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Glossary:

The following are defined terms in this document:

• DCMI term
  A DCMI term is a metadata element or qualifier defined in a DCMI recommendation.  Each DCMI term is identified by a Uniform Resource Identifier (URI) within a DCMI namespace.
   
• DCMI namespace
  A DCMI namespace is a collection of DCMI terms.  Each DCMI namespace is identified by a URI.
   
• DCMI recommendation
  A DCMI recommendation is a human-readable document that defines one or more DCMI terms.
   
• DCMI term declaration
  A DCMI term declaration is the machine-processable representation of one or more DCMI terms, expressed in a schema language.
   

I. Introduction

The use of XML namespaces [XML-NAMES] for the formal identification of metadata entities is a convention intended to support Web-addressable concepts that can be used across applications, and hence promote the possibility of shared semantics.  DCMI adopts this convention for the identification of all DCMI terms.  This document specifies the conventions used for identifying existing DCMI namespaces and any that are added in the future.

II. Namespace URIs used by the DCMI

The URI of the namespace for the Dublin Core Metadata Element Set (version 1.1) is:

http://purl.org/dc/elements/1.1/

The URI of the namespace used for other DCMI terms (qualifiers and additional elements) is:

http://purl.org/dc/terms/

The URI of the namespace for the DCMI Type Vocabulary [DCMI-Type] is:

http://purl.org/dc/dcmitype/

All DCMI namespace URIs will resolve to the DCMI term declaration for all the terms within that namespace.

The URI for each DCMI term is constructed by appending the term name to the namespace URI for that term.  For example:

http://purl.org/dc/elements/1.1/title

is the URI for the Title element in the Dublin Core Metadata Element Set (version 1.1).  Each DCMI term can be so identified.

The three currently approved DCMI namespace URIs are:

http://purl.org/dc/elements/1.1/	Dublin Core Metadata Element Set (version 1.1) (15 core elements)
http://purl.org/dc/terms/	Other DCMI terms (qualifiers and additional elements)
http://purl.org/dc/dcmitype/	DCMI Type Vocabulary (a DCMI controlled vocabulary)

Future DCMI namespace URIs will conform to this pattern:

http://purl.org/dc/namespace_label/

III. Policy concerning classes of changes to DCMI terms

Changes to DCMI terms or term declarations will occur from time to time for a variety of reasons. Such changes have varying implications for DCMI namespaces.  The following classes of changes are identified along with examples and associated implications for namespaces.

A. Minor editorial errata

Errors of spelling, punctuation, or other clerical mistakes discovered in DCMI recommendations and/or DCMI term declarations will be corrected without a comment period, following notification to the DCMI Usage Board [DCMI-USAGE], as long as, in the judgment of the DCMI directorate, there are no implications for negative impact on users or applications that rely on those DCMI term declarations.

Correction of minor editorial errata will result in no changes in DCMI namespace URIs.

B. Substantive editorial errata

Errors of substance discovered in DCMI recommendations and/or DCMI term declarations will trigger public notification of the correction to the general information email server (DC-General).   Errors that, in the judgment of the DCMI Directorate, compromise the immediate usefulness or accuracy of DCMI metadata systems will be corrected immediately (for example, an incorrect URL to a resource external to DCMI).  Others will be corrected following a 14-day public comment period to assure that changes do not adversely effect systems or applications which rely on the DCMI namespace infrastructure.

Correction of substantive editorial errata will result in no changes in DCMI namespace URIs.

C. Semantic changes in DCMI terms

Changes of definitions within DCMI recommendations and/or DCMI term declarations will be reflected in the affected DCMI recommendation and/or DCMI term declaration. If, in the judgment of the DCMI Directorate, such changes of meaning are likely to have substantial impact on either machine processing of DCMI terms or the functional semantics of the terms, then these changes will be reflected in a change of name or namespace for the DCMI term or terms in question.

D. Addition of DCMI term declarations to existing DCMI metadata packages

New terms will occasionally be added to existing DCMI namespaces.  Such additions will be uncommon for the Dublin Core Metadata Element Set, and somewhat more frequent for controlled vocabularies.

Addition of DCMI terms to existing namespaces will not trigger changes in namespace URIs.

IV. Persistence Policy

The DCMI recognizes that people and applications depend on the persistence of formal documents and machine processable schemas that have been made publicly available. In particular, the stability of namespace URIs for metadata terms is critical to interoperability over time. Thus, the wide promulgation of this set of URIs dictates that they be maintained to support legacy applications that have adopted them.

All DCMI namespaces adhere to the DCMI Persistence Policy [DCMI-PERSIST].

References

[XML-NAMES] Namespaces in XML, W3C Recommendation, 14 January 1999
http://www.w3.org/TR/REC-xml-names

[DCMI-TYPE] DCMI Type Vocabulary, DCMI Recommendation, 11 July 2000
http://dublincore.org/documents/dcmi-type-vocabulary/

[DCMI-USAGE] DCMI Usage Board

[DCMI-PERSIST] DCMI Persistence Policy
http://dublincore.org/about/persistence