ISO 10303-11:2004

Industrial automation systems and integration — Product data representation and exchange — Part 11: Description methods: The EXPRESS language reference manual

ISO 10303 specifies a language by which aspects of product data can be defined. The language is called EXPRESS. ISO 10303-11:2004 also specifies a graphical representation for a subset of the constructs in the EXPRESS language. This graphical representation is called EXPRESS-G. EXPRESS is a data specification language as defined in ISO 10303-1. It consists of language elements that allow an unambiguous data definition and specification of constraints on the data defined. The following are within the scope of ISO 10303-11:2004: data types; constraints on instances of the data types. The following are outside the scope of this part of ISO 10303: definition of database formats; definition of file formats; definition of transfer formats; process control; information processing; exception handling. EXPRESS is not a programming language.

Systèmes d'automatisation industrielle et intégration — Représentation et échange de données de produits — Partie 11: Méthodes de description: Manuel de référence du langage EXPRESS

General Information

• Status: Published
• Publication Date: 09-Nov-2004
• ICS: 25.040.40 - Industrial process measurement and control
• Technical Committee: ISO/TC 184/SC 4 - Industrial data
• Drafting Committee: ISO/TC 184/SC 4/WG 11 - Implementation methods and conformance methods
• Current Stage: 9093 - International Standard confirmed
• Start Date: 23-Jun-2025
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 10303-11:1994 - Industrial automation systems and integration — Product data representation and exchange — Part 11: Description methods: The EXPRESS language reference manual
• Effective Date: 15-Apr-2008
• Revises: ISO 10303-11:1994/Cor 1:1999 - Industrial automation systems and integration — Product data representation and exchange — Part 11: Description methods: The EXPRESS language reference manual — Technical Corrigendum 1
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 10303-11
Second edition
2004-11-01
Industrial automation systems and
integration — Product data
representation and exchange —
Part 11:
Description methods: The EXPRESS
language reference manual
Systèmes d'automatisation industrielle et intégration — Représentation
et échange de données de produits —
Partie 11: Méthodes de description: Manuel de référence du langage
EXPRESS
Reference number
©
ISO 2004
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ii © ISO 2004 – All rights reserved

Contents Page
0 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii
0.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii
0.2 Language overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii
1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3 Terms and definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3.1 Terms defined in ISO 10303–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3.2 Terms defined in ISO/IEC 10646 . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3.3 Other terms and definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
4 Conformance requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1 Formal specifications written in EXPRESS . . . . . . . . . . . . . . . . . . . . 5
4.1.1 Lexical language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1.2 Graphical form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.2 Implementations of EXPRESS . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.2.1 EXPRESS language parser . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.2.2 Graphical editing tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Fundamental principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6 Language specification syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1 The syntax of the specification . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.2 Special character notation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7 Basic language elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.1 Character set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.1.1 Digits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.1.2 Letters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.1.3 Special characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7.1.4 Underscore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7.1.5 Whitespace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7.1.6 Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7.2 Reserved words . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.2.1 Keywords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.2.2 Reserved words which are operators . . . . . . . . . . . . . . . . . . . . . 14
7.2.3 Built-in constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.2.4 Built-in functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.2.5 Built-in procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.3 Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.4 Identifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.5 Literals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.5.1 Binary literal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.5.2 Integer literal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.5.3 Real literal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.5.4 String literal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7.5.5 Logical literal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8 Data types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.1 Simple data types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
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8.1.1 Number data type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8.1.2 Real data type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8.1.3 Integer data type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.1.4 Logical data type. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.1.5 Boolean data type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.1.6 String data type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.1.7 Binary data type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
8.2 Aggregation data types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
8.2.1 Array data type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8.2.2 List data type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
8.2.3 Bag data type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
8.2.4 Set data type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
8.2.5 Value uniqueness on aggregates . . . . . . . . . . . . . . . . . . . . . . . . 27
8.3 Named data types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
8.3.1 Entity data type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
8.3.2 Defined data type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8.4 Constructed data types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8.4.1 Enumeration data type . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
8.4.2 Select data type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
8.5 Generalized data types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
8.6 Data type usage classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
8.6.1 Instantiable data types . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
8.6.2 Parameter data types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
8.6.3 Underlying data types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
9 Declarations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
9.1 Type declaration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
9.2 Entity declaration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
9.2.1 Attributes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
9.2.2 Local rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
9.2.3 Subtypes and supertypes . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
9.2.4 Abstract entity data type . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
9.2.5 Subtype/supertype constraints . . . . . . . . . . . . . . . . . . . . . . . . 55
9.2.6 Implicit declarations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
9.2.7 Specialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
9.3 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
9.4 Constant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
9.5 Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
9.5.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
9.5.2 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
9.5.3 Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
9.5.4 Local variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
9.6 Rule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
9.7 Subtype constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
9.7.1 Abstract supertype constraint . . . . . . . . . . . . . . . . . . . . . . . . 75
9.7.2 Total coverage subtypes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
9.7.3 Overlapping subtypes and their specification . . . . . . . . . . . . . . . . 76
10 Scope and visibility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
10.1 Scope rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
10.2 Visibility rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
10.3 Explicit item rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
10.3.1 Alias statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
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10.3.2 Attribute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
10.3.3 Constant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
10.3.4 Enumeration item . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
10.3.5 Entity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
10.3.6 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
10.3.7 Parameter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
10.3.8 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
10.3.9 Query expression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
10.3.10 Repeat statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
10.3.11 Rule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
10.3.12 Rule label . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
10.3.13 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
10.3.14 Subtype constraint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
10.3.15 Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
10.3.16 Type label . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
10.3.17 Variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
11 Interface specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
11.1 Use interface specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
11.2 Reference interface specification . . . . . . . . . . . . . . . . . . . . . . . . . . 87
11.3 The interaction of use and reference . . . . . . . . . . . . . . . . . . . . . . . . 88
11.4 Implicit interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
11.4.1 Constant interfaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
11.4.2 Defined data type interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . 90
11.4.3 Entity data type interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . 90
11.4.4 Function interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
11.4.5 Procedure interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
11.4.6 Rule interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
11.4.7 Subtype constraint interfaces . . . . . . . . . . . . . . . . . . . . . . . . . 91
12 Expression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
12.1 Arithmetic operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
12.2 Relational operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
12.2.1 Value comparison operators . . . . . . . . . . . . . . . . . . . . . . . . . . 95
12.2.2 Instance comparison operators . . . . . . . . . . . . . . . . . . . . . . . . 99
12.2.3 Membership operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
12.2.4 Interval expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
12.2.5 Like operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
12.3 Binary operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
12.3.1 Binary indexing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
12.3.2 Binary concatenation operator . . . . . . . . . . . . . . . . . . . . . . . . 104
12.4 Logical operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
12.4.1 NOT operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
12.4.2 AND operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
12.4.3 OR operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
12.4.4 XOR operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
12.5 String operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
12.5.1 String indexing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
12.5.2 String concatenation operator . . . . . . . . . . . . . . . . . . . . . . . . . 107
12.6 Aggregate operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
12.6.1 Aggregate indexing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
12.6.2 Intersection operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
12.6.3 Union operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
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12.6.4 Difference operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
12.6.5 Subset operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
12.6.6 Superset operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
12.6.7 Query expression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
12.7 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
12.7.1 Simple references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
12.7.2 Prefixed references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
12.7.3 Attribute references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
12.7.4 Group references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
12.8 Function call . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
12.9 Aggregate initializer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
12.10 Complex entity instance construction operator . . . . . . . . . . . . . . . . . . 118
12.11 Type compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
12.12 Select data types in expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
12.12.1 Select data types in unary expressions . . . . . . . . . . . . . . . . . . . . 120
12.12.2 Select data types in binary expressions. . . . . . . . . . . . . . . . . . . . 120
12.12.3 Select data types in ternary expressions . . . . . . . . . . . . . . . . . . . 121
13 Executable statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
13.1 Null (statement) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
13.2 Alias statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
13.3 Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
13.3.1 Assignment statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
13.3.2 Assignment compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
13.4 Case statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
13.5 Compound statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
13.6 Escape statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
13.7 If .Then .Else statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
13.8 Procedure call statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
13.9 Repeat statement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
13.9.1 Increment control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
13.9.2 While control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
13.9.3 Until control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
13.10 Return statement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
13.11 Skip statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
14 Built-in constants. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
14.1 Constant e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
14.2 Indeterminate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
14.3 False . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
14.4 Pi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
14.5 Self . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
14.6 True . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
14.7 Unknown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
15 Built-in functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
15.1 Abs - arithmetic function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
15.2 ACos - arithmetic function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
15.3 ASin - arithmetic function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
15.4 ATan - arithmetic function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
15.5 BLength - binary function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
15.6 Cos - arithmetic function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
15.7 Exists - general function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
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15.8 Exp - arithmetic function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
15.9 Format - general function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
15.9.1 Symbolic representation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
15.9.2 Picture representation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
15.9.3 Standard representation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
15.10 HiBound - arithmetic function . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
15.11 HiIndex - arithmetic function . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
15.12 Length - string function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
15.13 LoBound - arithmetic function . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
15.14 Log - arithmetic function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
15.15 Log2 - arithmetic function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
15.16 Log10 - arithmetic function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
15.17 LoIndex - arithmetic function . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
15.18 NVL - null value function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
15.19 Odd - arithmetic function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
15.20 RolesOf - general function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
15.21 Sin - arithmetic function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
15.22 SizeOf - aggregate function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
15.23 Sqrt - arithmetic function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
15.24 Tan - arithmetic function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
15.25 TypeOf - general function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
15.26 UsedIn - general function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
15.27 Value - arithmetic function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
15.28 Value in - membership function . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
15.29 Value unique - uniqueness function . . . . . . . . . . . . . . . . . . . . . . . . . 149
16 Built-in procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
16.1 Insert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
16.2 Remove . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
Annex A (normative) EXPRESS language syntax . . . . . . . . . . . . . . . . . . . . . 151
A.1 Tokens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
A.1.1 Keywords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
A.1.2 Character classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
A.1.3 Lexical elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
A.1.4 Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
A.1.5 Interpreted identifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
A.2 Grammar rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
A.3 Cross reference listing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
Annex B (normative) Determination of the allowed entity instantiations . . . . . . . . 166
B.1 Formal approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
B.2 Supertype and subtype constraint operators . . . . . . . . . . . . . . . . . . . . 167
B.2.1 OneOf . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
B.2.2 And . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
B.2.3 AndOr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
B.2.4 Precedence of operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
B.3 Interpreting the possible complex entity data types . . . . . . . . . . . . . . . . 168
Annex C (normative) Instance limits imposed by the interface specification. . . . . . . 181
Annex D (normative) EXPRESS-G: A graphical subset of EXPRESS . . . . . . . . . . 185
D.1 Introduction and overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
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D.2 Definition symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
D.2.1 Symbol for simple data types . . . . . . . . . . . . . . . . . . . . . . . . . 186
D.2.2 Symbols for constructed data types . . . . . . . . . . . . . . . . . . . . . 187
D.2.3 Symbols for defined data types . . . . . . . . . . . . . . . . . . . . . . . . 188
D.2.4 Symbols for entity data types . . . . . . . . . . . . . . . . . . . . . . . . . 188
D.2.5 Symbols for subtype constraints . . . . . . . . . . . . . . . . . . . . . . . 188
D.2.6 Symbols for functions and procedures . . . . . . . . . . . . . . . . . . . . 188
D.2.7 Symbols for rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
D.2.8 Symbols for schemas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
D.3 Relationship symbols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
D.4 Composition symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
D.4.1 Page references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
D.4.2 Inter-schema references . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
D.5 Entity level diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
D.5.1 Role names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
D.5.2 Cardinalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
D.5.3 Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
D.5.4 Constructed and defined data types . . . . . . . . . . . . . . . . . . . . . 193
D.5.5 Entity data types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
D.5.6 Inter-schema references . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
D.6 Schema level diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
D.7 Complete EXPRESS-G diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . 198
D.7.1 Complete entity level diagram . . . . . . . . . . . . . . . . . . . . . . . . 199
D.7.2 Complete schema level diagram . . . . . . . . . . . . . . . . . . . . . . . . 200
Annex E (normative) Protocol implementation conformance statement (PICS) . . . . . 201
E.1 EXPRESS language parser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
E.2 EXPRESS-G editing tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
Annex F (normative) Information object registration . . . . . . . . . . . . . . . . . . . 203
F.1 Document identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
F.2 Syntax identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
Annex G (normative) Generating a single schema from multiple schemas . . . . . . . . 204
G.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
G.2 Fundamental concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
G.3 Name munging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
G.3.1 Name clashes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
G.3.2 Identifiers as strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
G.4 Stage 1: multi-schema to intermediate schema conversion . . . . . . . . . . . . 207
G.4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
G.4.2 Primary population . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
G.4.3 Secondary population . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
G.4.4 Prune . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
G.4.5 Schema names and versions . . . . . . . . . . . . . . . . . . . . . . . . . . 222
G.5 Stage 2: convert intermediate schema to ISO 10303-11:1994 . . . . . . . . . . . 223
G.5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
G.5.2 Initialisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
G.5.3 Conversion of extensible constructed data types . . . . . . . . . . . . . . 223
G.5.4 Conversion of subtype constraints . . . . . . . . . . . . . . . . . . . . . . 228
G.5.5 Conversion of abstract entity and generalized types . . . . . . . . . . . . 231
G.5.6 Conversion of attributes renamed in a redeclaration . . . . . . . . . . . . 233
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Annex H (informative) Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
H.1 Relationships via attributes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
H.1.1 Simple relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
H.1.2 Collective relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
H.1.3 Distributive relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
H.1.4 Inverse attribute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
H.2 Subtype/supertype relationships . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Annex J (informative) EXPRESS models for EXPRESS-G illustrative examples . . . . 242
J.1 Example single schema model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
J.2 Relationship sampler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
J.3 Simple subtype/supertype tree . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
J.4 Attribute redeclaration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
J.5 Multi-schema models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
Annex K (informative) Deprecated features of EXPRESS . . . . . . . . . . . . . . . . . 248
Annex L (informative) Examples of the new EXPRESS constructs . . . . . . . . . . . . 249
L.1 Product management example . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
Figures
Figure B.1 — EXPRESS-G diagram of schema for example 1 on page 171 . . . . . . . . . 172
Figure B.2 — EXPRESS-G diagram of schema for example 2 on page 174 . . . . . . . . . 174
Figure B.3 — EXPRESS-G diagram of schema for example 3 on page 176 . . . . . . . . . 177
Figure D.1 — Complete entity level diagram of the example in J.1 on page 242 (Page 1 of 2)186
Figure D.2 — Complete entity level diagram of the example in J.1 on page 242 (Page 2 of 2)186
Figure D.3 — Symbols for EXPRESS simple data types . . . . . . . . . . . . . . . . . . . 186
Figure D.4 — Symbol for EXPRESS generic entity data type . . . . . . . . . . . . . . . . 187
Figure D.5 — Symbols for EXPRESS constructed data types . . . . . . . . . . . . . . . . 187
Figure D.6 — Abbreviated symbols for the EXPRESS constructed data types when used
as the representation of defined data types . . . . . . . . . . . . . . . . . . . . . . 187
Figure D.7 — Example of alternative methods for representing an enumeration data type 187
Figure D.8 — Symbols for EXPRESS extensible constructed data types . . . . . . . . . . 188
Figure D.9 — Symbol for EXPRESS defined data type. . . . . . . . . . . . . . . . . . . . 188
Figure D.10 — Symbol for an EXPRESS entity data type . . . . . . . . . . . . . . . . . . 188
Figure D.11 — Symbol for an EXPRESS subtype constraint . . . . . . . . . . . . . . . . 188
Figure D.12 — Symbol for a schema . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
Figure D.13 — Relationship line styles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
Figure D.14 — Partial entity level diagram illustrating relationship directions from the
example in J.2 on page 243 (Page 1 of 1) . . . . . . . . . . . . . . . . . . . . . . . 190
Figure D.15 — Composition symbols: page references . . . . . . . . . . . . . . . . . . . . 190
Figure D.16 — Composition symbols: inter-schema references . . . . . . . . . . . . . . . . 191
Figure D.17 — Complete entity level diagram of the example in J.2 on page 243 (Page 1
of 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
Figure D.18 — Extensible select data type diagram . . . . . . . . . . . . . . . . . . . . . 193
Figure D.19 — Symbol for denoting an ABSTRACT SUPERTYPE if the abstract con-
straint is defined within a SUBTYPE CONSTRAINT . . . . . . . . . . . . . . . . 195
Figure D.20 — Symbol denoting an ABSTRACT ENTITY . . . . . . . . . . . . . . . . . 195
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Figure D.21 — Example of the TOTAL OVER coverage constraint . . . . . . . . . . . . . 196
Figure D.22 — Complete entity level diagram of the inheritance graph from the example
in J.3 on page 244 (Page 1 of 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
Figure D.23 — Complete entity level diagram of the example in J.4 on page 245 showing
attribute redeclarations in subtypes (Page 1 of 1) . . . . . . . . . . . . . . . . . . . 197
Figure D.24 — Complete entity level diagram of the top schema of example 1 on page 245
illustrating inter-schema references (Page 1 of 1) . . . . . . . . . . . . . . . . . . . 197
Figure D.25 — Complete schema level diagram of example 1 on page 245 (Page 1 of 1) . 198
Figure D.26 — Complete schema level diagram of example 2 on page 246 (Page 1 of 1) . 199
Tables
Table 1 — EXPRESS keywords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 2 — EXPRESS reserved words which are operators . . . . . . . . . . . . . . . . . . 14
Table 3 — EXPRESS reserved words which are constants . . . . . . . . . . . . . . . . . . 15
Table 4 — EXPRESS reserved words which are function names . . . . . . . . . . . . . . . 15
Table 5 — EXPRESS reserved words which are procedure names . . . . . . . . . . . . . . 15
Table 6 — EXPRESS symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 7 — The use of data types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Table 8 — Supertype expression operator precedence . . . . . . . . . . . . . . . . . . . . . 59
Table 9 — Scope and identifier defining items . . . . . . . . . . . . . . . . . . . . . . . . . 79
Table 10 — Operator precedence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Table 11 — Pattern matching characters. . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Table 12 — NOT operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Table 13 — AND operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Table 14 — OR operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Table 15 — XOR operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Table 16 — Intersection operator – operand and result types . . . . . . . . . . . . . . . . 108
Table 17 — Union operator – operand and result types . . . . . . . . . . . . . . . . . . . 110
Table 18 — Difference operator – operand and result types . . . . . . . . . . . . . . . . . 110
Table 19 — Subset and superset operators - operand types . . . . . . . . . . . . . . . . . 111
Table 20 — Example symbolic formatting effects . . . . . . . . . . . . . . . . . . . . . . . 137
Table 21 — Picture formatting characters . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Table 22 — Example picture formatting effects . . . . . . . . . . . . . . . . . . . . . . . . 137
x �cISO 2004 — All rights reserved

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 nor-
mally 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.
InternationalStandardsaredraftedinaccordancewiththerulesgivenintheISO/IECDirectives,
Part 2.
ThemaintaskoftechnicalcommitteesistoprepareInternationalStandards. DraftInternational
Standards adopted by the technical committees are circulated to the member bodies for voting.
PublicationasanInternationalStandardrequiresapprovalbyatleast75%ofthememberbodies
casting a vote.
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.
ISO10303–11waspreparedbyTechnicalCommitteeISO/TC184,Industrialautomationsystems
and integration, Subcommittee SC 4, Industrial data.
This second edition of ISO 10303–11 constitutes a minor revision of the first edition (ISO 10303-
11:1994), which is provisionally retained in order to support continued use and maintenance of
implementations based on thefirst edition and to satisfy the normative references of other parts
of ISO 10303. This second edition also incorporates the Technical Corrigendum ISO 10303–
11:1994/Cor.1:1999(E).
ISO10303isorganizedasaseriesofparts,eachpublishedseparately. ThestructureofISO10303
is described in ISO 10303–1.
Each part of ISO 10303 is a member of one of the following series: description methods, im-
plementation methods, conformance testing methodology and framework, integrated generic
resources, integrated application resources, application protocols, abstract test suites, applica-
tion interpreted constructs, and application modules. This part is a member of the description
methods series.
A complete list of parts of ISO 10303 is available from the Internet:

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0 Introduction
0.1 General
ISO10303isanInternationalStandardforthecomputer-interpretablerepresentationofproduct
information and for the exchange of product data. The objective is to provide a neutral mech-
anism capable of describing products throughout their life cycle. This mechanism is suitable
not only for neutral file exchange, but also as a basis for implementing and sharing product
databases, and as a basis for archiving.
This part of ISO 10303 specifies the elements of the EXPRESS language. Each element of the
language is presented in its own context with examples. Simple elements are introducedfirst,
then more complex ideas are presented in an incremental manner.
The changes that lead to this edition were driven by requirements from multi-schema specifica-
tions. The new concepts constitute an architecture for extensible data models. The following
keywords have been added to this edition:
— based on;
— end subtype constraint;
— extensible;
— generic entity;
— renamed;
— subtype constraint;
— total over;
— with.
Schemas that contain these words as EXPRESS identifiers become invalid under this edition.
Else, the modifications that are incorporated in this edition are upwardly compatible with the
previous edition.
0.2 Language overview
EXPRESS is the name of a formal information requirements specification language. It is used
to specify the information requirements of other parts of ISO 10303. It is based on a number of
design goals among which are:
— the size and complexity of ISO 10303 demands that the language be parsable by both
computers and humans. Expressing the information elements of ISO 10303 in a less formal
manner would eliminate the possibility of employing computer automation in checking for
inconsistencies in presentation or for creating any number of secondary views, including
implementation views;
— thelanguageisdesignedtoenablepartitioningofthediversematerialaddressedbyISO10303.
The schema is the basis for partitioning and intercommunication;
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— the language focuses on the definition of entities, which represent objects of interest. The
definition of an entity is in terms of its properties, which are characterized by specification
of a domain and the constraints on that domain;
— thelanguageseekstoavoid, asfaraspossible, specificimplementationviews. However, itis
possibletomanufactureimplementationviews(suchasstaticfileexchange)inanautomatic
and straightforward manner.
InEXPRESS,entitiesaredefinedintermsofattributes: thetraitsorcharacteristicsconsidered
important for use and understanding. These attributes have a representation which might be a
simple data type (such as integer) or another entity type. A geometric point might be defined in
termsofthreerealnumbers. Namesaregiventotheattributeswhichcontributetothedefinition
of an entity. Thus, for a geometric point the three real numbers might be named x, y and z.
A relationship is established between the entity being defined and the attributes that define it,
and, in a similar manner, between the attribute and its representation.
++
NOTE 1 A number of languages have contributed to EXPRESS, in particular, Ada, Algol, C, C ,
Euler, Modula-2, Pascal, PL/I and SQL. Some facilities have been invented to make EXPRESS more
suitable for the job of expressing an information model.
NOTE 2 TheexamplesofEXPRESSusageinthismanualdonotconformtoanyparticularstylerules.
Indeed, the examples sometimes use poor style to conserve space or to show flexibility. The examples
are not intended to reflect the content of the information models defined in other parts of ISO 10303.
They are crafted to show particular features of EXPRESS. Any similarity between the examples and
the normative information models specified in other parts of ISO 10303 should be ignored.
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INTERNATIONAL STANDARD ISO 10303-11:2004(E)
Industrial automation systems and integration —
Product data representation and exchange —
Part 11:
Description methods: The EXPRESS language
reference manual
1 Scope
This part of ISO 10303 specifies a language by which aspects of product data can be defined.
The language is called EXPRESS.
This part of ISO 10303 also specifies a graphical representation for a subset of the constructs in
the EXPRESS language. This graphical representation is called EXPRESS-G.
EXPRESS is a data specification language as defined in ISO 10303-1. It consists of language
elements that allow an unambiguous data definition and specification of constraints on the data
defined.
The following are within the scope of this part of ISO 10303:
— data types;
— constraints on instances of the data types.
The following are outside the scope of this part of ISO 10303:
— definition of database formats;
— definition of file formats;
— definition of transfer formats;
— process control;
— information processing;
— exception handling.
EXPRESS is not a programming language.
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2 Normative references
The following referenced documents are indispensable for the application of this document. For
dated references, only the edition cited applies. For
...