Tabular content (UoM)

Table of Contents

1 Introduction
2 Simple SELECT queries
3 Advanced SELECT queries: Using ontology restrictions
- 3.1 Introduction
- 3.2 Find the permissible units for a quantity
4 Advanced SELECT queries: Combining PLM-RDL with external resources

1 Introduction

This page describes some typical SPARQL queries over the Unit of Measure ontology module. Any SELECT query will return a table of results.

Visit the Fuseki page to experiment with these queries yourself!

Like most SPARQL servers, Fuseki can provide tabular results as plain text in CSV and TSV format (filetypes text/csv and text/tab-separated-values), as well as JSON (filetype application/sparql-results+json) and XML (filetype application/sparql-results+xml).

2 Simple SELECT queries

2.1 Units of measure – getting started

To get started, we request a list of units of measure, retrieving for each of them the identifier of the resource in the ontology, which will be a Uniform Resource Identifier (URI), and its name, which will be a string. Names are, as is common practice, assigned using the rdfs:label RDF property.

In the UoM ontology, a unit of measure is a member of the ISO 15926-14 class lis:Scale, so this is what we’ll query for.

Writing lis:Scale is a convenient abbreviation for https://rds.posccaesar.org/ontology/lis14/rdl/Scale. The string lis: is called a prefix, and a prefixed URI like lis:Scale is sometimes called a “puri” (see here).

The following query specifies no sort order, so the particular list of results is likely to vary between runs – we are only asking for an arbitrary five.

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX lis: <http://rds.posccaesar.org/ontology/lis14/rdl/>
PREFIX rdl:   <http://rds.posccaesar.org/ontology/plm/rdl/>
select ?uom ?uom_label {
  ?uom a lis:Scale ; rdfs:label ?uom_label
}
limit 5

On this page, we will use prefixed URIs to prevent long identifiers from making the result tables hard to read. Use the tabs below to compare the two; the following examples will only have the abbreviated form.

Prefixed URIs

uom	uom_label
rdl:PCA_100003716	pascal
rdl:PCA_100003721	square metre
rdl:PCA_100003698	megawatt
rdl:PCA_100003707	millisecond
rdl:PCA_100003719	second (angle)

Full URIs

uom	uom_label
http://rds.posccaesar.org/ontology/plm/rdl/PCA_100003716	pascal
http://rds.posccaesar.org/ontology/plm/rdl/PCA_100003721	square metre
http://rds.posccaesar.org/ontology/plm/rdl/PCA_100003698	megawatt
http://rds.posccaesar.org/ontology/plm/rdl/PCA_100003707	millisecond
http://rds.posccaesar.org/ontology/plm/rdl/PCA_100003719	second (angle)

2.2 Units of measure – filtering by name

To find a selection of units, we can apply a filter. This query uses the SPARQL regex function to select only those units where the string “metre” appears in the name. We apply alphabetical order to the output table, with an order by clause.

Note the use of a in ?uom a lis:Scale, which simply is a built-in shorthand for rdf:type.

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX lis: <http://rds.posccaesar.org/ontology/lis14/rdl/>
PREFIX rdl:   <http://rds.posccaesar.org/ontology/plm/rdl/>
select ?uom ?uom_label {
  ?uom a lis:Scale ; rdfs:label ?uom_label
  filter( regex( ?uom_label, "metre" ))
}
order by ?uom_label
limit 5

uom	uom_label
rdl:PCA_100003663	centimetre
rdl:PCA_100003664	cubic decimetre
rdl:PCA_100003665	cubic metre
rdl:PCA_100003666	cubic metre per second
rdl:PCA_100003670	decimetre

2.3 Quantities – filtering by name

In the UoM ontology, a quantity, such as density or volume, is a subclass of the ISO 15926-14 class lis:PhysicalQuantity. The following query is very similar to the previous one, but uses rdfs:subClassOf instead of rdf:type.

This query has a slightly more sophisticated filter, using || to allow quantities with “density” or “volume” in the name.

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX lis: <http://rds.posccaesar.org/ontology/lis14/rdl/>
PREFIX rdl:   <http://rds.posccaesar.org/ontology/plm/rdl/>
select ?quantity ?quantity_label {
  ?quantity rdfs:subClassOf lis:PhysicalQuantity ; rdfs:label ?quantity_label
  filter( regex( ?quantity_label, "density" ) || regex( ?quantity_label, "volume" ) )
}
order by ?quantity_label
limit 5

quantity	quantity_label
rdl:PCA_100003569	current density
rdl:PCA_100003570	density
rdl:PCA_100003588	magnetic flux density
rdl:PCA_100003605	volume
rdl:PCA_100003606	volumetric flow rate

2.4 Quantities – default units of measure

Many (but not all) quantities in the UoM ontology have a default unit of measure assigned to them. The following query retrieves quantities together with default units.

Note the use in the query of rdl:PCA_100000510, which is the identifier for the default unit of measure relation (an OWL annotation property). We need to use this uninformative identifer, as SPARQL will not by itself pick out the right relation from its given name.

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX lis: <http://rds.posccaesar.org/ontology/lis14/rdl/>
PREFIX rdl:   <http://rds.posccaesar.org/ontology/plm/rdl/>
select ?quantity ?quantity_label ?default_uom ?default_uom_label {
  ?quantity rdfs:subClassOf lis:PhysicalQuantity ; rdfs:label ?quantity_label .
  ?quantity rdl:PCA_100000510 ?default_uom .  # "default unit of measure"
  ?default_uom a lis:Scale ; rdfs:label ?default_uom_label .
  filter( regex( ?quantity_label, "density" ) || regex( ?quantity_label, "volume" ) )
}
order by ?quantity_label
limit 5

quantity	quantity_label	default_uom	default_uom_label
rdl:PCA_100003570	density	rdl:PCA_100003685	kilogram per cubic metre
rdl:PCA_100003588	magnetic flux density	rdl:PCA_100003723	tesla
rdl:PCA_100003605	volume	rdl:PCA_100003665	cubic metre

2.5 Quantities and units – symbols

Many (but not all) quantities and units of measure in the UoM ontology have symbols assigned to them, using the om:symbol annotation property. The following query is an example. Here, we have left out the identifiers from the select list of variables to keep the table tidy.

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX lis: <http://rds.posccaesar.org/ontology/lis14/rdl/>
PREFIX rdl:   <http://rds.posccaesar.org/ontology/plm/rdl/>
PREFIX om: <http://www.ontology-of-units-of-measure.org/resource/om-2/>
select ?quantity_label ?quantity_symbol ?default_uom_label ?default_uom_symbol {
  ?quantity rdfs:subClassOf lis:PhysicalQuantity ; rdfs:label ?quantity_label ;
    om:symbol ?quantity_symbol .
  ?quantity rdl:PCA_100000510 ?default_uom .  # "default unit of measure"
  ?default_uom a lis:Scale ; rdfs:label ?default_uom_label ;
    om:symbol ?default_uom_symbol
  filter( regex( ?quantity_label, "density" ) || regex( ?quantity_label, "volume" ) )
}
order by ?quantity_label
limit 5

2.6 Datum types

Each of the quantities (subclasses of lis:PhysicalQuantity) in the UoM ontology is assigned a lis:ScalarQuantityDatum class. Any member of such a datum type will have at least two pointers – to a unit of measure, and to a numeric value. For details, see the more advanced queries below; here, we simply retrieve a list datum classes.

This query is similar to that of section Units of measure – filtering by name above, filtering on the term “electric” (but note that the relation is rdfs:subClassOf, not rdf:type).

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX lis: <http://rds.posccaesar.org/ontology/lis14/rdl/>
PREFIX rdl:   <http://rds.posccaesar.org/ontology/plm/rdl/>
select ?datum ?datum_label {
  ?datum rdfs:subClassOf lis:ScalarQuantityDatum ; rdfs:label ?datum_label
  filter( regex( ?datum_label, "electric" ))
}
order by ?datum_label
limit 5

datum	datum_label
rdl:PCA_100003640	electric charge datum
rdl:PCA_100003609	electric current datum
rdl:PCA_100003628	electric potential datum
rdl:PCA_100003629	electrical resistance datum

2.7 Datum types and applicable units

Each type of physical quantity datum will in general be related by the applicable unit of measure annotation property to a selection of units. This allows us to extend the previous query with a list of units for each datum type.

The annotation applicable unit of measure is a “convenience” annotation that allows for simple browsing and querying of units as related to quantities. There are also semantic restrictions to validate the correct use of units – for more information, see Advanced SELECT queries: Using ontology restrictions.

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX lis: <http://rds.posccaesar.org/ontology/lis14/rdl/>
PREFIX rdl:   <http://rds.posccaesar.org/ontology/plm/rdl/>
select ?datum ?datum_label ?applicable_uom ?applicable_uom_label {
  ?datum rdfs:subClassOf lis:ScalarQuantityDatum ; rdfs:label ?datum_label .
  filter( regex( ?datum_label, "electric" ))
  ?datum rdl:PCA_100003769 ?applicable_uom .  # "applicable uom"
  ?applicable_uom rdfs:label ?applicable_uom_label
}
order by ?datum_label
limit 5

datum	datum_label	applicable_uom	applicable_uom_label
rdl:PCA_100003640	electric charge datum	rdl:PCA_100003658	ampere hour
rdl:PCA_100003609	electric current datum	rdl:PCA_100003657	ampere
rdl:PCA_100003609	electric current datum	rdl:PCA_100003683	kiloampere
rdl:PCA_100003609	electric current datum	rdl:PCA_100003703	milliampere
rdl:PCA_100003628	electric potential datum	rdl:PCA_100003724	volt

2.8 Inline data: explicit lists using SPARQL values

In some cases, you will know precisely which resources you wish to query. The following query illustrates how the SPARQL values syntax allows you to provide an explicit, “inline” list of quantities.

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX lis: <http://rds.posccaesar.org/ontology/lis14/rdl/>
PREFIX rdl:   <http://rds.posccaesar.org/ontology/plm/rdl/>
select ?datum ?datum_label ?applicable_uom ?applicable_uom_label {
  values ?datum { rdl:PCA_100003609 rdl:PCA_100003628 } # electric current datum ; electric potential datum
  ?datum rdfs:label ?datum_label .
  ?datum rdl:PCA_100003769 ?applicable_uom .  # "applicable uom"
  ?applicable_uom rdfs:label ?applicable_uom_label
}
order by ?datum_label
limit 5

datum	datum_label	applicable_uom	applicable_uom_label
rdl:PCA_100003609	electric current datum	rdl:PCA_100003657	ampere
rdl:PCA_100003609	electric current datum	rdl:PCA_100003683	kiloampere
rdl:PCA_100003609	electric current datum	rdl:PCA_100003703	milliampere
rdl:PCA_100003628	electric potential datum	rdl:PCA_100003724	volt

3 Advanced SELECT queries: Using ontology restrictions

3.1 Introduction

The PLM-RDL is an OWL 2 ontology, which means that the type of the resources (classes, relations, individuals) it contains has a fixed meaning. The representation of meaning extends to various restrictions on the resources, not just on domain and range of relations, but also to class relationships, which can be quite complex. The restrictions are exploited in automated reasoning; see, e.g., this page for some characteristic examples.

To make full use of the UoM ontology in queries, we need to know how the OWL restrictions between quantities, datum types, and units are represented, and construct our SPARQL queries to match. We are helped by the fact that SPARQL syntax is very close to the common Turtle format for RDF, which is a readily available format for OWL. This section provides some examples.

3.2 Find the permissible units for a quantity

In this example, we select electric current and energy as our quantities of interest, and ask: which units of measure can be meaningfully used to represent values of these quantities?

This query will extend on the simpler approach of Datum types and applicable units, taking the quantity as the point of departure instead of the physical quantity datum type.

To answer this, first observe that we need to follow certain constraints on the resources involved.

Inspect ontology constraints

On the web page of the quantity energy, for example, the section Constraints tells us that this quantity is

qualityQuantifiedAs only energy datum

We can use the web browser and navigate to an item under Metadata for an applicable unit of measure, take for instance the unit joule. On the joule page, we find in the section Context, tab Types, this complex constraint:

inverse datumUOM only energy datum

This means we have a path via semantic constraints from the quantity to the unit of measure.

The query needs two steps,

from a quantity, find the datum type permitted for quantifying values
from the datum type, find the unit(s) permitted for the datum type

We need to look into the construction of the ontology to understand how the relevant restrictions can be queried.

See the page Query for graph content for instructions on how to inspect the details of resources in the ontology, such as is shown in the Turtle code examples below.

In the ontology, the first restriction we are after, between a quantity and the suitable datum type, is given in an OWL object property restriction. In the ontology source code, it looks like this (Turtle format):

rdl:PCA_100003578 a owl:Class ;
        rdfs:label "energy" ;
        rdfs:subClassOf [ a owl:Restriction ;
                          # rdl:PCA_100003625 is "energy datum"
                          owl:allValuesFrom  rdl:PCA_100003625 ;
                          owl:onProperty     lis:qualityQuantifiedAs
                        ] .

The second restriction, which says the joule unit may only be used for energy datum, has an “inverse” part which makes it one step more intricate. Note carefully, since a unit is not a class, but an OWL individual, the relation from the unit to the restriction is rdf:type, abbreviated as usual with a.

rdl:PCA_100003681 a owl:NamedIndividual , lis:Scale ;
  a [ a owl:Restriction ;
      owl:allValuesFrom  rdl:PCA_100003625 ;
      owl:onProperty [ owl:inverseOf  lis:datumUOM ] ] .

Assemble the query

Our SPARQL query will mimic the structure of the code examples above quite literally.

In the query, we apply a values clause listing the resources of interest, as described in the section Inline data: explicit lists using SPARQL values.

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX lis: <http://rds.posccaesar.org/ontology/lis14/rdl/>
PREFIX rdl:   <http://rds.posccaesar.org/ontology/plm/rdl/>
PREFIX om: <http://www.ontology-of-units-of-measure.org/resource/om-2/>
select ?quantity ?quantity_label ?datum_type ?datum_type_label ?uom ?uom_label {
  values ?quantity {
    rdl:PCA_100003574 # electric current
    rdl:PCA_100003578 # energy
  }
  ?quantity rdfs:label ?quantity_label ;
    rdfs:subClassOf [ a owl:Restriction ;
                      owl:allValuesFrom  ?datum_type ;
                      owl:onProperty lis:qualityQuantifiedAs ] .
  ?datum_type rdfs:label ?datum_type_label .
  ?uom rdfs:label ?uom_label ;
    a [ a owl:Restriction ;
        owl:allValuesFrom ?datum_type ;
        owl:onProperty [ owl:inverseOf  lis:datumUOM ] ] .
}
order by ?quantity_label
limit 5

quantity	quantity_label	datum_type	datum_type_label	uom	uom_label
rdl:PCA_100003574	electric current	rdl:PCA_100003609	electric current datum	rdl:PCA_100003657	ampere
rdl:PCA_100003574	electric current	rdl:PCA_100003609	electric current datum	rdl:PCA_100003703	milliampere
rdl:PCA_100003574	electric current	rdl:PCA_100003609	electric current datum	rdl:PCA_100003683	kiloampere
rdl:PCA_100003578	energy	rdl:PCA_100003625	energy datum	rdl:PCA_100003681	joule
rdl:PCA_100003578	energy	rdl:PCA_100003625	energy datum	rdl:PCA_100003713	newton metre

4 Advanced SELECT queries: Combining PLM-RDL with external resources

4.1 Introduction

Using a SPARQL service clause, we can write a federated query – a query that retrieves data not just from the PLM-RDL endpoint, but also from an “external” endpoint.

In the following sections, we illustrate how this query mechanism allows us to enrich the results of PLM-RDL queries with content from different, complementary sources.

The PLM-RDL UoM module includes cross-references, using the SKOS vocabulary, to external libraries. Primarily, reference is made to two ontologies of units of measure, those of QUDT.org and OM 2. These both provide public SPARQL endpoints that can be put to good use in federated queries.

4.2 Using QUDT to find CDD code and conversion factor

click this button to open the query in PCA Fuseki

A detailed account of how this query is assembled will be added as soon as time permits.

Show the SPARQL query

PREFIX owl:  <http://www.w3.org/2002/07/owl#>
PREFIX rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs:  <http://www.w3.org/2000/01/rdf-schema#>
PREFIX xsd:  <http://www.w3.org/2001/XMLSchema#>
PREFIX pca: <http://data.posccaesar.org/rdl/>
PREFIX lis: <http://rds.posccaesar.org/ontology/lis14/rdl/>
PREFIX rdl:   <http://rds.posccaesar.org/ontology/plm/rdl/>
PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
PREFIX pav: <http://purl.org/pav/>
PREFIX om: <http://www.ontology-of-units-of-measure.org/resource/om-2/>
PREFIX qudt: <http://qudt.org/schema/qudt/>
PREFIX quantitykind: <http://qudt.org/vocab/quantitykind/>
PREFIX unit: <http://qudt.org/vocab/unit/>
select distinct ?quantity_label ?uom_label ?iec61360Code ?conversionMultiplier ?qudt_uom
{
  values ?quantity_label { "length" }
  ?quantity rdfs:subClassOf lis:PhysicalQuantity ;
  rdfs:label ?quantity_label ;
  rdfs:subClassOf [ a owl:Restriction ;
                    owl:allValuesFrom  ?datum_type ;
                    owl:onProperty lis:qualityQuantifiedAs ] .
  ?datum_type rdfs:label ?datum_type_label .
  ?uom rdfs:label ?uom_label ;
  a [ a owl:Restriction ;
      owl:allValuesFrom ?datum_type ;
      owl:onProperty [ owl:inverseOf  lis:datumUOM ] ] .
  optional {
    ?uom skos:exactMatch ?qudt_uom . ?qudt_uom rdfs:isDefinedBy rdl:PCA_100003771 . # QUDT entities
  service <http://www.qudt.org/fuseki/qudt/sparql> {
    ?qudt_uom a qudt:Unit .
        optional { ?qudt_uom qudt:iec61360Code ?iec61360Code }
        optional {
          ?qudt_uom #qudt:isScalingOf? ?baseUnit ;
            qudt:conversionMultiplier ?conversionMultiplier .
        }
      }
    }
}
order by desc (?conversionMultiplier)

quantity_label	uom_label	iec61360Code	conversionMultiplier	qudt_uom
length	kilometre		1000.0	http://qudt.org/vocab/unit/KiloM
length	metre	0112/2///62720#UAA726	1.0	http://qudt.org/vocab/unit/M
length	foot (international)	0112/2///62720#UAA440	0.3048	http://qudt.org/vocab/unit/FT
length	decimetre	0112/2///62720#UAA412	0.1	http://qudt.org/vocab/unit/DeciM
length	inch (international)	0112/2///62720#UAA539	0.0254	http://qudt.org/vocab/unit/IN
length	centimetre	0112/2///62720#UAA375	0.01	http://qudt.org/vocab/unit/CentiM
length	millimetre	0112/2///62720#UAA862	0.001	http://qudt.org/vocab/unit/MilliM
length	micrometre	0112/2///62720#UAA090	0.000001	http://qudt.org/vocab/unit/MicroM
length	Angstroem
length	foot pound per pound
length	micrometre peak-to-peak
length	nanometre
length	parsec

4.3 Using QUDT to find measuring system and CDD identifier

The QUDT.org organization provides an extensive, general ontology of quantities and units of measure. The QUDT ontology provides a range of information that the PLM-RDL UoM module does not aim to cover.

The PLM-RDL quantities and units are provided with pointers to similar resources in QUDT where these have been possible to identify.

The following query retrieves units of measure from an explicit list of names, with their quantity types and symbols. Some of the names will not be found to match any unit in the UoM module, so we use OPTIONAL clauses liberally to show empty cells where there is no information to be found.

A detailed account of how this query is assembled will be added as soon as time permits.

Show the SPARQL query

PREFIX owl:  <http://www.w3.org/2002/07/owl#>
PREFIX rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs:  <http://www.w3.org/2000/01/rdf-schema#>
PREFIX xsd:  <http://www.w3.org/2001/XMLSchema#>
PREFIX pca: <http://data.posccaesar.org/rdl/>
PREFIX lis: <http://rds.posccaesar.org/ontology/lis14/rdl/>
PREFIX rdl:   <http://rds.posccaesar.org/ontology/plm/rdl/>
PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
PREFIX pav: <http://purl.org/pav/>
PREFIX om: <http://www.ontology-of-units-of-measure.org/resource/om-2/>
PREFIX qudt: <http://qudt.org/schema/qudt/>
PREFIX quantitykind: <http://qudt.org/vocab/quantitykind/>
PREFIX unit: <http://qudt.org/vocab/unit/>
select ?uom ?uom_l ?quantity ?quantity_l ?uom_symbol
(group_concat(?System_l; separator=", ") as ?System_from_QUDT)
(group_concat(?iec61360Code; separator=", ") as ?IEC61360_from_QUDT)
{
  # sample list of UoM names
  values ?uom_l { "bar absolute" "revolution per minute" "farad" "ampere hour" "piece"
    "kilogram per cubic metre" "pound per cubic foot" "ampere" "kiloampere" "kilonewton"
    "newton" "hertz" "milliampere per bar" "foot (international)" "inch (international)" }
  # put the entire query in "optional" to show the non-matches clearly
  optional { ?uom a lis:Scale ; rdfs:label ?uom_l
  # get symbol and quantity, via datum type
  { optional { ?uom om:symbol ?uom_symbol }
    optional {
    ?uom a [ a owl:Restriction ; owl:onProperty [ owl:inverseOf lis:datumUOM ] ; owl:allValuesFrom ?datum ] .
    ?datum rdfs:subClassOf [ a owl:Restriction ; owl:onProperty lis:quantifiesQuality ; owl:allValuesFrom ?quantity ] .
    ?quantity rdfs:label ?quantity_l
  }}
  # use QUDT match, where found, to show system and cdd code
  optional {
    ?uom skos:exactMatch ?qudt_uom . ?qudt_uom rdfs:isDefinedBy rdl:PCA_100003771 . # QUDT entities
    optional { service <http://www.qudt.org/fuseki/qudt/sparql> {
      optional { ?qudt_uom qudt:iec61360Code ?iec61360Code }
      optional {
        # uncomment if you want all related systems
        # ?unitOfSystem rdfs:subPropertyOf* qudt:unitOfSystem . ?qudt_uom ?unitOfSystem ?System .
        ?qudt_uom qudt:unitOfSystem ?System .
        ?System qudt:abbreviation ?System_l
      }
    }}
   }
  }
}
group by ?uom ?uom_l ?quantity ?quantity_l ?uom_symbol
order by ?uom_l
limit 30

uom	uom_l	quantity	quantity_l	uom_symbol	System_from_QUDT	IEC61360_from_QUDT
rdl:PCA_100003657	ampere	rdl:PCA_100003574	electric current	A	SI, SI	0112/2///62720#UAD717, 0112/2///62720#UAA101
rdl:PCA_100003658	ampere hour	rdl:PCA_100003573	electric charge	A h	CGS	0112/2///62720#UAA102
rdl:PCA_100003648	bar absolute	rdl:PCA_100003596	pressure	bara
rdl:PCA_100003674	farad	rdl:PCA_100003567	capacitance	F	CGS	0112/2///62720#UAA144
rdl:PCA_100003675	foot (international)	rdl:PCA_100003585	length	ft	US Customary, Imperial	0112/2///62720#UAA440, 0112/2///62720#UAA440
rdl:PCA_100003678	hertz	rdl:PCA_100003580	frequency	Hz		0112/2///62720#UAA170
rdl:PCA_100003680	inch (international)	rdl:PCA_100003585	length	in	US Customary, Imperial	0112/2///62720#UAA539, 0112/2///62720#UAA539
rdl:PCA_100003683	kiloampere	rdl:PCA_100003574	electric current	kA		0112/2///62720#UAA557
rdl:PCA_100003685	kilogram per cubic metre	rdl:PCA_100003570	density	kg/m3		0112/2///62720#UAA619
rdl:PCA_100003690	kilonewton	rdl:PCA_100003579	force	kN		0112/2///62720#UAA573
	milliampere per bar
rdl:PCA_100003712	newton	rdl:PCA_100003579	force	N		0112/2///62720#UAA235
	piece
	pound per cubic foot
rdl:PCA_100003655	revolution per minute	rdl:PCA_100003580	frequency	rpm		0112/2///62720#UAB231

4.4 Content from Wikidata

Using the SERVICE keyword, a query that combines PLM RDL data with Wikidata resources is possible. The following table shows formulae that describe a selection of quantities.

To be updated with a full query description.

PLM	wdLink	plmSymbol	wdSymbol	plmDimension	wdFormula
absorbed dose rate	Q69428958			L²T⁻³	${\dot {D}}={\frac {\mathrm {d} D}{\mathrm {d} t}}$
acceleration	Q11376	a		L¹T⁻²	${\boldsymbol {a}}={\frac {\mathrm {d} {\boldsymbol {v}}}{\mathrm {d} t}}$
angular acceleration	Q186300	α		T⁻²	${\boldsymbol {\alpha }}={\frac {\mathrm {d} {\boldsymbol {\omega }}}{\mathrm {d} t}}$
angular momentum	Q161254	L		M¹L²T⁻¹	${\boldsymbol {L}}={\boldsymbol {r}}\times {\boldsymbol {p}}$
apparent power	Q1930258				$\left\vert {\underline {S}}\right\vert =UI$
arc length	Q670036				$L(f)=\int _{a}^{b}\left\|f’(t)\right\|\ dt$
arc length	Q670036				$L(f)=\lim_{N\to \infty }\sum _{i=1}^{N}\left\|{\vec {r}}(t_{i})-{\vec {r}}(t_{i-1})\right\|$
area	Q11500	A	S	L²	$A=\iint \mathrm {d} x\mathrm {d} y$
atmospheric pressure	Q81809		p
capacitance	Q164399	C		M⁻¹L⁻²T⁴I²	$C=Q/U$
catalytic activity	Q1735592			T⁻¹N¹
catalytic activity concentration	Q69429678
density	Q29539	ρ	ρ	M¹L⁻³	$\rho ={\frac {\mathrm {d} m}{\mathrm {d} V}}$
dynamic viscosity	Q15152757	μ		M¹L⁻¹T⁻¹	$\tau _{xz}=\eta {\frac {\mathrm {d} v_{x}}{\mathrm {d} z}}$
electric charge	Q1111	Q	Q	T¹I¹	$\mathrm {d} Q=I\mathrm {d} t$
electric charge	Q1111	Q	q	T¹I¹	$\mathrm {d} Q=I\mathrm {d} t$
electric charge density	Q69425629			L⁻³T¹I¹	$\rho ={\frac {\mathrm {d} Q}{\mathrm {d} V}}$
electric current	Q29996	I	I	I¹
electric current	Q29996	I	J	I¹
electric field strength	Q20989	E		M¹L¹T⁻³I⁻¹	${\boldsymbol {E}}={\frac {\boldsymbol {F}}{q}}$
electric potential	Q55451	V		M¹L²T⁻³I⁻¹	$-\operatorname {\mathbf {grad} } V={\boldsymbol {E}}+{\frac {\partial {\boldsymbol {A}}}{\partial t}}$
electrical resistance	Q25358	R	R	M¹L²T⁻³I⁻²	$R={\frac {u}{i}}$
energy	Q11379	E		M¹L²T⁻²
energy density	Q828402			M¹L⁻¹T⁻²	$U=E/V$
entropy	Q5380792	S		M¹L²T⁻²Θ⁻¹	$S=\int {\frac {\delta Q}{T}}$
exposure	Q271960			M⁻¹T¹I¹	$H_{\mathrm {e} }=E_{\mathrm {e} }t$
exposure	Q336938			M⁻¹T¹I¹	$X={\frac {\mathrm {d} q}{\mathrm {d} m}}$
force	Q11402	F	F	M¹L¹T⁻²	${\boldsymbol {F}}=m{\boldsymbol {a}}$
force	Q11402	F	F	M¹L¹T⁻²	${\boldsymbol {F}}={\frac {\mathrm {d} {\boldsymbol {p}}}{\mathrm {d} t}}$
frequency	Q11652	f		T⁻¹	$f={\frac {1}{T}}$
heat capacity	Q179388	C_p		M¹L²T⁻²Θ⁻¹	$C={\frac {\mathrm {d} Q}{\mathrm {d} T}}$
heat transfer coefficient	Q634340			M¹T⁻³Θ⁻¹	$K={\frac {q}{\Delta T}}$
illuminance	Q194411	Φ		L⁻²J¹	$E_{\mathrm {v} }={\frac {\mathrm {d} \Phi _{\mathrm {v} }}{\mathrm {d} A}}$
impulse	Q837940	I			${\boldsymbol {I}}=\int _{t_{1}}^{t_{2}}{\boldsymbol {F}}\,\mathrm {d} t$
kinematic viscosity	Q15106259	ν		L²T⁻¹	$\nu =\eta /\rho$
length	Q36253	l	L	L¹
linear density	Q516372
linear mass density	Q56298294			M¹L⁻¹	$\rho _{l}={\frac {\mathrm {d} m}{\mathrm {d} l}}$
luminance	Q355386	L		L⁻²J¹	$L_{\mathrm {v} }={\frac {\mathrm {d} I_{\mathrm {v} }}{\mathrm {d} A}}{\frac {1}{\cos(\alpha )}}$
luminous flux	Q107780	F		J¹	$\Phi _{\mathrm {v} }={\frac {\mathrm {d} Q_{\mathrm {v} }}{\mathrm {d} t}}$
magnetic field strength	Q28123				${\boldsymbol {H}}={\frac {\boldsymbol {B}}{\mu _{0}}}-{\boldsymbol {M}}$
magnetic flux	Q177831	Φ		M¹L²T⁻²I⁻¹	$\Phi =\int \limits _{\mathrm {S} }{\boldsymbol {B}}\cdot {\boldsymbol {e}}_{\mathrm {n} }\mathrm {d} A$
magnetic flux density	Q30204	B	B	M¹T⁻²I⁻¹	${\boldsymbol {F}}=q,{\boldsymbol {v}}\times {\boldsymbol {B}}$
magnetic permeability	Q28352				${\boldsymbol {B}}=\mu {\boldsymbol {H}}$
mass	Q11423	m	M	M¹
mass	Q11423	m	m	M¹
mass flow	Q3265048			M¹T⁻¹	${\boldsymbol {j}}_{m}=\rho {\boldsymbol {v}}$
mass ratio	Q1563068		ζ	bar
molar energy	Q69427512			M¹L²T⁻²N⁻¹
molar entropy	Q68972876			M¹L²T⁻²Θ⁻¹N⁻¹	$S_{\mathrm {m} }=S/n$
molar mass	Q145623	M		M¹N⁻¹	$M=m/n$
molar volume	Q487112	V_m		L³N⁻¹	$V_{\mathrm {m} }=V/n$
moment of force	Q17232562	M		M¹L²T⁻²	${\boldsymbol {M}}={\boldsymbol {r}}\times {\boldsymbol {F}}$
permittivity	Q211569	ε		M⁻¹L⁻³T⁴I²	${\boldsymbol {D}}=\varepsilon {\boldsymbol {E}}$
power	Q25342	P		M¹L²T⁻³	$P={\frac {\mathrm {d} E}{\mathrm {d} t}}$
power density	Q3503313
pressure	Q39552	p		M¹L⁻¹T⁻²	$p={\frac {{\boldsymbol {e}}_{\mathrm {n} }\cdot {\boldsymbol {F}}}{A}}$
radiance	Q1411145	L		M¹T⁻³	$L_{\mathrm {e} }={\frac {\mathrm {d} I_{\mathrm {e} }}{\mathrm {d} A}}{\frac {1}{\cos \alpha }}$
radiant intensity	Q1253365	I		M¹L⁻²T⁻³	$I_{\mathrm {e} }={\frac {\mathrm {d} \Phi _{\mathrm {e} }}{\mathrm {d} \Omega }}$
reactive power	Q2144613				$Q=\operatorname {Im} {\underline {S}}$
solid angle	Q208476	Ω		1	$\Omega =A/r^{2}$
sound pressure level	Q14515278	SPL		M¹L¹T⁻³I⁻¹	$L_{p}=10\lg {\frac {p_{\mathrm {RMS} }^{2}}{p_{0}^{2}}}\mathrm {dB}$
specific absorption rate	Q914138
specific energy	Q3023293			L²T⁻²	$e=E/m$
specific heat capacity	Q487756	c_p		L²T⁻²Θ⁻¹	$c={\frac {C}{m}}$
specific weight	Q749542				$\gamma =\rho ,g$
speed	Q3711325	v		L¹T⁻¹	$v=s/t$
surface charge density	Q12799324				$\rho _{A}={\frac {\mathrm {d} Q}{\mathrm {d} A}}$
surface density	Q1907514				$\rho _{A}={\frac {\mathrm {d} m}{\mathrm {d} A}}$
surface tension	Q170749	γ		M¹T⁻²	$\gamma ={\frac {\mathrm {d} F}{\mathrm {d} l}}$
thermal conductivity	Q487005	κ		M¹L¹T⁻³Θ⁻¹	${\boldsymbol {q}}=-\lambda \operatorname {grad} (T)$
thermodynamic temperature	Q264647	T		Θ¹	$T=\left({\frac {\partial U}{\partial S}}\right)_{V,N}$
torque	Q48103			M¹L²T⁻²	$T={\boldsymbol {M}}\cdot {\boldsymbol {e}}_{\mathrm {Q} }$
turbidity	Q898574			1
volume	Q39297	V	V	L³	$V=\iiint \mathrm {d} x\mathrm {d} y\mathrm {d} z$
volume ratio	Q1647035			I¹
wavenumber	Q192510	σ		L⁻¹	$\sigma =1/\lambda$