The CIDOC CRM Format

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The CIDOC CRM Format
Martin Doerr
Institute of Computer Science
Foundation for Research and Technology - Hellas
Heraklion - Crete
Washington, Sept. 22, 1999
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The CIDOC CRM Definitions

• Entity is called anything like
• class, entity node, individual
• comparable to tables, but with meaning
• link is called anything like
• attribute, reference, link,
  property, relation
• comparable to table-column, but with a role
  meaning
• Entity and its subclass is anything like
• isA, subclass - superclass,
• derived class - parent class,
• generalization - specialization

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The CIDOC CRM Links

• Links
• Optional (need not be instantiated)
• Multivalued (e.g. has author!)
• Strictly inherited (both sides !)
• Can be specialized (see RDFsubproperty)
• Can have links (to refine roles etc.)
• can be implemented as entities if necessary...

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The CIDOC CRMImplicit Metamodel

• Entities are grouped by metaclasses
• ( belongs to)
• Links are group by metacategories
• like links between metacategories
• The Metamodel serves as comment
• But is formally correct
• could be used to guide extensions of the model

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The CIDOC CRMNaming Rules

• Entities are named using initial capitals.
• Entities are named using noun phrases (nominal
  group)
• Links are named using lower case letters and are
  labeled in both directions.
• Implementers can choose the appropriate part
• Links are listed by priority at Events,
  Objects, Actors,...
• Links are named using verbal phrases,
• states are named in present tense,
• actions are named in past tense.

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The CIDOC CRMScope Notes

• A statement that clarifies the meaning and usage
  an Entity or link
• Definition by properties, not linguistic!!
• Definition of scope - bounds and distinctions
  for the model
• Context of usage, purpose and implicit view
• Illustration by examples
• Guidance to similar, overlapping, associated
  concepts

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The CIDOC CRMFormat

• Entity names (terms) are presented as headings
  in bold
• face, preceded by the arithmetic identifier.
• The line Belongs to refers to the metaclass,
• The line Subclass of declares the superclass
  of the entity, from which it inherits links
• The line Superclass of is a cross-reference
  to the following subclasses of this entity.
• The line Scope note contains the textual
  definition of the concept the entity represents.
• The title Properties announces the list of
  links.
• Links are grouped by related meaning under
  metacategories, i.e. a series of titles as e.g.
  classifications etc., in normal face.

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The CIDOC CRMFormat

• Each link is represented by its forward and
  backward name, and the entity it links to,
  separated by colon.
• Links declared directly for the entity are given
  in bold face.
• Inherited links are given in italics as
  cross-references to the respective superclasses
  for better comprehension.
• Inherited links with redefined (restricted )
  target entity are given in bold face italics.
• Each link may be followed by a scope note for the
  link in an indented text in smaller characters.
• Links of links are given in an indented position
  in parenthesis under the respective link.

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The CIDOC CRMFormat

• The title The entity is referenced by
  announces the cross-reference list of links
  pointing to this entity.
• Each cross-link is represented by the entity it
  originates from, and its forward and backward
  name, separated by colon, and in normal face.
• The title The entity inherits references
  announces the cross-reference list of links
  pointing to any of the superclasses of this
  entity
• Each inherited cross-link is represented by the
  entity it originates from, and its forward and
  backward name, separated by colon, and in
  italics.