Specification

Predefined Template for UoM for submodel elements with values (normative)

Data Specification Unit of Measure Template Specification

This specification is only valid in combination with IDTA-01001-3-1 and IDTA-01003-a-3-1.

Template:	Unit of Measure
administration:	version: 3	revision: 0	creator: IDTA
id:	`https://admin-shell.io/DataSpecificationTemplates/DataSpecificationUnitOfMeasure/3`
dataSpecificationContent:	DataSpecificationUnitOfMeasure
Description (EN):	Data specification template for concept descriptions for Units of Measure.

Template:

Unit of Measure

administration:

version: 3

revision: 0

creator: IDTA

id:

https://admin-shell.io/DataSpecificationTemplates/DataSpecificationUnitOfMeasure/3

dataSpecificationContent:

DataSpecificationUnitOfMeasure

Description (EN):

Data specification template for concept descriptions for Units of Measure.

The ID of the data specification template was derived conformant to the grammar for semantic IDs for data specifications as defined in Part 1 of the document series, IDTA-01001, with the exception that the minor version was excluded because this ID is also part of the instances of Asset Administration Shells: This ID is used in hasDataSpecification/dataSpecification.

This namespace has the qualifier "UoM:".

Metamodel of Data Specification Unit of Measure

@startuml class DataSpecificationUnitOfMeasure<DataSpecificationContent> [Template] { +preferredName: ShortLangStringSet +symbol: string +code: string[0..1] +definition: LangStringSet[0..1] +preferredNameQuantity: LangStringSet[0..1] +quantityID: Identifier[0..1] +classificationSystem: string[0..1] } @enduml

Data Specification Attributes

Class:	DataSpecificationUnitOfMeasure <<Template>>
Explanation:	Content of data specification template for concept descriptions for Units of Measure
Inherits from:	DataSpecificationContent
id:	`https://admin-shell.io/DataSpecificationTemplates/DataSpecificationUnitOfMeasure/3/0/DataSpecificationUnitOfMeasure`
Attribute:	ID
Explanation	Type	Card.
preferredName	`https://admin-shell.io/DataSpecificationTemplates/DataSpecificationUnitOfMeasure/3/0/DataSpecificationUnitOfMeasure/preferredName`
Preferred name of the unit in different languages Note: To stay compliant with IEC 61360 each string shall have a length of maximum 255 and minimum of 1 characters. Note: It is advised to keep the length of the name limited to 35 characters. Example: "millimetre"	ShortLangStringSet	1
symbol	`https://admin-shell.io/DataSpecificationTemplates/DataSpecificationUnitOfMeasure/3/0/DataSpecificationUnitOfMeasure/symbol`
Symbol of the unit Example: “mm”	string	1
code	`https://admin-shell.io/DataSpecificationTemplates/DataSpecificationUnitOfMeasure/3/0/DataSpecificationUnitOfMeasure/code`
Code of the unit defined by the classification system Note: This is relevant if the classification system references the units differently from the unique unitID. This can e.g. be UNECE common codes or proprietary keys. Example: "MMT"	string	0..1
definition	`https://admin-shell.io/DataSpecificationTemplates/DataSpecificationUnitOfMeasure/3/0/DataSpecificationUnitOfMeasure/definition`
Definition in different languages Example: "0,001 fold of the SI base unit metre"	LangStringSet	0..1
preferredNameQuantity	`https://admin-shell.io/DataSpecificationTemplates/DataSpecificationUnitOfMeasure/3/0/DataSpecificationUnitOfMeasure/preferredNameQuantity`
Preferred name of the quantity in different languages. preferredNameQuantity and quantityID must be consistent if both attributes are set Note: To stay compliant with IEC 61360 each string shall have a length of maximum 255 and minimum of 1 characters. Note: It is advised to keep the length of the name limited to 35 characters. Example: "distance"	ShortLangStringSet	0..1
quantityId	`https://admin-shell.io/DataSpecificationTemplates/DataSpecificationUnitOfMeasure/3/0/DataSpecificationUnitOfMeasure/quantityId`
Unique ID of the quantity. preferredNameQuantity and quantityID must be consistent if both attributes are set Example: 0173-1#Z4-BAJ199#002	Identifier	0..1
classificationSystem	`https://admin-shell.io/DataSpecificationTemplates/DataSpecificationUnitOfMeasure/3/0/DataSpecificationUnitOfMeasure/classificationSystem`
Name of the classification system used for the definition of units and quantities Example: "ECLASS"	string	0..1

Class:

DataSpecificationUnitOfMeasure <<Template>>

Explanation:

Content of data specification template for concept descriptions for Units of Measure

Inherits from:

DataSpecificationContent

id:

https://admin-shell.io/DataSpecificationTemplates/DataSpecificationUnitOfMeasure/3/0/DataSpecificationUnitOfMeasure

Attribute:

Explanation

Type

Card.

preferredName

https://admin-shell.io/DataSpecificationTemplates/DataSpecificationUnitOfMeasure/3/0/DataSpecificationUnitOfMeasure/preferredName

Preferred name of the unit in different languages

Note: To stay compliant with IEC 61360 each string shall have a length of maximum 255 and minimum of 1 characters.

Note: It is advised to keep the length of the name limited to 35 characters.

Example: "millimetre"

ShortLangStringSet

symbol

https://admin-shell.io/DataSpecificationTemplates/DataSpecificationUnitOfMeasure/3/0/DataSpecificationUnitOfMeasure/symbol

Symbol of the unit

Example: “mm”

string

code

https://admin-shell.io/DataSpecificationTemplates/DataSpecificationUnitOfMeasure/3/0/DataSpecificationUnitOfMeasure/code

Code of the unit defined by the classification system

Note: This is relevant if the classification system references the units differently from the unique unitID. This can e.g. be UNECE common codes or proprietary keys.

Example: "MMT"

string

0..1

definition

https://admin-shell.io/DataSpecificationTemplates/DataSpecificationUnitOfMeasure/3/0/DataSpecificationUnitOfMeasure/definition

Definition in different languages

Example: "0,001 fold of the SI base unit metre"

LangStringSet

0..1

preferredNameQuantity

https://admin-shell.io/DataSpecificationTemplates/DataSpecificationUnitOfMeasure/3/0/DataSpecificationUnitOfMeasure/preferredNameQuantity

Preferred name of the quantity in different languages.

preferredNameQuantity and quantityID must be consistent if both attributes are set

Note: To stay compliant with IEC 61360 each string shall have a length of maximum 255 and minimum of 1 characters.

Note: It is advised to keep the length of the name limited to 35 characters.

Example: "distance"

ShortLangStringSet

0..1

quantityId

https://admin-shell.io/DataSpecificationTemplates/DataSpecificationUnitOfMeasure/3/0/DataSpecificationUnitOfMeasure/quantityId

Unique ID of the quantity.

preferredNameQuantity and quantityID must be consistent if both attributes are set

Example: 0173-1#Z4-BAJ199#002

Identifier

0..1

classificationSystem

https://admin-shell.io/DataSpecificationTemplates/DataSpecificationUnitOfMeasure/3/0/DataSpecificationUnitOfMeasure/classificationSystem

Name of the classification system used for the definition of units and quantities

Example: "ECLASS"

string

0..1

Primitive and Simple Data Types (normative)

All simple data types from Part 1 [1] apply also to the specifications described in this document.

Basic and Primitive Data Types

Table 1 lists the Primitives used in the metamodel. Primitive data types start with a capital letter.

Primitive Definition Value Examples

Table 1. Primitive DataTypes Used in Metamodel
Primitive	Definition	Value Examples
ShortLangStringSet	A LangStringSet with text values between 1 and 255 characters.	In xml: `<aas:langString lang="EN">This is a multi-language value in English</aas:langString> <aas:langString lang="DE">Das ist ein Multi-Language-Wert in Deutsch</aas:langString>` In rdf: `"This is a multi-language value in English"@en ; "Das ist ein Multi-Language-Wert in Deutsch"@de` In JSON: `"description": [ { "language":"en", "text": "This is a multi-language value in English." }, { "language":"de", "text": "Das ist ein Multi-Language-Wert in Deutsch." } ]`

ShortLangStringSet

A LangStringSet with text values between 1 and 255 characters.

In xml:

<aas:langString lang="EN">This is a multi-language value in English</aas:langString>
<aas:langString lang="DE">Das ist ein Multi-Language-Wert in Deutsch</aas:langString>

In rdf:

"This is a multi-language value in English"@en ;
"Das ist ein Multi-Language-Wert in Deutsch"@de

In JSON:

"description": [
   {
     "language":"en",
     "text": "This is a multi-language value in English."
   },
   {
     "language":"de",
     "text": "Das ist ein Multi-Language-Wert in Deutsch."
   }
]

General

Part 1 of this document series (IDTA-01001) introduces different serialization formats: XML, JSON and RDF. Part 1 also introduces the implementation guide for embedded data specifications. This is why the different formats are described in IDTA-01001.

Mappings from Common Dictionaries (informative)

General

As mentioned in the introduction of this document several dictionaries for units of measures exist. Typically, these dictionaries have their own philosophy of modelling the different aspects of units. This section provides a guide on how to map the most common dictionary entries to the Data Specification template.

Mapping

The table below provides the information for mapping the entries of the most common dictionaries or data models for UoM to the Concept Description specified in this document.

Table 2. Mappings of data dictionaries
AAS UoM	ECLASS	IEC CDD	UNECE Rec. 20	OPC UA	BIPM	SAMM^[1]
ConceptDescription/id	IRDI (or IRI^[2])	Code	prefix_^[2] + _Common Code	prefix_^[2] + _unitId	PID^[3]	Unit element URN
preferredName	Preferred name	Preferred name	Name	description	Unit	preferredName
symbol	Short name	Short name	Symbol	displayName	Symbol	symbol
code	IRDI	Code	Common Code	unitId	PID	commonCode^[4]
definition	Definition	Definition	Description	---	Definition	description
preferredNameQuantity	Quantity	Quantity	Quantity	QuantityType	Quantity	quantityKind/preferredName
quantityID	QuantityID	QuantityID	---	---	PID (of Quantity)	quantityKind
classificationSystem	"ECLASS"	"IEC CDD"	"UNECE"	---	"BIPM"	"UNECE" for units having a code, "SAMM" for units defined as part of SAMM^[5]

Table 3. Prefixes
Dictionary	prefix	Example for id
UNECE	"uncefact:UNECERec20Code/"	"uncefact:UNECERec20Code/MMT"
OPC UA	http://www.opcfoundation.org/UA/units/	http://www.opcfoundation.org/UA/units/5131860footnote:"MMT" → 0x004E4E54 → 5131860
ECLASS	https://api.eclass-cdp.com/	https://api.eclass-cdp.com/0173-1-05-AAA480-003
SAMM	urn:samm:org.eclipse.esmf.samm:unit:<version>#^[6]	urn:samm:org.eclipse.esmf.samm:unit:2.2.0#degreeCelsius^[7]

Note: OPC UA uses the attribute namespaceUri to denote the classification system. It is recommended to reference that classification system directly to avoid "double-mapping", if possible. E.g. the Table [Prefixes] illustrates how OPC UA maps the UNECE Common Code to an integer value (see explanation below).

In the OPC UA Specification Part 8, 5.6.3.4 a mapping from UNECE to the OPC UA information model is described as follows:

The namespaceUri shall be http://www.opcfoundation.org/UA/units/un/cefact
The Common Code (represented as an alphanumeric variable length of up to 3 characters) has been converted into a 32 Bit Integer and is used for the unitId. The following pseudo code specifies the conversion algorithm:

Int32 unitId = 0; Int32 c; for (i=0; i<=3;i++) {
c = CommonCode[i]; if (c == 0) break; // end of Common Code
unitId = unitId << 8; unitId = unitId | c;}

1. https://eclipse-esmf.github.io/samm-specification/snapshot/units.html

2. see Table [Prefixes]

3. Example for BIPM PID: https://si-digital-framework.org/SI/units/ampere

4. In SAMM only UNECE units have a commonCode value.

5. see https://github.com/eclipse-esmf/esmf-semantic-aspect-meta-model/blob/main/esmf-samm-build-plugin/src/main/resources/custom-units.ttl

6. Note: the namespace is versioned, not the single UoMs as for example in ECLASS

7. see https://eclipse-esmf.github.io/samm-specification/snapshot/appendix/unitcatalog.html, prefix "unit:" maps to urn:samm:org.eclipse.esmf.samm:unit:2.2.0# etc.