|Creators:||DCMI Usage Board|
|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 These principles were superseded in 2005 by the DCMI Abstract Model. This version is almost identical with an earlier version from 2003. The first version was published in 2002.|
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" .
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.
"Qualifiers" is the generic heading traditionally used for terms now usually referred to specifically as Element Refinements or Encoding Schemes.
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) . 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 . In DCMI practice, an Element Refinement refines just one parent DCMI property.
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 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 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 .
The Usage Board maintains the DCMI Type Vocabulary  -- 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.
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 .
 Usage Board process
 DCMI Namespace Policy
 RFC 2731
 DC-XML guidelines
 Expressing Qualified Dublin Core in RDF / XML
 Usage Guide
 DCMI Type Vocabulary
 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.
 DCMI Usage Board Review of Application Profiles