ISO/TS 24854-5:2026
(Main)Intelligent transport systems — Facilities layer services — Part 5: Message sets
- Abstract
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.
- Status
- Published
- Publication Date
- 07-Jun-2026
- 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
ISO/TS 24854-5:2026 is an ISO Technical Specification from ISO for intelligent transport systems (ITS) facilities layer services. It specifies guidelines and requirements for ITS station facilities layer service message sets (ITS-MsgSets), including how to define the set structure, build messages and ITS-MsgSetPDUs by concatenation, and receive them. It is aimed at engineers and implementers who need a common way to manage ITS messages at the facilities layer.
What does ISO/TS 24854-5:2026 specify?
ISO/TS 24854-5:2026 specifies how to create and use ITS-MsgSets for ITS station facilities layer services. The standard covers the internal structure of a message set, the way messages are combined into an ITS-MsgSetPDU, and how those PDUs are received and processed.
The document is organized into:
- Clause 5 - general information
- Clause 6 - ITS-MsgSet
- Clause 7 - ITS-MsgSetPDUs created from ITS-MsgSets
- Clause 8 - procedures
- Clause 9 - encoding and communications at lower layers
- Annex A - normative ASN.1
| Annex | What it covers |
|---|---|
| Annex A | Normative ASN.1 modules for ITS-MsgSetPDUs and ITS-MsgSets, including machine-readable definitions |
What are the key requirements of ISO/TS 24854-5:2026?
ISO/TS 24854-5:2026 defines ITS-MsgSets as registered, uniquely identified collections of ITS messages. It also defines how those sets are turned into protocol data units and how receivers split them back into messages. For implementers, the main task is to keep the set identity, message identity, and transport behavior consistent across the stack.
Identification and versioning
- Clause 6.1 requires each ITS-MsgSet to be uniquely distinguished by ITS-MsgSetID, using the registration framework from ISO 17419.
- Clause 6.1 requires each ITS-MsgID to be unique only within its own ITS-MsgSet.
- Clause 6.1 says versioning is handled by the design of the message set, not by giving the same set different ITS-MsgSetID values.
In practice, this means the set identity stays stable while versions are managed inside the message-set design, for example with version headers.
ASN.1 structure
- Clause 6.2 specifies that an ITS-MsgSet is defined in ASN.1 with an information object class and an information object set.
- Clause 6.2 gives the ITSmsgSetID range structure for one-, two-, three- and four-octet values.
- Clause 6.2 sets ITSmsgID to IntZeroMax by default, while allowing other ASN.1 types where a specific ITS-MsgSet needs them.
In practice, developers can generate or template a message set definition rather than hard-coding every message.
Message set PDUs
- Clause 7.1 defines an ITS-MsgSetPDU as a concatenation of messages from one or several ITS-MsgSets.
- Clause 7.1 allows the same ITS-MsgSet to appear more than once in a single ITS-MsgSetPDU.
- Clause 7.2 adds the rxProcess field, which tells the receiver what processing path to apply.
In practice, one PDU can carry several message groups, and the receiver can decide whether to split them and forward them onward.
Creation and reception procedures
- Clause 8.2 says the creator uses a two-step address: first the ITS-MsgSetID, then the ITS-MsgID.
- Clause 8.3 says the ITS-MsgSetPduP at the facilities layer splits received ITS-MsgSetPDUs into messages and forwards them to the registered ITS applications.
- Clause 8.3 assigns rxPduProcess1 to the split-and-forward procedure, while rxPduProcess0 is the unknown or management value.
In practice, a sender selects the message set first and then the message within that set, while the receiver routes the extracted message to the correct application.
Lower-layer handling
- Clause 8.3 identifies PORT_MSGSETPDU as the FNTP port number for ITS-MsgSetPDUs.
- Clause 9.2 requires a single encoding for all messages in one ITS-MsgSetPDU.
- Clause 9.3 requires a single ITS-S networking & transport layer protocol for one ITS-MsgSetPDU.
- Clause 9.4 requires a single ITS-S access technology for one ITS-MsgSetPDU.
In practice, this means mixed PDUs are allowed only when the contained messages can share the same encoding, transport protocol, and access technology. If messages with different stand-alone requirements are combined, those stand-alone requirements are ignored and a common suitable layer choice is used instead.
ASN.1 attachments
- Annex A says the ASN.1 modules in the electronic attachments prevail if there is any difference from the printed text.
- Annex A says BASIC-PER from ISO/IEC 8825-2 applies when no other encoding is explicitly required.
For implementers, this matters because the machine-readable files are the authoritative definitions for code generation and conformance work.
What terms does ISO/TS 24854-5:2026 define?
- ITS-MsgSet - A collection of one or more uniquely identified ITS messages.
- ITS-MsgSetPDU - A protocol data unit made from one or more messages from one or various ITS-MsgSets.
- ITS-MsgSetPduP - The ITS-MsgSet PDU parser that receives PDUs and forwards them to the correct station-internal destination.
- ITS-MsgSetPduC - The ITS-MsgSet PDU creator that concatenates messages from ITS-MsgSets and forwards the PDU onward.
- ITS-MsgID - The identifier of a message inside a given ITS-MsgSet.
- FNTP - Fast Networking & Transport layer Protocol, used here for ITS-MsgSetPDU reception and transmission.
- RITSI - Registry of Intelligent Transport System Items, where registered ITS-MsgSetID values are published.
- CAM - cooperative awareness message, cited as an example of a legacy ITS message.
- DENM - decentralized environmental message, cited as another example of a legacy ITS message.
Who uses ISO/TS 24854-5:2026?
ISO/TS 24854-5:2026 is used by ITS architects, facilities-layer developers, and message-set designers who need a registered way to define and exchange ITS messages. It is also relevant to system integrators working on ITS station facilities layer services, especially where messages must be grouped into PDUs and forwarded between the networking & transport layer and the facilities layer.
Quality managers and buyers in ITS projects can use it to check whether a solution handles message identification, PDU creation, and reception in a way that matches the ITS station architecture. It is also useful for teams dealing with legacy ITS messages such as CAM and DENM, because it states when those messages can share a combined PDU.
Which standards are used with ISO/TS 24854-5:2026?
| Standard | Contribution |
|---|---|
| ISO 17419 | Provides globally unique identification, including ITS-MsgSetID and the procedural framework for ITS-MsgSets. |
| ISO 21217 | Provides the ITS station and communication architecture and introduces the ITS message set concept. |
| ISO/IEC 8825-2 | Provides Packed Encoding Rules (PER) used when no other explicit encoding requirement is stated. |
| ISO 29281-1 | Provides FNTP, which is used for ITS-MsgSetPDU transmission and reception. |
| ISO 16460 | Is named with FNTP in the transport discussion for localized communications. |
| ISO/TS 17429 | Is referenced as the facilities handler context that will be integrated in a future part. |
| ISO/TS 21185 | Provides communication profiles for secure connections between trusted devices. |
| ISO 24102-6 | Provides path and flow management for ITS station management. |
| ISO/TS 24854-1 | Gives the basic introduction to the ISO 24854 series. |
| ISO/TS 24854-4:2026 | Is the future part referenced for the facilities services handler. |
What does the ISO/TS 24854-5:2026 document contain?
ISO/TS 24854-5:2026 contains a textual specification of ITS-MsgSets, ITS-MsgSetPDUs, and the procedures for creation, reception, transmission, and lower-layer handling. It also contains Annex A, which provides the normative ASN.1 modules for message sets and PDUs.
The annex includes:
- Figure 1, which illustrates an ITS-MsgSet identified by ITS-MsgSetID
- Figure 2, which illustrates an ITS-MsgSetPDU constructed from ITS-MsgSets
- Table A.1, which lists SHA-256 digests for the electronic ASN.1 files
- Example ASN.1 definitions for message sets in the two-octet and three-octet ITS-MsgSetID ranges
For implementers, Annex A is the part used to generate or verify machine-readable definitions, while Clauses 6 to 9 give the rules for how those definitions are used in systems and communication paths.
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Frequently Asked Questions
ISO/TS 24854-5:2026 is a technical specification published by the International Organization for Standardization (ISO). Its full title is "Intelligent transport systems — Facilities layer services — Part 5: Message sets". This standard covers: 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.
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.
ISO/TS 24854-5:2026 is classified under the following ICS (International Classification for Standards) categories: 35.240.60 - IT applications in transport. The ICS classification helps identify the subject area and facilitates finding related standards.
ISO/TS 24854-5:2026 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
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
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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,
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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)
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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
...