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. 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. 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. 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. 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. 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.