Dublin Core Metadaten

Dieses Dokument beschreibt das "Dublin Core Metadata Set", wie es im Projekt SSG-FI an der SUB Göttingen benutzt wird. Dieses Dokument besteht aus zwei Teilen, die die benutzte Syntax (auf deutsch) und die Semantik (auf englisch) von Dublin Core beschreiben. Die Zweisprachigkeit ergibt sich daraus, daß im ersten Teil beschrieben wird, was im Projekt implementiert wurde, während der zweite Teil eine Zusammenstellung aus Dokumenten der verschiedenen Dublin Core Arbeitsgruppen ist, die auf englisch veröffentlicht wurden.

Hauptquellen:

Dublin Core Metadata Element Set: Reference Description
(http://purl.oclc.org/metadata/dublin_core_elements)
Dublin Core Sub-elements (Paul Miller)
(http://www.mailbase.ac.uk/lists/dc-subelements/files/helsinki.html)
Dublin Core Qualifiers/Substructure (Rebecca Guenther)
(http://www.loc.gov/marc/dcqualif.html)
Tags for the Identification of Languages (H. Alvestrand)
(http://www.ietf.org/rfc/rfc1766.txt)
DUBLIN CORE ELEMENT: COVERAGE (Ad Hoc Working Group: Coverage Element)
(http://www.sdc.ucsb.edu/~mary/coverage.htm)

1. Die Syntax von Dublin Core in HTML

Die Dublin Core-Syntax im allgemeinen und zur Implementierung in HTML im besonderen ist (noch) nicht festgelegt, es bilden sich aber Regeln heraus, an denen sich das SSG-FI-Projekt orientiert.

Für die Beschreibung von HTML-Dokumenten ist im Kopf-Bereich (Header) die sogenannte Meta-Marke (Meta Tag) vorgesehen. Das Meta-Marke hat die Syntax

es wird also der Name und Inhalt der Meta-Marke in Anführungszeichen angegeben. Dieser Mechanismus wird für die Einfügung von Dublin-Core-Informationen in HTML angewandt und modifiziert.

Die Dublin Core Beschreibung besteht aus 15 Kategorien (elements), die jeweils Namen und Wert (contents) haben und durch zusätzliche Eigenschaften (qualifiers) verfeinert werden können. Der derzeitige Standard sind die drei sogenannten "Canberra Qualifiers" (nach DC4): SCHEME, TYPE und LANG (Schema, Typ und Sprache). Eine Sonderrolle nimmt TYPE ein: Diese Eigenschaft wird jetzt als Unterkategorie (Sub-element) bezeichnet und mit einer besonderen (Punkt-) Syntax angegeben.

Die Eigenschaften SCHEME und LANG werden einfach zusätzlich mit Werten in Anführungszeichen in das Meta-Tag eingefügt.
Beispiele:

Die Eigenschaften ROLE und FLAG sind derzeit nicht mehr in der Diskussion.

Die Unterkategorien werden mit einem Punkt getrennt an den Namen der DC-Kategorie angehängt. Dabei sollen keine Leerzeichen, Bindestriche oder Unterstreichungen benutzt werden, sondern die einzelnen Wörter mit großen Anfangsbuchstaben direkt aneinander gehängt werden. Darüber, ob das erste Wort groß oder klein geschrieben wird, gibt es unterschiedliche Angaben; von Dublin Core wird klein empfohlen, in Paul Millers Papier groß; im SSG-FI-Projekt werden Großbuchstaben bevorzugt.
Beispiele:

Damit ergeben sich insgesamt Ausdrücke der Art:

<META NAME="DC.Creator.PersonalName " SCHEME= "LNCAF" CONTENT="Le Hors, Arnaud">

2. Die Semantik von Dublin Core

DC.Title The name given to the resource by the creator or publisher
Sub-Element: Alternative
DC.Creator The person or organization primarily responsible for creating the intellectual content of the resource. For example, authors in the case of written documents, artists, photographers, or illustrators in the case of visual resources.
Sub-Element: PersonalName,.PersonalName.Address, .CorporateName, .CorporateName.Address
Scheme: LCNAF (Library of Congress Name Authority File)
DC.Subject The topic of the resource. Typically, subject will be expressed as keywords or phrases that describe the subject or content of the resource. The use of controlled vocabularies and formal classification schemes is encouraged.
Scheme: Unqualified: Keyword is default, LCSH (Library of Congress Subject Headings), MeSH (Medical Subject Headings, AAT (Art and Architechture Thesaurus), LCNAF (Library of Congress Name Authority File): for names used as subjects, DDC (Dewey Decimal Classification), LCC (Library of Congress Classification), NLM (National Library of Medicine Classification), UDC (Universal Decimal Classification
DC.Description A textual description of the content of the resource, including abstracts in the case of document-like objects or content descriptions in the case of visual resources.
Scheme: Abstract is default, URL
DC.Publisher The entity responsible for making the resource available in its present form, such as a publishing house, a university department, or a corporate entity.
Sub-Element: As DC.Creator.
DC.Contributor A person or organization not specified in a creator element who has made significant intellectual contributions to the resource but whose contribution is secondary to any person or organization specified in a creator element (for example, editor, transcriber, and illustrator).
Sub-Element: As DC.Creator.
Scheme: LCNAF (Library of Congress Name Authority File) At DC4 it was decided that role was not needed. It has thus not been included here. If needed, it could be included as a local extension.
DC.Date The date the resource was made available in its present form. Recommended best practice is an 8 digit number in the form YYYY-MM-DD as defined in ISO 8601. In this scheme, the date element 1994-11-05 corresponds to November 5, 1994. Many other schema are possible, but if used, they should be identified in an unambiguous manner.
Scheme: (Default is ISO 8601), ANSI X3.30, IETF RFC 822, (Others?)
DC.Type The category of the resource, such as home page, novel, poem, working paper, technical report, essay, dictionary. For the sake of interoperability, type should be selected from an enumerated list that is under development in the workshop series at the time of publication of this document.
Scheme: list of types is planned, minimal: Text, Image, Sound, Software, Data, Interactive; see http://sunsite.berkeley.edu/Metadata/types.html for current thinking on the application of this element.
DC.Format The data format of the resource, used to identify the software and possibly hardware that might be needed to display or operate the resource. For the sake of interoperability, format should be selected from an enumerated list that is under development in the workshop series at the time of publication of this document.
Sub-Element: No sub-elements at present, although it was recommended that either an existing SCHEME (such as the Getty's Art & Architecture Thesaurus) or a new one be recommended in order to better control the use of this element.
Scheme: IMT (i.e. MIME), DCPMT (Dublin Core Physical Medium Type)
DC.Identifier String or number used to uniquely identify the resource. Examples for networked resources include URLs and URNs (when implemented). Other globally unique identifiers,such as International Standard Book Numbers (ISBN) or other formal names would also be candidates for this element in the case of off-line resources.
Scheme: URL is default, URN (Uniform Resource Name), ISBN (International Standard Book Number), ISSN (International Standard Serial Number), SICI (Serial Item and Contribution Identifier), FPI (Formal Public Identifier)
DC.Source A string or number used to uniquely identify the work from which this resource was derived, if applicable. For example, a PDF version of a novel might have a source element containing an ISBN number for the physical book from which the PDF version was derived.
Scheme: Free text is default, URL, URN, ISBN, ISSN
DC.Language Language(s) of the intellectual content of the resource. Where practical, the content of this field should coincide with RFC 1766.
Scheme: IETF RFC 1766, Z39.53, ISO 639-1, ISO 639-2/B (after final publication)
DC.Relation The relationship of this resource to other resources. The intent of this element is to provide a means to express relationships among resources that have formal relationships to others, but exist as discrete resources themselves. For example, images in a document, chapters in a book, or items in a collection. Formal specification of relation is currently under development. Users and developers should understand that use of this element is currently considered to be experimental.
Scheme: Default is free text, URL, URN, ISBN
DC.Coverage The spatial and/or temporal characteristics of the resource. Formal specification of coverage is currently under development. Users and developers should understand that use of this element is currently considered to be experimental
Sub-Element: DC.Coverage.PeriodName, DC.Coverage.PlaceName, DC.Coverage.t, DC.Coverage.x, DC.Coverage.y, DC.Coverage.z, DC.Coverage.Polygon, DC.Coverage.Line, DC.Coverage.3d
DC.Rights A link to a copyright notice, to a rights-management statement, or to a service that would provide information about terms of access to the resource. Formal specification of rights is currently under development. Users and developers should understand that use of this element is currently considered to be experimental.
Scheme: Default is free text, URL, URN

© SSG-FI @ SUB Göttingen, 1997/98. Last update: May 14, 1998