International Classification for Standards

International Classification for Standards (ICS) is an international classification system for technical standards. It is designed to cover every economic sector and virtually every activity of humankind where technical standards may be used.

Developed and maintained by the International Organization for Standardization, the ICS is intended to be a continuous work in progress and is updated when necessary. The latest edition of the ICS can be downloaded free of charge from the ISO web site.

Anyone may submit a proposal for modifications or additions to the ICS.

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.

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:

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).

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

At present the classification includes 40 fields:

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

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 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: