ISO/TS 24854-5:2026

Intelligent transport systems — Facilities layer services — Part 5: Message sets

This document specifies guidelines and requirements for the creation and use of intelligent transport system (ITS) station facilities layer service "message sets" (ITS-MsgSets). This includes specification of the basic structure of ITS-MsgSets, the creation of a message as a concatenation of messages from ITS-MsgSets, and the reception of respective messages.

Systèmes de transport intelligents — Services de la couche des fonctionnalités — Partie 5: Ensembles de messages

General Information

• Status: Published
• Publication Date: 07-Jun-2026
• ICS: 35.240.60 - IT applications in transport
• Technical Committee: ISO/TC 204 - Intelligent transport systems
• Drafting Committee: ISO/TC 204/WG 18 - Cooperative systems
• Current Stage: 6060 - International Standard published
• Start Date: 08-Jun-2026
• Due Date: 12-Feb-2027
• Completion Date: 08-Jun-2026

Overview

ISO/TS 24854-5:2026 is a technical specification developed by the International Organization for Standardization (ISO) as part of the ISO 24854 series on intelligent transport systems (ITS). This part focuses specifically on facilities layer services – Message sets (ITS-MsgSets). The document provides guidelines and requirements for creating, identifying, managing, and using ITS station facilities layer message sets and their associated protocol data units (ITS-MsgSetPDUs).

Central to the document is the specification of message sets that enable interoperability, efficiency, and scalability within ITS stations by defining how messages are structured, concatenated, and processed across different subsystems and applications. This standard underpins safe and effective communication in intelligent transport environments.

Key Topics

• ITS-MsgSet Definition
  An ITS-MsgSet is a uniquely identified collection of one or more intelligent transport system messages, utilized within ITS stations.

• Message Creation
  The specification allows for dynamic creation of a message set, making it possible to concatenate multiple messages from various ITS-MsgSets into a single protocol data unit, known as an ITS-MsgSetPDU.

• Identification and Versioning
  Each message set is identified by a globally unique ITS-MsgSetID (as specified in ISO 17419). Internal versioning of message sets ensures traceability and consistent handling.

• Encoding and Communication Layers
  The document provides requirements for message encoding (such as ASN.1) and describes how messages are transmitted and received across lower communication layers, ensuring compatibility with existing ITS standards and legacy messages.

• Procedures for Reception and Transmission
  Guidelines detail how ITS stations should process incoming and outgoing message sets, ensuring correct forwarding and parsing at the facilities layer.

Applications

Implementing ISO/TS 24854-5:2026 offers significant practical value for developers, integrators, and operators of intelligent transport systems:

• Interoperability
  By standardizing the structure and identification of messages, this specification promotes seamless communication between diverse ITS stations and equipment, supporting multi-vendor compatibility.

• Efficiency in Data Transmission
  Concatenating messages from different sets into one ITS-MsgSetPDU reduces channel load and optimizes resource usage, as shared security and protocol overheads become fixed regardless of payload size.

• Support for Legacy and Modern Messages
  The standard enables integration of legacy ITS messages (such as CAM and DENM) with new ITS-MsgSets, simplifying migration and enhancing future-proofing in ITS deployments.

• Dynamic Adaptation
  The guidelines support dynamic creation and management of protocol data units, ensuring that evolving use cases and requirements can be addressed without extensive reengineering.

• Global Connectivity
  Unique identifiers and registry-based management of message sets facilitate global consistency and coordination throughout intelligent transport networks.

Related Standards

ISO/TS 24854-5:2026 builds upon and interacts with several important ITS standards, including:

• ISO 17419: Intelligent transport systems – Globally unique identification (for ITS-MsgSetID Assignment)
• ISO 21217: Intelligent transport systems – Station and communication architecture
• ISO/IEC 8825-2: ASN.1 encoding rules – Part 2: Specification of packed encoding rules (PER)
• ISO/TS 24854-1: General introduction and framework for ISO 24854 series
• ISO 29281-1 & ISO 16460: Fast Networking & Transport Protocol (FNTP) for vehicular communications
• SAE J2735: US DSRC message set dictionary
• ETSI EN 302 636: Geo-networking protocols for ITS

By conforming to ISO/TS 24854-5:2026, organizations ensure compatibility with a structured, globally recognized approach to ITS message handling, significantly strengthening the reliability, security, and scalability of intelligent transport solutions.

Standards Content (Sample)

Technical
Specification
ISO/TS 24854-5
First edition
Intelligent transport systems —
2026-06
Facilities layer services —
Part 5:
Message sets
Systèmes de transport intelligents — Services de la couche des
fonctionnalités —
Partie 5: Ensembles de messages
Reference number
© ISO 2026
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms. 2
5 General information . 2
6 ITS-MsgSet . 3
6.1 General .3
6.2 Creation of an ITS-MsgSet .3
7 ITS-MsgSetPDUs created from ITS-MsgSets . 5
7.1 General .5
7.2 Creation of ITS-MsgSetPDU .6
8 Procedures . 7
8.1 Creation of an ITS-MsgSet .7
8.2 Creation of ITS-MsgSetPDUs .7
8.3 Reception and transmission of ITS-MsgSetPDUs .8
9 Encoding and communications at lower layers . 8
9.1 General .8
9.2 Encoding of ITS-MsgSetPDUs .9
9.3 ITS-S networking & transport layer protocols .9
9.4 ITS-S access technologies .9
Annex A (normative) ASN.1 . 10
Bibliography .15

iii
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 204, Intelligent transport systems.
A list of all parts in the ISO 24854 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
Introduction
1)
A basic introduction to the ISO 24854 series is provided in ISO/TS 24854-1:— .
This document specifies an intelligent transport system message set (ITS-MsgSet) as a collection of one
or more uniquely identified ITS messages, where internal unique identification including versioning is
performed by the design of an ITS-MsgSet. ITS-MsgSets are introduced in the ITS architecture standard
ISO 21217. Various initial ITS messages have been outlined by various Standard Development Organizations
(SDOs) in the past without being specified as part of an ITS-MsgSet; these initial ITS messages can be
included in ITS-MsgSets.
An ITS-MsgSet is identified by a globally unique, registered ITS message set identifier (ITS-MsgSetID)
specified in ISO 17419. Registered values of ITS-MsgSetID are published in the ISO/TC 204 "Registry of
[1]
Intelligent Transport System Items" (RITSI) . Various versions of an ITS-MsgSet are identified by the same
value of ITS-MsgSetID, as versioning is performed internally by design of an ITS-MsgSet.
This document also specifies the ITS message set protocol data unit (ITS-MsgSetPDU) as a concatenation of
messages from ITS-MsgSets. For transmission and reception of ITS-MsgSetPDUs using the Fast Networking
& Transport Protocol (FNTP) specified in ISO 29281-1 and in ISO 16460, the necessary FNTP port number is
identified.
This document complements the procedural guidelines on ITS-MsgSets in ISO 17419 by providing technical
guidelines and requirements on the creation and usage of ITS-MsgSets and ITS-MSgSetPDUs. The techniques
specified in this document allow a dynamic creation of a protocol data unit (PDU) as a concatenation of
messages from several ITS-MsgSets, i.e. avoiding hard-coded messages. Combining several messages
reduces channel load, as the security overhead has a fixed size, i.e. independent of the size of the payload.
This approach could be considered as being similar to the natural language, where sentences are built with
defined words. However, so far there is no activity to specify details of such a consideration.
Throughout this document, the term "message" without a qualifier is used in the natural language meaning.
NOTE ISO/TS 14812 specifies the term "message" as " grouping of data elements, data frames, or data elements
and data frames that is used to convey information". Definitions of "data element" and "data frame" are also given in
ISO/TS 14812.
1) Under preparation. Stage at the time of publication: ISO/CD TS 24854-1:2026.

v
Technical Specification ISO/TS 24854-5:2026(en)
Intelligent transport systems — Facilities layer services —
Part 5:
Message sets
1 Scope
This document specifies guidelines and requirements for the creation and use of intelligent transport
system (ITS) station facilities layer service "message sets" (ITS-MsgSets). This includes specification of the
basic structure of ITS-MsgSets, the creation of a message as a concatenation of messages from ITS-MsgSets,
and the reception of respective messages.
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 17419, Intelligent transport systems —Globally unique identification
ISO 21217, Intelligent transport systems — Station and communication architecture
ISO/IEC 8825-2, Information technology — ASN.1 encoding rules — Part 2: Specification of Packed Encoding
Rules (PER)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 21217, ISO 17419 and the following
apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
ITS-MsgSet
ITS message set
collection of one or more uniquely identified intelligent transport system (ITS) messages
3.2
ITS-MsgSetPduP
ITS-MsgSet PDU parser
capability of the intelligent transport systems (ITS) facilities layer to receive protocol data units (PDUs)
that are concatenated messages from one or various ITS message sets (ITS-MsgSets), and to forward the
information to the correct station-internal destination

3.3
ITS-MsgSetPduC
ITS-MsgSet PDU creator
capability of the intelligent transport systems (ITS) facilities layer to create protocol data units (PDUs) by
concatenating messages from one or various intelligent transport system message sets (ITS-MsgSets), and
to forward the PDUs to the next applicable ITS station capability
3.4
ITS-MsgSetPDU
ITS-MsgSet protocol data unit
protocol data unit that consists of a concatenation of one or more messages from one or various intelligent
transport system message sets (ITS-MsgSets)
3.5
ITS-MsgID
ITS message identifier
identifier of messages of an intelligent transport system message set (ITS-MsgSet) being unique within the
given ITS-MsgSet
4 Symbols and abbreviated terms
ASN abstract syntax notation
CAM cooperative awareness message
DENM decentralized environmental message
DSRC dedicated short range communication
ETSI European Telecommunications Standards Institute
FNTP Fast Networking & Transport layer Protocol
IOC information object class
IOS information object set
IP Internet Protocol
PORT_MSGSETPDU FNTP port number for reception and transmission of ITS-MsgSetPDUs
RITSI Registry Oof Intelligent Transport Systems Items
5 General information
ISO 21217 originally introduced the concept of an "ITS message set" as a "set of messages designed for an ITS-
related purpose", without specifying any rules on how to construct ITS-MsgSets and how to use messages
of ITS-MsgSets. Several initial ITS-MsgSets are presented in ISO 21217. Messages specified in ETSI TC ITS
[13]
can also be managed in an ITS-MsgSet. The US DSRC message set dictionary specified in SAE J2735 is
compliant with the specification in this document. For more details, see ISO/TS 24854-1.
NOTE The textual presentation of ITS messages and ITS-MsgSets in ISO 21217 will be modified at a subsequent
systematic review to align the presentation with the terminology and specifications of this document.
In a subsequent step, procedural guidelines on the registration of ITS-MsgSets were specified in ISO 17419.
As part of these procedural guidelines, ISO 17419 specified the concept of the "ITS Message Set Identifier"
(ITS-MsgSetID) and the concept of the "ITS message". Registered values are published on the online registry,
[1]
RITSI .
The techniques specified in this document use the ASN.1 open type (keyword CLASS) to define information
object classes (IOCs) and information object sets (IOSs) for ITS-MsgSets and ITS message set protocol data
units (ITS-MsgSetPDUs). Respective ASN.1 modules are presented in Annex A.
The techniques specified in this document allow a reduction in channel load by sharing the security overhead
[12]
of fixed size amongst several messages (see ETSI TS 102 867Annex B ).
6 ITS-MsgSet
6.1 General
ITS-MsgSets are created as sets of messages for use in ITS.
ITS-MsgSets shall be uniquely distinguished by the ITS-MsgSetID of ASN.1 type ITSmsgSetID specified in
ISO 17419. Values of ITS-MsgSetID assigned to a specific ITS-MsgSet are registered in the online registry,
[1]
RITSI .
The messages of a specific ITS-MsgSet shall be uniquely distinguishable by an ITS message identifier (ITS-
MsgID); uniqueness is only required within a specific ITS-MsgSet. The preferred and recommended ASN.1
type of ITS-MsgID is IntZeroMax. IntZeroMax is specified in ISO 17419 as a non-negative Integer number.
Assignment of unique values of ITS-MsgID is within the scope of the respective specification of the respective
ITS-MsgSet.
Versioning of messages and ITS-MsgSets shall be done by suitable design of such messages and message sets,
e.g. by using “version headers”. Versioning shall not be achieved by means of different ITS-MsgSetID values.
In the case that messages of an ITS-MsgSet do not contain an explicit version identifier, different versions
of the same message may be contained in an ITS-MsgSet, and are thus distinguished as different messages.
Further details on versioning are out of scope of this document.
6.2 Creation of an ITS-MsgSet
An ITS-MsgSet is specified in ASN.1 with an IOC:

MSGSET::=CLASS{
&msgSetRef ITSmsgSetID, -- ID of ITS message set
&msgRef ITSmsgID, -- ITS message ID
&Message
}.
The IOC is globally uniquely identified by the registered value of its ITS-MsgSetID thisItsMsgSetID. The
details of the respective ASN.1 value thisItsMsgSetID depends on the size of the ITS-MsgSetID, i.e. whether
it is from the one, two, three or four octet range. The ASN.1 type ITSmsgSetID of ITS-MsgSetID is specified in
ISO 17419 as a variable length number.
One octet range:
thisItsMsgSetID ITSmsgSetID::=content: decimal presentation>
Two octet range:
thisItsMsgSetID ITSmsgSetID::=extension:content: through 16511 in decimal presentation>
Three octet range:
thisItsMsgSetID ITSmsgSetID::=extension:extension:content: 2.113.663 in decimal presentation>

Four octet range:
thisIitsMsgSetID ITSmsgSetID
::=extension:extension:extension:content: 270549119 in decimal presentation>
The default specification of the ITS message identifier is:

ITSmsgID::=IntZeroMax.
The set of ITS messages of an ITS-MsgSet is specified in ASN.1 as an IOS:

ITS-MsgsExample MSGSET::={msg0 | msg1 ,.}

with
msg0  MSGSET::={&msgSetID thisItsMsgSetID, &msgRef 0, &Message NULL}
msg1  MSGSET::={&msgSetID thisItsMsgSetID, &msgRef 1, &Message
MyExampleMessage}
where
— msg0 is the empty or unknown message;
— the ASN.1 type name MyExampleMessage shall be replaced by the desired message specification in
ASN.1 and its type name;
— the ASN.1 type name ITS-MsgsExample shall be replaced by the desired ASN.1 name for the respec-
tive IOS.
A single message is specified in ASN.1 as:

ITS-Message::=SEQUENCE{
-- selector of an ITS message
msgSelector MSGSET.&msgRef({ITS-MsgsExample}),
-- message of the selected ITS message set
msgType  MSGSET.&Message({ITS-MsgsExample}{@msgSelector})
}
A sequence of ITS messages from an ITS-MsgSet is specified as:

ITS-Messages::=SEQUENCE OF ITS-Message

A sequence of such messages (ITS-Messages) with a header containing the ITS-MsgSetID is specified as:

ITS-MessagesWithHeader::=SEQUENCE{
msgSet MSGSET.&msgSetRef(thisItsMsgSetID),
sequenceMessages ITS-Messages
}
Figure 1 illustrates this ASN.1 code.

Figure 1 — ITS-MsgSet identified by ITS-MsgSetID
The complete ASN.1 module for ITS-MsgSets is presented in Clause A.3.
7 ITS-MsgSetPDUs created from ITS-MsgSets
7.1 General
Figures 2 illustrates the creation of an ITS-MsgSet protocol data unit (ITS-MsgSetPDU), also simply referred
to as a “message”, from messages from one or several ITS-MsgSets.
Figure 2 — Illustration of an ITS-MsgSetPDU constructed from ITS-MsgSets

The ITS-MsgSetPDU is a sequence of elements of ITS-MsgSets, in which each sequence consists of an ITS-
MsgSetID followed by a sequence of information elements of ITS messages from the selected ITS-MsgSet,
with each such information element being a sequence of an ITS-MsgID followed by the corresponding ITS
message.
The same ITS-MsgSet can be used several times for a given ITS-MsgSetPDU.
7.2 Creation of ITS-MsgSetPDU
An ITS-MsgSetPDU is specified in ASN.1 with an IOC:

MSGSETS::=CLASS{
&msgSetRef ITSmsgSetID, -- ITS message set ID
&MessageSetMessages -- Messages from an ITS message set
}.
The information object class is globally uniquely identified by the registered value of its ITS-MsgSetID of
ASN.1 type ITSmsgSetID.
The set of ITS-MsgSetPDU is specified in ASN.1 as an IOS:

ITS-MsgSets MSGSETS::={msgSet0 | msgSet1 | msgSet2 /*| msg3 */,.}.

The number of elements in the IOS depends on the actual implementation needs. The ASN.1 definitions for
ITS-MsgSetID in the one, two and three octet range are as follows:

msgSet0 MSGSETS::={&msgSetRef content:0, &MessageSetMessages NULL
msgSet1 MSGSETS::={&msgSetRef extension:content:128,
&MessageSetMessages ITS-Example1SetMessages}
msgSet2 MSGSETS::={&msgSetRef e
...