Baseline Patterns

Table of Contents


It is useful to have some common baseline patterns to follow when using a very open ontology, like CIDOC-CRM. From working with datasets from across many different museums, the following patterns have been agreed on as useful ways to think about our cultural data.

These patterns are presented below with examples of how they are used in practice, but these are not intended to be exhaustive. The documentation for the different resource types will include more information about how they are used in different circumstances.

Core Properties

There are a few core properties that every resource should have for it to be a useful part of the world of Linked Open Data:

{
  "@context": "https://linked.art/ns/v1/linked-art.json", 
  "id": "https://linked.art/example/object/14", 
  "type": "ManMadeObject", 
  "_label": "Example Object"
}

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Types and Classifications

The CRM is a framework that must be extended via additional vocabularies and ontologies to be useful. The provided mechanism for doing this is the predicate crm:P2_has_type, mapped as classified_as in the model. The semantics of crm:P2_has_type are closer to "is classified as" or perhaps "has semantic tag", rather than "is an instance of the class" like rdf:type (mapped as type in the model). The type field is used for CRM defined classes, and as few other extensions as possible.

While any external vocabulary of terms can be used, the Getty Vocabularies are used whenever possible for consistency. The set of terms that have been identified as useful from those vocabularies is listed in the community best-practices.

Use cases for this pattern are in almost every example, but include:

Example:

The type of the object (an instance of ManMadeObject) is a painting (aat:300033618):

{
  "@context": "https://linked.art/ns/v1/linked-art.json", 
  "id": "https://linked.art/example/object/15", 
  "type": "ManMadeObject", 
  "_label": "Simple Example Painting", 
  "classified_as": [
    {
      "id": "http://vocab.getty.edu/aat/300033618", 
      "type": "Type", 
      "_label": "Painting"
    }, 
    {
      "id": "http://vocab.getty.edu/aat/300133025", 
      "type": "Type", 
      "_label": "Artwork"
    }
  ]
}

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Names and Identifiers for a Resource

Names

As the _label property is intended as internal documentation for the data, it is strongly recommended that every resource that should be rendered to an end user as an item of interest also have at least one specific name. This name could be for an object, a person, a group, an event or anything else. This pattern uses the identified_by property, with a Name resource. The value of the name is given in the content property of the Name.

If there is more than one name given, then there should be one that is classified_as the primary name for use. This is done by adding the Primary Name (aat:300404670) term to it.

{
  "@context": "https://linked.art/ns/v1/linked-art.json", 
  "id": "https://linked.art/example/object/16", 
  "type": "ManMadeObject", 
  "_label": "Painting: Pasture and Sheep", 
  "identified_by": [
    {
      "id": "https://linked.art/example/name/19", 
      "type": "Name", 
      "content": "Pasture and Sheep", 
      "classified_as": [
        {
          "id": "http://vocab.getty.edu/aat/300404670", 
          "type": "Type", 
          "_label": "Primary Name"
        }
      ]
    }
  ], 
  "classified_as": [
    {
      "id": "http://vocab.getty.edu/aat/300033618", 
      "type": "Type", 
      "_label": "Painting"
    }, 
    {
      "id": "http://vocab.getty.edu/aat/300133025", 
      "type": "Type", 
      "_label": "Artwork"
    }
  ]
}

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Identifiers

Many resources of interest are also given external identifiers, such as Accession Numbers for objects, ORCIDs for people or groups, lot numbers for auctions, and so forth. Identifiers are represented in a very similar way to names, but instead use the Identifier class. Identifiers will normally have a classification determining which sort of identifier it is, to distinguish between internal repository system assigned numbers from museum assigned accession numbers, for example.

As Identifiers and Names use the same identified_by property, the JSON will frequently have mixed classes in the array.

{
  "@context": "https://linked.art/ns/v1/linked-art.json", 
  "id": "https://linked.art/example/object/17", 
  "type": "ManMadeObject", 
  "_label": "Painting: ", 
  "identified_by": [
    {
      "id": "https://linked.art/example/identifier/5", 
      "type": "Identifier", 
      "content": "P1998-27", 
      "classified_as": [
        {
          "id": "http://vocab.getty.edu/aat/300312355", 
          "type": "Type", 
          "_label": "Accession Number"
        }
      ]
    }, 
    {
      "id": "https://linked.art/example/name/20", 
      "type": "Name", 
      "content": "Pasture and Sheep", 
      "classified_as": [
        {
          "id": "http://vocab.getty.edu/aat/300404670", 
          "type": "Type", 
          "_label": "Primary Name"
        }
      ]
    }
  ], 
  "classified_as": [
    {
      "id": "http://vocab.getty.edu/aat/300033618", 
      "type": "Type", 
      "_label": "Painting"
    }, 
    {
      "id": "http://vocab.getty.edu/aat/300133025", 
      "type": "Type", 
      "_label": "Artwork"
    }
  ]
}

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Statements about a Resource

In many cases, current data does not support the level of specificity that the full ontology assumes. For example, instead of a completely modeled set of parts with materials, many museum collection management systems allow only a single human-readable string for the "medium" or "materials statement". The same is true in many other situations, including rights or allowable usage statements, dimensions, edition statements and so forth. Any time that there is a description of the resource that has a more exact scope than just a general description, then this pattern can be used to record that descriptive text.

The pattern makes use of the Linguistic Object class -- a class for resources that identify a particular piece of textual content. These Linguistic Objects can then refer to any other resource to state what the content is about. They maintain the statement itself in the value property, and the language of the statement (if known) in the language property.

Use cases for this pattern include:

Example:

Having only a textual description of the materials in English, the value "Oil on Canvas" is recorded as referring to the painting as a "materials" (aat:300010358) statement:

{
  "@context": "https://linked.art/ns/v1/linked-art.json", 
  "id": "https://linked.art/example/object/18", 
  "type": "ManMadeObject", 
  "_label": "Example Painting on Canvas", 
  "classified_as": [
    {
      "id": "http://vocab.getty.edu/aat/300033618", 
      "type": "Type", 
      "_label": "Painting"
    }, 
    {
      "id": "http://vocab.getty.edu/aat/300133025", 
      "type": "Type", 
      "_label": "Artwork"
    }
  ], 
  "referred_to_by": [
    {
      "id": "https://linked.art/example/object/18/statement/1", 
      "type": "LinguisticObject", 
      "content": "Oil on Canvas", 
      "classified_as": [
        {
          "id": "http://vocab.getty.edu/aat/300010358", 
          "type": "Type", 
          "_label": "Material Statement"
        }, 
        {
          "id": "http://vocab.getty.edu/aat/300418049", 
          "type": "Type", 
          "_label": "Brief Text"
        }
      ], 
      "language": [
        {
          "id": "http://vocab.getty.edu/aat/300388277", 
          "type": "Language", 
          "_label": "English"
        }
      ]
    }
  ]
}

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Parts

Describing the hierarchy of parts of resources is a core pattern for having increasingly granular or specific descriptions. These partitionings can be physical (the frame is part of the painting), temporal (World War Two is part of the modern era), linguistic (the first chapter is part of the manuscript's text), or more closely related to membership in a set (the painting is part of the collection).

The advantage of partitioning is that more specific information can be provided about each part, as a thing separate from the whole. For example the material of the frame part could be specified as oak, whereas the material of the support part could be specified as canvas.

{
  "@context": "https://linked.art/ns/v1/linked-art.json", 
  "id": "https://linked.art/example/object/19", 
  "type": "ManMadeObject", 
  "_label": "Example Painting", 
  "classified_as": [
    {
      "id": "http://vocab.getty.edu/aat/300033618", 
      "type": "Type", 
      "_label": "Painting"
    }, 
    {
      "id": "http://vocab.getty.edu/aat/300133025", 
      "type": "Type", 
      "_label": "Artwork"
    }
  ], 
  "made_of": [
    {
      "id": "http://vocab.getty.edu/aat/300015045", 
      "type": "Material", 
      "_label": "watercolors"
    }
  ], 
  "part": [
    {
      "id": "https://linked.art/example/object/19/part/1", 
      "type": "ManMadeObject", 
      "_label": "Canvas Support", 
      "classified_as": [
        {
          "id": "http://vocab.getty.edu/aat/300014844", 
          "type": "Type", 
          "_label": "Support"
        }
      ], 
      "made_of": [
        {
          "id": "http://vocab.getty.edu/aat/300014078", 
          "type": "Material", 
          "_label": "canvas"
        }
      ]
    }
  ]
}

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Similary, a distinction between the abstract information content and the physical carriers of that content gives us the ability to separately partition objects from text or image content. For example, the content of the first ledger from a dealer's records contains the content of the first row of that ledger without saying anything about where that information might be carried.

{
  "@context": "https://linked.art/ns/v1/linked-art.json", 
  "id": "https://linked.art/example/text/6", 
  "type": "LinguisticObject", 
  "_label": "Content of Ledger 1", 
  "part": [
    {
      "id": "https://linked.art/example/text/6/part/1", 
      "type": "LinguisticObject", 
      "_label": "Content of Row 1"
    }
  ]
}

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