HTML and CSS Reference
In-Depth Information
The
Dublin Core Metadata Element Set
defines the 15 fundamental elements of Dublin Core, including
contributor
,
coverage
,
creator
,
date
,
description
,
format
,
identifier
,
language
,
publisher
,
relation
,
rights
,
source
,
subject
,
title
, and
type
[106]. If these elements are used exclusively, we are talking about
Simple Dublin
Core
. The extended set of elements is a higher level of Dublin Core called
Qualified Dublin Core
, which provides
more specific elements. In addition to the general rules of Simple Dublin Core, further rules apply for Qualified
Dublin Core. Qualified Dublin Core properties can be not only the 15 Dublin Core elements but also other elements
recommended by the Dublin Core Metadata Initiative or DCMI element refinements. Optionally, Qualified Dublin
Core values might have associated encoding schemes, each of which is identified by a name. Element refinements are
handled similarly to properties (element refinement name associated with a Dublin Core namespace).
Dublin Core Namespaces
Dublin Core namespaces can be declared by the
rel
attribute on the (X)HTML
link
element or with the
xmlns
attribute in XML. The (X)HTML declaration consists of a prefix and a namespace URI (see Listing 7-31).
Listing 7-31.
A Dublin Core Namespace Declaration
<link rel="schema.DC" href="
http://purl.org/dc/elements/1.1/
" />
The namespace URIs of all DCMI properties, classes, and encoding schemes are defined by the following DCMI
namespace URIs [107]:
•
Classes in the DCMI Type Vocabulary
•
Terms used in the DCMI Abstract Model
•
The Dublin Core Metadata Element Set, Version 1.1 (the 15 original elements)
•
All other DCMI properties, classes, and encoding schemes
The DCMI Abstract Model also applies some semantic concepts of the Resource Description Framework and
RDF Schema (RDFS), including
resource
,
property
/
element
,
class
,
syntax encoding scheme
, some relationships
(
has domain
,
has range
,
sub-property of
,
sub-class of
), and the concept of plain and typed value strings [108].
Simple Dublin Core
Dublin Core records consist of one or more properties and their associated property values (Listing 7-32).
Listing 7-32.
A DC Property (
Creator
) and a Value Associated with It (
John Smith
)
<meta
name="DC.Creator" content="John Smith"
/>
Each property should be an element from the
Dublin Core Metadata Element Set
. All properties are optional
and may be repeated [109]. The DC property values are considered as literal strings and might have an associated
language (for example,
en-US
). Dublin Core records and the resources they are applied to are not linked; however,
such a linkage can optionally be provided by the
identifier
element with the resource URI as the property value
(Listing 7-33).
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