Contents of Iconclass

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'.

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 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 provide greater legibility. However the implementation of notations with 'spaces' can be rather demanding in computer projects and has therefore been abandoned in many computer projects.

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, all subsequent descents in the hierarchy take place by extending the notation to the right with more digits.

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 principle: all subsequent descents in the hierarchy take place by extending the notation to the right with 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
  • keys
  • doubling of the letter
  • structural digits
  • 71H7131 Bathsheba (alone) with David's letter

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", 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 platform is created within the hierarchy.

Example from division 2 of the Iconclass system:

  • 25G41 flowers
  • 25G41(...) flowers (with NAME)
  • 25G41(LILY) lily
  • 25G41(ROSE) 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. However, a large number of proper names of historical persons or fictional characters have found their own place in Iconclass, their life stories can often further subdivided by means of structural digits, for example 11H(BONAVENTURA) or 98B(CAESAR).


Keys are elements of the Iconclass system that are declared in lists. A list of keys is valid for a certain range of notations. 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
  • ...etc.
  • 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.

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
*since 31AA means female, the implied meaning of 31A is male

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:

Example (classical gods):

  • 1 early life
  • 2 love-affairs
  • 3 most important deeds
  • 92B3 (story of) Apollo
  • 92B32 love-affairs of Apollo

Example (saints):

  • 1 specific aspects
  • 2 early life
  • 3 personal devotion
  • 11H(FRANCIS) founder of the Order of Friars Minor (Franciscans),
  • Francis(cus) of Assisi; possible attributes: book, crucifix, lily, skull, stigmata
  • 11H(FRANCIS)2 early life of St. Francis of Assisi

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, 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.

Key moments: production, retrieval, display

The issue of linking your own online catalogue to the Iconclass system, maintained by RKD, is relevant at three key moments in the indexing and publishing process: first, when you are producing information about your collection; second, when that information needs to be retrieved from your database; and, third, once the information that has been found must be displayed.

In a production phase, i.e. when you are describing your collection, you need an easy way to find the concepts that best match the item in front of you. For this, you now have unlimited access to the online Iconclass 2100 Browser. Whether you need to find the definition of a composite narrative scene or of a straightforward everyday event, you will be able to use a keyword search to locate the concept you need in the system.

Expert knowledge may be required to identify this illustration from a medieval Valerius Maximus manuscript as that of two Roman noblemen making their peace after a disagreement, but we only need everyday terms to describe the gestures that express their reconciliation: they are lifting their hat and they are embracing each other.

Searching the new Iconclass Browser using these keywords, lifting and hat, will find us the concept shown here in its hierarchical context.

As you can see, the textual explanation of the notation contains both words. Please note that all the other words shown here can also be used for retrieval if the notation 33A11 is transferred to a user's database.The same gesture, but in a very different context and in a very different catalogue: according to the caption, the lady shows 'Schlechte Manieren' (bad manners) by completely ignoring the gentleman who is politely lifting his hat in salute.

RKD's Iconclass system can now be directly connected to online catalogues like these. Thus it can help both the indexer who has to decide which concepts (notations) to copy from the system, and the end user of the catalogue who simply wants to ask for scenes of people lifting their hat, not knowing anything about this or any other notation. So, in your own online catalogue, you merely need to have the Iconclass notations in place to allow for keyword retrieval. With the help of the same Iconclass system, you will also be able to display the meaning and context of a notation. Thus: