Relation Element Working Draft

This report is a record of the efforts of the Relations working group constituted following the Helsinki Metadata Workshop (DC-5) of October, 1997. The recommendations are provisional and can be expected to evolve in the light of further implementation experience.

I.     It is important to indicate the relation between one information resource and another in metadata for discovery. Because each information resource may have its own metadata set, these relations need to be explicit.

II.     Relations are indicated in Dublin Core™ metadata by the Relation element. Relation has two sub-elements: Relation.Identifier and Relation.Type.

III.    The value assigned to Relation.Identifier identifies the metadata of the related resource or, where this is not possible, the related resource itself. For more information on the use of this sub-element, see the description of the Identifier element.

IV.    The value assigned to Relation.Type describes the nature of the relationship between the current resource and the resource identified by Relation.Identifier. The value of this sub-element is selected from a list of possible values. The DC community has constructed such a list; this is described below. Other organisations may construct their own lists, at the cost of interoperability. In due course, scheme identification will be used to indicate which list of values, and associated meanings, is being invoked.

V.     The DC list of values for the Relation.Type sub-element follows.

         Six pairs of relations are defined at this time.

a) Part/Whole relations are those in which one resource is a physical or logical part of another. The corresponding values of Relation.Type are:

IsPartOf

HasPart

b) Version relations are those in which one resource is an historical state or edition of another resource by the same creator. The corresponding values of Relation.Type are:

IsVersionOf

HasVersion

c) Format transformation relations are those in which one resource has been derived from another by a reproduction or reformatting technology which is not fundamentally an interpretation but is intended to be a representation. The corresponding values of Relation.Type are:

IsFormatOf

HasFormat

d) Reference relations are those in which the author of one resource cites, acknowledges, disputes or otherwise refers to another resource. The corresponding values of Relation.Type are:

References

IsReferencedBy

e) Creative relations are those in which one resource is a performance, production, derivation, translation, adaptation or interpretation of another resource. The corresponding values of Relation.Type are:

IsBasedOn

IsBasisFor

f) Dependency relations are those in which one resource requires another resource for its functioning, delivery, or content and cannot be used without the related resource being present. The corresponding values of Relation.Type are:

Requires

IsRequiredBy

VI.     Specialized communities will need to extend the references relations to express specific types of references or authorial claims.

VII.     When the Relation element is used in unqualified Dublin Core™ metadata, the values of the two sub-elements may be placed directly within the Relation element. If this is done, recommended best practice is to place first the value of the Relation.Type sub-element and second the value of the Relation.Identifier sub-element, separating the two with a space, eg:

IsBasedOn http://a.b.c/foo.bar