International Classification for Standards

Purpose

The ICS serves as a structure for catalogues and databases of technical standards and other normative documents, and as a basis for standing-order systems for international, regional and national standards.

Classification principles

The ICS uses an hierarchical classification, which consists of three nested levels called fields (Level 1), groups (Level 2) and sub-groups (Level 3). Each field is subdivided into groups, which are further divided into sub-groups.

All classification levels are designated by a classification code (called notation) and a title. The notation is a set of Arabic numerals.

Top-level items, which have no parent levels, use a two-digit notation, for example:

43 ROAD VEHICLE ENGINEERING

The notations for groups and sub-groups include the parent-level notations. The example below shows a notation for Sub-Group 20 (Level 3), which belongs to Group 040 (Level 2) in Field 43 (Level 1).

43.040.20 Lighting, signaling and warning devices

Level 1 (Fields)

A field is the first level in the International Classification for Standards. It may represent one or a combination of the following:

A sector of the economy such as agriculture, mining, construction or the packaging industry;

A technology such as telecommunications or food processing;

An activity such as environment protection, safety assurance and protection of public health;

A field of science such as mathematics or astronomy.

At present the classification includes 40 fields.

01 General. Terminology. Standardization. Documentation 03 Sociology. Services. Formation And Management Of Business Entities. Administration. Transportation 07 Mathematics. Natural Sciences 11 Health Care Technology 13 Environment. Health. Safety 17 Metrology And Measurement. Physical Phenomena 19 Testing 21 Mechanical Systems And Components For General Use 23 Fluid Systems And Components For General Use 25 Manufacturing Engineering 27 Energy And Thermal Engineering 29 Electrical Engineering 31 Electronics 33 Telecommunications. Audio And Video Engineering 35 Information Technology. Office Machines 37 Image Technology 39 Precision Mechanics. Jewelry 43 Road Vehicle Engineering 45 Railway Engineering 47 Shipbuilding And Marine Structures 49 Aircraft And Space Vehicle Engineering 53 Hoisting And Conveying Equipment. Materials Handling 55 Packaging And Distribution Of Goods 59 Textile And Leather Technology 61 Clothing Industry 65 Agriculture 67 Food Technology 71 Chemical And Petrochemical Technology 73 Mining And Minerals 75 Petroleum, Natural Gas, And Related Technologies 77 Metallurgy 79 Wood Technology 81 Glass And Ceramics Industries 83 Rubber, Asbestos, And Plastics Industries 85 Pulp And Paper Technology 87 Paint And Coating Industries 91 Construction. Building Materials 93 Civil Engineering 95 Military Engineering 97 Household And Commercial Equipment. Recreation. Sports

Level 2 (Groups)

The ICS second level, the group, is a subdivision of the field.

Level 3 (Sub-Groups)

Sub-groups are used in the ICS to subdivide groups into subjects that certain to a particular aspect of the subject covered by a given group. Regardless of the subject, virtually all groups include a sub-group No. 01 that covers the complete subject of the respective group. In addition, most of the groups contain a sub-group No. 99 for standards on subjects which do not correspond either to the subjects of the general sub-groups or to the subjects of the specific sub-groups of the respective groups.

Level 4 (Units)

Level 4 subdivisions are not part of the official ICS document. The ICS rules however allow users of the classification system to subdivide the official ICS sub-groups into so-called units, making them a Level 4 component of the International Classification for Standards. This is accomplished by adding a two-digit number to the notation of the sub-group being subdivided. However, instead of a period, new notations use a hyphen as a separator. For example:

35.220.20-10 Magnetic tapes

Statistics

The International Classification for Standards has 99 top-level divisions of which only 40 are presently used. The remaining 59 divisions are reserved for topics that are not yet known.

There are three "official" levels in the ICS system, each holding ninety nine (99), nine hundred and ninety nine (999) and ninety nine (99) subsets, respectively.

Each field of the ICS is designed to hold a maximum of 999 groups. The number 999 is a Kaprekar number since its square (999² = 998,001) can be split into two parts, 998 and 001, which add up to the original number again (998 + 001 = 999).

Although any group in the ICS may contain no more than 99 "official" sub-groups, the holding capacity of the group can be expanded 99 times by using "unofficial" Level 4 subdivisions, an option that is built into the ICS. Adding Level 4 subdivisions to all sub-groups within a group increases the group's holding capacity to 9 801 subjects. Splitting this number into two parts, 98 and 01, and then adding them produces 99, the maximum number of "official" sub-groups in any given group of the ICS.

The expanded version of the International Classification for Standards is capable of covering nearly 1 billion subjects (969,328,701 to be exact). This can be achieved without any restructuring of its numerical coding system. Since there are currently about 780 000 national standards in the world, the number of subjects that the ICS can offer for classification purposes exceeds 1 200 times the total number of documents that are available for classification.