The International Classification for Standards (ICS) is a convention managed by the International Organization for Standardization (ISO) and used in catalogues of international, regional, and national standards and other normative documents.

There are a large number of standards covering virtually every activity of the humankind, such as, standards for packaging and distribution of goods, civil engineering standards, military engineering standards, standards for petroleum and related technologies, chemical technology standards, food industry and food technology standards, standards for textile and leather technology and many more.

ICS facilitates reaching any standards quickly to benefit from and organize them as well as making search for standards an easy procedure which serves beneficiaries. The world standardization organizations have coordinated their efforts and cooperated to unify the system used in classifying the standards.

The ICS uses a 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 technologysuch as telecommunications or food processing;

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

A fieldof science such as mathematics or astronomy.

At present the classification includes 40 fields as listed on the left side of the page.

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

An interesting fact about the International Classification for Standards is that it 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.