Industrial automation systems and integration -- Product data representation and exchange

This document specifies a mapping of SysML (ISO/IEC 19514:2017) constructs to EXPRESS (ISO 10303-11:2004) elements for the purpose of representing SysML model represented in XMI (ISO/IEC 19509:2014) as EXPRESS (ISO 10303-11:2004) schemas. The specified mapping is a one-way transformation from SysML information model represented in XMI into an EXPRESS schema. NOTE      Due to this limitation 10303-16 does not define the transformation of arbitrary SysML models to EXPRESS. The following are within the scope of this document: —   the transformation of SysML metamodel constructs represented in XMI to EXPRESS elements for the purpose of representing SysML information models as EXPRESS schemas. The following are outside the scope of this document: —   the transformation of SysML metamodel constructs into EXPRESS elements that are not used in the STEP Extended Architecture. NOTE      The STEP Extended Architecture is defined in References [8], [9] and [10]. —   the transformation of SysML metamodel constructs into EXPRESS elements for other purposes than representing SysML constructs as STEP concepts; —   codes and scripts to transform SysML XMI to EXPRESS schema; —   the transformation of SysML constraints (OCL[5]) into EXPRESS global and local rules; —   the transformation of EXPRESS elements into SysML constructs.

Systèmes d'automatisation industrielle et intégration -- Représentation et échange de données de produits

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Status
Published
Publication Date
05-Jul-2021
Current Stage
5060 - Close of voting Proof returned by Secretariat
Start Date
07-Jun-2021
Completion Date
07-Jun-2021
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TECHNICAL ISO/TS
SPECIFICATION 10303-16
First edition
2021-07
Industrial automation systems
and integration — Product data
representation and exchange —
Part 16:
Description methods: SysML XMI to
EXPRESS transformation
Reference number
ISO/TS 10303-16:2021(E)
ISO 2021
---------------------- Page: 1 ----------------------
ISO/TS 10303-16:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TS 10303-16:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms, definitions and abbreviated terms ................................................................................................................................ 2

3.1 Terms and definitions ....................................................................................................................................................................... 2

3.1.1 Terms and definitions for generic concepts ............................................................................................. 2

3.1.2 Terms and definitions for SysML constructs ........................................................................................... 3

3.2 Abbreviated terms ............................................................................................................................................................................... 5

4 SysML XMI to EXPRESS.................................................................................................................................................................................... 5

4.1 General ........................................................................................................................................................................................................... 5

4.2 Presentation conventions .............................................................................................................................................................. 5

4.3 Common mapping conventions ................................................................................................................................................ 5

4.3.1 Reference to external files ....................................................................................................................................... 5

4.3.2 xmi:id, xmi: uuid, and UUID ..................................................................................................................................... 6

4.3.3 Assumed sysml:Blo ck in fragments ................................................................................................................. 6

4.3.4 Containment and reference relationship .................................................................................................... 6

4.3.5 Used stereotypes to represent STEP concepts ....................................................................................... 6

4.3.6 Select type not treated as SysML supertype............................................................................................. 7

4.4 Mapping of the primary schema .............................................................................................................................................. 7

4.5 Mapping of Entities ............................................................................................................................................................................. 7

4.5.1 General mapping of Entity ....................................................................................................................................... 7

4.5.2 Mapping of abstract entity ...................................................................................................................................... 7

4.5.3 Mapping of entity with one supertype .......................................................................................................... 8

4.5.4 Mapping of entity with multiple supertypes ........................................................................................... 8

4.6 Mapping of simple type ................................................................................................................................................................... 9

4.7 Mapping of aggregation type ...................................................................................................................................................11

4.8 Mapping of aggregation of aggregation type..............................................................................................................12

4.9 Mapping of Select type ..................................................................................................................................................................13

4.9.1 General mapping of select type ........................................................................................................................13

4.9.2 Mapping of select type containing value type .....................................................................................14

4.10 Mapping of enumeration type ................................................................................................................................................15

4.11 Mapping of entity attribute .......................................................................................................................................................15

4.11.1 Mapping of multiplicity and optionality ...................................................................................................16

4.11.2 Attribute typed as an Entity ................................................................................................................................18

4.11.3 Attribute typed as Select ........................................................................................................................................18

4.11.4 Attribute typed as Enumeration type .........................................................................................................19

Annex A (normative) Information object registration ...................................................................................................................20

Annex B (informative) EXPRESS/Information modelling constructs and the equivalent

SysML modelling constructs ..................................................................................................................................................................21

Bibliography .............................................................................................................................................................................................................................33

© ISO 2021 – All rights reserved iii
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ISO/TS 10303-16:2021(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 184, Automation systems and integration,

Subcommittee SC 4, Industrial data.
A list of all parts in the ISO 10303 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/TS 10303-16:2021(E)
Introduction

ISO 10303 is an International Standard for the computer-interpretable representation and exchange

of product data. The objective is to provide a neutral mechanism capable of describing product data

throughout the life cycle of a product and independent from any particular system. The nature of this

description makes it suitable not only for neutral file exchange, but also as a basis for implementing and

sharing product databases and archiving.

10303-16 is a member of the description methods series. This document specifies a mapping of SysML

XMI to the EXPRESS language.

The STEP APs Domain models and the STEP Core Model are information model layer components that

are part of the STEP Extended Architecture. These components are developed using SysML. In the past

STEP information models were developed using the EXPRESS language. For legacy reasons it is therefore

required to provide an EXPRESS schema derived from the SysML domain model. It is mandatory that

the transformation from the SysML model to the EXPRESS schema is defined by a reference standard

and guarantee a repeatable process applicable to future application protocols developments.

The Object Management Group (OMG) has standardized the XML Metadata Interchange specification

(XMI) that integrates the OMG Systems Modeling Language (SysML), the OMG Unified Modeling

Language (UML), the OMG Meta-Object Facility (MOF) and the World Wide Web Consortium (W3C)

Extensible Markup Language (XML) standards. SysML inherits the XMI interchange capability from

UML. XMI is a mechanism for the interchange of metadata between UML-based modeling tools and MOF-

based metadata repositories. OMG has also standardized an XMI compliant interchange format for the

SysML thus specifying a lexical representation of SysML models based on a standardized metamodel

of the SysML. That lexical representation includes, among other things, the ability to interchange data

type information, class information (or entities), groupings of classes providing namespaces for the

classes (or schemas), associations between classes and inheritance between classes (or subtypes).

ISO has standardized the EXPRESS language (ISO 10303-11:2004). It is used to specify information

requirements in ISO 10303.

10303-16 specifies a description method of the STEP Parts family, which defines the transformation of

SysML constructs to the EXPRESS elements. Because the XMI standard specifies the XML representation

of SysML metamodel constructs, standardizing the binding of SysML constructs into EXPRESS elements

supports the representation of SysML models as EXPRESS schemas. SysML metamodel concepts that

appear in SysML Block Diagrams are mapped into data specifications defined by EXPRESS schemas.

This document does not map all SysML metamodel constructs to EXPRESS elements, because 10303

SysML models do not use all SysML metamodel constructs.

The EXPRESS schemas are derived from the domain model by applying the implementation bindings

on the SysML XMI. The EXPRESS binding is realized with XSL transformations, which transforms the

SysML model into an EXPRESS Schema. The specified binding is a one-way transformation from SysML

information model represented in XMI into an EXPRESS schema. Due to this limitation 10303-16 does

not define the transformation of arbitrary SysML models to EXPRESS.

Readers of 10303-16 require detailed knowledge of the EXPRESS language, and SysML.

The structure, conventions and concepts of the EXPRESS language are defined in ISO 10303-11:2004.

The main component of this standard is:

— the specification of the transformation from SysML XMI to EXPRESS for each STEP element modelled

in SysML.
© ISO 2021 – All rights reserved v
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TECHNICAL SPECIFICATION ISO/TS 10303-16:2021(E)
Industrial automation systems and integration — Product
data representation and exchange —
Part 16:
Description methods: SysML XMI to EXPRESS
transformation
1 Scope

This document specifies a mapping of SysML (ISO/IEC 19514:2017) constructs to EXPRESS

(ISO 10303-11:2004) elements for the purpose of representing SysML model represented in XMI

(ISO/IEC 19509:2014) as EXPRESS (ISO 10303-11:2004) schemas. The specified mapping is a one-way

transformation from SysML information model represented in XMI into an EXPRESS schema.

NOTE Due to this limitation 10303-16 does not define the transformation of arbitrary SysML models to

EXPRESS.
The following are within the scope of this document:

— the transformation of SysML metamodel constructs represented in XMI to EXPRESS elements for

the purpose of representing SysML information models as EXPRESS schemas.
The following are outside the scope of this document:

— the transformation of SysML metamodel constructs into EXPRESS elements that are not used in the

STEP Extended Architecture.
NOTE The STEP Extended Architecture is defined in References [8], [9] and [10].

— the transformation of SysML metamodel constructs into EXPRESS elements for other purposes than

representing SysML constructs as STEP concepts;
— codes and scripts to transform SysML XMI to EXPRESS schema;
[5]

— the transformation of SysML constraints (OCL ) into EXPRESS global and local rules;

— the transformation of EXPRESS elements into SysML constructs.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 10303-1, Industrial automation systems and integration — Product data representation and

exchange — Part 1: Overview and fundamental principles

ISO 10303-11:2004, Industrial automation systems and integration — Product data representation and

exchange — Part 11: Description methods: The EXPRESS language reference manual

ISO/IEC 19505-1:2012, Information technology — Object Management Group Unified Modeling Language

(OMG UML) — Part 1: Infrastructure
© ISO 2021 – All rights reserved 1
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ISO/TS 10303-16:2021(E)

ISO/IEC 19509:2014, Information technology — Object Management Group XML Metadata Interchange

(XMI)

ISO/IEC 19514:2017, Information technology — Object management group systems modeling language

(OMG SysML)
W3C Recommendation: Extensible Markup Language (XML) 1.0 (Fifth Edition)
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 10303-11, ISO/IEC 19505-1,

ISO/IEC 19514 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1.1 Terms and definitions for generic concepts
3.1.1.1
data

representation of information in a formal manner suitable for communication, interpretation, or

processing by human beings or computers
[SOURCE: ISO 10303-1:2021, 3.1.29]
3.1.1.2
data model

description of the organization of data in the management information system of an enterprise

[SOURCE: ISO/IEC 2382:2015, 2121422]
3.1.1.3
EXPRESS
language by which aspects of product data can be defined
[SOURCE: ISO/TS 10303-15:2021, 3.1.1.1]
3.1.1.4
information
facts, concepts, or instructions
[SOURCE: ISO 10303-1:2021, 3.1.41]
3.1.1.5
information model
conceptual model of product data

Note 1 to entry: In ISO 10303, an information model is based on the object-relationship modeling technique that

organizes the product data as represented in different system aspects.

Note 2 to entry: In ISO 10303, information models may be developed using EXPRESS modeling language.

EXAMPLE Application resource model for ISO 10303-242 managed model-based 3D engineering.

[SOURCE: ISO 10303-1:2021, 3.1.42, modified — In the definition, "formal" has been replaced with

"conceptual"; in Note 2 to entry, "are" has been replaced with "may be"; the Example has been changed.]

2 © ISO 2021 – All rights reserved
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ISO/TS 10303-16:2021(E)
3.1.2 Terms and definitions for SysML constructs
3.1.2.1
association

association classifies a set of tuples representing links between typed model elements

Note 1 to entry: The full definition is provided in ISO/IEC 19505-1:2012, 11.5.
3.1.2.2
auxiliary
stereotype applied to an abstract block that has no properties

Note 1 to entry: The full definition is provided in ISO/IEC 19505-1:2012, Clause 22.

3.1.2.3
block
modular construct used for defining an entity.

Note 1 to entry: Application activity model concepts, application data planning objects, application domain

model business objects, core model objects and ARM in SysML Entities. They can include reference, part, value

properties, and constraints. They can be specializations of other blocks.

Note 2 to entry: The full definition is provided in ISO/IEC 19514:2017, Clause 8.

3.1.2.4
canonical XMI

specific constrained format of XMI that minimizes variability and provides more predictable

identification and ordering
Note 1 to entry: A canonical XMI file is itself a valid XMI file.
Note 2 to entry: The full definition is provided in ISO/IEC 19509:2014, Annex B.
3.1.2.5
composite aggregation
responsibility for the existence of the composed object

Note 1 to entry: If a composite object is deleted, all of its part instances that are objects are deleted with it.

Note 2 to entry: The full definition is provided in ISO/IEC 19505-1:2012, 11.4.1.

3.1.2.6
connector

link between two or more instances playing owned or inherited roles within a StructuredClassifier

Note 1 to entry: The full definition is provided in ISO/IEC 19505-1:2012, 11.2.3.3.

3.1.2.7
enumeration
value type whose values are enumerated in the model as enumeration literals

Note 1 to entry: The full definition is provided in ISO/IEC 19505-1:2012, 10.2.3.3.

3.1.2.8
enumeration literal
user defined data value for an enumeration

Note 1 to entry: The full definition is provided in ISO/IEC 19505-1:2012, 10.2.3.3.

© ISO 2021 – All rights reserved 3
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ISO/TS 10303-16:2021(E)
3.1.2.9
data type
type whose instances are identified only by their value

Note 1 to entry: The full definition is provided in ISO/IEC 19505-1:2012, 10.2.3.1.

3.1.2.10
generalization

directed relationship between a more general supertype and a more specific subtype

Note 1 to entry: Each generalization relates a specific classifier to a more general classifier. Given a classifier,

the transitive closure of its general classifiers is often called its generalizations, and the transitive closure of

its specific classifiers is called its specializations. The immediate generalizations are also called the classifier’s

subtype, and where the classifier is a class, its supertype.
Note 2 to entry: The full definition is provided in ISO/IEC 19505-1:2012, C.1.1.
3.1.2.11
part property

property that specifies a part with strong ownership and coincidental lifetime of its containing block

Note 1 to entry: It describes a local usage or a role of the typing block in the context of the containing block. Every

part property has composite aggregation and is typed by a block.

Note 2 to entry: The full definition is provided in ISO/IEC 19514:2017, 8.3.2.3, paragraph 6.

3.1.2.12
primitive type
definition of a predefined data type, without any substructure

Note 1 to entry: The full definition is provided in ISO/IEC 19505-1:2012, Clause 21.

3.1.2.13
reference property
property that specifies a reference of its containing block to another block

Note 1 to entry: The full definition is provided in ISO/IEC 19514:2017, 8.3.2.3, paragraph 6.

3.1.2.14
stereotype

limited kind of metaclass that cannot be used by itself but must always be used in conjunction with one

of the metaclasses it extends

Note 1 to entry: The full definition is provided in ISO/IEC 19505-1:2012, 12.3.3.4.

3.1.2.15
value property
property of a block that is typed with a value type

Note 1 to entry: The full definition is provided in ISO/IEC 19514:2017, 8.3.2.3, paragraph 6.

3.1.2.16
value type

a stereotype of UML data type that is used to define types of values that may be used to express

information but cannot be identified as the target of any reference

Note 1 to entry: The full definition is provided in ISO/IEC 19514:2017, 8.3.2.14.

4 © ISO 2021 – All rights reserved
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ISO/TS 10303-16:2021(E)
3.2 Abbreviated terms
CXMI canonical XMI
ID identifier
OCL object constraint language
OMG object management group
STEP standard for the exchange of product model data
SysML systems modeling language
UML unified modeling language
UUID universal unique identifier
XMI XML meta-data interchange
XML extensible markup language
4 SysML XMI to EXPRESS
4.1 General

This clause describes the concepts and rules for the transformation mapping from a STEP SysML model

stored as a CXMI file to an EXPRESS Schema.

This document shall be unambiguously identified in an open information system by the code defined in

Annex A.
4.2 Presentation conventions

For ease of identification, separate boxes are used for the fragments of SysML, CXMI and EXPRESS.

The items significant to the section are usually in bold, but more than text effects may be used where

needed to support the explanation. Triple dots (“…”) are used to hide content not relevant to an extract.

Curly brackets “{xxx}” are used to contain descriptive words of the content in the resulting CXMI.

4.3 Common mapping conventions
4.3.1 Reference to external files

All the references in the SysML Canonical XMI fragments are given as x mi: idr e f which assumes that

the referenced element is contained in the same XMI file. When the referenced element is in a different

XMI file the href is used instead. This will be the case for all reference to primitives and may be case for

other references.
Canonical XMI: type href relative reference to element in DataTypes.xmi
CXMI:

Text

...other tags...

© ISO 2021 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO/TS 10303-16:2021(E)
Canonical XMI: general href relative reference to element in another XMI file
CXMI:

DateTimeAssignment



...other tags...

4.3.2 xmi:id, xmi: uuid, and UUID

A CXMI file uses xmi:id value to make references between all kinds of elements. An xmi:id can be in an

x mi: idr e f attribute.
[4]

Xmi: uuid (UUID ), is not relevant to be included in the mapping transformations. After the first

mapping clause, this attribute will be omitted.
4.3.3 Assumed sysml: Block in fragments

For all the fragments that refer to Block, the following shows how a block is defined in the Canonical

XMI. This is not repeated in the remaining fragments, where only x mi: t y p e = ”uml: C la s s” is included and

the s ys ml: Blo ck is assumed:
SysML:
Class <>
CXMI:




StepEntityName

4.3.4 Containment and reference relationship

The EXPRESS language does not distinguish between reference relationships and containment

relationships. SysML supports both types of relationships. Therefore, in 4.11, no distinction is made

whether an association between two entities is realized by reference or by relationship.

4.3.5 Used stereotypes to represent STEP concepts
Two existing UML stereotypes are used to represent specific STEP concepts:

— <> stereotypes represent select data objects. Select data objects are represented as

abstract Blocks in SysML;
— <> stereotypes represent two specific types of Blocks:
— blocks that represents list of lists;

— block that represents Value Type in order to be able to include them as member in selects.

6 © ISO 2021 – All rights reserved
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ISO/TS 10303-16:2021(E)
4.3.6 Select type not treated as SysML supertype

In STEP concepts, select types are not defined as entities but as types and are therefore not defined as

supertypes of an entity. In SysML an entity identifies the supertype entities and select types using the

generalization relationship. For this document supertype excludes any select types.

4.4 Mapping of the primary schema
SysML:

Package that includes directly the STEP data model represented in SysML and intended to

be transformed and implemented
CXMI:

STEP_AP242_Domain_model
EXPRESS:
SCHEMA STEP_AP242_Domain_model;
4.5 Mapping of Entities
4.5.1 General mapping of Entity

For each SysML block declaration (that is not an abstract <>), the EXPRESS Schema shall

contain the definition of a new entity data type corresponding to that SysML block.

SysML:
Class <>
CXMI:

StepEntityName
EXPRESS:
ENTITY StepEntityName;
4.5.2 Mapping of abstract entity
A SysML abstract block shall be transformed to an EXPRESS abstract supertype.
SysML:
Class <> with abstract parameter set as true
CXMI representation:

StepEntityName
true
© ISO 2021 – All rights reserved 7
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ISO/TS 10303-16:2021(E)
EXPRESS:
ENTITY StepEntityName
ABSTRACT SUPERTYPE;
...
4.5.3 Mapping of entity with one supertype
A SysML subtype Block shall be mapped to an EXPRESS subtype.
SysML:

Class <> with general parameter including the name of the supertype block. The

supertyping is, formally, represented as a generalization relationship from the subtype

block to the supertype block.
CXMI:

SubtypeEntity



EXPRESS:
ENTITY SubtypeEntity
SUBTYPE OF (NameOfSupertypeEntity);
If the SupertypeEntity has only one subtype:
ENTITY NameOfSupertypeEntity
SUPERTYPE OF (Subty
...

TECHNICAL ISO/TS
SPECIFICATION 10303-16
First edition
Industrial automation systems
and integration — Product data
representation and exchange —
Part 16:
Description methods: SysML XMI to
EXPRESS transformation
PROOF/ÉPREUVE
Reference number
ISO/TS 10303-16:2021(E)
ISO 2021
---------------------- Page: 1 ----------------------
ISO/TS 10303-16:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TS 10303-16:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms, definitions and abbreviated terms ................................................................................................................................ 2

3.1 Terms and definitions ....................................................................................................................................................................... 2

3.1.1 Terms and definitions for generic concepts ............................................................................................. 2

3.1.2 Terms and definitions for SysML constructs ........................................................................................... 3

3.2 Abbreviated terms ............................................................................................................................................................................... 5

4 SysML XMI to EXPRESS.................................................................................................................................................................................... 5

4.1 General ........................................................................................................................................................................................................... 5

4.2 Presentation conventions .............................................................................................................................................................. 5

4.3 Common mapping conventions ................................................................................................................................................ 5

4.3.1 Reference to external files ....................................................................................................................................... 5

4.3.2 xmi:id, xmi: uuid, and UUID ..................................................................................................................................... 6

4.3.3 Assumed sysml:Blo ck in fragments ................................................................................................................. 6

4.3.4 Containment and reference relationship .................................................................................................... 6

4.3.5 Used stereotypes to represent STEP concepts ....................................................................................... 6

4.3.6 Select type not treated as SysML supertype............................................................................................. 7

4.4 Mapping of the primary schema .............................................................................................................................................. 7

4.5 Mapping of Entities ............................................................................................................................................................................. 7

4.5.1 General mapping of Entity ....................................................................................................................................... 7

4.5.2 Mapping of abstract entity ...................................................................................................................................... 7

4.5.3 Mapping of entity with one supertype .......................................................................................................... 8

4.5.4 Mapping of entity with multiple supertypes ........................................................................................... 8

4.6 Mapping of simple type ................................................................................................................................................................... 9

4.7 Mapping of aggregation type ...................................................................................................................................................11

4.8 Mapping of aggregation of aggregation type..............................................................................................................12

4.9 Mapping of Select type ..................................................................................................................................................................13

4.9.1 General mapping of select type ........................................................................................................................13

4.9.2 Mapping of select type containing value type .....................................................................................14

4.10 Mapping of enumeration type ................................................................................................................................................15

4.11 Mapping of entity attribute .......................................................................................................................................................15

4.11.1 Mapping of multiplicity and optionality ...................................................................................................16

4.11.2 Attribute typed as an Entity ................................................................................................................................18

4.11.3 Attribute typed as Select ........................................................................................................................................18

4.11.4 Attribute typed as Enumeration type .........................................................................................................19

Annex A (normative) Information object registration ...................................................................................................................20

Annex B (informative) EXPRESS/Information modelling constructs and the equivalent

SysML modelling constructs ..................................................................................................................................................................21

Bibliography .............................................................................................................................................................................................................................33

© ISO 2021 – All rights reserved PROOF/ÉPREUVE iii
---------------------- Page: 3 ----------------------
ISO/TS 10303-16:2021(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www. iso. org/directives ).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or on

the ISO list of patent declarations received (see www. iso. org/patents ).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www. iso. org/

iso/foreword . html.

This document was prepared by Technical Committee ISO/TC 184, Automation systems and integration,

Subcommittee SC 4, Industrial data.

A list of all parts in the ISO 10303 series can be found on the ISO website at https:// standards. iso. org/

iso/ 10303/ tech/step _titles. htm.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www. iso. org/members . html.
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ISO/TS 10303-16:2021(E)
Introduction

ISO 10303 is an International Standard for the computer-interpretable representation and exchange

of product data. The objective is to provide a neutral mechanism capable of describing product data

throughout the life cycle of a product and independent from any particular system. The nature of this

description makes it suitable not only for neutral file exchange, but also as a basis for implementing and

sharing product databases and archiving.

10303-16 is a member of the description methods series. This document specifies a mapping of SysML

XMI to the EXPRESS language.

The STEP APs Domain models and the STEP Core Model are information model layer components that

are part of the STEP Extended Architecture. These components are developed using SysML. In the past

STEP information models were developed using the EXPRESS language. For legacy reasons it is therefore

required to provide an EXPRESS schema derived from the SysML domain model. It is mandatory that

the transformation from the SysML model to the EXPRESS schema is defined by a reference standard

and guarantee a repeatable process applicable to future application protocols developments.

The Object Management Group (OMG) has standardized the XML Metadata Interchange specification

(XMI) that integrates the OMG Systems Modeling Language (SysML), the OMG Unified Modeling

Language (UML), the OMG Meta-Object Facility (MOF) and the World Wide Web Consortium (W3C)

Extensible Markup Language (XML) standards. SysML inherits the XMI interchange capability from

UML. XMI is a mechanism for the interchange of metadata between UML-based modeling tools and MOF-

based metadata repositories. OMG has also standardized an XMI compliant interchange format for the

SysML thus specifying a lexical representation of SysML models based on a standardized metamodel

of the SysML. That lexical representation includes, among other things, the ability to interchange data

type information, class information (or entities), groupings of classes providing namespaces for the

classes (or schemas), associations between classes and inheritance between classes (or subtypes).

ISO has standardized the EXPRESS language (ISO 10303-11:2004). It is used to specify information

requirements in ISO 10303.

10303-16 specifies a description method of the STEP Parts family, which defines the transformation of

SysML constructs to the EXPRESS elements. Because the XMI standard specifies the XML representation

of SysML metamodel constructs, standardizing the binding of SysML constructs into EXPRESS elements

supports the representation of SysML models as EXPRESS schemas. SysML metamodel concepts that

appear in SysML Block Diagrams are mapped into data specifications defined by EXPRESS schemas.

This document does not map all SysML metamodel constructs to EXPRESS elements, because 10303

SysML models do not use all SysML metamodel constructs.

The EXPRESS schemas are derived from the domain model by applying the implementation bindings

on the SysML XMI. The EXPRESS binding is realized with XSL transformations, which transforms the

SysML model into an EXPRESS Schema. The specified binding is a one-way transformation from SysML

information model represented in XMI into an EXPRESS schema. Due to this limitation 10303-16 does

not define the transformation of arbitrary SysML models to EXPRESS.

Readers of 10303-16 require detailed knowledge of the EXPRESS language, and SysML.

The structure, conventions and concepts of the EXPRESS language are defined in ISO 10303-11:2004.

The main component of this standard is:

— the specification of the transformation from SysML XMI to EXPRESS for each STEP element modelled

in SysML.
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TECHNICAL SPECIFICATION ISO/TS 10303-16:2021(E)
Industrial automation systems and integration — Product
data representation and exchange —
Part 16:
Description methods: SysML XMI to EXPRESS
transformation
1 Scope

This document specifies a mapping of SysML (ISO/IEC 19514:2017) constructs to EXPRESS

(ISO 10303-11:2004) elements for the purpose of representing SysML model represented in XMI

(ISO/IEC 19509:2014) as EXPRESS (ISO 10303-11:2004) schemas. The specified mapping is a one-way

transformation from SysML information model represented in XMI into an EXPRESS schema.

NOTE Due to this limitation 10303-16 does not define the transformation of arbitrary SysML models to

EXPRESS.
The following are within the scope of this document:

— the transformation of SysML metamodel constructs represented in XMI to EXPRESS elements for

the purpose of representing SysML information models as EXPRESS schemas.
The following are outside the scope of this document:

— the transformation of SysML metamodel constructs into EXPRESS elements that are not used in the

STEP Extended Architecture.
NOTE The STEP Extended Architecture is defined in References [8], [9] and [10].

— the transformation of SysML metamodel constructs into EXPRESS elements for other purposes than

representing SysML constructs as STEP concepts;
— codes and scripts to transform SysML XMI to EXPRESS schema;
[5]

— the transformation of SysML constraints (OCL ) into EXPRESS global and local rules;

— the transformation of EXPRESS elements into SysML constructs.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 10303-1, Industrial automation systems and integration — Product data representation and

exchange — Part 1: Overview and fundamental principles

ISO 10303-11:2004, Industrial automation systems and integration — Product data representation and

exchange — Part 11: Description methods: The EXPRESS language reference manual

ISO/IEC 19505-1:2012, Information technology — Object Management Group Unified Modeling Language

(OMG UML) — Part 1: Infrastructure
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ISO/TS 10303-16:2021(E)

ISO/IEC 19509:2014, Information technology — Object Management Group XML Metadata Interchange

(XMI)

ISO/IEC 19514:2017, Information technology — Object management group systems modeling language

(OMG SysML)
W3C Recommendation: Extensible Markup Language (XML) 1.0 (Fifth Edition)
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 10303-11, ISO/IEC 19505-1,

ISO/IEC 19514 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1.1 Terms and definitions for generic concepts
3.1.1.1
data

representation of information in a formal manner suitable for communication, interpretation, or

processing by human beings or computers
[SOURCE: ISO 10303-1:2021, 3.1.29]
3.1.1.2
data model

description of the organization of data in the management information system of an enterprise

[SOURCE: ISO/IEC 2382:2015, 2121422]
3.1.1.3
EXPRESS
language by which aspects of product data can be defined
[SOURCE: ISO/TS 10303-15:2021, 3.1.1.1]
3.1.1.4
information
facts, concepts, or instructions
[SOURCE: ISO 10303-1:2021, 3.1.41]
3.1.1.5
information model
conceptual model of product data

Note 1 to entry: In ISO 10303, an information model is based on the object-relationship modeling technique that

organizes the product data as represented in different system aspects.

Note 2 to entry: In ISO 10303, information models may be developed using EXPRESS modeling language.

EXAMPLE Application resource model for ISO 10303-242 managed model-based 3D engineering.

[SOURCE: ISO 10303-1:2021, 3.1.42, modified — In the definition, "formal" has been replaced with

"conceptual"; in Note 2 to entry, "are" has been replaced with "may be"; the Example has been changed.]

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ISO/TS 10303-16:2021(E)
3.1.2 Terms and definitions for SysML constructs
3.1.2.1
association

association classifies a set of tuples representing links between typed model elements

Note 1 to entry: The full definition is provided in ISO/IEC 19505-1:2012, 11.5.
3.1.2.2
auxiliary
stereotype applied to an abstract block that has no properties

Note 1 to entry: The full definition is provided in ISO/IEC 19505-1:2012, Clause 22.

3.1.2.3
block
modular construct used for defining an entity.

Note 1 to entry: Application activity model concepts, application data planning objects, application domain

model business objects, core model objects and ARM in SysML Entities. They can include reference, part, value

properties, and constraints. They can be specializations of other blocks.

Note 2 to entry: The full definition is provided in ISO/IEC 19514:2017, Clause 8.

3.1.2.4
canonical XMI

specific constrained format of XMI that minimizes variability and provides more predictable

identification and ordering
Note 1 to entry: A canonical XMI file is itself a valid XMI file.
Note 2 to entry: The full definition is provided in ISO/IEC 19509:2014, Annex B.
3.1.2.5
composite aggregation
responsibility for the existence of the composed object

Note 1 to entry: If a composite object is deleted, all of its part instances that are objects are deleted with it.

Note 2 to entry: The full definition is provided in ISO/IEC 19505-1:2012, 11.4.1.

3.1.2.6
connector

link between two or more instances playing owned or inherited roles within a StructuredClassifier

Note 1 to entry: The full definition is provided in ISO/IEC 19505-1:2012, 11.2.3.3.

3.1.2.7
enumeration
value type whose values are enumerated in the model as enumeration literals

Note 1 to entry: The full definition is provided in ISO/IEC 19505-1:2012, 10.2.3.3.

3.1.2.8
enumeration literal
user defined data value for an enumeration

Note 1 to entry: The full definition is provided in ISO/IEC 19505-1:2012, 10.2.3.3.

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ISO/TS 10303-16:2021(E)
3.1.2.9
data type
type whose instances are identified only by their value

Note 1 to entry: The full definition is provided in ISO/IEC 19505-1:2012, 10.2.3.1.

3.1.2.10
generalization

directed relationship between a more general supertype and a more specific subtype

Note 1 to entry: Each generalization relates a specific classifier to a more general classifier. Given a classifier,

the transitive closure of its general classifiers is often called its generalizations, and the transitive closure of

its specific classifiers is called its specializations. The immediate generalizations are also called the classifier’s

subtype, and where the classifier is a class, its supertype.
Note 2 to entry: The full definition is provided in ISO/IEC 19505-1:2012, C.1.1.
3.1.2.11
part property

property that specifies a part with strong ownership and coincidental lifetime of its containing block

Note 1 to entry: It describes a local usage or a role of the typing block in the context of the containing block. Every

part property has composite aggregation and is typed by a block.

Note 2 to entry: The full definition is provided in ISO/IEC 19514:2017, 8.3.2.3, paragraph 6.

3.1.2.12
primitive type
definition of a predefined data type, without any substructure

Note 1 to entry: The full definition is provided in ISO/IEC 19505-1:2012, Clause 21.

3.1.2.13
reference property
property that specifies a reference of its containing block to another block

Note 1 to entry: The full definition is provided in ISO/IEC 19514:2017, 8.3.2.3, paragraph 6.

3.1.2.14
stereotype

limited kind of metaclass that cannot be used by itself but must always be used in conjunction with one

of the metaclasses it extends

Note 1 to entry: The full definition is provided in ISO/IEC 19505-1:2012, 12.3.3.4.

3.1.2.15
value property
property of a block that is typed with a value type

Note 1 to entry: The full definition is provided in ISO/IEC 19514:2017, 8.3.2.3, paragraph 6.

3.1.2.16
value type

a stereotype of UML data type that is used to define types of values that may be used to express

information but cannot be identified as the target of any reference

Note 1 to entry: The full definition is provided in ISO/IEC 19514:2017, 8.3.2.14.

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ISO/TS 10303-16:2021(E)
3.2 Abbreviated terms
CXMI canonical XMI
ID identifier
OCL object constraint language
OMG object management group
STEP standard for the exchange of product model data
SysML systems modeling language
UML unified modeling language
UUID universal unique identifier
XMI XML meta-data interchange
XML extensible markup language
4 SysML XMI to EXPRESS
4.1 General

This clause describes the concepts and rules for the transformation mapping from a STEP SysML model

stored as a CXMI file to an EXPRESS Schema.

This document shall be unambiguously identified in an open information system by the code defined in

Annex A.
4.2 Presentation conventions

For ease of identification, separate boxes are used for the fragments of SysML, CXMI and EXPRESS.

The items significant to the section are usually in bold, but more than text effects may be used where

needed to support the explanation. Triple dots (“…”) are used to hide content not relevant to an extract.

Curly brackets “{xxx}” are used to contain descriptive words of the content in the resulting CXMI.

4.3 Common mapping conventions
4.3.1 Reference to external files

All the references in the SysML Canonical XMI fragments are given as x mi: idr e f which assumes that

the referenced element is contained in the same XMI file. When the referenced element is in a different

XMI file the href is used instead. This will be the case for all reference to primitives and may be case for

other references.
Canonical XMI: type href relative reference to element in DataTypes.xmi
CXMI:

Text

...other tags...

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ISO/TS 10303-16:2021(E)
Canonical XMI: general href relative reference to element in another XMI file
CXMI:

DateTimeAssignment



...other tags...

4.3.2 xmi:id, xmi: uuid, and UUID

A CXMI file uses xmi:id value to make references between all kinds of elements. An xmi:id can be in an

x mi: idr e f attribute.
[4]

Xmi: uuid (UUID ), is not relevant to be included in the mapping transformations. After the first

mapping clause, this attribute will be omitted.
4.3.3 Assumed sysml: Block in fragments

For all the fragments that refer to Block, the following shows how a block is defined in the Canonical

XMI. This is not repeated in the remaining fragments, where only x mi: t y p e = ”uml: C la s s” is included and

the s ys ml: Blo ck is assumed:
SysML:
Class <>
CXMI:




StepEntityName

4.3.4 Containment and reference relationship

The EXPRESS language does not distinguish between reference relationships and containment

relationships. SysML supports both types of relationships. Therefore, in 4.11, no distinction is made

whether an association between two entities is realized by reference or by relationship.

4.3.5 Used stereotypes to represent STEP concepts
Two existing UML stereotypes are used to represent specific STEP concepts:

— <> stereotypes represent select data objects. Select data objects are represented as

abstract Blocks in SysML;
— <> stereotypes represent two specific types of Blocks:
— blocks that represents list of lists;

— block that represents Value Type in order to be able to include them as member in selects.

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ISO/TS 10303-16:2021(E)
4.3.6 Select type not treated as SysML supertype

In STEP concepts, select types are not defined as entities but as types and are therefore not defined as

supertypes of an entity. In SysML an entity identifies the supertype entities and select types using the

generalization relationship. For this document supertype excludes any select types.

4.4 Mapping of the primary schema
SysML:

Package that includes directly the STEP data model represented in SysML and intended to

be transformed and implemented
CXMI:

STEP_AP242_Domain_model
EXPRESS:
SCHEMA STEP_AP242_Domain_model;
4.5 Mapping of Entities
4.5.1 General mapping of Entity

For each SysML block declaration (that is not an abstract <>), the EXPRESS Schema shall

contain the definition of a new entity data type corresponding to that SysML block.

SysML:
Class <>
CXMI:

StepEntityName
EXPRESS:
ENTITY StepEntityName;
4.5.2 Mapping of abstract entity
A SysML abstract block shall be transformed to an EXPRESS abstract supertype.
SysML:
Class <> with abstract parameter set as true
CXMI representation:

StepEntityName
true
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ISO/TS 10303-16:2021(E)
EXPRESS:
ENTITY StepEntityName
ABSTRACT SUPERTYPE;
...
4.5.3 Mapping of entity with one supertype
A SysML subtype Block shall be mapped to an EXPRESS subtype.
SysML:

Class <> with general parameter including the name of the supertype block. The

supertyping is, formally, represented as a generalization relationship from the subtype

block to the supertype block.
CXMI:

SubtypeEntity

...

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