Introduction to Object ID
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categories of information
Type Title
Materials Subject
Measurements Date
Inscriptions Maker
Distinguishing Description


What is pictured or represented (e.g., landscape, battle, woman holding child)?
A description of any subject depicted or represented is potentially one of the most important ways of identifying an object or finding an image of it. However, describing subject matter in a way that is useful to others is one of the most difficult parts of the documentation process.

Different individuals may describe the same subject matter in different ways. The point is made by a true story: An oil painting recorded on a law-enforcement database, but not matched with a recovered painting, was interpreted differently by two individuals. A view of the city of Lincoln, England, with the cathedral looming above the houses, was described by the creator of the record as a townscape, while the person who searched for it used the term cathedral and did not find the painting. Both persons were correct, but both provided only part of the information necessary to enable matching identification to be made.

In descriptions of subject matter, the recorded information should be self-explanatory to anyone without specialist or culturally specific knowledge. For example, experts might identify a statue of a man wearing a lion skin and holding a club as a depiction of Hercules and a Hindu representation of an eagle as Garuda, but those not familiar with classical mythology and Hindu culture may not understand the references. One way around this problem is to describe the subject matter in both specialist and non-specialist terms, combining that which is actually visible with its meaning, e.g., Marsyas | naked male figure with arms above head, bound hand and foot.

Subject matter can be recorded in two ways: It can take the form of a textual description that enables others to visualize the object, particularly useful if there is no photograph of the object. Or it can be recorded as a series of keywords, a useful approach when searching for the object in a retrieval system (see discussion under Type of Object).

The keyword approach calls for a controlled vocabulary (e.g., interior scene, figure(s), animal(s)), which permits more accurate retrieval of records. This approach is also well suited to multilingual databases, since individual keywords can be coded and linked to their equivalents in other languages. The disadvantage of the keyword approach is that it can limit users to a relatively small number of choices, and cannot convey information as nuanced as the textual description. However, the two ways of recording subject matter can be complementary. A number of systems record subject matter both as free-text descriptions and as keywords.

The most extensive iconographic classification system for describing subject matter is ICONCLASS (, a database that provides a collection of ready-made definitions of objects, persons, events, situations, and abstract ideas. The ICONCLASS hierarchy is divided into ten basic classes intended to comprise all the principal aspects of what can be represented: Religion and Magic (1), Nature (2), Human Being, Man in General (3), Society, Civilization, Culture (4), Abstract Ideas and Concepts (5), History (6), Bible (7), Literature (8), Classical Mythology and Ancient History (9), and Abstract Art, Non-representational Art (0). The notation codes used are alpha-numeric, with one digit added for every level in the hierarchy.

A 17th century Dutch print entitled "House built upon a rock, house built upon sand," depicts landscape with castle on rock; windmill in background. Its ICONCLASS classification reads as follows: rock-formations (25H1123), castle (41A12), windmill (47D31),"house built upon a rock; house built upon sand" doctrine of Christ on love. (Matthew 7:24-27; Luke 6:47-49)(73C7455).

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