prEN ISO 6346

SLOVENSKI STANDARD
01-december-2025
Tovorni zabojnik - Kodiranje, identifikacija in označevanje (ISO/DIS 6346:2025)
Freight containers - Coding, identification and marking (ISO/DIS 6346:2025)
Frachtcontainer - Kodierung, Identifizierung und Kennzeichnung (ISO/DIS 6346:2025)
Conteneurs pour le transport de marchandises - Codage, identification et marquage
(ISO/DIS 6346:2025)
Ta slovenski standard je istoveten z: prEN ISO 6346
ICS:
55.180.10 Večnamenski kontejnerji General purpose containers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 6346
ISO/TC 104/SC 4
Freight containers — Coding,
Secretariat: AFNOR
identification and marking
Voting begins on:
Conteneurs pour le transport de marchandises — Codage,
2025-09-05
identification et marquage
Voting terminates on:
ICS: 55.180.10 2025-11-28
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document has not been edited by the ISO Central Secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Reference number
ISO/DIS 6346:2025(en)
DRAFT
ISO/DIS 6346:2025(en)
International
Standard
ISO/DIS 6346
ISO/TC 104/SC 4
Freight containers — Coding,
Secretariat: AFNOR
identification and marking
Voting begins on:
Conteneurs pour le transport de marchandises — Codage,
identification et marquage
Voting terminates on:
ICS: 55.180.10
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document has not been edited by the ISO Central Secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2025
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
BE CONSIDERED IN THE LIGHT OF THEIR
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NATIONAL REGULATIONS.
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TO SUBMIT, WITH THEIR COMMENTS,
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NOTIFICATION OF ANY RELEVANT PATENT
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Website: www.iso.org
Published in Switzerland Reference number
ISO/DIS 6346:2025(en)
ii
ISO/DIS 6346:2025(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
4 Identification system and its associated marks . 2
4.1 Identification system .2
4.1.1 General .2
4.1.2 Owner code .2
4.1.3 Equipment category identifier .2
4.1.4 Serial number .3
4.1.5 Check digit .3
4.2 Identification marks .3
5 Size and type codes and their associated marks . 3
5.1 Purpose .3
5.2 Size and type codes .3
5.2.1 General .3
5.2.2 Size: two alphanumeric characters . .3
5.2.3 Type: two characters .4
6 Operational marks . 4
6.1 General .4
6.2 Mandatory operational marks.4
6.2.1 Maximum gross and tare masses .4
6.2.2 Air/surface container symbol .4
6.2.3 Warning sign of overhead electrical danger .4
6.2.4 Height mark for containers higher than 2,6 m (8 ft 6 in) .5
6.2.5 Width mark for containers with an overall width greater than 2 438 m (8 ft). .5
6.3 Optional operational mark (maximum mass of payload) .5
7 Physical display of marks . 5
7.1 Size and colour of marks .5
7.2 Layout and location of marks .5
7.2.1 Layout of marks .6
7.2.2 Location of marks .8
Annex A (normative) Determination of check digit .12
Annex B (normative) Symbol to denote air/surface container . 14
Annex C (normative) Sign warning of overhead electrical danger .15
Annex D (normative) Size code designation . .16
Annex E (normative) Type Code designation .18
Annex F (normative) Height marks for containers higher than 2,6 m (8 ft 6 in) .24
Annex G (normative) Overall width marks for containers wider than 2 438 m (8 ft) .25
Bibliography .26

iii
ISO/DIS 6346:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent
rights identified during the development of the document will be in the Introduction and/or on the ISO list of
patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 104, Freight containers, Subcommittee SC 4,
Identification and communication, in collaboration with European Committee for Standardization (CEN)
Technical Committee CEN/TC 119, Intermodal loading units and Cargo securing (ILUCS), in accordance with
the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This fourth edition cancels and replaces the third edition (ISO 6346:1995), which has been technically
revised. It also incorporates the Amendment ISO 6346:1995/Amd 3:2012.
The main changes are as follows:
— Incorporation of previous amendments to the standard to include the provision of markings to identify
containers with reduced stacking or racking;
— Inclusion of new markings to identify over width containers.
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.
This corrected version of ISO 6346:2022 incorporates the following corrections:
— to be added
iv
DRAFT International Standard ISO/DIS 6346:2025(en)
Freight containers — Coding, identification and marking
1 Scope
1.1 This document provides a system for the identification and presentation of information about freight
containers. The identification system is intended for general application, for example in documentation,
control and communications (including automatic data processing systems), as well as for display on the
containers themselves.
The methods of displaying identification and certain other data (including operational data) on containers
by means of permanent marks are included.
1.2 This document specifies:
a) a container identification system, with an associated system for verifying the accuracy of its use, having:
— mandatory marks for the presentation of the identification system for visual interpretation, and
— features to be used in optional Automatic Equipment Identification (AEI) and electronic data
interchange (EDI);
b) a coding system for data on container size and type, with corresponding marks for their display;
c) operational marks, both mandatory and optional;
d) physical presentation of marks on the container.
1.3 All markings not denoted as ‘optional’ shall be considered mandatory. The terms “mandatory” and
“optional” in this document are used to differentiate those ISO marking provisions which shall necessarily
be fulfilled by all containers from those which are not required of all containers. The optional marks are
included to further comprehension and promote uniform application of the optional mark. If a choice has
been made to display an optional mark, the provisions laid down in this document relating to the mark shall
be applied. The terms “mandatory” and “optional” do not refer to requirements of any regulatory body.
1.4 This document applies to all freight containers covered by International Standards ISO 668, parts 1 to
5 of ISO 1496, ISO 8323 and should, wherever appropriate and practicable, be applied:
— to containers other than those covered by the International Standards mentioned in Clause 2;
— to container-related and/or detachable equipment.
NOTE 1 Containers marked according to previous editions of ISO 6346 need not be re-marked.
1.5 This document does not cover temporary operational marks of any kind, permanent marks, data plates,
etc. which may be required by intergovernmental agreements, national legislation or nongovernmental
organizations.
NOTE 2 Some of the major international conventions whose container-marking requirements are not covered in
this document are as follows:
— International Convention for Safe Containers (1972, as amended) (CSC), International Maritime Organization (IMO);
— Customs Convention on Containers 1956 and 1972, related to temporary admission and transport under customs seal.
— Convention on Temporary Admission (Istanbul, 26 June 1990), related to temporary admission.

ISO/DIS 6346:2025(en)
It should not be assumed that this list is exhaustive.
This document does not cover the display of technical data on tank containers (see ISO 1496-3), nor does it,
in any way, include identification marks or safety signs for items of cargo which may be carried in freight
containers.
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 10374, Freight containers — Automatic identification
3 Terms and definitions
No terms and definitions are listed in this document.
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/
4 Identification system and its associated marks
4.1 Identification system
4.1.1 General
The identification system shall consist only of the following elements, all of which shall be included:
— owner code: three letters (see 4.1.2);
— equipment category identifier: one letter (see 4.1.3);
— serial number: six numerals (see 4.1.4);
— check digit: one numeral (see 4.1.5).
4.1.2 Owner code
Reference (1) in Figures 1 to 4
The container owner’s code shall consist of three capital letters, shall be unique and shall be registered with
the Registration Authority.
The name and contact information of the Registration Authority for this document can be found at www .iso
.org/ maintenance _agencies.
4.1.3 Equipment category identifier
Reference (2) in Figures 1 to 4
The equipment category identifier consists of one capital letter of the Latin alphabet as follows:

ISO/DIS 6346:2025(en)
— U for all freight containers;
— J for detachable freight container-related equipment;
— Z for trailers and chassis.
4.1.4 Serial number
Reference (3) in Figures 1 to 4
The container serial number shall consist of six Arabic numerals. If the series of significant numerals does
not total six, they shall be preceded by sufficient zeroes to make up six numerals (for example, if the series of
significant numerals is 1234, the serial number is 001234).
4.1.5 Check digit
Reference (4) in Figures 1 to 4
The check digit provides a means of validating the transmission accuracy of the owner code and serial
number and shall be determined as in Annex A. The check digit shall validate the owner code, equipment
category identifier and serial number of the container.
4.2 Identification marks
The use of marks in accordance with the identification system specified in 4.1, i.e. owner code, equipment
category identifier, serial number and check digit, is mandatory for freight containers and recommended for
all equipment as stated in 4.1.3. The characteristics (size, shape, layout, etc.) detailed in 7.1 and 7.2.1 shall be
displayed as nearly as practicable in accordance with Clause 7, i.e., legible to the human eye.
5 Size and type codes and their associated marks
5.1 Purpose
The type and main external dimensions of the container shall be identified with codes marked on the
container.
5.2 Size and type codes
5.2.1 General
This information is mandatory for the marking of containers covered by the International Standards listed
in Clause 2 and shall be coded as in 5.2.2 and 5.2.3.
The size and type codes, when displayed on the container, shall be used as a whole, i.e., the information must
not be broken into its component parts.
The size and type codes shall be displayed in accordance with Clause 7.
5.2.2 Size: two alphanumeric characters
Reference (5) in Figures 1 to 4
The container size (i.e. external dimensions) shall be indicated by two characters as follows:
— First character: numeric or alphabetic character representing the length.
— Second character: numeric or alphabetic character representing the width and the height.
These two characters shall be determined in accordance with Annex D.

ISO/DIS 6346:2025(en)
5.2.3 Type: two characters
Reference (6) in Figures 1 to 4
The container type and main characteristics shall be indicated by two characters as follows:
— First character: alphabetic character representing the container type.
— Second character: numeric or alphabetic character representing main characteristics related to the
container type.
These two characters shall be selected in accordance with Annex E.
NOTE For the purpose of exchanging data when indication of the main characteristics is not essential, the “type
group code designation” as shown in Annex E can be used.
6 Operational marks
6.1 General
The marks in this section are not intended to correspond to any particular code (e.g., for use in data
transmission or any other purpose). They are solely intended as markings for use on freight containers to
convey certain information or give visual warnings.
6.2 Mandatory operational marks
6.2.1 Maximum gross and tare masses
The maximum gross and tare masses shall be marked on a container as:
MAX GROSS 00 000 kg
00 000 lb
TARE 00 000 kg
00 000 lb
For safety reasons, containers tested in conformance with the approved methods specified in that part
of ISO 1496 applicable to the type of container in question, i.e., parts 1, 2, 3, 4 or 5 of ISO 1496, shall be
uniformly marked with the maximum gross mass.
Furthermore, the “maximum gross mass” marked on the container in accordance with this document shall
be identical to that shown on the CSC Safety Approval Plate.
As indicated above, the masses shall be expressed in both kilograms (kg) and pounds (lb).
NOTE 1 kg = 2,204 lb.
6.2.2 Air/surface container symbol
All air/surface containers shall display the symbol specified in Annex B.
6.2.3 Warning sign of overhead electrical danger
All containers equipped with ladders shall display a warning sign in accordance with the details given in
Annex C.
ISO/DIS 6346:2025(en)
6.2.4 Height mark for containers higher than 2,6 m (8 ft 6 in)
All containers higher than 2,6 m (8 ft 6 in) shall bear the following mandatory marks:
a) on both sides, a height mark similar to that described in Annex F;
b) an area of alternating black and yellow stripes on the top members of each end frame and side wall at
each corner adjacent to the corner fitting, of 300 mm (12 in) minimum length, that can be seen from the
ground or from the top. See Figure 5.
In addition, any other optional marks, such as a mirror image of the mark described in Annex F, may be
displayed at any convenient location (e.g., front wall).
6.2.5 Width mark for containers with an overall width greater than 2 438 m (8 ft).
All containers with an overall width greater than 2 438 m (8 ft) shall bear a mark similar to that described in
Annex G on the ends and the roof at both ends.
Where there is insufficient space to fit the marking on the ends or the roof, for example on tank containers,
the marking shall be as wide as is practicable on the ends and may be omitted on the roof.
6.3 Optional operational mark (maximum mass of payload)
It is common industry practice to mark containers with maximum payload in addition to the maximum
gross and tare masses.
If used, the maximum mass of payload should be marked on a container in accordance with the requirements
of 6.2.1, positioned after the maximum gross and tare masses as follows:
7 Physical display of marks
7.1 Size and colour of marks
The letters and numerals of the owner code, equipment category identifier, serial number and check digit
shall be not less than 100 mm (4 in) high.
The letters and numerals for MAX GROSS, TARE and, when used, PAYLOAD shall be not less than 50 mm (2
in) high.
All characters shall be of proportionate width and thickness, they shall be durable and in a colour contrasting
with that of the container.
7.2 Layout and location of marks
The requirements of this clause are particularly applicable to containers of the “closed box” type. For
containers of other types, all possible practicable steps should be taken to follow the marking layout and
location given for the “closed box” type of container.

ISO/DIS 6346:2025(en)
7.2.1 Layout of marks
7.2.1.1 General
The layout of the owner code, equipment category identifier, serial number and check digit on containers
shall preferably be in one single horizontal line (see Figure 1). Where constructional features of the container
dictate otherwise, the layout may be vertical (see Figure 2).
The layout of size and type codes should, as far as practicable, be in a single horizontal line underneath
the horizontal line giving the owner code, equipment category identifier, serial number and check digit (see
Figure 1).
When the owner code, equipment category identifier, serial number and check digit are displayed vertically,
the size and type codes should be placed adjacent to the other mandatory marks (see Figure 2 and Figure 3).
If, on some special-purpose containers, a fully horizontal or fully vertical layout is not possible, the layout
of the other mandatory identification marks shall be maintained in the horizontal or vertical groupings as
specified below (see Figure 3 and Figure 4).
On those special-purpose containers where a fully horizontal or fully vertical layout is not possible and the
layout of the other mandatory identification marks is horizontal, the size and type codes should be placed
beneath the other mandatory marks (see Figure 4).
NOTE T
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