International Classification for Standards (ICS)

The Importance of ICS :

      The International Classification for Standards (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. In previous years, the International Organization for Standardization,  abbreviated as (ISO), has agreed with national standards organizations on using the Universal Decimal Classification (UDC) to classify the standards issued by each organization. Each standard carries a UDC number that determines its subject. The standard may have more than one classification notation according to the nature of subjects or subject fields.

ICS Improvement Stages :​

      At the beginning of 90s, the UDC system was insufficient for the classification of standards. Thus, the International Organization for Standardization set and disseminated a special standards classification system known as the International Classification for Standards, abbreviated as ICS. Four editions and a special appendix of additions and modifications until 2001 were issued. The system passed through several stages of improvement which are as follows :

​ Arabicization :​

      The system was issued in English. The Public Administration of Information Technology in Saudi Standards, Metrology and Quality Organization translated this international classification into Arabic to serve standardization bodies, specialized standardization information centers and beneficiaries of standards in general in Arab world. 
      This work has faced some difficulties including the differences in Arabicizing the foreign terms especially technical ones. There were also some difficulties related to preparing the alphabetical index which depends on storing texts in computer and using tags, also known as keywords, to show the classification notation. The difficulties were resulted from the nature of Arabic language which differs from English in this sense, especially the use of the definite Arabic article "أل" at the beginning  of a word or the attachment of some pronouns to words such as in "أجهزتها". Among other difficulties were also the use of singular and plural forms which leads to the separation of words such as in "رافعة" and "روافع" according to their positions in the alphabetical order.

Alphabetical Index :​

      Despite the importance of the alphabetical index and its significant role in facilitating the search process for subjects and allocating the proper notation for each subject, no complete dependence on the alphabetical index shall be made, but systematic tables shall be verified to ensure that the notation is suitable with the subject field. Valves, for example, have several uses in different scientific fields. For instance, safety valves are classified in 13.240, valves in general in 23.060 and plastic pipes manufacturing in 83.140.30, etc. Thus, the proper procedure is to use the alphabetical index to narrow the search and then to use the tables to allocate the suitable subject field for the standard being classified.

Ways of Using the Printed Index :

      Due to the differences in Arabicizing terms and in spelling the words, it is preferred that the beneficiary of this classification continues his/her search if the required word, such as "vegetables", is not found, by trying to search for its synonym such as "veggies". The beneficiary may not find the singular form of a word such as "fruit"; therefore, he/she needs to search for the plural form "fruits". Sometimes the two forms such as "water" and "waters," according to the nature of usage, are used as in "drinking water" and "mineral waters". It is also possible to search by using the general name of a subject such as "furnishings". In this type of indexes which depends on a natural language, there are no references or combinations of subjects as in relative alphabetical indexes. Words are arranged alphabetically in indexes according to the Arab Standard No. 499 known as the Unified Arab Codes (UAC). Thus, all the words starting with "أ" come first followed by words starting with "إ" and then those starting with "ا". Therefore, it is important to pay attention to this matter and to other issues related to the alphabetical order when searching in the printed index.
      The International Organization for Standardization (ISO) set this classification as to represent the general approaches of the international standards subjects; thus, this classification provides a wide coverage for scientific and technical subjects, such as industries and telecommunications. At the same time, the classification does not provide a detailed coverage for social, religious and other humanitarian subjects. However, the system allows for proper additions to local subjects from which Arab organizations can benefit in covering Arab and Islamic subjects. Because it is expected that this edition will be implemented in standards organizations and information centers, any modifications or additions can be made in accordance with the nature of subjects.

Purposes of the ICS :

  1. The ICS is intended to serve as a structure for catalogues of international, regional and national standards and other normative documents, and as a basis for standing-order systems for international standards. It may also be used for classifying standards and other normative documents in databases, libraries, information centers, etc.
  2. The ICS should facilitate the harmonization of information and ordering tools such as catalogues, selective lists, bibliographies and databases on magnetic and optical media thus promoting the world-wide dissemination of international, regional and national standards.    

Description of the ICS :​

1. For the purposes of this document, the general term "standard" is applied to all international, regional and national normative documents, such as standards, technical reports, standardized profiles, technical specifications, technical regulations, guides, codes of practice, technology trends assessments, etc. and the drafts of such documents.
2. The ICS is a hierarchical classification which consists of three levels.
3. Level 1 covers 40 fields of activity in standardization, e.g. road vehicle engineering, agriculture, metallurgy. Each field has a two-digit notation, e.g.
                 43          ROAD VEHICLE ENGINEERING.
4. The fields are subdivided into 377 groups (level 2). The notation of a group consists of the field notation(two digit) and a three-digit group number, separated by a point (a comma in Arabic) e.g.
                 43.040 Road vehicle systems.  
5. 144 of the 392 groups are further divided into 909 sub-groups (level 3). The notation of a sub-group consists of the group notation and a two-digit number, separated by a point (a comma in Arabic), e.g.
                  43.040.20 Lighting, signaling and warning devices.
6. A number of group and sub-group titles are followed by scope notes and/or reference notes, indicated by asterisks in the ICS. . A scope note, as a rule, lists subjects covered by a given group/subgroup or defines the subject of a given group/sub-group. A reference note refers to a subject, related to a given group/sub-group, which is covered by another group/sub-group.
7. All groups divided into sub-groups contain, with a few exceptions, a subgroup which covers the complete subject of the respective group. Such general subject sub-groups have notations terminating with ".01". For example, the group
        07.100 Microbiology
 contains as a first sub-group
       07.100.01 Microbiology in general
which shall include standards covering the subject of microbiology in general, e.g. the standard:
     ISO 4831:1991, Microbiology – General guidance.
while standards covering medical microbiology, microbiology of water or food microbiology shall be included respectively in other specific sub-groups: 07.100.10, 07.100.20 or 07.100.30.
8. Most of the groups divided into sub-groups contain a sub-group having the notation terminating with ".99". Such sub-groups include standards on subjects which do not correspond either to the subjects of the general subgroups or to the subjects of the specific sub-groups of the respective groups. For example, the subject of the standard      
          ISO 10945:1994, Hydraulic fluid power – Gas -loaded accumulators – Dimensions of gas ports
does not correspond either to the subject of the sub-group
      23.100.01 Fluid power systems in general
or to the specific subjects of the sub-groups:
    23.100.10 Pumps and motors
    23.100.20 Cylinders
    23.100.40 Piping and couplings.
In this case, it shall be included in the sub-group
    23.100.99 Other fluid power system components
The above rule does not apply in the ICS if all standards related to a group can be included either in the general sub-group or in the specific sub-groups.
For example, the group
    21.100 Bearings
contains the general subject sub-group
    21.100.01 Bearings in general
and specific sub-groups
    21.100.10 Plain bearings
    21.100.20 Rolling bearings
 The group does not contain a sub-group
   21.100.99 Other bearings
 since all bearings belong only to two types of bearings: plain bearings and rolling bearings. 

Rules for the use of the ICS​ :​

      The latest edition of the ICS with the subsequent issues of the ICS Update should be used for indexing standards and other normative documents and their drafts. Before indexing standards for the first time, the indexer should first carefully study the present rules and the ICS structure.
      Standards should be classified according to their subjects. The indexer should first identify the appropriate field for a given subject, then allocate the appropriate group notation, and, further, the sub-group's notation if the group is subdivided. For example, the standard
 ISO 3412:1992, Road vehicles – Screened and waterproof spark - plugs and their connections – Types 1A and 1B
 belong to the field
     43 Road vehicle engineering
The appropriate group within the field is
    43.060 Internal combustion engines for road vehicles
and the appropriate sub-group within the group is
    43.060.50 Electrical equipment. Control systems
      If the field of application of a standard is not clear from its content, indexers may take into account the scopes of the relevant technical committee, subcommittee and working group responsible for the development of the standard.
      The alphabetical index of the ICS may be used as a supplementary tool for identifying the appropriate field, group, sub-group, but the notations found in the index shall be carefully verified against the systematic table. The reason is that only the systematic table contains the full information relating to a group notation, such as its title, the field to which it belongs, the subdivision into sub-groups, sometimes the scope note, and the reference note(s) showing its relationship with other group(s) or sub-group(s). Otherwise errors in indexing may occur.
      It is recommended to use all levels available for classifying a given standard. For example, the standards
     ISO 7228:1993,    anaesthetic machines for use with humans
    ISO 7864:1993,    sterile hypodermic needles for single use
    ISO 7740:1985,   instruments for surgery– Fitting dimensions
should be classified respectively in sub-groups, – Test method shall be included in the two sub-groups,
    23.040.20,      Plastics pipes
    23.040.45,   Plastics fittings
while the standard
    ISO 8159:1987, Textiles – Morphology of fibers and yarns – Vocabulary
shall be included in the three sub-groups
   01.040.59 Textile and leather technology (Vocabularies)
   59.060.01 Textile fibers in general
   59.080.20 Yarns
However, it is recommended to avoid the allocation of more than four notations to one document.

Standards included in the groups : 

01.040  Vocabularies
01.060 Quantities and units
 01.070 Colour coding
01.075 Character symbols
01.080.20  Graphical symbols for use on specific equipment
 01.080.30 Graphical symbols for use on mechanical engineering and construction drawings, diagrams, plans, maps and other technical product documentation
shall be included in other groups and/or sub-groups according to the subject of documentation; e.g. the standard
 ISO 1942-2:1989, dental vocabulary- Part 4: Dental equipment 


shall be included in the two sub-groups : 

01.040.11 Health care technology (vocabulary)
11.060.20 Dental equipment
 while the standard
ISO 4605-1:1991 Earth-moving machinery – Symbols for operator controls and other displays – Part 1: Common symbols, and 
ISO 6405: 1991 Earth moving machinery – Moving symbols
shall be included in the sub-group
01.080.20  Graphical symbols for use on specific equipment
and the group
53.100 Earth- moving machinery
A standard containing definitions which apply only for the purpose of that standard shall not be classified into the group
01.040 Vocabularies
 Amendments, addenda and technical corrigenda to a standard shall have the same notations as the standard itself.
Standards for systems, components, spare parts and materials used for specific equipment, machines and installations should be classified in the respective groups and sub-groups containing standards for the equipment, machines and installations if the ICS does not contain groups or sub-groups specially designated for classifying the relevant systems, components, spare parts and materials, e.g. the standard
ISO 5996: 1984, Trailed agricultural vehicles – Brakes and braking devices – Laboratory test method
should be included in the sub-group
 65.060.10 Agricultural tractors and trailed vehicles
 since the ICS does not contain a group/sub-group for braking systems of agricultural machinery, while the standard
 ISO 4251-1:1992, Tyres and rims for agricultural tractors and machines – Part 1: Tyre designation and dimensions
should be included in the sub-group
 83.160.30 Tyres for agricultural machinery
Where a group is further subdivided into sub-groups, only the notations of the sub-groups shall be allocated to standards, e.g. the standard
ISO  4254-1:1989, Tractors and machinery for agriculture and forestry- Technical means for ensuring safety - Part 1: General
 shall be classified under the title of the sub-group
65.060.01 Agricultural machines and equipment in general
and not under the title of the group
 65.060 Agricultural machines, implements and equipment
If the subject of a standard covers two or more sub-groups within a group which contains these sub-groups plus sub-groups with notations terminating with ".01" and/or ".99", that standard shall be classified under the notation terminating with ".01", e.g. the standard:
ISO 4829-1:1986, Steel and cast iron – Determination of total silicon content – Reduced molybdosilicate spectrophotometric method – Part 1: Silicon contents between 0.05 and 1.0% 
shall be classified under the title of the sub-group
77.080.01 Ferrous metals in general
and not under the titles of the sub-groups
77.080.10  Irons
77.080.20 Steels
since irons and steels completely cover the ferrous metals subject. Similarly, the standard
ISO 6632:1981 Fruits, vegetables and derived products- Determination of volatile acidity
shall be classified under the title of the sub-group
67.080.01  Fruits, vegetables and derived products in general
and not under the title of the sub-groups
67.080.10 Fruits and derived products
 67.080.20 Vegetables and derived products
since the group Fruits and Vegetables contains only
67.080.01 Fruits, vegetables and derived products in general
67.080.10 Fruits derived products
67.080.20 Vegetables and derived products
A sub-group or a group may be further subdivided by the user into respectively either several units (level 4) or new sub-groups (level 3). For the purpose of distinguishing subdivisions from those given in the classification, new notations shall be created using a hyphen, e.g. the sub-group
35.220.20 Magnetic data storage devices in general

may be further subdivided into the following:

35.220.20- 01 Magnetic data storage devices in general
 35.220.20- 10 Magnetic tapes
35.220.20- 20 Magnetic disks
35.220.20- 30 Magnetic cards
 35.220.20- 99 Other magnetic data storage devices
 The same thing applies to subdividing any group, e.g. the group
53.100  Earth-moving machinery
may be subdivided into the following new sub-groups:
53.100-01 Earth-moving machinery in general
 53.100-10 Tractors
 53.100-20 Excavators 
 53.100- 30 Loaders
 53.100-40 Graders
 53.100-99 Other earth-moving machinery
 However, such subdivisions should be used very restrictively and avoided wherever possible. The preferred solution should be to address the question to the entity in charge of  ICS about the need of further subdivisions.
A semicolon should be used for separating notations in printed documents. To provide consistency in the presentation of notations, they should be sorted in ascending numerical order, e.g. ICS notations for ISO 815:1987 should be indicated as follows: 01.040.59; 59.060.01; 59.080.20. For data exchange, the rules set up in the second edition of the ISONET Manual should be used.
3.14 Fields
and also the fields and the groups for which the scopes contain an indication that this field or group includes standards for general use, e.g.
         13.110  Safety of machinery
                        *This group includes standards only for general use
shall contain only standards for general use which may be applied by
different industries. For example, the standard
ISO 10317:1992, Rolling bearings – Metric tapered roller bearings –Designation system
which may be applied by different industries, shall be included in the subgroup
21.100.20 Rolling bearings
while standards
ISO 6045:1987,       Shipbuilding and marine structures – Bearings   for derrick goosenecks – Assemblies and components
ISO 3464:1977,     Textile machinery and accessories -- Bearings for bottom rollers and allied dimensions -- Caps with central nose and caps with side lugs
which are designated for application by specific industries, shall be included respectively in the sub-groups related to those industries, namely
47.020.40        Lifting and cargo handling equipment
59.120.10,      Spinning, twisting and texturing machines
The standard
ISO 1167:1996,      Thermoplastic pipes for the conveyance of
fluids – Resistance to internal pressure –Test method
which is applied for general purposes and may be used by different
industries, shall be included in the sub-group
23.040.20       Plastic pipes
while the standard
ISO 4437:1988,       Buried polyethylene (PE) pipes for the supply of gaseous fuels – Metric series – Specifications
which is designated for specific purposes of natural gas handling, shall be
included respectively in the group related to those specific purposes (from
the point of view of using the product) and in the sub-group related to the
relevant type of product (from the point of view of manufacturing the
product), namely
75.200       Petroleum products and natural gas handling equipment
83.140.30       Plastic pipes and fittings for non-fluid use
The standard
ISO/TR 12100-2:1992,    Safety of machinery – Basic concepts, general principles for design – Part 2: Technical principles
shall be included in the group
13.110      Safety of machinery
while the standard
ISO 4254-1:1989,     Tractors and machinery for agriculture and forestry –Technical means for ensuring safety –Part 1: General
shall not be included in the above group since it is designated for use by
only one industry, the agricultural machinery engineering sector; the
standard shall be included in the sub-group
65.060.01     Agricultural machines and equipment in general
3.15   If a group/sub-group has a reference note to another group/sub-group, the standards related to the subject indicated in the relevant reference note shall be classified in the referenced group/sub-group. For example, the sub-group
81.060.20    Ceramic products
contains the reference note
*Sanitary ceramic products, see 91.100.25
therefore, standards for sanitary ceramic products shall be classified into the sub-group
91.100.25     Sanitary installations
and not into the sub-group
81.060.20    Ceramic products
3.16    If an international standard is adopted as a regional and/or national
standard, the regional and/or national standard shall have the notation(s)
allocated to the international standard. Similarly, if a regional standard is
adopted as a national standard, the latter shall have the notation(s) allocated to the regional standard.
3.17    In general, to provide worldwide consistency in indexing, indexers
should be guided by the practices of allocation of ICS notations applied for international standards (in the first place) and regional standards.
3.18    Identified errors in indexing due to misallocation of ICS notations,
transposing of figures in ICS notations, typographical errors, etc. should be notified to the organization concerned.
4  Updating of the ICS
4.1  The classification is updated according to needs. Any user may submit proposals for modifications and/or additions to the ICS. Such proposals should be sent to the ISO Central Secretariat at the following address:
rue de Varembe , 1
Case postale 56
CH-1211 GENEVE 20
Tel : +41 22 749 01 11
Fax: + 41 22 733 66 26


Last modified 20 Oct 2020
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