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 / 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": "aat:300033618","type": "Type","label": "Painting"}, 
    {"id": "aat:300133025","type": "Type","label": "Artwork"}
  ]
}

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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 are sometimes immediately obvious (the frame is part of the painting) and sometimes rather abstract (the concept of oak is part of the broader concept of wood).

Objects

Objects can be partitioned into separate pieces, with more specific information provided about each piece. The individual pieces do not need to be physically separated or even separable from the whole, just objectively defined.

Use cases for this pattern include:

Example:

A painting (aat:300033618) is made of watercolor paint (aat:300015045) on a support (aat:300014844) made of canvas (aat:300014078):

{
  "@context": "https://linked.art/ns/v1/linked-art.json", 
  "id": "https://linked.art/example/object/16", 
  "type": "ManMadeObject", 
  "label": "Example Painting", 
  "classified_as": [
    {"id": "aat:300033618","type": "Type","label": "Painting"}, 
    {"id": "aat:300133025","type": "Type","label": "Artwork"}
  ], 
  "made_of": [
    {"id": "aat:300015045","type": "Material","label": "watercolors"}
  ], 
  "part": [
    {
      "id": "https://linked.art/example/object/16/part/1", 
      "type": "ManMadeObject", 
      "label": "Canvas Support", 
      "classified_as": [
        {"id": "aat:300014844","type": "Type","label": "Support"}
      ], 
      "made_of": [{"id": "aat:300014078","type": "Material","label": "canvas"}]
    }
  ]
}

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Time Periods and Events

In order to make assertions about events or time periods that occur within some larger context, the same pattern of asserting a part-of/has-part relationship is useful.

Use cases for this pattern include:

Example:

An auction (aat:300054751) consists of many activities in which a particular lot is auctioned:

{
  "@context": "https://linked.art/ns/v1/linked-art.json", 
  "id": "https://linked.art/example/activity/11", 
  "type": "Activity", 
  "label": "Example Auction", 
  "classified_as": [
    {"id": "aat:300054751","type": "Type","label": "Auctioning"}
  ], 
  "part": [
    {
      "id": "https://linked.art/example/activity/11/part/1", 
      "type": "Activity", 
      "label": "Example Auction of Lot"
    }
  ]
}

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Locations

Locations can be made more specific by saying that the smaller region is part of the larger region.

Use cases for this pattern include:

Example:

The "W02" gallery (aat:300240057) is part of the museum, which is in Los Angeles (tgn:7023900-place):

{
  "@context": "https://linked.art/ns/v1/linked-art.json", 
  "id": "https://linked.art/example/place/6", 
  "type": "Place", 
  "label": "Example Museum Building", 
  "part": [
    {
      "id": "https://linked.art/example/place/6/part/1", 
      "type": "Place", 
      "label": "Gallery W204", 
      "classified_as": [{"id": "aat:300240057","type": "Type","label": "Gallery"}]
    }
  ], 
  "part_of": [
    {"id": "tgn:7023900-place","type": "Place","label": "Los Angeles"}
  ]
}

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Use of Gazeteers

It is preferable to rely on linked controlled vocabulary systems that include hierarchies whenever possible, rather than duplicating the geographical structure into the metadata of other resources.

Information / Linguistic Objects

The model makes a distinction between the abstract information content and the physical carriers of that content. Using this separation, we can distinguish between the textual or otherwise semantic partitioning of the content (such as chapter, verse or scene) and the physical partitioning of the carriers of that content, using the Object model described above.

Use cases for this pattern include:

Example:

The content of the first ledger from a dealer's records contains the content of the first row of that ledger.

{
  "@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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Concept Hierarchy

Similarly, concepts can be arranged in parent/child hierarchies where the parent concepts include all of the child concepts.

Use cases for this pattern include:

Example:

The concept of being the side of an object (aat:300404461) is part of the concept of being some portion of an object (aat:300190691).

{
  "@context": "https://linked.art/ns/v1/linked-art.json", 
  "id": "https://linked.art/example/object/17", 
  "type": "ManMadeObject", 
  "label": "Side of an Object", 
  "classified_as": [
    {
      "id": "aat:300404461", 
      "type": "Type", 
      "label": "Sides", 
      "part_of": [
        {"id": "aat:300190691","type": "Type","label": "Object portions"}
      ]
    }
  ]
}

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Organizations

Organizations are modeled as Groups which can have members that are part of that group. The members can themselves be groups, allowing a hierarchy to be created in the same way as for parts of the classes above. Note that this pattern uses member rather than part, as instances of both Group and Person share the same membership relationship, rather than a strict partitioning.

Use cases for this pattern include:

Example:

The Paintings Department (aat:300263534) is part of the Example Museum (aat:300312281)

{
  "@context": "https://linked.art/ns/v1/linked-art.json", 
  "id": "https://linked.art/example/group/7", 
  "type": "Group", 
  "label": "Example Museum Organization", 
  "member": [
    {
      "id": "https://linked.art/example/group/7/part/1", 
      "type": "Group", 
      "label": "Paintings Department", 
      "classified_as": [
        {"id": "aat:300263534","type": "Type","label": "Department"}
      ]
    }
  ], 
  "classified_as": [{"id": "aat:300312281","type": "Type","label": "Museum"}]
}

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Membership in a Collection

Collections are modeled as Aggregations of objects. Aggregations are conceptual sets of resources. Like member for participation in Groups, this is also not strict partitioning as any resource can be part of an Aggregation, and the same Aggregation can include many different types of resource. Instead of part, we use the term aggregates.

Use cases for this pattern include:

Example:

A Painting is a member of the Paintings Collection.

{
  "@context": "https://linked.art/ns/v1/linked-art.json", 
  "id": "https://linked.art/example/set/6", 
  "type": "Aggregation", 
  "label": "Paintings Collection", 
  "aggregates": [
    {
      "id": "https://linked.art/example/object/18", 
      "type": "ManMadeObject", 
      "label": "Example Painting", 
      "classified_as": [{"id": "aat:300033618","type": "Type","label": "Painting"}]
    }
  ]
}

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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/19", 
  "type": "ManMadeObject", 
  "label": "Example Painting on Canvas", 
  "classified_as": [
    {"id": "aat:300033618","type": "Type","label": "Painting"}, 
    {"id": "aat:300133025","type": "Type","label": "Artwork"}
  ], 
  "referred_to_by": [
    {
      "id": "https://linked.art/example/object/19/statement/1", 
      "type": "LinguisticObject", 
      "value": "Oil on Canvas", 
      "classified_as": [
        {"id": "aat:300010358","type": "Type","label": "Material Statement"}, 
        {"id": "aat:300418049","type": "Type","label": "Brief Text"}
      ], 
      "language": [{"id": "aat:300388277","type": "Language","label": "English"}]
    }
  ]
}

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