Iconclass basics


The unique elements of the Iconclass system are its alphanumeric classification codes, called notations. Notations always begin with one of the digits 0 - 9, corresponding with the ten main divisions of Iconclass. Notations can be used to describe or index the subjects of visual documents regardless of the complexity of the subjects. Several notations can be used to describe complex subjects. Every notation is part of a hierarchical structure and, as such, incorporates all of its iconographical broader terms. The text explaining the meaning of an Iconclass notation is the notation's 'textual correlate', the actual definition of the concept.

Main divisions of the Iconclass classification system

The main divisions of the Iconclass system are represented by digits 0 to 9. Of these ten 'main divisions', the numbers 1 to 5 are 'general' topics, designed to comprise all the principal aspects of what can be represented. Divisions 6 through 9 accommodate 'special' topics, coherent subject matter of a narrative nature, with an emphasis on the Bible (7) and Classical Mythology (9). A tenth division, represented by the number 0, was added to the digital version in 1996 at the request of Iconclass users, to accommodate abstract art.

  0 Abstract, Non-representational Art
  1 Religion and Magic
  2 Nature
  3 Human being, Man in general
  4 Society, Civilization, Culture
  5 Abstract Ideas and Concepts
  6 History
  7 Bible
  8 Literature
  9 Classical Mythology and Ancient History

Subdivisions: Increasing specificity

Within each division of Iconclass, definitions are organized according to a logic of increasing specificity. A main division is divided further into a maximum of nine subdivisions by adding a second digit to the right of the first one. Division 2 Nature, for example, is subdivided in the following way:

  21 the four elements, and ether, the fifth element
  22 natural phenomena
  23 time
  24 the heavens (celestial bodies)
  25 earth, world as celestial body
  26 meteorological phenomena
  29 surrealia, surrealistic representations

The third level of specificity is attained by adding a letter in upper case. For reasons of legibility in the original printed version of Iconclass, the letter 'J' was omitted. Thus the addition of a letter permits as many as 25 subdivisions instead of 9, and it also increases the legibility of the notations.

  • Blank spaces on either side of the capital letter and between successive pairs of digits also provided greater legibility in the printed edition. However, the implementation of notations with 'spaces' causes most algorithms to interpret a notation as a "sentence" of separate words and is therefore advised against.

Take a look, for example, at the subdivisions of 25 earth, world as a celestial body:

  25A maps, atlases
  25B continents represented allegorically
  25C geological phenomena
  25D rock types; minerals and metals; soil types
  25E geological chronological division; historical geology
  25F animals
  25G plants; vegetation
  25H landscapes
  25I city view, and landscape with manmade constructions
  25K landscapes in the non-temperate zone, exotic landscapes
  25L cities represented allegorically or symbolically
  25M the Seven Wonders of the World

From the letter(s) onward, subsequent descents in the hierarchy take place in principle by extending the notation to the right with more digits. The main exception to this rule - bracketed text - will be explained below.

The following example shows the first subdivision of 25F animals:

  25F1 groups of animals
  25F2 mammals
  25F3 birds
  25F4 reptiles
  25F5 amphibians
  25F6 fishes
  25F7 lower animals
  25F8 extinct animals
  25F9 misshapen animals; monsters
  25N fictitious countries

Hierarchical path

The following example from division 7 Bible shows the hierarchical path principle: all subsequent descents in the hierarchy take place by extending the notation to the right with a letter and more digits:

  7 Bible
  71 Old Testament
  71H story of David
  71H7 David and Bathsheba (2 Samuel 11-12)
  71H71 David, from the roof (or balcony) of his palace, sees Bathsheba bathing
  71H713 Bathsheba receives a letter from David


A standard entry in the Iconclass system consists of a notation and its textual correlate. The Iconclass system offers the user additional features to increase the accuracy of meaning of a notation in a more or less systematic way. These features are:

--Bracketed text
--Doubling of the letter
--Structural digits

Bracketed text

Bracketed text is a feature that enables the user to break away from the hierarchy of alphanumeric notations. At certain points in the hierarchy the user is invited, by the phrase: "with NAME" (or an equivalent expression), to add a species name, a proper name, a number, or a combination of these in parentheses to the end of a notation. Thus a non-hierarchical - alphabetical and/or numerical - listing is created within the hierarchy.

Example from division 2 of the Iconclass system:

  25G41 flowers
  25G41(...) flowers (with NAME)
  25G41(LILY) flowers: lily
  25G41(ROSE) flowers: rose

Notations that are ready to accept an entry of bracketed text, for example 25G41(..), form an integral part of the Iconclass system. Usually, notations with bracketed text spelled out, for example 25G41(ROSE), are incorporated in the Iconclass Browser only for notations that have literary warrant in the Iconclass Bibliography.
The core of the Iconclass systems thus also includes quite a large number of historical people, like saints and persons from classical history. Not only have they found their place in Iconclass as named entities, but their life stories can be further subdivided systematically by means of so-called structural digits. Here are two examples of this combination:
The notation 11H(FRANCIS)59 contains the saint's name in brackets while the structural digit 59 indicates the scene of the stigmatization:

In 98B(CAESAR)68 the digits 68 are used because they encode the death of someone from classical history.



Keys are flexible elements of the Iconclass system that allow you to add more detail to a basic concept. They are shown in the browser as a clickable list of concept definitions between brackets, below the hierarchical "children" of a concept. A set of keys is often also hierarchically subdivided.
Keys are context-sensitive, so they are always made valid for a specific range of concepts. Keys are made up of strings of digits, occasionally of digits and word(s). Keys are preceded by the plus "+" sign and placed between brackets. They are placed at the end of a notation and add a 'shade of meaning' to the definition or meaning of the notation proper. Example:

The notation for a lion is 25F23(LION). Keys, valid for notations beginning with 25F, are:

  (+1) animals used symbolically
  (+11) bestiaries, 'Physiologus'
  (+12) heraldic animals
  (+2) sex and age of animals; propagation of animals

Key (+12) adds the notion 'heraldic' to the concept 'lion': the notation for a heraldic lion reads 25F23(LION)(+12)


Queue of key

Certain keys can be expanded with digits from a 'queue'. The keys +1 to +6 of 25FF, for example, all indicating an abnormal part, limb or organ of a fabulous beast, can be expanded with one or more digits from a queue indicating the part or limb affected: 1 head, 11 nose, tusk, etc. Thus 25FF241(+511) denotes a 'unicorn with nose or tusk in an unusual place'. The added part (11) is referred to as "Queue of Key". Some 'queues' are made up of an entire key from a different part of Iconclass. In the online browser keys and queues are automatically merged whenever this is required by the original instructions.

Doubling of letter

At several points, Iconclass offers the option to duplicate the upper case letter of a notation and, in this way, modify its meaning. Letter duplication or doubling the letter is context sensitive: it is valid only for certain parts of the system. Within a declared range, duplication has a specific meaning. Often some kind of opposition is intended. Examples:

  25F animals
  25FF fabulous animals
  31A the (nude) human figure [male]*
  31AA the (nude) human figure; female
  42D25 wedding feast, wedding meal [indoors]*
  42DD25 wedding feast, wedding meal; out of doors

* the meaning of 31AA is made explicit as 'female', so 'male' is implied for 31A; in similar fashion 'indoors' is implied for 42D25

Structural Digits

Originally, at the time when Iconclass was devised, structural digits were guidelines in structuring the information concerning certain large groups of characters, such as Greek gods, persons from classical history, or male and female saints. All important episodes in a character's lifetime were numbered consecutively with 'structural' digits:

Structural digits share with key numbers the property of having an intrinsic meaning which is valid only for a particular part of the Iconclass system. Like keys, structural digits are declared in lists, valid for a particular range of the system. Structural digits can be used to make cross-sections through the system which are very interesting from an iconographical point of view. Unlike keys, structural digits are not flagged by a symbol like a plus-sign, but form an integral part of a notation. There are no formal rules to establish that a certain digit is in fact a structural digit, other than the declaration that it is. This makes it impossible to identify a structural digit if it is simply embedded in a string of digits.

Examples of structural digits available to express events from the story of classical gods:

  1 early life
  2 love-affairs
  3 most important deeds

so structural digit 2 indicates a "love-affair". Basic notations for a few of those gods are:

  92B1 (story of) Jupiter (Zeus)
  92B3 (story of) Apollo (Phoebus)
  92B4 (story of) Mars (Ares)

Love-affairs of Jupiter, Apollo or Mars will be indicated by the digit 2 immediately following the basic notation.

The love-affairs in these paintings are indicated by the concepts below. On the fifth position of each notation you will see the structural digit 2. The basic notation for other classical gods or heroes, however, can be shorter or longer than four positions. Obviously, in those cases the position of the 2 will shift.

   92B1217 · Jupiter wooing Danae; she is usually lying in bed receiving a shower of gold
   92B1218 · Jupiter, usually in the shape of a white bull, abducts Europa and carries her across the water
   92B325 · Apollo pursuing the nymph Daphne (as yet not metamorphosed)
   92B4233 · Mars and Venus surprised by Vulcan; he catches them in a net

That is why the Iconclass Browser uses a highly specific rule-base to interpret the elements of a notation.

Cross references

Subjects can be related in many different ways, both thematically and visually, and Iconclass contains a wide variety of cross references linking them.
As you can see in the Browser screen shot below, three cross references point to related terms from 52B1 · Thinking, Thought, Reflection; 'Pensiero' (Ripa). One of them - to 11R4 · active vs. contemplative life - was singled out to illustrate the principle.

In actual practice cross references are a useful discovery tool. They do not convey the conclusion that images are related, but provide the suggestion that further research might be useful. Angelika Kauffmann's La Penserosa was tagged with 52B1 in the Virtuelles Kupferstichkabinett's database, while the young woman in the print by Pieter van den Berge, tagged with 11R4 in the Rijksmuseum's database, is contemplating life as an independent woman, a married woman or a nun. Juxtaposing the two does not suggest any historical relationship; it is merely a hint, automatically generated by the structure of the Iconclass schedules.


Text about keywords of the entry vocabulary