ISO 14813-6:2017

INTERNATIONAL ISO
STANDARD 14813-6
Second edition
2017-11
Intelligent transport systems —
Reference model architecture(s) for
the ITS sector —
Part 6:
Use of ASN.1
Systèmes intelligents de transport (ITS) — Architecture(s) de modèle
de référence pour le secteur ITS —
Partie 6: Présentation de données dans ASN.1
Reference number
ISO 14813-6:2017(E)
©
ISO 2017

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ISO 14813-6:2017(E)

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ISO 14813-6:2017(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 4
5 Requirements . 4
5.1 General requirements . 4
5.1.1 Use of ASN.1 is mandatory . 4
5.1.2 Consistency with the CIDCR . 4
5.1.3 Limited use of OCTET STRING . 5
5.1.4 ASN.1 historical name . 5
5.2 Encoding rules . 5
5.3 Module definitions . 5
5.3.1 General requirements . 5
5.3.2 Conformance . 6
5.3.3 Name . 6
5.3.4 Identification . 6
5.3.5 Tag default . 6
5.3.6 Version and revision . 7
5.4 Data type assignments . 7
5.4.1 General. 7
5.4.2 Message versioning . 7
5.4.3 Contents of message or aggregate domain . 8
5.4.4 Reference style in NamedTypes . 8
5.4.5 Comments . 8
5.4.6 Version Control of data types . 8
Annex A (normative) ASN.1 module .10
Annex B (normative) Data concept definitions .11
Bibliography .15
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ISO 14813-6:2017(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 on 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 the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 204, Intelligent transport systems.
This second edition cancels and replaces the first edition (ISO 14813-6:2009), which has been
technically revised.
The main changes compared to the previous edition are as follows:
— The requirement to use the aligned variant of the PER ASN.1 encoding rules is relaxed; any set of
ASN.1 encoding is now allowed;
— All new messages are now required to include a version number within its structure;
— Additional rules are defined to create unambiguous references to entries within the CIDCR;
— ASN.1 comments are now only allowed for informative text;
— OID assignments are now consistent with the rules defined in ISO 14817-3.
A list of all the parts in the ISO 14813 series, can be found on the ISO website.
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ISO 14813-6:2017(E)

Introduction
This document is part of a series of international standards that provides a form and structure to the
reference architectures for intelligent transport systems (ITS). Specifically, this document defines
the consistent use of abstract syntax notation one (ASN.1) [ISO/IEC 8824 (all parts)] within ITS
International Standards.
The previous versions of this document reflected the best practices at the time that they were written.
This revised document clarifies and updates its predecessors by reflecting the current best practices.
ITS International Standards and systems are not required to use ASN.1 as their only means of encoding
and transfer. In cases, other methods will be used because of industry practices or efficiency in certain
situations. However, ITS International Standards and data concept specifications are required to a)
elaborate their data in a consistent form using ASN.1 to promote interoperability and reuse; and b)
where ASN.1 is the chosen encoding method, define specific encoding rules based on the ISO/IEC 8825
series of standards.
ASN.1 and its encoding rules provide a means of achieving interoperability of otherwise incompatible
data. Within an ASN.1 data stream there may be a requirement to embed information that uses other
notations or encoding rules. To achieve this, levels of identification are required to precede certain data
elements, to enable the comprehension of data messages.
Users of this document should also be aware that data concepts defined in ITS International Standards
should also be fully documented per the rules of the ISO 14817 series of standards.
ASN.1 syntax
As stated in its defining document (ISO/IEC 8824-1), abstract syntax notation one (ASN.1) is a standard
notation used for the formal definition of data types, values, and constraints on data types. An important
feature of ASN.1 is its ability to enable separation of the specification of the message content, e.g. data
structures, from the specification of the encoding of messages, e.g. BER, DER, PER, OER, XER, XML.
ASN.1 provides the following advantages by separating the structure definition from the encoding rules:
— Easy mapping to different syntaxes, including mapping to programming language data structures
for easy implementation and mapping to compact binary forms for both security and bandwidth
purposes.
— Provision of tools for validation of message syntax and processing of message content, including
application-independent encode/decode libraries.
— Automatic generation of test suites.
— Checking for completion and validity.
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INTERNATIONAL STANDARD ISO 14813-6:2017(E)
Intelligent transport systems — Reference model
architecture(s) for the ITS sector —
Part 6:
Use of ASN.1
1 Scope
This document provides a formal means to achieve consistency in the use of ASN.1 when specifying
data types that are to be used in ITS International Standards. This is designed to ensure unambiguous
and interoperable data exchange while providing consistent documentation of these exchanges. This
document provides the necessary specifications to ensure consistent interpretation by providing
formal references to several standards and in some cases specifying additional rules to promote greater
consistency among standards.
This document does not require the use of ASN.1 for anything other than providing data type definitions
in a common and flexible form. This document makes specific provision for the support of:
— Embedding other extant standardised encoding formats, e.g. jpg, while maintaining interoperability
and reuse within ITS;
— Allowing alternative representations of data type definitions, e.g. XML schema;
— Allowing alternative encoding of defined data.
The rules presented in this document enable data types to be recorded in a common ITS data registry,
and in ITS International Standards, in a common and consistent form.
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/IEC 8824 (all parts), Information technology — Abstract Syntax Notation One (ASN.1)
ISO/IEC 8825 (all parts), Information technology — ASN.1 Encoding Rules
ISO 14817-1, Intelligent transport systems — ITS central data dictionaries — Part 1: Requirements for ITS
data definitions
3 Terms and definitions
For the purposes of this document, the terms and definitions given and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1
ASN.1 module
module that conforms to ISO/IEC 8824-1:2015
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ISO 14813-6:2017(E)

3.2
ASN.1 data type
name of a lexical ASN.1 item, typereference, as defined in ISO/IEC 8824-1:2015, 12.2
EXAMPLE MyType
3.3
ASN.1 data type definition
TypeAssignment declaration, as defined in ISO/IEC 8824-1:2015, 16.1
EXAMPLE MyType ::= INTEGER
3.4
aggregate domain
data concept representing a specific syntactic grouping of data elements and/or data frames
3.5
custom extension
customization of a standardised structure to support local, regional, and/or proprietary information
3.6
data concept
abstract entity that generalizes characteristics of interest about information systems and which can be
specified using a structured format composed of a set of meta-attributes
Note 1 to entry: ISO 14817-1 defines a structured format for specifying several types of data concepts. The
minimum required meta-attributes include a name, a definition, an object identifier, and a data concept type.
Note 2 to entry: Information systems frequently need to exchange messages. The atomic unit of a message is
called a data element. A data element is a single property of an object class expressed using a specific (atomic)
representation called a value domain. The concepts of “message”, “data element”, “object class”, “property”, and
“value domain” (among others) are data concepts.
3.7
data element
data concept representing a single property about an object class and which is represented using a
specific and atomic value domain, i.e. a representational form that uses a basic ASN.1 data type
3.8
data frame
data concept represented by a specific aggregate domain and that describes information of interest
through a useful grouping of more atomic properties about one or more object classes
[SOURCE: ISO 14817-1:2015, 4.18]
3.9
data type
domain of values
Note 1 to entry: This is synonymous with the term “type”, as defined in ISO/IEC 8824-1:2015.
3.10
data unit
data structure that is a logical unit of interchange between peer entities
3.11
ITS data concept
any data concept specified or referenced by an ITS International Standard or otherwise managed or
stored in the CIDCR
Note 1 to entry: Data concepts are often specified for data exchange, but may also be specified for encoding and
local storage, encoding followed by encrypting or hashing, or other purposes.
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ISO 14813-6:2017(E)

3.12
ITS International Standard
any standard developed by ISO/TC 204
3.13
message
data concept that is a grouping of data elements, data frames, or data elements and data frames that is
used to convey a complete set of information
[SOURCE: ISO 14817-1:2015, 4.35, modified – the Note 1 to entry is deleted.]
3.14
MIB
Module that conforms to IETF RFC 2578
3.15
module
data concept that contains the formal syntactic definition, and optionally the semantic definition, of
a defined set of other data concepts that are all version-controlled as a single unit; a module can be
represented in multiple languages (e.g., ASN.1 or XML Schema) and compiled by computer systems
[SOURCE: ISO 14817-1:2015, 4.40]
3.16
module identifier
instance of an object identifier data type used to identify a module
Note 1 to entry: In ISO/IEC 8824-1 a module identifier is defined as:
ModuleIdentifier::=
Modulereference
DefinitiveIdentifier
If the "DefinitiveIdentifier" is not empty, the denoted object identifier value unambiguously and uniquely
identifies the module being defined.
3.17
non-ASN.1 data type
data type definition that does not conform to ISO/IEC 8824 (all parts)
3.18
object class
data concept representing a set of objects that share the same properties, relationships, and semantics
3.19
object identifier
ordered list of primary integer values from the root of the international object identifier tree to a node,
which unambiguously identifies that node
[SOURCE: ISO/IEC 9834-1:2012, 3.5.11]
3.20
value domain
data concept representing a defined data type
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ISO 14813-6:2017(E)

4 Abbreviated terms
ASN.1 Abstract Syntax Notation.1
CIDCR Central ITS Data Concept Registry
ITS Intelligent Transport Systems
MIB Management Information Base
SNMP Simple Network Management Protocol
TC Technical Committee
XML eXtensible Markup Language
5 Requirements
5.1 General requirements
5.1.1 Use of ASN.1 is mandatory
Data may be organised and presented in many forms in ITS standards but in order to achieve consistency
and interoperability, wherever data is defined in an ITS standard, its syntax shall be provided in
Abstract Syntax Notation.1 (ASN.1) data type as detailed in this document. Other formats, e.g
...