Dublin Core

Dublin Core Metadate Initiative (DCMI) is a standard for define metadata used in documents such as eBooks. It is used in ePUB and other document formats. It is supported by XMP.

example

A simple example is shown below

 <metadata xmlns:dc="http://purl.org/dc/elements/1.1/"
              xmlns:opf="http://www.idpf.org/2007/opf">
         <dc:title>Alice in Wonderland</dc:title>
         <dc:language>en</dc:language>
         <dc:identifier id="BookId" opf:scheme="ISBN">
          123456789X
         </dc:identifier>
         <dc:creator opf:role="aut">Lewis Carroll</dc:creator>
 </metadata>

The dc prefix means that this is from Dublin Core specification.

The model

Dublin Core uses property-pair values to describe elements of metadata. As can be seen in the example a typical meta data item follows the html/xml standards of a tag inside matching "< >" and "</ >" with the definition inside the the pair. If an explanation of the data is needed then a property=value pair is used inside the opening "< >". The value portion of the property/value pair is usually literal but can also be a reference such as a URL. There should only be one value for a property. Both tags and property names are predefined in the DC specification.

Entries are not limited to a single value. For example if there are two primary authors the entire creator entry can be repeated.

The language is a required entry for metadata and the data is consistent with the language specified and assumes an available character set in the language has been specified earlier.

The Dublin Core Metadata Element Set is a vocabulary of fifteen properties for use in resource description. These 15 properties are approved as ISO/ANSI/IETF RFC standards.

Useful data elements

The following items are very useful for eBooks. Multiple entries may be used. These are part of the official 15 Dublin Core elements recognized by the W3C unless marked.

• dc:contributor -> Contributors to the resource (other than the authors; roles like illustrator, editor, ...).
• dc:coverage -> The location, spatial, or jurisdiction of this item (not used much in eBooks)
• dc:creat or -> The primary authors, creators, of the resource (listed in order of precedence, if significant). This could also be the company or organization.
• dc:date -> Date that something interesting happened to the resource. Could be a temporal range, should be listed using [W3CDTF] http://www.w3.org/TR/NOTE-datetime format.
• dcterms:modified -> a required metadata item for ePub 3 to show the date the ePub was modified. It is inside a meta tag.
• dc:description -> A textual description of the content of the eBook. Multiple values may be present for different languages. This may be used by dealers to describe and promote the book. There is also a dcterms:description.
• dc:format -> The MIME type or format, Usually not used in eBooks since this is a given. It sometimes contains the dimensions. It is also available in dcterms.
• dc:identifier ->Text defining a unique identifier of the resource. Also in dcterms.
• dc:language -> Locale, languages used in document, per RFC 4646
• dc:publisher -> External Publishers making the resource available.
• dc:relation -> Text relationships to other documents such as a member of a series.
• dc:rights -> Informal rights statement (copyrights), selected by language. Also in dcterms.
• dc:source -> Unique identifier of the work from which this resource was derived. Needed for translations. Also in dcterms.
• dc:subject -> genre, also in dcterms.
• dc:title -> The title of the document, or the name given to the resource. Typically, it will be a name by which the resource is formally known. Also in dcterms
• dc:type -> A document type; for example, novel, poem, or working paper. DCMI Type Vocabulary recommended.

Terms

The following is extracted from the Dublin Core Wiki. The main difference between the legacy namespace and the terms namespace is the definition of ranges for most terms of the last and the definition of a domain for some of them.

Terms can have either literal or non-literal. In non-literal there is a reference entry that points to a collection of values instead of a single value. The literal value terms is the shorter of the two lists and most applicable to eBook metadata. It includes:

dcterms:alternative - alternative or extended title
dcterms:available - a date range such as 2006-07
dcterms:bibliographicCitation - A single citation
dcterms:created - A date, could be approximate or qualified with "before" or other text.
dcterms:date - a date used to identify the document.
dcterms:dateAccepted - a date
dcterms:dateCopyrighted - a date
dcterms:dateSubmitted - a date
dcterms:identifier
dcterms:issued - a date
dcterms:modified - used with a date to show when the eBook was last modified.
dcterms:title - The title
dcterms:valid - a date range

For more information

• http://dublincore.org/
• http://dublincore.org/specifications/
• http://dublincore.org/documents/abstract-model/
• http://dublincore.org/documents/dces/ - The 15 ISO approved Metadata Element Set entries.
• http://wiki.dublincore.org/index.php/Main_Page Dublin Core Wiki
• http://id.loc.gov/vocabulary/relators.html Relators defines roles of contributors that can be in dublin core role entry.