Public comment on revised DCMI Abstract Model
The DCMI Abstract Model, which attained the status of DCMI Recommendation in March 2005, has been revised in light of discussion and feedback from the DCMI Architecture Working Group, the DCMI Usage Board, and the broader community and has been posted for a four-week public comment period [1]. The major differences between this revised version and the previous version [2] are summarized below. A revised DCMI Namespace Policy [3] proposing a new DCMI namespace for Abstract Model entities has been posted for comment at the same time.
Interested members of the public are invited to post comments on these Proposed Recommendations to the DC-ARCHITECTURE mailing list, including "[DCAM Public Comment]" in the subject line [4]. Public Comment will continue from 5 February through 5 March 2007.
[1] http://stage.dublincore.org/documents/2007/02/05/abstract-model/
[2] http://dublincore.org/documents/2005/03/07/abstract-model/
[3] http://stage.dublincore.org/documents/2007/02/05/dcmi-namespace/
[4] http://www.jiscmail.ac.uk/lists/dc-architecture.html
Changes in the DCMI Abstract Model, 2005 to 2007
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Added a table explicitly mapping Abstract Model entities to properties and classes of the Resource Description Framework (RDF) and RDF Schema (RDFS). The DCMI Abstract Model defines a particular Description Model on the basis of RDFS semantics.
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Added a separate Vocabulary Model specifying the types of "terms" used in Dublin Core metadata descriptions and including support for formal domains and ranges for properties. The declaration of a vocabulary of classes and their use as domains and ranges for DCMI properties is the focus of a separate Public Comment period.
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Changed the definition of 'vocabulary encoding scheme' -- defined in 2005 as "a class that indicates that the value of a property is taken from a controlled vocabulary" -- to mean "an enumerated set of resources" of which the value is a member. (A value can be described as an instance of a class by other means, such as by a separate statement to this effect).
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Updated the definition of 'rich representation', adding the notion of 'media type'.
Other editorial changes
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Tightened the definition of 'syntax encoding scheme', explicitly mapping the concept to the RDF Schema class 'Datatype'.
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Tightened terminology and wordings to clarify meaning (e.g., by consistently using phrases instead of sentences for definitions; by referring to 'described resource' instead of just 'resource'; by using the phrase "separate 'description' about the 'value'" instead of a modeling entity for 'separate description').
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Shortened the document by removing sections describing related issues such as 'dumb-down' (formerly Section 5), 'structured values' (formerly Appendix A), and specific encoding guidelines (formerly Appendixes B, C, and D). Much of this material will be provided in revised form in more user-oriented documentation.
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Added a table mapping current Abstract Model terminology to the terminology in legacy DCMI "grammatical principles" documentation (now Appendix A).
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Permitted a value string to be associated with either a language tag or syntax encoding scheme, or neither, but not both.
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Added a note to the effect that classes can be declared explicitly or inferred from the domains and ranges of properties. Dropped the guideline that in DCMI metadata descriptions, the class of the resource being described should be indicated by the value of the Dublin Core Type property.
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Simplified the Description Model, removing 'marked-up text' and 'structured value string' as separate entities and rearranging the diagram to improve readability.
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Added placeholder URIs identifying DCMI Abstract Model entities in a new DCMI namespace. The corresponding revision of the DCMI Namespace Policy is the focus of a separate Public Comment period.
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Replaced QNames throughout the document with full URIs.