ISO/FDIS 6346

ISO/DISFDIS 6346:2026(en)
Date: 2026-01-132025-11-18
ISO/TC 104/SC 04/WG 1 4
Secretariat: AFNOR
Date: 2026-05-29
Freight containers — Coding, identification and marking
Conteneurs pour le transport de marchandises — Codage, identification et marquage
FDIS stage
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ii
Contents
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
4.2 Identification marks . 3
5 Size and type codes and their associated marks . 3
5.1 Purpose . 3
5.2 Size and type codes . 4
6 Operational marks . 4
6.1 General. 4
6.2 Mandatory operational marks . 4
6.3 Optional operational mark (maximum mass of payload) . 5
7 Physical display of marks . 6
7.1 Size and colour of marks . 6
7.2 Layout and location of marks . 6
Annex A (normative) Determination of check digit . 15
Annex B (normative) Symbol to denote air/surface container . 18
Annex C (normative) Sign warning of overhead electrical danger . 20
Annex D (normative) Size code designation . 22
Annex E (normative) Type Code designation. 25
Annex F (normative) Height marks for containers higher than 2,6 m (8 ft 6 in) . 32
Annex G (normative) Overall width marks for containers wider than 2 438 mm (8 ft) . 34
Bibliography . 35

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/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 104, Freight containers, Subcommittee SC 4,
Identification and communication, in collaboration with the 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).
, or both.This fifth edition cancels and replaces the fourthfourthfourth edition (ISO 6346:2022), which has
been technically revised.
The main changes are as follows:
— — Amendmentsimprovements made to improve the readability of the various tables related to code
characters (Table D.1, Table D.2, (Table D.1, Table D 2);
— — Amendmentsmodification to Table E.1Table E.1 to add for new detailed type codes and to improve
descriptionsdescription of existing codes.;
— removal of the limitation for marking only containers built in conformance with the ISO 1496 series, which
can be marked with ISO Size Type Codes.
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.
- 2026 Editorial improvements to improve the readability of the document and ensure that ISO house
styles are adhered to.
- detailed type codes and to improve descriptions of existing codes
iv
- Editorial changes to figures to ensure greater clarity
— — Removal of the limitation for marking only containers built in compliance with the ISO 1496
series can be marked with ISO Size Type Codes.
v
Freight containers — Coding, identification and marking
1 Scope
1.1 1.1 This document specifies a system for the identification and presentation of information about
freight containers. The identification system gives guidelines for general application, for example in
documentation, control and communications (including automatic data processing systems), as well as for
display on the containers themselves.
It defines the methods of displaying identification and certain other data (including operational data) on
containers by means of permanent marks.
1.2 1.2 This document specifies:
a) a) a container identification system, with an associated system for verifying the accuracy of its
use; of marks;
b) b) a coding system for data on container size and type, with corresponding marks for their
display;
c) c) operational marks, both mandatory and optional;
d) d) physical presentation of marks on the container.
1.3 1.3 This document defines the terms “mandatory” and “optional” and provides guidelines for the
use of the designated marks. The terms “mandatory” and “optional” do not refer to the requirements of any
regulatory body.
1.4 1.4 This document is applicable to all freight containers covered by ISO 668, the ISO 1496, and
series, ISO 8323 and establishes where marks, areisis applicable to:
— — to containers other than those covered by the standardsInternational Standards listed in
Clause 2Clause 2;;
— — to container-related or detachable equipment, or both.
NOTE 1 Containers marked according to previous editions of ISO 6346this document need not be re-marked.
1.5 1.5 This document does not apply to temporary operational marks of any kind, permanent marks,
data plates, etc. which can 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.
This list is not 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 maycan 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 1496 (all parts), Series 1 freight containers — Specification and testing
ISO 8323:1985, Freight containers — Air/surface (intermodal) general purpose containers — Specification and
tests
ISO 10374, Freight containers — Automatic identification
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
3.1 Mandatory
mandatory mark
Marksmark applied to the container that areis essential to identify the owner, the specification of the container
and the safe operation of the container.
3.2
3.2 Optional
optional mark
Marksmarks applied to the container that provideprovides additional information to providefor a greater
comprehension of the operation of the container and its use.
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
See Key reference (1) in Figures 1Figures 1 to 44
The container owner 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
See Key reference (2) in Figures 1Figures 1 to 44
The equipment category identifier consists of one capital letter of the Latin alphabet as follows:
— U for all freight containers;
— J for detachable freight container-related equipment;
— Z for trailers and chassis.
4.1.4 Serial number
See Key reference (3) in Figures 1Figures 1 to 44
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
See Key reference (4) in Figures 1Figures 1 to 44
The check digit provides a means of validating the transmission accuracy of the owner code and serial number
and shall be determined in accordance with Annex AAnnex 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 4.14.1,, 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 4.1.34.1.3. The characteristics (size, shape, layout, etc.) detailed in 7.17.1 and
7.2.17.2.1 shall be displayed as nearly as practicable in accordance with Clause 7Clause 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
standardsInternational Standards listed in Clause 2Clause 2 and shall be coded as in 5.2.25.2.2 and 5.2.35.2.3.
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 7Clause 7.
5.2.2 Size: two alphanumeric characters
See Key reference (5) in Figures 1Figures 1 to 44
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 DAnnex D.
5.2.3 Type: two characters
See Key reference (6) in Figures 1Figures 1 to 44
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 EAnnex 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 EAnnex 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 the ISO 1496
series applicable to the type of container in question 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
[3][10]
identical to that shown on the International Convention for Safe Containers (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 BAnnex 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 CAnnex C.
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) a) on both sides, a height mark similar to that described in Annex FAnnex F;;
b) 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 5Figure 5.
In addition, any other optional marks, such as a mirror image of the mark described in Annex FAnnex 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 mm (8 ft).
All containers with an overall width greater than 2 438 mm (8 ft) shall bear a mark similar to that described
in Annex GAnnex 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 6.2.16.2.1,, 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.
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 1Figure 1).). Where constructional features of the
container dictate otherwise, the layout may be vertical (see Figure 2Figure 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 1Figure 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 2Figure 2 and
Figure 3Figure 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 3Figure 3 and Figure 4Figure 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 4Figure 4).).
NOTE The boxes around the markings in the figures represent the approximate shape of the side walls and the
markings are positioned relative to the side wall.
The size and type codes should be used as a whole (see 5.25.2).).
The owner code and equipment category identifier shall be joined and shall be separated from the serial
number by at least one character space. The serial number shall be separated from the check digit by one
character space and the check digit shall be displayed in a box.
EXAMPLE
A general purpose container in accordance with ISO 1496, having passive vents at the upper part of the cargo space, a
length of 6 058 mm, a width of 2 438 mm, a height of 2 591 mm, having a unique registered owner code of ABZ, an
equipment category identifier of U and a serial number of 001234 will have the layout as shown in Figure 1Figure 1 to
Figure 4Figure 4.
Key
1 owner code
2 equipment category identifier
3 serial number
4 check digit
5 size code
6 type code
Figure 1 — Mandatory identification marks -— preferred horizontal layout
Key
1 owner code
2 equipment category identifier
3 serial number
4 check digit
5 size code
6 type code
Figure 2 — Mandatory identification marks -— preferred vertical layout
Key
1 owner code
2 equipment category identifier
3 serial number
4 check digit
5 size code
6 type code
Figure 3 — Mandatory identification marks -— Alternative (multiple column) vertical layout
Key
1 owner code
2 equipment category identifier
3 serial number
4 check digit
5 size code
6 type code
Figure 4 — Mandatory identification marks -— Alternative horizontal grouping layout
7.2.1.2 Mandatory operational marks
The layout of maximum gross and tare masses shall be as stated in 6.2.16.2.1.
The layout of the air/surface container symbol shall be as shown in Annex BAnnex B.
The layout of the sign warning of overhead electrical danger shall be
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