical constant is a physical quantity that is generally believed to be both universal in nature and constant in time. It can be contrasted with a mathematical constant, which is a fixed numerical value but does not directly involve any physical measurement. There are many physical constants in science, some of the most widely recognized being the speed of light in vacuum c, Newton's gravitational constant G, Planck's constant h, the electric permittivity of free space ε0, and the elementary charge e. Physical constants can take many dimensional forms, or may be dimensionless depending on the system of quantities and units used.
qudt:PlaneAngleUnit
qudt:Prefix
qudt:Quantifiable
Quantifiable ascribes to some thing the capability of being measured, observed, or counted.
qudt:Quantity
A quantity is the measurement of an observable property of a particular object, event, or physical system. A quantity is always associated with the context of measurement (i.e. the thing measured, the measured value, the accuracy of measurement, etc.) whereas the underlying quantity kind is independent of any particular measurement. Thus, length is a quantity kind while the height of a rocket is a specific quantity of length; its magnitude that may be expressed in meters, feet, inches, etc. Examples of physical quantities include physical constants, such as the speed of light in a vacuum, Planck's constant, the electric permittivity of free space, and the fine structure constant.
In other words, quantities are quantifiable aspects of the world, such as the duration of a movie, the distance between two points, velocity of a car, the pressure of the atmosphere, and a person's weight; and units are used to describe their numerical measure.
Many quantity kinds are related to each other by various physical laws, and as a result, the associated units of some quantity kinds can be expressed as products (or ratios) of powers of other quantity kinds (e.g., momentum is mass times velocity and velocity is defined as distance divided by time). In this way, some quantities can be calculated from other measured quantities using their associations to the quantity kinds in these expressions. These quantity kind relationships are also discussed in dimensional analysis. Those that cannot be so expressed can be regarded as "fundamental" in this sense.
A quantity is distinguished from a "quantity kind" in that the former carries a value and the latter is a type specifier.
qudt:QuantityKind
A Quantity Kind is any observable property that can be measured and quantified numerically. Familiar examples include physical properties such as length, mass, time, force, energy, power, electric charge, etc. Less familiar examples include currency, interest rate, price to earning ratio, and information capacity.
qudt:QuantityKindDimensionVector
A Quantity Kind Dimension Vector describes the dimensionality of a quantity kind in the context of a system of units. In the SI system of units, the dimensions of a quantity kind are expressed as a product of the basic physical dimensions mass (\(M\)), length (\(L\)), time (\(T\)) current (\(I\)), amount of substance (\(N\)), luminous intensity (\(J\)) and absolute temperature (\(\theta\)) as \(dim \, Q = L^{\alpha} \, M^{\beta} \, T^{\gamma} \, I ^{\delta} \, \theta ^{\epsilon} \, N^{\eta} \, J ^{\nu}\).
The rational powers of the dimensional exponents, \(\alpha, \, \beta, \, \gamma, \, \delta, \, \epsilon, \, \eta, \, \nu\), are positive, negative, or zero.
For example, the dimension of the physical quantity kind \(\it{speed}\) is \(\boxed{length/time}\), \(L/T\) or \(LT^{-1}\), and the dimension of the physical quantity kind force is \(\boxed{mass \times acceleration}\) or \(\boxed{mass \times (length/time)/time}\), \(ML/T^2\) or \(MLT^{-2}\) respectively.
qudt:QuantityKindDimensionVector_CGS
A CGS Dimension Vector is used to specify the dimensions for a C.G.S. quantity kind.
qudt:QuantityKindDimensionVector_CGS-EMU
A CGS EMU Dimension Vector is used to specify the dimensions for EMU C.G.S. quantity kind.
qudt:QuantityKindDimensionVector_CGS-ESU
A CGS ESU Dimension Vector is used to specify the dimensions for ESU C.G.S. quantity kind.
qudt:QuantityKindDimensionVector_CGS-GAUSS
A CGS GAUSS Dimension Vector is used to specify the dimensions for Gaussioan C.G.S. quantity kind.
qudt:QuantityKindDimensionVector_CGS-LH
A CGS LH Dimension Vector is used to specify the dimensions for Lorentz-Heaviside C.G.S. quantity kind.
qudt:QuantityKindDimensionVector_ISO
qudt:QuantityKindDimensionVector_Imperial
qudt:QuantityKindDimensionVector_SI
qudt:QuantityType
\(\textit{Quantity Type}\) is an enumeration of quanity kinds. It specializes \(\boxed{dtype:EnumeratedValue}\) by constrinaing \(\boxed{dtype:value}\) to instances of \(\boxed{qudt:QuantityKind}\).
qudt:QuantityValue
A Quantity Value expresses the magnitude and kind of a quantity and is given by the product of a numerical value n and a unit of measure U. The number multiplying the unit is referred to as the numerical value of the quantity expressed in that unit. Refer to NIST SP 811 section 7 for more on quantity values.
qudt:RatioScale
The ratio type takes its name from the fact that measurement is the estimation of the ratio between a magnitude of a continuous quantity and a unit magnitude of the same kind (Michell, 1997, 1999). A ratio scale possesses a meaningful (unique and non-arbitrary) zero value. Most measurement in the physical sciences and engineering is done on ratio scales. Examples include mass, length, duration, plane angle, energy and electric charge. In contrast to interval scales, ratios are now meaningful because having a non-arbitrary zero point makes it meaningful to say, for example, that one object has "twice the length" of another (= is "twice as long"). Very informally, many ratio scales can be described as specifying "how much" of something (i.e. an amount or magnitude) or "how many" (a count). The Kelvin temperature scale is a ratio scale because it has a unique, non-arbitrary zero point called absolute zero.
qudt:Rule
qudt:RuleType
qudt:ScalarDatatype
Scalar data types are those that have a single value. The permissible values are defined over a domain that may be integers, float, character or boolean. Often a scalar data type is referred to as a primitive data type.
qudt:Scale
Scales (also called "scales of measurement" or "levels of measurement") are expressions that typically refer to the theory of scale types.
qudt:ScaleType
qudt:SignednessType
Specifics whether a value should be signed or unsigned.
qudt:SolidAngleUnit
The solid angle subtended by a surface S is defined as the surface area of a unit sphere covered by the surface S's projection onto the sphere. A solid angle is related to the surface of a sphere in the same way an ordinary angle is related to the circumference of a circle. Since the total surface area of the unit sphere is 4*pi, the measure of solid angle will always be between 0 and 4*pi.
qudt:StringEncodingType
A "Encoding" with the following instance(s): "UTF-16 String", "UTF-8 Encoding".
qudt:StructuredDatatype
A "Structured Datatype", in contrast to scalar data types, is used to characterize classes of more complex data structures, such as linked or indexed lists, trees, ordered trees, and multi-dimensional file formats.
qudt:Symbol
qudt:SystemOfQuantityKinds
A system of quantity kinds is a set of one or more quantity kinds together with a set of zero or more algebraic equations that define relationships between quantity kinds in the set. In the physical sciences, the equations relating quantity kinds are typically physical laws and definitional relations, and constants of proportionality. Examples include Newton’s First Law of Motion, Coulomb’s Law, and the definition of velocity as the instantaneous change in position. In almost all cases, the system identifies a subset of base quantity kinds. The base set is chosen so that all other quantity kinds of interest can be derived from the base quantity kinds and the algebraic equations. If the unit system is explicitly associated with a quantity kind system, then the unit system must define at least one unit for each quantity kind. From a scientific point of view, the division of quantities into base quantities and derived quantities is a matter of convention.
qudt:SystemOfUnits
A system of units is a set of units which are chosen as the reference scales for some set of quantity kinds together with the definitions of each unit. Units may be defined by experimental observation or by proportion to another unit not included in the system. If the unit system is explicitly associated with a quantity kind system, then the unit system must define at least one unit for each quantity kind.
qudt:TransformType
qudt:Unit
A unit of measure, or unit, is a particular quantity value that has been chosen as a scale for measuring other quantities the same kind (more generally of equivalent dimension). For example, the meter is a quantity of length that has been rigorously defined and standardized by the BIPM (International Board of Weights and Measures). Any measurement of the length can be expressed as a number multiplied by the unit meter. More formally, the value of a physical quantity Q with respect to a unit (U) is expressed as the scalar multiple of a real number (n) and U, as \(Q = nU\).
qudt:UserQuantityKind
qudt:abbreviation
An abbreviation for a unit is a short ASCII string that is used in place of the full name for the unit in contexts where non-ASCII characters would be problematic, or where using the abbreviation will enhance readability. When a power of abase unit needs to be expressed, such as squares this can be done using abbreviations rather than symbols. For example, sq ft means square foot, and cu ft means cubic foot.
qudt:allowedUnitOfSystem
This property relates a unit of measure with a unit system that does not define the unit, but allows its use within the system. An allowed unit must be convertible to some dimensionally eqiuvalent unit that is defined by the system.
qudt:baseCGSUnitDimensions
qudt:baseCGSUnitDimensions is a string datatype property expressing the dimensions of a unit, or quantity, as a vector over the base units in the CGS System.
qudt:baseDimensionEnumeration
This property associates a system of quantities with an enumeration that enumerates the base dimensions of the system in canonical order.
qudt:baseISOUnitDimensions
qudt:baseISOUnitDimensions is a string datatype property expressing the dimensions of a unit, or quantity, as a vector over the base units in the ISO System.
qudt:baseImperialUnitDimensions
qudt:baseImperialUnitDimensions is a string datatype property expressing the dimensions of a unit, or quantity, as a vector over the base units in the Imperial System.
qudt:baseSIUnitDimensions
qudt:baseSIUnitDimensions is a string datatype property expressing the dimensions of a unit, or quantity, as a vector over the base units. For example, in the SI system \(capacitance\) has the unit \(Farad\) and base unit dimensions of \(C^2 \cdot s^2 / (kg \cdot m^2)\).
qudt:baseUSCustomaryUnitDimensions
"qudt:baseUSCustomaryUnitDimensions" is a string datatype property expressing the dimensions of a unit, or quantity, as a vector over the base units in the US Customary System.
qudt:baseUnitDimensions
"qudt:baseUnitDimensions" is a string datatype property expressing the dimensions of a unit, or quantity, as a vector over the base units.
qudt:baseUnitOfSystem
This property relates a unit of measure to the system of units in which it is defined as a base unit for the system. The base units of a system are used to define the derived units of the system by expressing the derived units as products of the base units raised to a rational power.
qudt:byteOrder
Byte order is an enumeration of two values: 'Big Endian' and 'Little Endian' and is used to denote whether the most signiticant byte is either first or last, respectively.
qudt:code
A code is a string that uniquely identifies a QUDT concept. The use of this property has been deprecated.
qudt:coherentUnitOfSystem
A coherent unit of measurement for a unit system is a defined unit that may be expressed as a product of powers of the system's base units with the proportionality factor of one. A system of units is coherent with respect to a system of quantities and equations if the system of units is chosen in such a way that the equations between numerical values have exactly the same form (including the numerical factors) as the corresponding equations between the quantities. For example, the 'newton' and the 'joule'. These two are, respectively, the force that causes one kilogram to be accelerated at 1 metre per second per second, and the work done by 1 newton acting over 1 metre. Being coherent refers to this consistent use of 1. In the old c.g.s. system , with its base units the centimetre and the gram, the corresponding coherent units were the dyne and the erg, respectively the force that causes 1 gram to be accelerated at 1 centimetre per second per second, and the work done by 1 dyne acting over 1 centimetre. So \(1 newton = 10^5\,dyne\), \(1 joule = 10^7\,erg\), making each of the four compatible in a decimal sense within its respective other system, but not coherent therein.
qudt:coherentUnitSystem
A system of units is coherent with respect to a system of quantities and equations if the system of units is chosen in such a way that the equations between numerical values have exactly the same form (including the numerical factors) as the corresponding equations between the quantities. In such a coherent system, no numerical factor other than the number 1 ever occurs in the expressions for the derived units in terms of the base units. For example, the \(newton\) and the \(joule\). These two are, respectively, the force that causes one kilogram to be accelerated at 1 metre per (1) second per (1) second, and the work done by 1 newton acting over 1 metre. Being coherent refers to this consistent use of 1. In the old c.g.s. system , with its base units the centimetre and the gram, the corresponding coherent units were the dyne and the erg, respectively the force that causes 1 gram to be accelerated at 1 centimetre per (1) second per (1) second, and the work done by 1 dyne acting over 1 centimetre. So \(1\,newton = 10^5 dyne\), \(1 joule = 10^7 erg\), making each of the four compatible in a decimal sense within its respective other system, but not coherent therein.
qudt:currencyExponent
The currency exponent indicates the number of decimal places between a major currency unit and its minor currency unit. For example, the US dollar is the major currency unit of the United States, and the US cent is the minor currency unit. Since one cent is 1/100 of a dollar, the US dollar has a currency exponent of 2. However, the Japanese Yen has no minor currency units, so the yen has a currency exponent of 0.
qudt:definedUnitOfSystem
This property relates a unit of measure with the unit system that defines the unit.
qudt:derivedCoherentUnitOfSystem
This property relates a unit of measure to the unit system in which the unit is derived from the system's base units with a proportionality constant of one.
qudt:derivedNonCoherentUnitOfSystem
This property relates a unit of measure to the unit system in which the unit is derived from the system's base units without proportionality constant of one.
qudt:derivedUnitOfSystem
This property relates a unit of measure to the system of units in which it is defined as a derived unit. That is, the derived unit is defined as a product of the base units for the system raised to some rational power.
qudt:example
The 'qudt:example' property is used to annotate an instance of a class with a reference to a concept that is an example. The type of this property is 'rdf:Property'. This allows both scalar and object ranges.
qudt:expression
An 'expression' is a finite combination of symbols that are well-formed according to rules that apply to units of measure, quantity kinds and their dimensions.
qudt:generalization
This property relates a quantity kind to its generalization. A quantity kind, PARENT, is a generalization of the quantity kind CHILD only if: 1. PARENT and CHILD have the same dimensions in every system of quantities; 2. Every unit that is a measure of quantities of kind CHILD is also a valid measure of quantities of kind PARENT.
qudt:hasAllowedUnit
This property relates a unit system with a unit of measure that is not defined by or part of the system, but is allowed for use within the system. An allowed unit must be convertible to some dimensionally eqiuvalent unit that is defined by the system.
qudt:hasBaseUnit
This property relates a system of units to a base unit defined within the system. The base units of a system are used to define the derived units of the system by expressing the derived units as products of the base units raised to a rational power.
qudt:hasCoherentUnit
A coherent unit of measurement for a unit system is a defined unit that may be expressed as a product of powers of the system's base units with the proportionality factor of one.
qudt:hasDefinedUnit
This property relates a unit system with a unit of measure that is defined by the system.
qudt:hasDerivedUnit
This property relates a system of units to a unit of measure that is defined within the system in terms of the base units for the system. That is, the derived unit is defined as a product of the base units for the system raised to some rational power.
qudt:hasNonCoherentUnit
A coherent unit of measurement for a unit system is a defined unit that may be expressed as a product of powers of the system's base units with the proportionality factor of one.
qudt:hasUnit
This property relates a system of units with a unit of measure that is either a) defined by the system, or b) accepted for use by the system and is convertible to a unit of equivalent dimension that is defined by the system. Systems of units may distinguish between base and derived units. Base units are the units which measure the base quantities for the corresponding system of quantities. The base units are used to define units for all other quantities as products of powers of the base units. Such units are called derived units for the system.
qudt:id
The "qudt:id" is an identifier string that uniquely identifies a QUDT concept. The identifier is constructed using a prefix. For example, units are coded using the pattern: "UCCCENNNN", where "CCC" is a numeric code or a category and "NNNN" is a digit string for a member element of that category. For scaled units there may be an addition field that has the format "QNN" where "NN" is a digit string representing an exponent power, and "Q" is a qualifier that indicates with the code "P" that the power is a positive decimal exponent, or the code "N" for a negative decimal exponent, or the code "B" for binary positive exponents.
qudt:informativeReference
Provides a way to reference a source that provided useful but non-normative information.
qudt:isDeltaQuantity
This property is used to identify a Quantity instance that is a measure of a change, or interval, of some property, rather than a measure of its absolute value. This is important for measurements such as temperature differences where the conversion among units would be calculated differently because of offsets.
qudt:isoNormativeReference
Provides a way to reference the ISO unit definition.
qudt:latexSymbol
The symbol is a glyph that is used to represent some concept, typically a unit or a quantity, in a compact form. For example, the symbol for an Ohm is \(ohm\). This contrasts with 'unit:abbreviation', which gives a short alphanumeric abbreviation for the unit, 'ohm' for Ohm.
qudt:maxExclusive
maxExclusive is the exclusive upper bound of the value space for a datatype with the ordered property. The value of maxExclusive must be in the value space of the base type or be equal to {value} in {base type definition}.
qudt:maxInclusive
maxInclusive is the inclusive upper bound of the value space for a datatype with the ordered property. The value of maxInclusive must be in the value space of the base type.
qudt:minExclusive
minExclusive is the exclusive lower bound of the value space for a datatype with the ordered property. The value of minExclusive must be in the value space of the base type or be equal to {value} in {base type definition}.
qudt:minInclusive
minInclusive is the inclusive lower bound of the value space for a datatype with the ordered property. The value of minInclusive must be in the value space of the base type.
qudt:negativeDeltaLimit
A negative change limit between consecutive sample values for a parameter. The Negative Delta may be the encoded value or engineering units value depending on whether or not a Calibrator is defined.
qudt:normativeReference
Provides a way to reference information that is an authorative source providing a standard definition
qudt:oleDBName
OLE DB (Object Linking and Embedding, Database, sometimes written as OLEDB or OLE-DB), an API designed by Microsoft, allows accessing data from a variety of sources in a uniform manner. The API provides a set of interfaces implemented using the Component Object Model (COM); it is otherwise unrelated to OLE.
qudt:plainTextDescription
A plain text description is used to provide a description with only simple ASCII characters for cases where LaTeX , HTML or other markup would not be appropriate.
qudt:positiveDeltaLimit
A positive change limit between consecutive sample values for a parameter. The Positive Delta may be the encoded value or engineering units value depending on whether or not a Calibrator is defined.
qudt:quantity
a property to relate an observable thing with a quantity (qud:Quantity)
qudt:relativeStandardUncertainty
The relative standard uncertainty of a measurement is the (absolute) standard uncertainty divided by the magnitude of the exact value.
qudt:relevantUnit
This property is used for qudt:Discipline instances to identify the Unit instances that are used within a given discipline.
qudt:specialization
This property relates a quantity kind to its specialization(s). For example, linear velocity and angular velocity are both specializations of velocity.
qudt:standardUncertainty
The standard uncertainty of a quantity is the estimated standard deviation of the mean taken from a series of measurements.
qudt:symbol
The symbol is a glyph that is used to represent some concept, typically a unit or a quantity, in a compact form. For example, the symbol for an Ohm is \(ohm\). This contrasts with 'unit:abbreviation', which gives a short alphanumeric abbreviation for the unit, 'ohm' for Ohm.
qudt:ucumCaseInsensitiveCode
ucumCode associates a QUDT unit with a UCUM case-insensitive code.
qudt:ucumCaseSensitiveCode
ucumCode associates a QUDT unit with with a UCUM case-sensitive code.
qudt:ucumCode
ucumCode associates a QUDT unit with its UCUM code (case-sensitive).
In SHACL the values are derived from specific ucum properties using 'sh:values'.
qudt:udunitsCode
The UDUNITS package supports units of physical quantities. Its C library provides for arithmetic manipulation of units and for conversion of numeric values between compatible units. The package contains an extensive unit database, which is in XML format and user-extendable. The package also contains a command-line utility for investigating units and converting values.
qudt:uneceCommonCode
The UN/CEFACT Recommendation 20 provides three character alphabetic and alphanumeric codes for representing units of measurement for length, area, volume/capacity, mass (weight), time, and other quantities used in international trade. The codes are intended for use in manual and/or automated systems for the exchange of information between participants in international trade.
qudt:unit
A reference to the unit of measure of a quantity (variable or constant) of interest.
qudt:unitOfSystem
This property relates a unit of measure with a system of units that either a) defines the unit or b) allows the unit to be used within the system.
qudt:value
A property to relate an observable thing with a value that can be of any simple XSD type
qudt:CT_COUNTABLY-INFINITE
URI: http://qudt.org/schema/qudt/CT_COUNTABLY-INFINITE
A set of numbers is called countably infinite if there is a way to enumerate them. Formally this is done with a bijection function that associates each number in the set with exactly one of the positive integers. The set of all fractions is also countably infinite. In other words, any set \(X\) that has the same cardinality as the set of the natural numbers, or \(| X | \; = \; | \mathbb N | \; = \; \aleph0\), is said to be a countably infinite set.
qudt:CT_FINITE
URI: http://qudt.org/schema/qudt/CT_FINITE
Any set \(X\) with cardinality less than that of the natural numbers, or \(| X | \\; < \; | \\mathbb N | \), is said to be a finite set.
qudt:CT_UNCOUNTABLE
URI: http://qudt.org/schema/qudt/CT_UNCOUNTABLE
Any set with cardinality greater than that of the natural numbers, or \(| X | \; > \; | \mathbb N | \), for example \(| R| \; = \; c \; > |\mathbb N |\), is said to be uncountable.
qudt:DoublePrecisionEncoding
URI: http://qudt.org/schema/qudt/DoublePrecisionEncoding
qudt:IEEE754_1985RealEncoding
URI: http://qudt.org/schema/qudt/IEEE754_1985RealEncoding
qudt:ISO8601-UTCDateTime-BasicFormat
URI: http://qudt.org/schema/qudt/ISO8601-UTCDateTime-BasicFormat
qudt:LongUnsignedIntegerEncoding
URI: http://qudt.org/schema/qudt/LongUnsignedIntegerEncoding
qudt:ShortSignedIntegerEncoding
URI: http://qudt.org/schema/qudt/ShortSignedIntegerEncoding
qudt:ShortUnsignedIntegerEncoding
URI: http://qudt.org/schema/qudt/ShortUnsignedIntegerEncoding
qudt:SinglePrecisionRealEncoding
URI: http://qudt.org/schema/qudt/SinglePrecisionRealEncoding
qudt:UnsignedIntegerEncoding
URI: http://qudt.org/schema/qudt/UnsignedIntegerEncoding
vaem:GMD_QUDT-SCHEMA
URI: http://www.linkedmodel.org/schema/vaem#GMD_QUDT-SCHEMA
The QUDT, or "Quantity, Unit, Dimension and Type" schema defines the base classes properties, and restrictions used for modeling physical quantities, units of measure, and their dimensions in various measurement systems. The goal of the QUDT ontology is to provide a unified model of, measurable quantities, units for measuring different kinds of quantities, the numerical values of quantities in different units of measure and the data structures and data types used to store and manipulate these objects in software.
Except for unit prefixes, all units are specified in separate vocabularies. Descriptions are provided in both HTML and LaTeX formats. A quantity is a measure of an observable phenomenon, that, when associated with something, becomes a property of that thing; a particular object, event, or physical system.
A quantity has meaning in the context of a measurement (i.e. the thing measured, the measured value, the accuracy of measurement, etc.) whereas the underlying quantity kind is independent of any particular measurement. Thus, length is a quantity kind while the height of a rocket is a specific quantity of length; its magnitude that may be expressed in meters, feet, inches, etc. Or, as stated at Wikipedia, in the language of measurement, quantities are quantifiable aspects of the world, such as time, distance, velocity, mass, momentum, energy, and weight, and units are used to describe their measure. Many of these quantities are related to each other by various physical laws, and as a result the units of some of the quantities can be expressed as products (or ratios) of powers of other units (e.g., momentum is mass times velocity and velocity is measured in distance divided by time).
vaem:QUDT
URI: http://www.linkedmodel.org/schema/vaem#QUDT
QUDT is a non-profit organization that governs the QUDT ontologies.
qudt:LatexString
A type of string in which some characters may be wrapped with '\(' and '\) characters for LaTeX rendering.
qudt:UCUMci
Lexical pattern for the case-insensitive version of UCUM code
qudt:UCUMci-term
Lexical pattern for the terminal symbols in the case-insensitive version of UCUM code
qudt:UCUMcs
Lexical pattern for the case-sensitive version of UCUM code
qudt:UCUMcs-term
Lexical pattern for the terminal symbols in the case-sensitive version of UCUM code
qudt:valueUnion
A datatype that is the union of numeric xsd data types. "numericUnion" is equivalent to the xsd specification that uses an xsd:union of memberTypes="xsd:decimal xsd:double xsd:float xsd:integer".
xsd:integer[>= 0 , <= 100]