SIS Ontology
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SIS Ontology

Release: 2026-10-21

This version:
https://ptb.de/sis/v0.2.0/
Previous version:
https://ptb.de/sis/v0.1.0/
Revision:
v0.2.0
Issued on:
2026-10-21
Authors:
Giacomo Lanza , Physikalisch-Technische Bundesanstalt (PTB)
Moritz Jordan , Physikalisch-Technische Bundesanstalt (PTB)
Contributors:
Benedikt Seeger , Physikalisch-Technische Bundesanstalt (PTB)
Eva Vanessa Stehr , Physikalisch-Technische Bundesanstalt (PTB)
Daniel Hutzschenreuter, Physikalisch-Technische Bundesanstalt (PTB)
Publisher:
Physikalisch-Technische Bundesanstalt (PTB)
Download serialization:
JSON-LD RDF/XML N-Triples TTL
License:
https://creativecommons.org/licenses/by/4.0/
Visualization:
Visualize with WebVowl
Cite as:
Giacomo Lanza , Moritz Jordan . SIS Ontology. Revision: v0.2.0. Retrieved from: https://ptb.de/sis/v0.2.0/
Vocabulary maintained at:
https://gitlab1.ptb.de/d-ptb/d-si/ontology-d-si
Provenance of this page
Ontology Specification Draft

Abstract

Ontology presenting the schema for metrologically correct representation of quantity values including numerical value, kind of quantity, measurement unit and uncertainty declaration.

Introduction back to ToC

## Motivation The D-SI ontology (SIS) provides a generic framework for a complete semantic description of numerical quantity values conform to the BIPM brochure, the VIM and the GUM. It covers ............. The SIS ontology is developed at PTB within the working group on "Data for metrology" / in the framework of ..... and it evolves continuously thanks to a fruitful exchange with some standardization initiatives covering different use cases about metrological services and research data management: the workforce on Digital Calibration Certificates and the workgroup "Metadata4Ing". ## Usage The ontology SIS is a collection of terms (classes and properties) which can be used to enrich a research data set with semantic and machine-readable metadata, in order to annotate it or to integrate it in a database or a larger knowledge graph. The metadata can be serialized in formats like [JSON-LD](https://www.w3.org/TR/json-ld11/), [YAML-LD](https://json-ld.github.io/yaml-ld/spec/) or [Turtle](https://www.w3.org/TR/turtle/). More details about these semantic formats and detailed instructions how to semantically describe a data set and its generation process are collected in ....., together with practical examples. ## Design The collected classes and properties are organised in a logical and hierarchical structure and either self-defined within SIS, or reused [from other ontologies](#5-references). Subordinate classes and relations can be built according to the two principles of _inheritance_ and _modularity_. _Inheritance_ means that a subclass inherits all properties of its superordinate class, possibly adding some new ones. _Modularity_ means that all expansions are independent of each other; this makes possible for instance to generate expanded ontologies for any possible combinations of method × object of research. New concepts and properties are located in the namespace of SIS (`sis:`). For readability and compatibility reasons, SIS does not import complete ontologies. Instead, it references single existing classes and properties on which the `sis` classes and properties are based, including either their identifiers, or a relevant subset of the axioms from the original ontology. ## Availability The SIS ontology is available for download as a whole in several serializations: [TTL](ontology.ttl), [N-Triples](ontology.nt), [RDF/XML](ontology.owl) and [JSON-LD](ontology.jsonld). Application profiles in form of SHACL shapes (serialized in TTL) are available here: [shapes.ttl](shapes.ttl) Some examples / usage recommendations are available in TTL format: - [complex_cartesian.ttl](examples/complex_cartesian.ttl) - [complex_polar.ttl](examples/complex_polar.ttl) - [complexlist_cartesian.ttl](examples/complexlist_cartesian.ttl) - [complexlist_polar.ttl](examples/complexlist_polar.ttl) - [constant_boltzman.ttl](examples/constant_boltzman.ttl) - [constant_elementary_charge.ttl](examples/constant_elementary_charge.ttl) - [list.ttl](examples/list.ttl) - [real_with_coverageIntervalMU.ttl](examples/real_with_coverageIntervalMU.ttl) - [real_with_expandedMU.ttl](examples/real_with_expandedMU.ttl) - [real_with_standardMU.ttl](examples/real_with_standardMU.ttl) - [reallist_with_multivariateMU.ttl](examples/reallist_with_multivariateMU.ttl) --- ## General structure of an ontology An ontology models a defined knowledge sector by introducing classes and properties. A **class** stands for a group of individuals that all share some common properties. A **subclass** stands for a subset of this group. For example, the class [Quantity numerical value](#QuantityValue) is the most general class for the numerical value of a variable; [complex value](#Complex) is a subclass of [Quantity numerical value](#QuantityValue); the complex magnetic flux density measured in the lab ABC in the experiment XY is an **instance** of these classes, i.e. a **named individual** belonging to the class _Quantity numerical value_ and the subclass _complex value_. No individuals are included in the main ontology, but a list of [_constants_](#Constant) is attached in a separate file. Properties that are attributes of a class are called **datatype properties**. For instance, a [_univariate uncertainty declaration_](#ProcessingStep) has the following datatype properties: [_uncertainty value_](#hasUncertaintyValue), [_unit string_](#hasUnitString). The **range** of a property defines the data type of a property. For example, a [_unit string_](#hasunitString) has as a range a `xsd:string` with a particular formatting; a [_coverage probability_](#.....) has the range `xsd:double` with the restriction $0

SIS Ontology: Overview back to ToC

This ontology has the following classes and properties.

Classes

Object Properties

Data Properties

Annotation Properties

Named Individuals

SIS Ontology: Description back to ToC

Classes for single quantity values

![SIS Ontology Overview](images/sis-overview.svg) The most general expression for quantities is the class [Quantity numerical value](#QuantityValue), defined just as a superclass of more specific classes which differ mainly in the way they express the numerical value and measurement uncertainty. Single numerical variables can belong to the class [Real](#Real) or to the class [Complex](https://ptb.gitlab.io/dcc/ontology-d-si/#Real). Complex variables can be expressed in [Cartesian form](#ComplexCartesian) (with the same kind of quantity on both components) or in [polar form](#ComplexPolar) (where the second component, the phase angle, is dimensionless and accepts only angular units). Additionally, the class [Constant](#Constant) was defined for variables with a fixed value, which are usually assigned a standard uncertainty, in contrast to measured variables, which are normally assigned an expanded uncertainty (to stress the measurement confidence). Reals and constants are assigned a single [numerical value](#hasValue). Complexes have either [real](#hasValueReal) and [imaginary](#hasValueImag) components, or a [magnitude](#hasMagnitude) and a [phase](#hasPhase). All these properties accept a numerical value, preferably a `xsd:double`, including infinity??? The [kind of quantity](#hasQuantityType) is expressed via an object property linking an entry from an external terminology, preferably the SI Reference Point (only for fundamental quantities) or QUDT (for most quantities). The measurement unit can be expressed in two ways: either [as a string](#hasUnitIdentifier) formatted conform to the `siunitx` syntax, or [as a link to an entry](:hasSIMeasurementUnit) from an external terminology. We recommend hoosing the SI Reference Point, which is able to automatically generate any compound unit (such as `Joule/Kelvin mole`). The two writing systems are equivalent, as the same platform is able to convert among them. Other attributes common to all these classes are a [time stamp](#hasDateTime), a human-readable [label](#hasLabel) and the [number of significant digits / position of the least significant digit](#hasSignificantDigit).

Classes for multiple quantity values

Multiple measurement variables, or series of measurements of the same variable, can be expressed with list-like objects. SIS covers the following cases: a [list of real values](#RealList), a [list of complex values](#ComplexList), as well as a [list of lists](), which can contain other lis-like objects and can be used in an iterative way. The components of a list-like object, [real value in list](#RealInList) and [complex value in list](#ComplexInList), differ to the single-valued types in that they inherit some attributes (such as the measurement unit) from the list and thus need no separate unit annotation.

Uncertainty declarations

A [measurement uncertainty](#MeasurementUncertainty) is expressed via a complex object grouping many attributes. Depending on dimensionality, it can be [univariate](#MeasurementUncertaintyUnivariate) (for a single real value), [bivariate](#MeasurementUncertaintyBivariate) (for a single complex value) or [multivariate](#MeasurementUncertaintyMultivariate) (for a list of values). or [multivariate2](#ListMeasurementUncertaintyUnivariate)????? An univariate uncertainty declaration can be reported in three ways: [standard](#StandardMU), i.e. expressed by the standard deviation (common practice for constants); [expanded](#ExpandedMU), i.e. expressed by the standard deviation multiplied by a [coverage factor](#hasCoverageFactor) $k>1$ to increase the confidence (common practice for measured values); [confidence interval](#CoverageIntervalMU), expressed by a [minimum](#hasIntervalMin) and [maximum](#hasIntervalMax) value. Depending on the type, the corresponding uncertainty value ([standard](#hasValueStandardMU) or [expanded](#hasValueExpandedMU)) is included, as well as the [coverage probability](#hasCoverageProbability) and underlying [probability distribution density]() where appropriate. All these attributes are also numeric, possibly with restrictions (minimum $<$ maximum, $u>0$, $k>1$, $0

Cross-reference for SIS Ontology classes, object properties and data properties back to ToC

This section provides details for each class and property defined by SIS Ontology.

Classes

complex quantity value in Cartesian formc back to ToC or Class ToC

IRI: https://ptb.de/sis/ComplexCartesian

has super-classes
complex quantity value c
is disjoint with
complex quantity value in polar form c

complex quantity value in polar formc back to ToC or Class ToC

IRI: https://ptb.de/sis/ComplexPolar

has super-classes
complex quantity value c
is disjoint with
complex quantity value in Cartesian form c

complex value in Cartesian formc back to ToC or Class ToC

IRI: https://ptb.de/sis/ComplexInListCartesian

has super-classes
complex value in a list c
is disjoint with
complex value in polar form c

complex value in polar formc back to ToC or Class ToC

IRI: https://ptb.de/sis/ComplexInListPolar

has super-classes
complex value in a list c
is disjoint with
complex value in Cartesian form c

constantc back to ToC or Class ToC

IRI: https://ptb.de/sis/Constant

Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#constantQuantityType
has super-classes
real value c

covariance elementc back to ToC or Class ToC

IRI: https://ptb.de/sis/Covariance

Each covariance component is defined by - element value (decimal value type) - element unit (string - SI format)
has super-classes
Quantity value c
is in domain of
has column index dp, has row index dp
is in range of
has covariance element op

covariance matrixc back to ToC or Class ToC

IRI: https://ptb.de/sis/CovarianceMatrix

Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#covarianceMatrixType
has super-classes
Quantity value c
is in domain of
has covariance element op
is in range of
has covariance matrix op

coverage intervalc back to ToC or Class ToC

IRI: https://ptb.de/sis/CoverageIntervalMU

Definition of coverage interval measurement uncertainty data.
Structure for stating a probabilistic-symmetric coverage interval for a real uncertainty, to be applied to a sis:Real quantity value
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#coverageIntervalMUType
has super-classes
univariate measurement uncertainty c
is in domain of
has interval maximum dp, has interval minimum dp
is in range of
has coverage interval op
is disjoint with
expanded uncertainty c, standard uncertainty c

ellipsoidal uncertainty regionc back to ToC or Class ToC

IRI: https://ptb.de/sis/EllipsoidalRegion

Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#ellipsoidalRegionType
has super-classes
uncertainty region c
is in range of
has ellipsoidal region op
is disjoint with
rectangular uncertainty region c

expanded uncertaintyc back to ToC or Class ToC

IRI: https://ptb.de/sis/ExpandedMU

Definition of expanded measurement uncertainty data.
Structure for stating an expanded measurement, model, or simulation uncertainty, e.g., to be applied to a sis:Real quantity value
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#expandedMUType
has super-classes
univariate measurement uncertainty c
is in domain of
has expanded measurement uncertainty value dp
is in range of
has expanded uncertainty op
is disjoint with
coverage interval c, standard uncertainty c

Interval of real valuesc back to ToC or Class ToC

IRI: https://ptb.de/sis/RealInterval

Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#realIntervalType
has super-classes
Quantity value c
is in domain of
has interval value lower bound dp, has interval value upper bound dp

Kind of quantity according to QUDTc back to ToC or Class ToC

IRI: https://qudt.org/schema/qudt/QuantityKind

Kind of quantity according to the SI reference Pointc back to ToC or Class ToC

IRI: http://si-digital-framework.org/SI#QuantityKind

listc back to ToC or Class ToC

IRI: https://ptb.de/sis/List

list of lists, real lists and/or complex lists
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#listType
has super-classes
Quantity value c
is in domain of
has list items op

list of complex quantity valuesc back to ToC or Class ToC

IRI: https://ptb.de/sis/ComplexList

Complex lists should either be a sis:ComplexListPolar or sis:ComplexListCartesian.
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#complexListType
is equivalent to
List of complex quantity values in cartesian form c or list of complex quantity values in polar form c
has super-classes
Quantity value with multivariate measurement uncertainty c
has sub-classes
List of complex quantity values in cartesian form c, list of complex quantity values in polar form c

List of complex quantity values in cartesian formc back to ToC or Class ToC

IRI: https://ptb.de/sis/ComplexListCartesian

Example 
:someComplexListCartesian a sis:ComplexListCartesian ;
                          sis:hasQuantityType quantitykind:ElectricCharge ;
                          sis:hasUnitIdentifier "\ampere"^^xsd:string ;
                          sis:hasMeasurementUnit units:ampere ;
                          sis:hasComplexListCartesianItems [ a rdf:List ;
                                                             rdf:first [ a sis:ComplexInListCartesian ;
                                                                         sis:hasValueReal "-10.310"^^xsd:double ;
                                                                         sis:hasValueImag "5.010"^^xsd:double ;
                                                                       ] ;
                                                             rdf:rest [ a rdf:List ;
                                                                        rdf:first [ a sis:ComplexInListCartesian ;
                                                                                    sis:hasValueReal "-10.310"^^xsd:double ;
                                                                                    sis:hasValueImag "5.010"^^xsd:double ;
                                                                                 ] ;
                                                                        rdf:rest rdf:nil
                                                                      ]
                                                           ] .
Short syntax:
:someComplexCartesianList a sis:ComplexListCartesian ;
                          sis:hasQuantityType quantitykind:ElectricCharge ;
                          sis:hasUnitIdentifier "\ampere"^^xsd:string ;
                          sis:hasMeasurementUnit units:ampere ;
                          sis:hasComplexListCartesianItems ( [ a sis:ComplexInListCartesian ;
                                                               sis:hasValueReal "-10.310"^^xsd:double ;
                                                               sis:hasValueImag "5.010"^^xsd:double ;
                                                             ]
                                                             [ a sis:ComplexInListCartesian ;
                                                               sis:hasValueReal "-10.310"^^xsd:double ;
                                                               sis:hasValueImag "5.010"^^xsd:double ;
                                                             ]
                                                           ) .
has super-classes
list of complex quantity values c
is in domain of
has complex cartesian list items op
is disjoint with
list of complex quantity values in polar form c

list of complex quantity values in polar formc back to ToC or Class ToC

IRI: https://ptb.de/sis/ComplexListPolar

Example 
:someComplexListPolar a sis:ComplexListPolar ;
                      sis:hasQuantityType quantitykind:ElectricCharge ;
                      sis:hasUnitIdentifier "\ampere"^^xsd:string ;
                      sis:hasMeasurementUnit units:ampere ;
                      sis:hasUnitPhaseIdentifier "\metre\metre\tothe{-1}"^^xsd:string ;
                      sis:hasComplexListPolarItems [ a rdf:List ;
                                                     rdf:first [ a sis:ComplexInListPolar ;
                                                                 sis:hasValueMagnitude "3.0"^^xsd:double ;
                                                                 sis:hasValuePhase "20.0"^^xsd:double ;
                                                               ] ;
                                                     rdf:rest [ a rdf:List ;
                                                                rdf:first [ a sis:ComplexInListPolar ;
                                                                            sis:hasValueMagnitude "-1.0"^^xsd:double ;
                                                                            sis:hasValuePhase "35.0"^^xsd:double ;
                                                                          ] ;
                                                                rdf:rest rdf:nil
                                                              ]
                                                   ] .
Short syntax:
:someComplexListPolar a sis:ComplexListPolar ;
                      sis:hasQuantityType quantitykind:ElectricCharge ;
                      sis:hasUnitIdentifier "\ampere"^^xsd:string ;
                      sis:hasMeasurementUnit units:ampere ;
                      sis:hasUnitPhaseIdentifier "\metre\metre\tothe{-1}"^^xsd:string ;
                      sis:hasComplexListPolarItems ( [ a sis:ComplexInListPolar ;
                                                       sis:hasValueMagnitude "3.0"^^xsd:double ;
                                                       sis:hasValuePhase "20.0"^^xsd:double ;
                                                      ]
                                                      [ a sis:ComplexInListPolar ;
                                                        sis:hasValueMagnitude "-1.0"^^xsd:double ;
                                                        sis:hasValuePhase "35.0"^^xsd:double ;
                                                      ]
                                                    ) .
has super-classes
list of complex quantity values c
is in domain of
has complex polar list items op
is disjoint with
List of complex quantity values in cartesian form c

list of real valuesc back to ToC or Class ToC

IRI: https://ptb.de/sis/RealList

Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#realListType
Example 
:someRealList a sis:RealList ;
              sis:hasMeasurementUnit units:metre ;
              sis:hasUnitIdentifier "\second"^^xsd:string ;
              sis:hasRealListItems [ a rdf:List ;
                                     rdf:first [ a sis:RealInList ;
                                                 sis:hasValue "1.0"^^xsd:double ;
                                               ] ;
                                     rdf:rest [ a rdf:List ;
                                                rdf:first [ a sis:RealInList ;
                                                            sis:hasValue "1.0"^^xsd:double ;
                                                          ] ;
                                                rdf:rest rdf:nil ;
                                              ]
                                   ] .
Short syntax:
:someRealList a sis:RealList ;
              sis:hasMeasurementUnit units:metre ;
              sis:hasUnitIdentifier "\second"^^xsd:string ;
              sis:hasRealListItems ( [ a sis:RealInList ;
                                       sis:hasValue "1.0"^^xsd:double ;
                                     ]
                                     [ a sis:RealInList ;
                                       sis:hasValue "1.0"^^xsd:double ;
                                     ]
                                   ) .
has super-classes
Quantity value with multivariate measurement uncertainty c, Quantity value with univariate measurement uncertainty c
is in domain of
has real list items op

measurement uncertaintyc back to ToC or Class ToC

IRI: https://ptb.de/sis/MeasurementUncertainty

Superclass of all measurement uncertainty constructs in the D-SI
has sub-classes
multivariate measurement uncertainty c, univariate measurement uncertainty c
is in range of
has uncertainty declaration op

Measurement unit according to QUDTc back to ToC or Class ToC

IRI: https://qudt.org/schema/qudt/Unit

Measurement unit according to SIRPc back to ToC or Class ToC

IRI: http://si-digital-framework.org/SI#MeasurementUnit

multivariate measurement uncertaintyc back to ToC or Class ToC

IRI: https://ptb.de/sis/MeasurementUncertaintyMultivariate

has super-classes
measurement uncertainty c
has sub-classes
uncertainty region c
is in domain of
has covariance matrix op
is in range of
has multivariate measurement uncertainty op

Quantity valuec back to ToC or Class ToC

IRI: https://ptb.de/sis/QuantityValue

Superclass of Real, Constant, Complex, List, RealList, RealInList, ComplexList, ComplexInList, and Hybrid. Contains one or more numerical values with a unit.
has sub-classes
Interval of real values c, Quantity value with multivariate measurement uncertainty c, Quantity value with univariate measurement uncertainty c, covariance element c, covariance matrix c, list c

Quantity value with multivariate measurement uncertaintyc back to ToC or Class ToC

IRI: https://ptb.de/sis/QuantityValueMultivariate

General class for numerical variables having a multivariate measurement uncertainty
has super-classes
Quantity value c
has sub-classes
complex quantity value c, complex value in a list c, list of complex quantity values c, list of real values c
is in domain of
has ellipsoidal region op, has multivariate measurement uncertainty op, has rectangular region op

Quantity value with univariate measurement uncertaintyc back to ToC or Class ToC

IRI: https://ptb.de/sis/QuantityValueUnivariate

General class for numerical variables having a univariate measurement uncertainty
has super-classes
Quantity value c
has sub-classes
list of real values c, real value c, real value in a list c
is in domain of
has univariate measurement uncertainty op

real valuec back to ToC or Class ToC

IRI: https://ptb.de/sis/Real

(Real value +- uncertainty) x measurement unit, i.e., a scalar value with a measurement unit and an uncertainty indication
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#realQuantityType
has super-classes
Quantity value with univariate measurement uncertainty c
has sub-classes
constant c

real value in a listc back to ToC or Class ToC

IRI: https://ptb.de/sis/RealInList

Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#realInListType
has super-classes
Quantity value with univariate measurement uncertainty c

rectangular uncertainty regionc back to ToC or Class ToC

IRI: https://ptb.de/sis/RectangularRegion

Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#rectangularRegionType
has super-classes
uncertainty region c
is in range of
has rectangular region op
is disjoint with
ellipsoidal uncertainty region c

standard uncertaintyc back to ToC or Class ToC

IRI: https://ptb.de/sis/StandardMU

Definition of standard measurement uncertainty data.
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#standardMUType
has super-classes
univariate measurement uncertainty c
is in range of
has standard measurement uncertainty op
is disjoint with
coverage interval c, expanded uncertainty c

univariate measurement uncertaintyc back to ToC or Class ToC

IRI: https://ptb.de/sis/MeasurementUncertaintyUnivariate

has super-classes
measurement uncertainty c
has sub-classes
coverage interval c, expanded uncertainty c, standard uncertainty c
is in range of
has univariate measurement uncertainty op

Object Properties

has complex cartesian list itemsop back to ToC or Object Property ToC

IRI: https://ptb.de/sis/hasComplexListCartesianItems

points to the first rdf:List element that points the first complex cartesian instance in the list and to another rdf:List
has domain
List of complex quantity values in cartesian form c
has range
List c

has complex polar list itemsop back to ToC or Object Property ToC

IRI: https://ptb.de/sis/hasComplexListPolarItems

points to the first rdf:List element that points the first complex polar instance in the list and to another rdf:List
has domain
list of complex quantity values in polar form c
has range
List c

has covariance elementop back to ToC or Object Property ToC

IRI: https://ptb.de/sis/hasCovariance

has domain
covariance matrix c
has range
covariance element c

has covariance matrixop back to ToC or Object Property ToC

IRI: https://ptb.de/sis/hasCovarianceMatrix

has domain
multivariate measurement uncertainty c
has range
covariance matrix c

has coverage intervalop back to ToC or Object Property ToC

IRI: https://ptb.de/sis/hasCoverageIntervalMU

has super-properties
has univariate measurement uncertainty op
has range
coverage interval c

has ellipsoidal regionop back to ToC or Object Property ToC

IRI: https://ptb.de/sis/hasEllipsoidalRegion

has super-properties
has multivariate measurement uncertainty op
has domain
Quantity value with multivariate measurement uncertainty c
has range
ellipsoidal uncertainty region c

has expanded uncertaintyop back to ToC or Object Property ToC

IRI: https://ptb.de/sis/hasExpandedMU

has super-properties
has univariate measurement uncertainty op
has range
expanded uncertainty c

has list itemsop back to ToC or Object Property ToC

IRI: https://ptb.de/sis/hasListItems

has list, real list and/or complex list in list
has domain
list c
has range
List c

has measurement unitop back to ToC or Object Property ToC

IRI: https://ptb.de/sis/hasMeasurementUnit

SI compatible measurement unit associated to a quantity, expressed as the identifier of a term from a controlled terminology. We recommend choosing terms from the SI reference point https://si-digital-framework.org/SI/units/. A possible alternative choice is QUDT http://qudt.org/vocab/unit.
has range
Measurement unit according to SIRP c or Measurement unit according to QUDT c

has multivariate measurement uncertaintyop back to ToC or Object Property ToC

IRI: https://ptb.de/sis/hasMeasurementUncertaintyMultivariate

has super-properties
has uncertainty declaration op
has sub-properties
has ellipsoidal region op, has rectangular region op
has domain
Quantity value with multivariate measurement uncertainty c
has range
multivariate measurement uncertainty c

has quantity typeop back to ToC or Object Property ToC

IRI: https://ptb.de/sis/hasQuantityType

Standardized kind of quantity associated to a quantity value, expressed as the identifier of a term from a controlled terminology. We recommend choosing high-level terms (energy, length) from the SI reference point and more specific terms (electric energy, enthalpy, diameter, depth) from QUDT.
has range
Kind of quantity according to the SI reference Point c or Kind of quantity according to QUDT c

has real list itemsop back to ToC or Object Property ToC

IRI: https://ptb.de/sis/hasRealListItems

points to the first rdf:List element that points the first real instance in the list and to another rdf:List
has domain
list of real values c
has range
List c

has rectangular regionop back to ToC or Object Property ToC

IRI: https://ptb.de/sis/hasRectangularRegion

has super-properties
has multivariate measurement uncertainty op
has domain
Quantity value with multivariate measurement uncertainty c
has range
rectangular uncertainty region c

has standard measurement uncertaintyop back to ToC or Object Property ToC

IRI: https://ptb.de/sis/hasStandardMU

has super-properties
has univariate measurement uncertainty op
has range
standard uncertainty c

has uncertainty declarationop back to ToC or Object Property ToC

IRI: https://ptb.de/sis/hasMeasurementUncertainty

has sub-properties
has multivariate measurement uncertainty op, has univariate measurement uncertainty op
has range
measurement uncertainty c

has univariate measurement uncertaintyop back to ToC or Object Property ToC

IRI: https://ptb.de/sis/hasMeasurementUncertaintyUnivariate

has super-properties
has uncertainty declaration op
has sub-properties
has coverage interval op, has expanded uncertainty op, has standard measurement uncertainty op
has domain
Quantity value with univariate measurement uncertainty c
has range
univariate measurement uncertainty c

Data Properties

has amplitudedp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasValueMagnitude

Scientific decimal format for numerical values.
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#decimal
has range
double

has column indexdp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasColumnIndex

has domain
covariance element c
has range
positive Integer

has coverage factordp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasCoverageFactor

Scientific decimal format for coverage factor values for uncertainties that must be greater than one or equal to one. Based on type xs:double.
points to the coverage factor, i.e., to a factor (greater than or equal to unity) by which the expanded uncertainty relates to the standard uncertainty
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#kValueType
has range
double

has coverage probabilitydp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasCoverageProbability

Decimal format for coverage probability values for uncertainties. The value must be within the interval [0,1]. The scientific exponent "e" (or "E") is not allowed. Based on type xs:double.
points to the probability (between 0 and 1) ascribed to the event of the actual value falling within the range asserted by the given uncertainty declaration
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#probabilityValueType
has range
double

has expanded measurement uncertainty valuedp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasValueExpandedMU

Scientific decimal format for numerical values of expanded measurement uncertainty that must be positive (greater than zero or equal to zero). Based on type xs:double.
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#valueExpandedMU
has domain
expanded uncertainty c
has range
double

has imaginary partdp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasValueImag

Scientific decimal format for numerical values.
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#decimal
has range
double

has interval lower bound excludeddp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasIntervalValueLowerBoundExcluded

has super-properties
has interval value lower bound dp

has interval lower bound includeddp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasIntervalValueLowerBoundIncluded

has super-properties
has interval value lower bound dp

has interval maximumdp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasIntervalMax

Scientific decimal format for numerical values. Based on type xs:double.
upper boundary of the coverage interval
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#intervalMaxType
has domain
coverage interval c
has range
double

has interval minimumdp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasIntervalMin

Scientific decimal format for numerical values. Based on type xs:double.
lower boundary of the coverage interval
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#intervalMin
has domain
coverage interval c
has range
double

has interval upper bound excludeddp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasIntervalValueUpperBoundExcluded

has super-properties
has interval value upper bound dp

has interval upper bound includeddp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasIntervalValueUpperBoundIncluded

has super-properties
has interval value upper bound dp

has interval value lower bounddp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasIntervalValueLowerBound

has sub-properties
has interval lower bound excluded dp, has interval lower bound included dp
has domain
Interval of real values c
has range
double

has interval value upper bounddp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasIntervalValueUpperBound

has sub-properties
has interval upper bound excluded dp, has interval upper bound included dp
has domain
Interval of real values c
has range
double

has numerical valuedp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasValue

Scientific decimal format for numerical values.
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#decimalType
has range
double

has phasedp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasValuePhase

Scientific decimal format for numerical values.
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#decimal
has range
double

has phase unit identifierdp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasUnitPhaseIdentifier

xsd:string described by the following regular expression: "(((\\\\deca)|(\\\\hecto)|(\\\\mega)|(\\\\giga)|(\\\\tera)|(\\\\peta)|(\\\\exa)|(\\\\zetta)|(\\\\yotta)|(\\\\deci)|(\\\\centi)|(\\\\milli)|(\\\\micro)|(\\\\nano)|(\\\\pico)|(\\\\femto)|(\\\\atto)|(\\\\zepto)|(\\\\yocto)|(\\\\kibi)|(\\\\mebi)|(\\\\gibi)|(\\\\tebi)|(\\\\pebi)|(\\\\exbi)|(\\\\zebi)|(\\\\yobi))*\\\\radian)|(\\\\metre\\\\tothe\\{0\\})|(\\\\metre\\\\tothe\\{-1\\})|(\\\\degree)|(\\\\arcminute)|(\\\\arcsecond)" Unit associated to an angular quantity, associated to a phase angle, expressed as a xs:string. Allowed values are chosen from the BIPM SI brochure (9th edition). The recommended syntax is defined in the SmartCom-D-SI brochure and is based on the siunitx LaTeX package.
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#unitPhase
has range
string

has real partdp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasValueReal

Scientific decimal format for numerical values.
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#decimal
has range
double

has row indexdp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasRowIndex

has domain
covariance element c
has range
positive Integer

has significant digitdp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasSignificantDigit

This property specifies the integer value of an exponent of a power of ten. The resulting power of ten corresponds to the rounding range defined in ISO 80000-1:2022.
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#significantDigit
has range
integer

has standard uncertaintydp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasValueStandardMU

Scientific decimal format for numerical values of standard measurement uncertainty that must be positive (greater than zero or equal to zero). Based on type xs:double.
The standard measurement uncertainty is the measurement uncertainty expressed as a standard deviation
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#valueStandardMU
has range
double

has statistical distributiondp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasDistribution

points to a descriptor/label of the assumed underlying distribution
has range
string

has time stampdp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasDateTime

has range
date Time

has unit identifierdp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasUnitIdentifier

xsd:string described by the following regular expression: "((((\\kilogram)|(\\decibel)|(\\degreecelsius)|(\\mmhg)|(\\minute)|(\\hour)|(\\day))(\\tothe\{-?\d+(\.\d+)?\})?)|(((\\deca)|(\\hecto)|(\\mega)|(\\giga)|(\\tera)|(\\peta)|(\\exa)|(\\zetta)|(\\yotta)|(\\deci)|(\\centi)|(\\milli)|(\\micro)|(\\nano)|(\\pico)|(\\femto)|(\\atto)|(\\zepto)|(\\yocto)|(\\kibi)|(\\mebi)|(\\gibi)|(\\tebi)|(\\pebi)|(\\exbi)|(\\zebi)|(\\yobi))?((\\gram))(\\tothe\{-?\d+(\.\d+)?\})?)|(((\\deca)|(\\hecto)|(\\kilo)|(\\mega)|(\\giga)|(\\tera)|(\\peta)|(\\exa)|(\\zetta)|(\\yotta)|(\\centi)|(\\milli)|(\\micro)|(\\nano)|(\\pico)|(\\femto)|(\\atto)|(\\zepto)|(\\yocto)|(\\kibi)|(\\mebi)|(\\gibi)|(\\tebi)|(\\pebi)|(\\exbi)|(\\zebi)|(\\yobi))?((\\bel))(\\tothe\{-?\d+(\.\d+)?\})?)|((\\one))|(((\\deca)|(\\hecto)|(\\kilo)|(\\mega)|(\\giga)|(\\tera)|(\\peta)|(\\exa)|(\\zetta)|(\\yotta)|(\\deci)|(\\centi)|(\\milli)|(\\micro)|(\\nano)|(\\pico)|(\\femto)|(\\atto)|(\\zepto)|(\\yocto)|(\\kibi)|(\\mebi)|(\\gibi)|(\\tebi)|(\\pebi)|(\\exbi)|(\\zebi)|(\\yobi))?((\\metre)|(\\second)|(\\ampere)|(\\kelvin)|(\\mole)|(\\candela)|(\\degree)|(\\arcminute)|(\\arcsecond)|(\\radian)|(\\steradian)|(\\hertz)|(\\newton)|(\\pascal)|(\\joule)|(\\watt)|(\\coulomb)|(\\volt)|(\\farad)|(\\ohm)|(\\siemens)|(\\weber)|(\\tesla)|(\\henry)|(\\lumen)|(\\lux)|(\\becquerel)|(\\sievert)|(\\gray)|(\\katal)|(\\hectare)|(\\litre)|(\\tonne)|(\\electronvolt)|(\\dalton)|(\\astronomicalunit)|(\\neper)|(\\percent)|(\\ppm)|(\\byte)|(\\bit)|(\\angstrom)|(\\bar)|(\\atomicunittime)|(\\atomicmassunit)|(\\barn)|(\\clight)|(\\electronmass)|(\\elementarycharge)|(\\naturalunittime)|(\\hartree)|(\\bohr)|(\\nauticalmile)|(\\knot)|(\\planckbar))(\\tothe\{-?\d+(\.\d+)?\})?))+(\\per((((\\kilogram)|(\\decibel)|(\\degreecelsius)|(\\mmhg)|(\\minute)|(\\hour)|(\\day))(\\tothe\{-?\d+(\.\d+)?\})?)|(((\\deca)|(\\hecto)|(\\mega)|(\\giga)|(\\tera)|(\\peta)|(\\exa)|(\\zetta)|(\\yotta)|(\\deci)|(\\centi)|(\\milli)|(\\micro)|(\\nano)|(\\pico)|(\\femto)|(\\atto)|(\\zepto)|(\\yocto)|(\\kibi)|(\\mebi)|(\\gibi)|(\\tebi)|(\\pebi)|(\\exbi)|(\\zebi)|(\\yobi))?((\\gram))(\\tothe\{-?\d+(\.\d+)?\})?)|(((\\deca)|(\\hecto)|(\\kilo)|(\\mega)|(\\giga)|(\\tera)|(\\peta)|(\\exa)|(\\zetta)|(\\yotta)|(\\centi)|(\\milli)|(\\micro)|(\\nano)|(\\pico)|(\\femto)|(\\atto)|(\\zepto)|(\\yocto)|(\\kibi)|(\\mebi)|(\\gibi)|(\\tebi)|(\\pebi)|(\\exbi)|(\\zebi)|(\\yobi))?((\\bel))(\\tothe\{-?\d+(\.\d+)?\})?)|((\\one))|(((\\deca)|(\\hecto)|(\\kilo)|(\\mega)|(\\giga)|(\\tera)|(\\peta)|(\\exa)|(\\zetta)|(\\yotta)|(\\deci)|(\\centi)|(\\milli)|(\\micro)|(\\nano)|(\\pico)|(\\femto)|(\\atto)|(\\zepto)|(\\yocto)|(\\kibi)|(\\mebi)|(\\gibi)|(\\tebi)|(\\pebi)|(\\exbi)|(\\zebi)|(\\yobi))?((\\metre)|(\\second)|(\\ampere)|(\\kelvin)|(\\mole)|(\\candela)|(\\degree)|(\\arcminute)|(\\arcsecond)|(\\radian)|(\\steradian)|(\\hertz)|(\\newton)|(\\pascal)|(\\joule)|(\\watt)|(\\coulomb)|(\\volt)|(\\farad)|(\\ohm)|(\\siemens)|(\\weber)|(\\tesla)|(\\henry)|(\\lumen)|(\\lux)|(\\becquerel)|(\\sievert)|(\\gray)|(\\katal)|(\\hectare)|(\\litre)|(\\tonne)|(\\electronvolt)|(\\dalton)|(\\astronomicalunit)|(\\neper)|(\\percent)|(\\ppm)|(\\byte)|(\\bit)|(\\angstrom)|(\\bar)|(\\atomicunittime)|(\\atomicmassunit)|(\\barn)|(\\clight)|(\\electronmass)|(\\elementarycharge)|(\\naturalunittime)|(\\hartree)|(\\bohr)|(\\nauticalmile)|(\\knot)|(\\planckbar))(\\tothe\{-?\d+(\.\d+)?\})?))+)?$|(^\|.*$)" Unit associated to a quantity, expressed as a xs:string. Allowed values are chosen from the BIPM SI brochure (9th edition). The recommended syntax is defined in the SmartCom-D-SI brochure and is based on the siunitx LaTeX package.
Is defined by
https://www.ptb.de/si/v2.2.1/SI_Format.xsd#unit
has range
string

has verbose namedp back to ToC or Data Property ToC

IRI: https://ptb.de/sis/hasLabel

has range
string

Annotation Properties

abstractap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/abstract

affiliationap back to ToC or Annotation Property ToC

IRI: https://schema.org/affiliation

bug databaseap back to ToC or Annotation Property ToC

IRI: http://usefulinc.com/ns/doap#bug-database

contributorap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/contributor

createdap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/created

creatorap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/creator

definitionap back to ToC or Annotation Property ToC

IRI: http://www.w3.org/2004/02/skos/core#definition

distributionap back to ToC or Annotation Property ToC

IRI: http://www.w3.org/ns/dcat#distribution

documentationap back to ToC or Annotation Property ToC

IRI: http://www.loc.gov/premis/rdf/v3/documentation

exampleap back to ToC or Annotation Property ToC

IRI: http://www.w3.org/2004/02/skos/core#example

has Syntaxap back to ToC or Annotation Property ToC

IRI: https://w3id.org/mod#hasSyntax

issuedap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/issued

languageap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/language

licenseap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/license

nameap back to ToC or Annotation Property ToC

IRI: http://xmlns.com/foaf/0.1/name

preferred Namespace Prefixap back to ToC or Annotation Property ToC

IRI: http://purl.org/vocab/vann/preferredNamespacePrefix

preferred Namespace Uriap back to ToC or Annotation Property ToC

IRI: http://purl.org/vocab/vann/preferredNamespaceUri

publisherap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/publisher

replacesap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/replaces

repositoryap back to ToC or Annotation Property ToC

IRI: http://usefulinc.com/ns/doap#repository

rightsap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/rights

titleap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/title

Named Individuals

0000 0002 2190 6931ni back to ToC or Named Individual ToC

IRI: https://orcid.org/0000-0002-2190-6931

belongs to
Person c
has facts
name ap "Benedikt Seeger "
affiliation ap 05r3f7h03 ni

0000 0002 2239 3955ni back to ToC or Named Individual ToC

IRI: https://orcid.org/0000-0002-2239-3955

belongs to
Person c
has facts
name ap "Giacomo Lanza "
affiliation ap 05r3f7h03 ni

0000 0002 6461 2554ni back to ToC or Named Individual ToC

IRI: https://orcid.org/0000-0002-6461-2554

belongs to
Person c
has facts
name ap "Eva Vanessa Stehr "
affiliation ap 05r3f7h03 ni

0000 0002 9095 0063ni back to ToC or Named Individual ToC

IRI: https://orcid.org/0000-0002-9095-0063

belongs to
Person c
has facts
name ap "Daniel Hutzschenreuter"
affiliation ap 05r3f7h03 ni

0000 0003 0941 5950ni back to ToC or Named Individual ToC

IRI: https://orcid.org/0000-0003-0941-5950

belongs to
Person c
has facts
name ap "Moritz Jordan "
affiliation ap 05r3f7h03 ni

05r3f7h03ni back to ToC or Named Individual ToC

IRI: https://ror.org/05r3f7h03

belongs to
Organization c
has facts
name ap "Physikalisch-Technische Bundesanstalt (PTB)"

ontology.jsonldni back to ToC or Named Individual ToC

IRI: https://ptb.de/sis/ontology.jsonld

belongs to
Distribution c
has facts
has Syntax ap J S O N L D ep

ontology.ntni back to ToC or Named Individual ToC

IRI: https://ptb.de/sis/ontology.nt

belongs to
Distribution c
has facts
has Syntax ap N Triples ep

ontology.owlni back to ToC or Named Individual ToC

IRI: https://ptb.de/sis/ontology.owl

belongs to
Distribution c
has facts
has Syntax ap R D F X M L ep

ontology.ttlni back to ToC or Named Individual ToC

IRI: https://ptb.de/sis/ontology.ttl

belongs to
Distribution c
has facts
has Syntax ap Turtle ep

Legend back to ToC

c: Classes
op: Object Properties
dp: Data Properties
ni: Named Individuals
ep: External Properties

References back to ToC

Hutzschenreuter, Daniel et al (2020). SmartCom Digital System of Units (D-SI): Guide for the use of the metadata-format used in metrology for the easy-to-use, safe, harmonised and unambiguous digital transfer of metrological data - Second Edition (D-SI 1.3.0-2). Zenodo. https://doi.org/10.5281/zenodo.3816686 Jordan, Moritz and Lanza, Giacomo. ..... Reused Ontologies: * DCAT = [Data Catalog](http://www.w3.org/ns/dcat) * DCC = [Digital Calibration Certificate](https://ptb.de/dcc/) * DCTERMS = [Dublin Core Terms](http://purl.org/dc/terms/) * FOAF = [Friend of a Friend](http://xmlns.com/foaf/0.1/) * OWL = [Web Ontology Language](https://www.w3.org/TR/owl-overview/) * QUDT = [Quantities, Units, Dimensions and Types](http://www.qudt.org/catalog/qudt-catalog.html) * RDF = [Resource Description Framework](https://www.w3.org/TR/rdf11-concepts/) * RDFS = [RDF Schema](https://www.w3.org/TR/rdf-schema/) * SCHEMA = [schema.org](https://schema.org/) * SIRP = [SI Reference Point](http://si-digital-framework.org/SI#) * SKOS = [Simple Knowledge Organization System](https://www.w3.org/TR/skos-reference/) * XSD = [XML Schema Definition](https://www.w3.org/TR/xmlschema11-1/)
null

Acknowledgments back to ToC

The authors would like to thank [Silvio Peroni](http://www.essepuntato.it/) for developing [LODE](http://www.essepuntato.it/lode), a Live OWL Documentation Environment, which is used for representing the Cross Referencing Section of this document and [Daniel Garijo](https://w3id.org/people/dgarijo) for developing [Widoco](https://github.com/dgarijo/Widoco), the program used to create the template used in this documentation. The authors would like to thank Thomas Wiedenhöfer, Oksana Bär and Wiebke Heeren for their previous work in the project SmartCom; Joachim Meier, Shanna Schönhals and Muhammed-Ali Demir for fruitful input; Dorothea Iglezakis ans Marc Furhmans for the users' feedback.