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DCMI Grammatical Principles

Title: DCMI Grammatical Principles (SUPERSEDED, SEE DCMI Abstract Model)
Creator: DCMI Usage Board
Latest version:
Date modified: 2007-12-03
Description: This document describes the grammatical principles
                     that governed decisions of the Usage Board in
                     2003 and 2004. These principles were superseded in
                     2005 by the DCMI Recommendation DCMI Abstract Model.
                     The text of this document is identical to the text
                     of the 2003-11-18 version.

  1. Scope of this grammar

This grammar presents the typology of DCMI metadata terms and describes the principles underlying their definition and use. As defined in the "Namespace Policy for the Dublin Core", a DCMI term is "a DCMI element, a DCMI qualifier or term from a DCMI-maintained controlled vocabulary." A DCMI namespace, in turn, is "a collection of DCMI terms" [2].

  1. Elements and qualifiers

2.1. Elements

An Element is a property of a resource. As intended here, "properties" are attributes of resources -- characteristics that a resource may "have", such as a Title, Publisher, or Subject.

2.2. Qualifiers

"Qualifiers" is the generic heading traditionally used for terms now usually referred to specifically as Element Refinements or Encoding Schemes.

2.2.1. Element Refinements. An Element Refinement is a property of a resource which shares the meaning of a particular DCMI Element but with narrower semantics. In some application environments (notably HTML-based encodings), Element Refinements are used together with Elements in the manner of natural-language "qualifiers" (i.e., adjectives) [3]. However, since Element Refinements are properties of a resource (like Elements), Element Refinements can alternatively be used in metadata records independently of the properties they refine [9]. In DCMI practice, an Element Refinement refines just one parent DCMI property.

2.2.2. Encoding Schemes. An Encoding Scheme provides contextual information or parsing rules that aid in the interpretation of a term value. Such contextual information may take the form of controlled vocabularies, formal notations, or parsing rules. If an Encoding Scheme is not understood by a client or agent, the value may still be useful to a human reader. There are two types of Encoding Scheme: Vocabulary Encoding Schemes Vocabulary Encoding Schemes indicate that the value is a term from a controlled vocabulary, such as the value "China - History" from the Library of Congress Subject Headings. Syntax Encoding Schemes Syntax Encoding Schemes indicate that the value is a string formatted in accordance with a formal notation, such as "2000-01-01" as the standard expression of a date.

2.3. Dumb-down Principle

The qualification of Dublin Core Elements is guided by a rule known colloquially as the Dumb-Down Principle. According to this rule, a client should be able to ignore any qualifier and use the value as if it were unqualified. While this may result in some loss of specificity, the remaining term value (minus the qualifier) must continue to be generally correct and useful for discovery. Qualification is therefore supposed only to refine, not extend the semantic scope of an Element.

2.4. Appropriate values

Best practice for a particular Element or Qualifier may vary by context. Definitions may provide some guidance; other information may be found in the Usage Guide [6].

3. Vocabulary Terms

The Usage Board maintains the DCMI Type Vocabulary [7] -- a general, cross-domain list of recommended terms that may be used as values for the Resource Type element to identify the genre of a resource. The member terms of the DCMI Type Vocabulary are called Vocabulary Terms.

If a Vocabulary Term is hierarchically related to another Vocabulary Term, the relationship indicators "Broader Than" and "Narrower Than" are used reciprocally in their term declarations.

  1. Application Profiles

In DCMI usage, an Application Profile is a declaration of which metadata terms an organization, information resource, application, or user community uses in its metadata [10].


[1] [2] [3] [4] [5] [6] [7] [8] [9] A shift from the former view to the latter is reflected in the names assigned by the Usage Board to Element Refinements, with a move away from adjective-like names such as "created" (approved in July 2000) towards noun-phrase-like names such as "dateCopyrighted" (approved in July 2002). One consequence of using Element Refinements independently of Elements is that information about relationships between them will reside outside of the metadata records in separate schemas that applications needing to perform operations such as dumb-down will need to consult. [10]