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+ <title>Resource Description Framework (RDF): Concepts and Abstract Syntax</title>
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+ <a href="http://www.w3.org/"><img height="48" width="72" alt=
+ "W3C" src="http://www.w3.org/Icons/w3c_home" /></a>
+
+ <h1 id="title">Resource Description Framework (RDF):<br />
+ Concepts and Abstract Syntax</h1>
+
+ <h2 id="doctype">W3C Recommendation 10 February 2004</h2>
+
+
+
+
+ <dl>
+ <dt>This version:</dt>
+
+ <dd><a href=
+ "http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/">
+http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/</a></dd>
+
+ <dt>Latest version:</dt>
+
+ <dd><a href=
+ "http://www.w3.org/TR/rdf-concepts/">http://www.w3.org/TR/rdf-concepts/</a></dd>
+
+ <dt>Previous version:</dt>
+
+ <dd><a href=
+ "http://www.w3.org/TR/2003/PR-rdf-concepts-20031215/">http://www.w3.org/TR/2003/PR-rdf-concepts-20031215/</a></dd>
+
+ <dt>Editors:</dt>
+
+ <dd><a href="http://www.ninebynine.org/">Graham Klyne</a> (Nine
+ by Nine), <<a href=
+ "mailto:GK@NineByNine.org">gk@ninebynine.org</a>></dd>
+
+ <dd><a href="http://www-uk.hpl.hp.com/people/jjc/">Jeremy J.
+ Carroll</a> (Hewlett Packard Labs), <<a href=
+ "mailto:jjc@hpl.hp.com">jjc@hpl.hp.com</a>></dd>
+
+ <dt>Series editor:</dt>
+
+ <dd><a href="http://www-uk.hpl.hp.com/people/bwm/">Brian
+ McBride</a> (Hewlett Packard Labs) <<a href=
+ "mailto:bwm@hplb.hpl.hp.com">bwm@hplb.hpl.hp.com</a>></dd>
+ </dl>
+
+
+
+
+
+
+
+
+<p>Please refer to the <a
+href="http://www.w3.org/2001/sw/RDFCore/errata#rdf-concepts"><strong>errata</strong></a>
+for this document, which may include some normative corrections.</p>
+
+<p>See also <a href="http://www.w3.org/2001/sw/RDFCore/translation/rdf-concepts">translations</a>.</p>
+
+<p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"> Copyright</a> © 2004 <a href="http://www.w3.org/"><acronym title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><acronym title="Massachusetts Institute of Technology">MIT</acronym></a>, <a href="http://www.ercim.org/"><acronym title="European Research Consortium for Informatics and Mathematics">ERCIM</acronym></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>, <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>, <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document use</a> and <a href="http://www.w3.org/Consortium/Legal/copyright-software">software licensing</a> rules apply.</p>
+
+ <hr title="Separator for header" />
+ </div>
+
+ <h2 class="nonum"><a id="abstract" name=
+ "abstract">Abstract</a></h2>
+
+ <p>The Resource Description Framework (RDF) is a framework for
+ representing information in the Web.</p>
+ <p>RDF Concepts and Abstract Syntax defines an abstract syntax
+ on which RDF is based, and which serves to link its concrete
+ syntax to its formal semantics. It also includes discussion of
+ design goals, key concepts, datatyping, character normalization
+ and handling of URI references.</p>
+
+<div class="status">
+
+<h2 class="nonum">
+<a id="status" name="status">Status of this Document</a>
+</h2>
+<!-- Start Status-Of-This-Document Text -->
+
+<p>This document has been reviewed by W3C Members and other interested
+parties, and it has been endorsed by the Director as a <a
+href="http://www.w3.org/2003/06/Process-20030618/tr.html#RecsW3C">W3C
+Recommendation</a>. W3C's role in making the Recommendation is to
+draw attention to the specification and to promote its widespread
+deployment. This enhances the functionality and interoperability of
+the Web.</p>
+
+<p>This is one document in a <a
+href="http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/#section-Introduction">set
+of six</a> (<a
+href="http://www.w3.org/TR/2004/REC-rdf-primer-20040210/">Primer</a>,
+<a
+href="http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/">Concepts</a>,
+<a
+href="http://www.w3.org/TR/2004/REC-rdf-syntax-grammar-20040210/">Syntax</a>,
+<a
+href="http://www.w3.org/TR/2004/REC-rdf-mt-20040210/">Semantics</a>,
+<a
+href="http://www.w3.org/TR/2004/REC-rdf-schema-20040210/">Vocabulary</a>,
+and <a
+href="http://www.w3.org/TR/2004/REC-rdf-testcases-20040210/">Test
+Cases</a>) intended to jointly replace the original Resource
+Description Framework specifications, <a
+href="http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/">RDF Model and Syntax (1999
+Recommendation)</a> and <a
+href="http://www.w3.org/TR/2000/CR-rdf-schema-20000327/">RDF Schema
+(2000 Candidate Recommendation)</a>. It has been developed by the <a
+href="http://www.w3.org/2001/sw/RDFCore/">RDF Core Working Group</a>
+as part of the <a href="http://www.w3.org/2001/sw/">W3C Semantic Web
+Activity</a> (<a href="http://www.w3.org/2001/sw/Activity">Activity
+Statement</a>, <a
+href="http://www.w3.org/2002/11/swv2/charters/RDFCoreWGCharter">Group
+Charter</a>) for publication on 10 February 2004.
+</p>
+
+<p>Changes to this document since the <a
+href="http://www.w3.org/TR/2003/PR-rdf-concepts-20031215/"
+shape="rect">Proposed Recommendation Working Draft</a> are detailed in
+the <a href="#changes" shape="rect">change log</a>. </p>
+
+<p> The public is invited to send comments to <a
+href="mailto:www-rdf-comments@w3.org">www-rdf-comments@w3.org</a> (<a
+href="http://lists.w3.org/Archives/Public/www-rdf-comments/">archive</a>)
+and to participate in general discussion of related technology on <a
+href="mailto:www-rdf-interest@w3.org"
+shape="rect">www-rdf-interest@w3.org</a> (<a
+href="http://lists.w3.org/Archives/Public/www-rdf-interest/"
+shape="rect">archive</a>). </p>
+
+<p>A list of <a href="http://www.w3.org/2001/sw/RDFCore/impls">
+implementations</a> is available.</p>
+
+<p>The W3C maintains a list of <a href="http://www.w3.org/2001/sw/RDFCore/ipr-statements"
+rel="disclosure">any patent disclosures related to this work</a>.</p>
+
+<p><em>This section describes the status of this document at the time of its
+publication. Other documents may supersede this document. A list of current W3C
+publications and the latest revision of this technical report can be found in
+the <a href="http://www.w3.org/TR/">W3C technical reports index</a> at
+http://www.w3.org/TR/.</em></p>
+
+<!-- End Status-Of-This-Document Text -->
+
+</div>
+
+
+ <div class="toc">
+ <h2 class="nonum"><a id="contents" name="contents">Table of
+ Contents</a></h2>
+
+ <ul class="toc">
+ <li class="tocline">
+ <a href="#section-Introduction"><strong>1.
+ Introduction</strong></a>
+
+ <ul class="toc">
+ <li class="tocline"><a href="#section-Structure">1.1
+ Structure of this Document</a></li>
+
+ </ul>
+ </li>
+
+ <li class="tocline">
+ <a href="#section-Overview"><strong>2. Motivations and Goals</strong></a>
+
+ <ul class="toc">
+ <li class="tocline"><a href="#section-motivation">2.1
+ Motivation</a></li>
+
+ <li class="tocline">
+ <a href="#section-design-goals">2.2 Design Goals</a>
+
+ <ul class="toc">
+ <li class="tocline"><a href="#section-simple-data-model">2.2.1 A
+ Simple Data Model</a></li>
+
+ <li class="tocline"><a href="#section-formal-semantics">2.2.2 Formal
+ Semantics and Inference</a></li>
+
+ <li class="tocline"><a href="#section-extensible-vocab">2.2.3
+ Extensible URI-based Vocabulary</a></li>
+
+ <li class="tocline"><a href="#section-xml-serialization">2.2.4
+ XML-based Syntax</a></li>
+
+ <li class="tocline"><a href="#section-use-xsd">2.2.5 Use
+ XML Schema Datatypes</a></li>
+
+ <li class="tocline"><a href="#section-anyone">2.2.6 Anyone
+ Can Make Statments About Any Resource</a></li>
+
+ </ul>
+ </li>
+</ul>
+</li>
+
+ <li class="tocline">
+ <a href="#section-Concepts"><strong>3. RDF Concepts</strong></a>
+
+ <ul class="toc">
+ <li class="tocline"><a href="#section-data-model">3.1 Graph
+ Data Model</a></li>
+
+ <li class="tocline"><a href=
+ "#section-URI-Vocabulary">3.2 URI-based Vocabulary
+ and Node Identification</a></li>
+
+ <li class="tocline"><a href="#section-Datatypes-intro">3.3
+ Datatypes</a></li>
+
+ <li class="tocline"><a href="#section-Literals">3.4
+ Literals</a></li>
+
+
+ <li class="tocline"><a href=
+ "#section-SimpleFacts">3.5 RDF Expression of Simple
+ Facts</a></li>
+
+ <li class="tocline"><a href="#section-Entailment">3.6
+ Entailment</a></li>
+ </ul>
+ </li>
+ <li class="tocline"><a href="#section-URIspaces"><strong>4. RDF
+ Vocabulary URI and Namespace (Normative)</strong></a></li>
+ <li class="tocline">
+ <a href="#section-Datatypes"><strong>5. Datatypes (Normative)</strong></a>
+
+ <ul class="toc">
+ <li class="tocline"><a href="#section-XMLLiteral">5.1
+ XML Content within an RDF Graph</a></li>
+ </ul>
+ </li>
+
+ <li class="tocline">
+ <a href="#section-Graph-syntax"><strong>6. Abstract
+ Syntax (Normative)</strong></a>
+
+ <ul class="toc">
+ <li class="tocline"><a href="#section-triples">6.1 RDF
+ Triples</a></li>
+
+ <li class="tocline"><a href="#section-rdf-graph">6.2 RDF
+ Graph</a></li>
+
+ <li class="tocline"><a href="#section-graph-equality">6.3 Graph
+ Equivalence</a></li>
+
+ <li class="tocline"><a href="#section-Graph-URIref">6.4 RDF
+ URI References</a></li>
+
+ <li class="tocline">
+ <a href="#section-Graph-Literal">6.5 RDF Literals</a>
+
+ <ul class="toc">
+ <li class="tocline"><a href=
+ "#section-Literal-Equality">6.5.1 Literal
+ Equality</a></li>
+
+ <li class="tocline"><a href=
+ "#section-Literal-Value">6.5.2 The Value Corresponding
+ to a Typed Literal</a></li>
+ </ul>
+ </li>
+
+ <li class="tocline"><a href="#section-blank-nodes">6.6 Blank Nodes</a></li>
+ </ul>
+ </li>
+
+ <li class="tocline">
+ <a href="#section-fragID"><strong>7. Fragment Identifiers
+</strong></a>
+ </li>
+
+ <li class="tocline"><a href=
+ "#section-Acknowledgments"><strong>8.
+ Acknowledgments</strong></a></li>
+
+ <li class="tocline">
+ <a href="#section-References"><strong>9.
+ References</strong></a>
+
+ <ul class="toc">
+ <li class="tocline"><a href=
+ "#section-Normative-References">9.1 Normative
+ References</a></li>
+
+ <li class="tocline"><a href=
+ "#section-Informative-References">9.2 Informational
+ References</a></li>
+ </ul>
+ </li>
+
+ <li class="tocline">
+ <a href="#section-Revisions"><strong>A: Revisions Since Last Call Working Draft of 10 October 2003</strong></a>
+
+ </li>
+ </ul>
+
+ </div>
+ <hr />
+
+ <h2><a id="section-Introduction" name="section-Introduction">1.
+ Introduction</a></h2>
+
+ <p>The Resource Description Framework (RDF) is a framework for
+ representing information in the Web.</p>
+
+ <p>This document defines an abstract syntax on which RDF is based,
+ and which serves to link its concrete syntax to its formal
+ semantics.
+This abstract syntax is quite distinct from XML's tree-based infoset [<a
+ href="#ref-xml-infoset">XML-INFOSET</a>]. It also includes discussion of design goals,
+ key concepts, datatyping, character normalization
+ and handling of URI references.</p>
+
+ <p>Normative documentation of RDF falls into the following
+ areas:</p>
+
+ <ul>
+ <li>XML serialization syntax [<a href=
+ "#ref-rdf-syntax">RDF-SYNTAX</a>],</li>
+
+ <li>formal semantics [<a href=
+ "#ref-rdf-semantics">RDF-SEMANTICS</a>], and</li>
+
+ <li>this document, (sections 4, 5 and 6).</li>
+ </ul>
+
+ <p>Within this document, normative sections are explicitly labelled as such.
+Explicit notes are informative.</p>
+
+ <p>The framework is designed so that vocabularies can be layered.
+The RDF and RDF vocabulary definition (RDF schema)
+languages
+ [<a href="#ref-rdf-vocabulary">RDF-VOCABULARY</a>] are the first
+ such vocabularies.
+
+ Others (cf. OWL [<a href="#ref-owl">OWL</a>] and
+ the applications mentioned in the primer
+ [<a href=
+ "#ref-rdf-primer">RDF-PRIMER</a>]) are in development.</p>
+
+ <h3><a id="section-Structure" name="section-Structure">1.1
+ Structure of this Document</a></h3>
+
+ <p>In <a href="#section-Overview">section 2</a>,
+the background rationale and design goals
+are introduced.
+Key concepts follow in <a href="#section-Concepts">section 3</a>.
+<a href="#section-URIspaces">Section 4</a> discusses URI references
+reserved for use by RDF.
+</p>
+
+
+ <p><a href="#section-Datatypes">Section 5</a> discusses datatypes.
+XML content of
+ literals is described in <a href="#section-XMLLiteral">section
+ 5.1</a>, and the abstract syntax is defined in <a href=
+ "#section-Graph-syntax">section 6</a> of this document.</p>
+
+ <p><a href="#section-fragID">Section 7</a> discusses the role of fragment
+ identifiers in URI references used with RDF.</p>
+
+ <h2><a id="section-Overview" name="section-Overview">2. Motivations and Goals</a></h2>
+
+ <p>RDF has an abstract syntax that reflects a simple graph-based
+ data model, and formal semantics with a rigorously defined notion
+ of entailment providing a basis for well founded deductions in RDF
+ data.</p>
+
+ <h3><a id="section-motivation" name="section-motivation">2.1 Motivation</a></h3>
+
+ <p>The development of RDF has been motivated by the following uses,
+ among others:</p>
+
+ <ul>
+ <li>Web metadata: providing information about Web resources and
+ the systems that use them (e.g. content rating, capability
+ descriptions, privacy preferences, etc.)</li>
+
+ <li>Applications that require open rather than constrained
+ information models (e.g. scheduling activities, describing
+ organizational processes, annotation of Web resources, etc.)</li>
+
+ <li>To do for machine processable information (application data)
+ what the World Wide Web has done for hypertext: to allow data to
+ be processed outside the particular environment in which it was
+ created, in a fashion that can work at Internet scale.</li>
+
+ <li>Interworking among applications: combining data from several
+ applications to arrive at new information.</li>
+
+ <li>Automated processing of Web information by software agents:
+ the Web is moving from having just human-readable information to
+ being a world-wide network of cooperating processes. RDF provides
+ a world-wide lingua franca for these processes.</li>
+ </ul>
+
+ <p>RDF is designed to represent information in a minimally
+ constraining, flexible way. It can be used in isolated
+ applications, where individually designed formats
+ might be more direct and easily understood, but RDF's generality offers greater value from
+ sharing. The value of information thus increases as it becomes
+ accessible to more applications across the entire Internet.</p>
+
+ <h3><a id="section-design-goals" name="section-design-goals">2.2 Design Goals</a></h3>
+
+ <p>The design of RDF is intended to meet the following goals:</p>
+
+ <ul>
+ <li>having a simple data model</li>
+ <li>having formal semantics and provable inference</li>
+ <li>using an extensible URI-based vocabulary</li>
+ <li>using an XML-based syntax</li>
+ <li>supporting use of XML schema datatypes</li>
+ <li>allowing anyone to make statements about any
+ resource</li>
+ </ul>
+
+ <h4><a id="section-simple-data-model" name="section-simple-data-model">2.2.1 A Simple Data
+ Model</a></h4>
+
+ <p>RDF has a simple data model that is easy for applications to
+ process and manipulate. The data model is independent of any
+ specific serialization syntax.</p>
+
+ <p class="note"><strong>Note:</strong> the term "model" used here in "data model" has a
+ completely different sense to its use in the term "model theory".
+ See [<a href=
+ "#ref-rdf-semantics">RDF-SEMANTICS</a>]
+ for more information about "model
+ theory" as used in the literature of mathematics and logic.</p>
+
+ <h4><a id="section-formal-semantics" name="section-formal-semantics">2.2.2 Formal Semantics
+ and Inference</a></h4>
+
+ <p>RDF has a formal semantics which provides a dependable basis for
+ reasoning about the meaning of an RDF expression. In particular, it
+ supports rigorously defined notions of entailment which provide a
+ basis for defining reliable rules of inference in RDF data.</p>
+
+ <h4><a id="section-extensible-vocab" name="section-extensible-vocab">2.2.3 Extensible
+ URI-based Vocabulary</a></h4>
+
+ <p>The vocabulary is fully extensible, being based on URIs with
+ optional fragment identifiers (<cite>URI references</cite>, or
+ <cite>URIrefs</cite>). URI references are used for naming all kinds
+ of things in RDF.</p>
+
+ <p>The other kind of value that appears in RDF data is a
+ literal.</p>
+
+ <h4><a id="section-xml-serialization" name="section-xml-serialization">2.2.4 XML-based
+ Syntax</a></h4>
+
+ <p>RDF has a recommended XML serialization form [<a href=
+ "#ref-rdf-syntax">RDF-SYNTAX</a>], which can be used to encode the
+ data model for exchange of information among applications.</p>
+
+ <h4><a id="section-use-xsd" name="section-use-xsd">2.2.5 Use XML Schema
+ Datatypes</a></h4>
+
+ <p>RDF can use values represented according to XML schema datatypes
+ [<a href="#ref-xml-schema2">XML-SCHEMA2</a>], thus assisting the
+ exchange of information between RDF and other XML applications.</p>
+
+ <h4><a id="section-anyone" name="section-anyone">2.2.6 Anyone Can Make
+ Statements About Any Resource</a></h4>
+
+ <p>To facilitate operation at Internet scale, RDF is an
+ open-world framework that allows anyone to make statements
+ about any resource.</p>
+ <p>In general, it is not assumed that complete information
+ about any resource is available. RDF does not prevent anyone
+ from making assertions that are nonsensical or inconsistent
+ with other statements, or the world as people see it. Designers
+ of applications that use RDF should be aware of this and may
+ design their applications to tolerate incomplete or
+ inconsistent sources of information.</p>
+
+<!-- here -->
+ <h2><a id="section-Concepts" name="section-Concepts">3. RDF
+ Concepts</a></h2>
+
+ <p>RDF uses the following key concepts:</p>
+
+ <ul>
+ <li>Graph data model</li>
+
+ <li>URI-based vocabulary</li>
+
+ <li>Datatypes</li>
+
+ <li>Literals</li>
+
+ <li>XML serialization syntax</li>
+
+ <li>Expression of simple facts</li>
+
+ <li>Entailment</li>
+ </ul>
+
+ <h3><a id="section-data-model" name="section-data-model">3.1 Graph Data
+ Model</a></h3>
+
+ <p>The underlying structure of any expression in RDF is a
+ collection of triples, each consisting of a subject, a
+ predicate and an object. A set of such triples is called an RDF
+ graph (defined more formally in
+<a href="#section-Graph-syntax">section 6</a>). This can be
+ illustrated by a node and directed-arc diagram, in which each
+ triple is represented as a node-arc-node link (hence the term
+ "graph").</p>
+ <div class="block">
+ <p><img src="Graph-ex.gif"
+ alt="image of the RDF triple comprising (subject, predicate, object)"
+ height="72" width="361" /></p>
+ </div>
+ <p>Each triple represents a statement of a relationship between
+ the things denoted by the nodes that it links. Each triple has
+ three parts:</p>
+ <ol>
+ <li>a <a href="#dfn-subject">subject</a>,</li>
+ <li>an <a href="#dfn-object">object</a>, and</li>
+ <li>a <a href="#dfn-predicate">predicate</a> (also called a
+ <a href="#dfn-property">property</a>) that denotes a
+ relationship.</li>
+ </ol>
+ <p>The direction of the arc is significant: it always points
+ toward the object.</p>
+ <p>The <a href="#section-Graph-Node">nodes</a> of an RDF graph
+ are its subjects and objects.</p>
+ <p>The assertion of an RDF triple says that some relationship,
+ indicated by the predicate, holds between the things denoted by
+ subject and object of the triple. The assertion of an RDF graph
+ amounts to asserting all the triples in it, so the meaning of
+ an RDF graph is the conjunction (logical AND) of the statements
+ corresponding to all the triples it contains. A formal account
+ of the meaning of RDF graphs is given in [<a
+ href="#ref-rdf-semantics">RDF-SEMANTICS</a>].</p>
+
+
+ <h3><a id="section-URI-Vocabulary" name=
+ "section-URI-Vocabulary">3.2 URI-based Vocabulary and Node
+ Identification</a></h3>
+
+
+ <p>A node may be a URI with optional fragment identifier (<a
+ href="#dfn-URI-reference">URI reference</a>, or <dfn><a
+ id="dfn-URIref" name="dfn-URIref">URIref</a></dfn>), a literal,
+ or blank (having no separate form of identification).
+ Properties are <cite>URI references</cite>. (See [<a
+ href="#ref-uris">URI</a>], section 4, for a description of URI
+ reference forms, noting that relative URIs are not used in an
+ RDF graph. See also <a href="#section-Graph-URIref">section
+ 6.4</a>.)</p>
+ <p>A URI reference or literal used as a node identifies what
+ that node represents. A URI reference used as a predicate
+ identifies a relationship between the things represented by the nodes it connects. A
+ predicate URI reference may also be a node in the graph.</p>
+ <p>A <a href="#dfn-blank-node">blank node</a> is a node that is
+ not a URI reference or a literal. In the RDF abstract syntax, a
+ blank node is just a unique node that can be used in one or
+ more RDF statements, but has no intrinsic name.</p>
+ <p>A convention used by some linear representations of an RDF
+ graph to allow several statements to reference the same
+ unidentified resource is to use a <dfn><a
+ id="dfn-blank-node-id" name="dfn-blank-node-id">blank node
+ identifier</a></dfn>, which is a local identifier that can be
+ distinguished from all URIs and literals. When graphs are
+ merged, their blank nodes must be kept distinct if meaning is
+ to be preserved; this may call for re-allocation of blank node
+ identifiers. Note that such blank node identifiers are not part
+ of the RDF abstract syntax, and the representation of triples
+ containing blank nodes is entirely dependent on the particular
+ concrete syntax used.</p>
+
+
+ <h3><a name="section-Datatypes-intro" id="section-Datatypes-intro">3.3
+ Datatypes</a></h3>
+
+ <p>Datatypes are used by RDF in the representation of values such
+ as integers, floating point numbers and dates.</p>
+
+ <p>
+A datatype consists of a lexical space, a value space and a lexical-to-value
+mapping, see <a href="#section-Datatypes">section 5</a>.
+</p>
+
+ <p>For example, the lexical-to-value mapping for the XML Schema datatype
+ <var>xsd:boolean</var>, where each member of the value space
+ (represented here as 'T' and 'F') has two lexical representations,
+ is as follows:</p>
+
+ <table border="1" cellpadding="5" summary=
+ "A table detailing the xsd:boolean datatype.">
+ <tr>
+ <th align="left">Value Space</th>
+
+ <td>{T, F}</td>
+ </tr>
+
+ <tr>
+ <th align="left">Lexical Space</th>
+
+ <td>{"0", "1", "true", "false"}</td>
+ </tr>
+
+ <tr>
+ <th align="left">Lexical-to-Value Mapping</th>
+
+ <td>{<"true", T>, <"1", T>, <"0", F>,
+ <"false", F>}</td>
+ </tr>
+ </table>
+
+ <p>RDF predefines just one datatype <a href=
+ "#dfn-rdf-XMLLiteral" class="code">rdf:XMLLiteral</a>, used for
+ embedding XML in RDF (see <a href="#section-XMLLiteral">section
+ 5.1</a>).</p>
+
+ <p>There is no built-in concept of numbers or dates or other common
+ values. Rather, RDF defers to datatypes that are defined
+ separately, and identified with URI references.
+ The predefined XML Schema
+ datatypes [<a href="#ref-xml-schema2">XML-SCHEMA2</a>] are expected
+ to be widely used for this purpose.</p>
+
+
+ <p>RDF provides no mechanism for defining new datatypes. XML Schema
+ Datatypes [<a href="#ref-xml-schema2">XML-SCHEMA2</a>] provides an
+ extensibility framework suitable for defining new datatypes for use
+ in RDF.</p>
+
+ <h3><a name="section-Literals" id="section-Literals">3.4
+ Literals</a></h3>
+
+ <p>Literals are used to identify values such as numbers and dates
+ by means of a lexical representation. Anything represented by a
+ literal could also be represented by a URI, but it is often more
+ convenient or intuitive to use literals.</p>
+
+ <p>A literal may be the object of an RDF statement, but not the
+ subject or the predicate.</p>
+
+ <p>Literals may be <cite>plain</cite> or <cite>typed</cite> :</p>
+
+ <ul>
+ <li>A <a href="#dfn-plain-literal" >plain literal</a> is a string combined
+ with an optional language tag. This may be used for
+ plain text in a natural language. As recommended in the RDF
+ formal semantics [<a href=
+ "#ref-rdf-semantics">RDF-SEMANTICS</a>], these plain literals are
+ self-denoting.</li>
+
+
+
+ <li>A <a href="#dfn-typed-literal" >typed literal</a> is a string combined with a
+ datatype URI. It denotes the
+ member of the identified datatype's value space obtained by
+ applying the lexical-to-value mapping to the literal string.</li>
+ </ul>
+
+ <p>Continuing the example from <a href="#section-Datatypes-intro">section
+ 3.3</a>, the typed literals that can be defined using the XML
+ Schema datatype <var>xsd:boolean</var> are:</p>
+
+ <table border="1" cellpadding="5" summary=
+ "This table lists the literals of type xsd:boolean.">
+ <tr>
+ <th>Typed Literal</th>
+
+ <th>Lexical-to-Value Mapping</th>
+
+ <th>Value</th>
+ </tr>
+
+ <tr>
+ <td align="center"><xsd:boolean, "true"></td>
+
+ <td align="center"><"true", T></td>
+
+ <td align="center">T</td>
+ </tr>
+
+ <tr>
+ <td align="center"><xsd:boolean, "1"></td>
+
+ <td align="center"><"1", T></td>
+
+ <td align="center">T</td>
+ </tr>
+
+ <tr>
+ <td align="center"><xsd:boolean, "false"></td>
+
+ <td align="center"><"false", F></td>
+
+ <td align="center">F</td>
+ </tr>
+
+ <tr>
+ <td align="center"><xsd:boolean, "0"></td>
+
+ <td align="center"><"0", F></td>
+
+ <td align="center">F</td>
+ </tr>
+ </table>
+
+ <p>For text that may contain
+ markup, use typed literals
+with type <a href="#section-XMLLiteral">rdf:XMLLiteral</a>.
+If language annotation is required,
+it must be explicitly included as markup, usually by means of an
+<code>xml:lang</code> attribute.
+<a href="#ref-xhtml">[XHTML]</a> may be included within RDF
+in this way. Sometimes, in this latter case,
+ an additional <code>span</code> or <code>div</code>
+ element is needed to carry an
+<code>xml:lang</code> or <code>lang</code> attribute.
+ </p>
+
+<p>
+The string in both plain and typed literals is recommended to
+be in Unicode Normal Form C <a href="#ref-nfc">[NFC]</a>. This is motivated
+by <a href="#ref-charmod">[CHARMOD]</a> particularly
+<a href="http://www.w3.org/TR/2003/WD-charmod-20030822/#sec-Normalization">section 4
+Early Uniform Normalization</a>.
+</p>
+
+ <h3><a id="section-SimpleFacts" name="section-SimpleFacts">3.5
+ RDF Expression of Simple Facts</a></h3>
+
+
+ <p>Some simple facts indicate a relationship between
+ two things.
+Such a fact may be represented as an RDF triple in which the predicate
+names the relationship, and the subject and object denote the two things.
+
+
+ A familiar representation of such a fact might be
+ as a row in a table in a relational database. The table has
+ two columns, corresponding to the subject and the object of the
+ RDF triple.
+ The name of the table corresponds to the predicate
+ of the RDF triple. A further familiar representation may be as a
+ two place predicate
+ in first order logic.</p>
+
+ <p>
+Relational databases permit a table to have an arbitrary number of columns,
+a row of which expresses information corresponding to a predicate in first
+order logic with an arbitrary number of places. Such a row, or predicate,
+has to be decomposed for representation as RDF triples. A simple form of
+decomposition introduces a new blank node, corresponding to the row, and a
+new triple is introduced for each cell in the row. The subject of each
+triple is the new blank node, the predicate corresponds to the column name,
+and object corresponds to the value in the cell. The new blank node may
+also have an <span class="code">rdf:type</span> property whose value corresponds
+to the table name.
+</p>
+
+ <p>As an example, consider Figure 6 from the
+ [<a href=
+ "#ref-rdf-primer">RDF-PRIMER</a>]:
+
+</p>
+
+ <div class="figure">
+ <img src="fig6may19" alt=
+ "Using a Blank Node" width="100%" /><br />
+ RDF Primer Figure 6: Using a Blank Node
+ </div>
+
+
+ <p>
+This information might correspond to a row in a table <span class="code">"STAFFADDRESSES"</span>,
+ with a primary key
+<span class="code">STAFFID</span>,
+ and additional columns
+<span class="code">STREET</span>,
+<span class="code">STATE</span>,
+<span class="code">CITY</span> and
+<span class="code">POSTALCODE</span>.
+ </p>
+
+ <p>
+Thus, a more complex fact is expressed in RDF using a
+conjunction (logical-AND) of simple binary relationships. RDF does not
+provide means to express negation (NOT) or disjunction (OR). </p>
+
+ <p>Through its use of extensible URI-based vocabularies, RDF
+ provides for expression of facts about arbitrary subjects; i.e.
+ assertions of named properties about specific named things. A URI
+ can be constructed for any thing that can be named, so RDF facts
+ can be about any such things. <!--
+ And, as noted above, RDF also
+ provides for expression of assertions about unnamed things, which
+ may be fully identifiable in terms of such assertions [<a
+ href="#ref-tap-rbd">TAP-RBD</a>].
+ -->
+ </p>
+
+
+ <h3><a id="section-Entailment" name="section-Entailment">3.6
+ Entailment</a></h3>
+
+ <p>The ideas on meaning and inference in RDF are underpinned by the
+ formal concept of <a href="http://www.w3.org/TR/2004/REC-rdf-mt-20040210/#entail">
+<cite>entailment</cite></a>, as
+ discussed in the RDF
+ semantics document [<a href=
+ "#ref-rdf-semantics">RDF-SEMANTICS</a>].
+In brief, an RDF expression A is said to
+<dfn>entail</dfn> another RDF expression B if every possible
+arrangement of things in the world that makes A true also makes B
+true. On this basis, if the truth of A is presumed or demonstrated
+then the truth of B can be inferred .
+</p>
+
+
+ <h2><a id="section-URIspaces" name="section-URIspaces">4. RDF
+ Vocabulary URI and Namespace (Normative)</a></h2>
+
+ <p>
+
+RDF uses URI references to identify resources and properties. Certain
+URI references are given specific meaning by RDF. Specifically, URI
+references with the following leading substring are defined by the RDF
+specifications:
+
+</p>
+ <ul>
+ <li><span
+ class="code">http://www.w3.org/1999/02/22-rdf-syntax-ns#</span>
+ (conventionally associated with namespace prefix <span
+ class="code">rdf:</span>)</li>
+<!--
+ <li><span
+ class="code">http://www.w3.org/2000/01/rdf-schema#</span>
+ (conventionally associated with namespace prefix <span
+ class="code">rdfs:</span>)</li>
+-->
+ </ul>
+ <p>Used with the RDF/XML serialization, this URI prefix
+ string corresponds to XML namespace names [<a
+ href="#ref-namespaces">XML-NS</a>] associated with the RDF
+ vocabulary terms.</p>
+ <div class="note">
+ <p><strong>Note:</strong> this namespace name is the same
+ as that used in the earlier RDF recommendation [<a
+ href="#ref-rdf-ms">RDF-MS</a>].</p>
+ </div>
+ <p>Vocabulary terms in the <span class="code">rdf:</span>
+ namespace are listed in <a
+ href="http://www.w3.org/TR/2004/REC-rdf-syntax-grammar-20040210/#section-Namespace">
+ section 5.1</a> of the RDF syntax specification [<a
+ href="#ref-rdf-syntax">RDF-SYNTAX</a>]. Some of these terms are
+ defined by the RDF specifications to denote specific concepts.
+ Others have syntactic purpose (e.g. rdf:ID is part of
+ the RDF/XML syntax).</p>
+<!--
+ <p>Vocabulary terms defined in the <span
+ class="code">rdfs:</span> namespace are defined in the RDF
+ schema vocabulary specification [<a
+ href="#ref-rdf-vocabulary">RDF-VOCABULARY</a>].</p>
+-->
+
+ <h2><a name="section-Datatypes" id="section-Datatypes">5.
+ Datatypes (Normative)</a></h2>
+
+<p>
+The datatype abstraction used in RDF is compatible with
+the abstraction used in
+XML Schema Part 2:
+ Datatypes [<a href="#ref-xml-schema2">XML-SCHEMA2</a>].</p>
+<p>
+A datatype consists of a lexical space, a value space and a lexical-to-value
+mapping.
+</p>
+<p>The <dfn><a id="dfn-lexical-space"
+ name="dfn-lexical-space">lexical space</a></dfn> of a datatype is a set of Unicode [<a
+ href="#ref-unicode">UNICODE</a>] strings.</p>
+<p>
+The <dfn><a id="dfn-lexical-to-value-mapping" name=
+ "dfn-lexical-to-value-mapping">lexical-to-value mapping</a></dfn> of a datatype is a set of pairs whose
+first element belongs to
+the <dfn><a href="#dfn-lexical-space">lexical space</a></dfn> of the datatype,
+and the second element belongs to the
+ <dfn><a id="dfn-value-space"
+ name="dfn-value-space">value space</a></dfn> of the datatype:
+</p>
+<ul>
+<li>
+Each member of the lexical space is paired with (maps to) exactly one member
+of the value space.
+</li>
+<li>
+Each member of the value space may be paired with any number (including
+zero) of members of the lexical space (lexical representations for that
+value).
+</li>
+</ul>
+<p>
+A datatype is identified by one or more URI references.
+</p>
+<p>
+RDF may be used with any datatype definition that conforms to this
+abstraction, even if not defined in terms of XML Schema.
+</p>
+ <p>Certain XML Schema built-in datatypes are not suitable for use
+ within RDF. For example, the
+<a href="http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/#QName">QName</a>
+datatype requires a namespace declaration to be in scope during
+ the mapping, and is not recommended for use in RDF.
+[<a href=
+ "#ref-rdf-semantics">RDF-SEMANTICS</a>] contains
+a
+<a href="http://www.w3.org/TR/2004/REC-rdf-mt-20040210/#dtype_interp">more detailed discussion</a>
+ of specific XML Schema built-in datatypes. </p>
+
+<div class="note">
+<p><strong>Note:</strong> When the datatype is defined using XML Schema:
+</p>
+<ul>
+<li>
+All values correspond to some lexical form, either using
+the lexical-to-value mapping of the datatype or if it is a union
+datatype with a lexical mapping associated with one of the member
+datatypes.
+</li>
+<li>
+XML Schema facets remain part of the datatype and are used by the XML
+Schema mechanisms that control the lexical space and the value space;
+however, RDF does not define a standard mechanism to access these facets.</li>
+
+<li>In [<a href="#ref-xml-schema1">XML-SCHEMA1</a>],
+<a href="http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/#section-White-Space-Normalization-during-Validation">
+white space normalization</a> occurs
+during
+<a href="http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/#key-vn">validation</a>
+according to the value of the
+<a href="http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/#rf-whiteSpace">whiteSpace
+facet</a>. The lexical-to-value mapping used in RDF datatyping
+occurs after this, so that the whiteSpace facet has no
+effect in RDF datatyping.
+</li>
+</ul>
+
+
+</div>
+
+ <h3><a id="section-XMLLiteral" name="section-XMLLiteral">5.1 XML
+ Content within an RDF Graph</a></h3>
+
+ <p>RDF provides for XML content as a possible literal value. This
+ typically originates from the use of
+ <span class="code">rdf:parseType="Literal"</span> in the RDF/XML Syntax [<a
+ href="#ref-rdf-syntax">RDF-SYNTAX</a>].</p>
+
+ <p>Such content is indicated in an RDF graph using a typed literal
+ whose datatype is a special built-in datatype
+ <dfn><a id="dfn-rdf-XMLLiteral" name= "dfn-rdf-XMLLiteral" class="code">rdf:XMLLiteral</a></dfn>,
+ defined as follows.</p>
+
+
+ <dl>
+ <dt><a name="XMLLiteral-uri" id="XMLLiteral-uri">A URI reference for
+identifying this datatype</a></dt>
+
+ <dd>is
+ <span class="code">http://www.w3.org/1999/02/22-rdf-syntax-ns#XMLLiteral</span>.</dd>
+
+
+
+
+ <dt><a name="XMLLiteral-lexical-space" id="XMLLiteral-lexical-space">The lexical space</a></dt>
+
+<dd>is the set of all
+strings:
+<ul>
+<li>which are well-balanced, self-contained
+<a href="http://www.w3.org/TR/2000/REC-xml-20001006#NT-content">
+XML content</a>
+[<a href="#ref-xml">XML</a>];
+</li>
+<li>for which encoding as UTF-8
+[<a href="#ref-rfc-2279">RFC 2279</a>] yields
+<a href="http://www.w3.org/TR/2002/REC-xml-exc-c14n-20020718/#def-exclusive-canonical-XML">
+exclusive
+Canonical XML </a> (with comments, with empty
+<a href="http://www.w3.org/TR/2002/REC-xml-exc-c14n-20020718/#def-InclusiveNamespaces-PrefixList">
+InclusiveNamespaces PrefixList
+</a>) <a href="#ref-xml-xc14n">[XML-XC14N]</a>;
+</li>
+<li>for which embedding between an arbitrary XML start tag and an end tag
+yields a document conforming to <a href=
+ "http://www.w3.org/TR/1999/REC-xml-names-19990114/">XML
+ Namespaces</a> <a href="#ref-namespaces">[XML-NS]</a></li>
+</ul>
+</dd>
+
+
+ <dt><a name="XMLLiteral-value-space" id="XMLLiteral-value-space">The value space</a></dt>
+
+ <dd>is a set of entities, called XML values, which is:
+<ul>
+<li>disjoint from the lexical space;</li>
+<li>disjoint from the value space of any datatype that is not explicitly defined as a sub- or supertype of this datatype;</li>
+
+<li>disjoint from the set of Unicode character strings [<a
+ href="#ref-unicode">UNICODE</a>] strings;</li>
+<li>and in 1:1 correspondence with the lexical space.</li>
+</ul>
+</dd>
+
+ <dt><a name="XMLLiteral-mapping" id="XMLLiteral-mapping">The lexical-to-value mapping</a></dt>
+
+ <dd>
+is a one-one mapping from the lexical space onto the value space,
+ i.e. it is both injective and surjective.
+</dd>
+
+
+
+ </dl>
+
+
+ <p class="note"><strong>Note:</strong> Not all values of this datatype are compliant
+ with XML 1.1 [<a href="#ref-xml-1-1">XML 1.1</a>]. If compliance
+ with XML 1.1 is desired, then only those values that are
+<a href="http://www.w3.org/TR/2002/CR-xml11-20021015/#sec2.13">fully
+ normalized</a> according to XML 1.1 should be used.</p>
+
+ <p class="note"><strong>Note:</strong> XML values can be thought of as the
+[<a href="#ref-xml-infoset">XML-INFOSET</a>] or the
+[<a href="#ref-xpath">XPATH</a>]
+nodeset corresponding to the lexical form, with an appropriate equality
+function.</p>
+
+ <p class="note"><strong>Note:</strong> RDF applications may use additional equivalence relations, such as
+that which relates an
+<a href="http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/#string"><code>xsd:string</code></a>
+
+with an <code>rdf:XMLLiteral</code> corresponding to
+a single text node of the same string.</p>
+
+
+
+ <h2><a id="section-Graph-syntax" name="section-Graph-syntax">6.
+ Abstract Syntax (Normative)</a></h2>
+
+
+ <p>This section defines the RDF abstract syntax. The RDF abstract
+ syntax is a set of triples, called the RDF graph.</p>
+
+ <p>This section also defines equivalence between RDF graphs. A
+ definition of equivalence is needed to support the RDF Test Cases [<a
+ href="#ref-rdf-tests">RDF-TESTS</a>] specification.</p>
+
+<div class="note">
+<p><a name="implementation-note" id="implementation-note"><strong>Implementation Note:</strong></a>
+This <em>abstract</em> syntax is the
+syntax over which the formal semantics are defined.
+Implementations are free to represent RDF graphs in
+any other equivalent form. As an example:
+in an RDF graph,
+literals with datatype <tt>rdf:XMLLiteral</tt> can be represented
+in a non-canonical
+format, and canonicalization performed during the comparison between two
+such literals. In this example the comparisons may be
+being performed either between syntactic structures or
+between their denotations in the domain of discourse.
+Implementations that do not require any such comparisons can
+hence be optimized.
+</p>
+</div>
+
+ <h3><a id="section-triples" name="section-triples">6.1 RDF
+ Triples</a><a id="xtocid103646" name="xtocid103646"> </a></h3>
+
+ <p>An <dfn><a id="dfn-rdf-triple" name="dfn-rdf-triple">RDF
+ triple</a></dfn> contains three components:</p>
+
+ <ul>
+ <li>the <dfn><a id="dfn-subject" name="dfn-subject">subject</a></dfn>,
+which is an <a href="#dfn-URI-reference">RDF URI reference</a>
+or a <a href="#dfn-blank-node">blank node</a>
+</li>
+
+ <li>the <dfn><a id="dfn-predicate" name="dfn-predicate">predicate</a></dfn>, which is an <a href=
+ "#dfn-URI-reference">RDF URI reference</a></li>
+
+ <li>the <dfn><a id="dfn-object" name="dfn-object">object</a></dfn>,
+which is an <a href="#dfn-URI-reference">RDF URI reference</a>,
+a <a href="#dfn-literal">literal</a>
+or a <a href="#dfn-blank-node">blank node</a>
+</li>
+
+ </ul>
+ <p>An RDF triple is conventionally written in the order subject,
+ predicate, object.</p>
+
+ <p>The predicate is also known as the <dfn><a name="dfn-property"
+ id="dfn-property">property</a></dfn> of the triple.</p>
+
+ <h3><a id="section-rdf-graph" name="section-rdf-graph">6.2 RDF Graph</a><a id="xtocid103647" name="xtocid103647"> </a></h3>
+
+ <p>An <dfn><a id="dfn-rdf-graph" name="dfn-rdf-graph">RDF
+ graph</a></dfn> is a set of RDF triples.</p>
+
+ <p>The set of <dfn><a name="dfn-node" id="dfn-node">nodes</a><a name="section-Graph-Node" id="section-Graph-Node"> </a></dfn> of an RDF graph is the set of subjects and objects of
+ triples in the graph.</p>
+
+
+ <h3><a id="section-graph-equality" name="section-graph-equality">6.3 Graph
+ Equivalence</a></h3>
+
+ <p>Two RDF graphs <var>G</var> and <var>G'</var> are equivalent if there
+ is a bijection <var>M</var> between the sets of nodes of the two graphs,
+ such that:</p>
+
+ <ol>
+ <li><var>M</var> maps blank nodes to blank nodes.</li>
+ <li><var>M(lit)=lit</var> for all <a href=
+ "#dfn-literal">RDF literals</a> <var>lit</var> which
+ are nodes of <var>G</var>.</li>
+
+ <li><var>M(uri)=uri</var> for all <a href=
+ "#dfn-URI-reference">RDF URI references</a> <var>uri</var>
+ which are nodes of <var>G</var>.</li>
+
+ <li>The triple <var>( s, p, o )</var> is in <var>G</var> if and
+ only if the triple <var>( M(s), p, M(o) )</var> is in
+ <var>G'</var></li>
+ </ol>
+ <p>With this definition, <var>M</var> shows how each blank node
+ in <var>G</var> can be replaced with
+ a new blank node to give <var>G'</var>.</p>
+
+
+
+ <h3><a id="section-Graph-URIref" name="section-Graph-URIref">6.4
+ RDF URI References</a></h3>
+
+
+
+ <p>A <dfn><a id="dfn-URI-reference" name="dfn-URI-reference">URI reference</a></dfn> within an RDF graph (an RDF URI reference) is a
+ Unicode string [<a href="#ref-unicode">UNICODE</a>] that:
+</p>
+<ul>
+<li>does not contain any control characters ( #x00 - #x1F, #x7F-#x9F)
+</li>
+<li>and
+ would produce a
+valid URI character sequence (per RFC2396 [<a href=
+ "#ref-uris">URI</a>], sections 2.1)
+representing an absolute URI with optional
+fragment identifier
+ when subjected to the encoding described below.
+</li>
+</ul>
+<p>
+The encoding consists of:
+</p>
+<ol>
+<li>encoding the Unicode string as UTF-8
+[<a href=
+ "#ref-rfc-2279">RFC-2279</a>], giving a sequence of octet values.
+</li>
+<li>
+%-escaping octets that do not correspond to permitted US-ASCII characters.
+</li>
+</ol>
+<p>
+The disallowed octets that must be %-escaped include all those that do not
+correspond to US-ASCII characters, and the excluded characters listed in
+Section 2.4 of [<a href=
+ "#ref-uris">URI</a>], except for the number sign (#), percent sign (%),
+and the square bracket characters re-allowed in [<a href=
+ "#ref-rfc-2732">RFC-2732</a>].
+</p>
+<p>
+Disallowed octets must be escaped with the URI escaping mechanism (that is, converted to %HH,
+where HH is the 2-digit hexadecimal numeral corresponding to the octet value).
+</p>
+
+
+ <p>Two RDF URI references are equal if and only if they compare as
+ equal, character by character, as Unicode strings.</p>
+
+ <div class="note">
+
+ <p><strong>Note:</strong> RDF URI references are compatible with the <a
+ href=
+ "http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/#anyURI"><cite>
+ anyURI</cite></a> datatype as defined by XML schema datatypes [<a
+ href="#ref-xml-schema2">XML-SCHEMA2</a>], constrained to be an
+ absolute rather than a relative URI reference.</p>
+
+ <p><strong>Note:</strong> RDF URI references are compatible with <a href=
+ "http://www.w3.org/TR/2003/PR-xml-names11-20031105/#IRIs">International Resource
+ Identifiers</a> as defined by [<a href="#ref-xml-names11">XML
+ Namespaces 1.1</a>].</p>
+
+
+
+ <p><strong>Note:</strong> this section anticipates an RFC on Internationalized Resource
+Identifiers. Implementations may issue warnings concerning the use
+of RDF URI References that do not conform with [<a href="#ref-iri">IRI draft</a>] or its
+successors.</p>
+
+ <p><strong>Note:</strong> The restriction to absolute URI references is
+ found in this abstract syntax. When there is a well-defined base
+ URI, concrete syntaxes, such as RDF/XML, may permit relative URIs
+ as a shorthand for such absolute URI references.</p>
+
+
+ <p><strong>Note:</strong> Because of the risk of confusion between
+RDF URI references that would
+be equivalent if derefenced, the use of %-escaped characters in RDF URI
+references is strongly discouraged. See also the
+<a href=
+"http://www.w3.org/2001/tag/issues.html#URIEquivalence-15">
+URI equivalence issue</a> of
+the Technical Architecture Group [<a href="#ref-TAG">TAG</a>].</p>
+ </div>
+
+ <h3><a id="section-Graph-Literal" name="section-Graph-Literal">6.5
+ RDF Literals</a></h3>
+
+
+<p>A <dfn><a id="dfn-literal" name="dfn-literal">literal</a></dfn> in an RDF graph
+contains one or two named components.</p>
+<p>All literals have a <dfn><a id="dfn-lexical-form" name=
+ "dfn-lexical-form">lexical form</a></dfn> being a Unicode [<a
+ href="#ref-unicode">UNICODE</a>] string, which SHOULD be in Normal Form C [<a
+ href="#ref-nfc">NFC</a>].</p>
+
+
+<p><dfn><a id="dfn-plain-literal" name="dfn-plain-literal">Plain literals</a></dfn> have
+ a <a href="#dfn-lexical-form">lexical form</a> and optionally a
+<dfn><a id="dfn-language-identifier" name=
+ "dfn-language-identifier">language tag</a></dfn> as
+defined by [<a href="#ref-rfc-3066">RFC-3066</a>], normalized to lowercase.</p>
+
+<p><dfn><a id="dfn-typed-literal" name="dfn-typed-literal">Typed literals</a></dfn> have a <a href="#dfn-lexical-form">lexical form</a> and a <dfn><a id="dfn-datatype-URI" name=
+ "dfn-datatype-URI">datatype URI</a></dfn> being an <a href=
+ "#dfn-URI-reference">RDF URI reference</a>.</p>
+
+
+
+ <div class="note">
+ <p><strong>Note:</strong> Literals in which the lexical form begins with a
+ composing character (as defined by [<a href=
+ "#ref-charmod">CHARMOD</a>]) are allowed however they may cause
+ interoperability problems, particularly with XML version 1.1 [<a
+ href="#ref-xml-1-1">XML 1.1</a>].</p>
+
+ <p><strong>Note:</strong> When using the language tag, care must be
+ taken not to confuse language with locale. The language
+ tag relates only to human language text. Presentational
+ issues should
+ be addressed in end-user applications.</p>
+
+ <p><strong>Note:</strong> The case normalization of
+language tags is part of
+ the description of the abstract syntax, and consequently the abstract
+ behaviour of RDF applications. It does not constrain an
+ RDF implementation to actually normalize the case. Crucially, the result
+ of comparing two language tags should not be sensitive to the case of
+ the original input.</p>
+
+ </div>
+
+ <h4><a id="section-Literal-Equality" name=
+ "section-Literal-Equality">6.5.1 Literal Equality</a></h4>
+
+ <p>Two literals are equal if and only if all of the following
+ hold:</p>
+
+ <ul>
+ <li>The strings of the two lexical forms compare equal, character
+ by character.</li>
+
+ <li>Either both or neither have language tags.</li>
+
+ <li>The language tags, if any, compare
+ equal.</li>
+
+ <li>Either both or neither have datatype URIs.</li>
+
+ <li>The two datatype URIs, if any, compare equal, character by
+ character.</li>
+ </ul>
+
+ <p class="note"><strong>Note:</strong> RDF Literals are distinct and distinguishable
+ from RDF URI references; e.g. http://example.org as an RDF
+ Literal (untyped, without a language tag) is not equal to
+ http://example.org as an RDF URI reference.</p>
+
+ <h4><a id="section-Literal-Value" name=
+ "section-Literal-Value">6.5.2 The Value Corresponding to a Typed
+ Literal</a></h4>
+
+ <p>The datatype URI refers to a <a href=
+ "#section-Datatypes">datatype</a>. For XML Schema <a href=
+ "http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/#built-in-datatypes">
+ built-in</a> datatypes, URIs such as
+ <span class="code">http://www.w3.org/2001/XMLSchema#int</span> are used. The URI
+ of the datatype <a href=
+ "#section-XMLLiteral" class="code">rdf:XMLLiteral</a> may be used.
+ There may be other, implementation dependent, mechanisms by which
+ URIs refer to datatypes.</p>
+
+ <p>The <em>value</em> associated with a typed literal is found by
+ applying the lexical-to-value mapping associated with the datatype URI to
+ the lexical form.
+ </p>
+
+ <p>
+ If the lexical form is not in
+ the lexical space of the datatype associated with the datatype URI,
+then no literal value can be associated with the typed literal.
+Such a case, while in error, is not <em>syntactically</em> ill-formed.</p>
+<!--
+ <p>A typed literal for which the datatype does not map the lexical
+ form to a value is not syntactically ill-formed.</p>
+-->
+
+
+ <p class="note"><strong>Note:</strong>
+In application contexts, comparing the values of typed literals (see
+<a href="#section-Literal-Value">
+section
+6.5.2</a>)
+is usually more helpful than comparing their syntactic forms (see
+<a href="#section-Literal-Equality">
+section
+6.5.1</a>).
+Similarly, for comparing RDF Graphs,
+semantic notions of entailment (see
+[<a href=
+ "#ref-rdf-semantics">RDF-SEMANTICS</a>]) are usually
+more helpful than syntactic equality (see
+<a href="#section-graph-equality">
+section
+6.3</a>).</p>
+<h3><a id="section-blank-nodes" name="section-blank-nodes">6.6 Blank Nodes</a></h3>
+<p>
+The <dfn><a id="dfn-blank-node" name="dfn-blank-node">blank nodes</a></dfn> in an RDF graph
+are drawn from an infinite set.
+This set of blank nodes, the set of all <a href="#dfn-URI-reference">RDF URI references</a>
+and the set of all <a href="#dfn-literal">literals</a> are pairwise disjoint.
+</p>
+<p>
+Otherwise, this set of blank nodes is arbitrary.
+</p>
+<p>RDF makes no reference to any internal structure of blank nodes.
+Given two blank nodes, it is
+possible to determine whether or not they are the same.</p>
+
+
+ <h2><a id="section-fragID" name="section-fragID">7. Fragment
+ Identifiers</a></h2>
+
+ <p>RDF uses an <a href="#dfn-URI-reference">RDF URI
+ Reference</a>, which may include a fragment identifier, as a
+ context free identifier for a resource. RFC 2396 [<a
+ href="#ref-uris">URI</a>] states that the meaning of a fragment
+ identifier depends on the MIME content-type of a document, i.e.
+ is context dependent.</p>
+ <p>These apparently conflicting views are reconciled by
+ considering that a URI reference in an RDF graph is treated
+ with respect to the MIME type <span
+ class="code">application/rdf+xml</span> [<a
+ href="#ref-rdf-mime-type">RDF-MIME-TYPE</a>]. Given an RDF URI
+ reference consisting of an absolute URI and a fragment
+ identifier, the fragment identifer identifies the same thing
+ that it does in an <span
+ class="code">application/rdf+xml</span> representation of the
+ resource identified by the absolute URI component. Thus:</p>
+ <ul>
+ <li>we assume that the URI part (i.e. excluding fragment
+ identifier) identifies a resource, which is presumed to have
+ an RDF representation. So when <span
+ class="code">eg:someurl#frag</span> is used in an RDF
+ document, <span class="code">eg:someurl</span> is taken to
+ designate some RDF document (even when no such document can
+ be retrieved).</li>
+ <li><span class="code">eg:someurl#frag</span> means the thing
+ that is indicated, according to the rules of the <span
+ class="code">application/rdf+xml</span> MIME content-type as
+ a "fragment" or "view" of the RDF document at <span
+ class="code">eg:someurl</span>. If the document does not
+ exist, or cannot be retrieved, or is available only in
+ formats other than <span
+ class="code">application/rdf+xml</span>, then exactly what
+ that view may be is somewhat undetermined, but that does not
+ prevent use of RDF to say things about it.</li>
+ <li>the RDF treatment of a fragment identifier allows it to
+ indicate a thing that is entirely external to the document,
+ or even to the "shared information space" known as the Web.
+ That is, it can be a more general idea, like some particular
+ car or a mythical Unicorn.</li>
+ <li>in this way, an <span
+ class="code">application/rdf+xml</span> document acts as an
+ intermediary between some Web retrievable documents (itself,
+ at least, also any other Web retrievable URIs that it may
+ use, possibly including schema URIs and references to other
+ RDF documents), and some set of possibly abstract or non-Web
+ entities that the RDF may describe.</li>
+ </ul>
+ <p>This provides a handling of URI references and their
+ denotation that is consistent with the RDF model theory and
+ usage, and also with conventional Web behavior. Note that
+ nothing here requires that an RDF application be able to
+ retrieve any representation of resources identified by the URIs
+ in an RDF graph.</p>
+
+
+
+ <h2 class="nonum"><a id="section-Acknowledgments" name=
+ "section-Acknowledgments">8. Acknowledgments</a></h2>
+
+ <p>This document contains a significant contribution from Pat
+ Hayes, Sergey Melnik and Patrick Stickler, under whose leadership
+ was developed the framework described in the RDF family of
+ specifications for representing datatyped values, such as integers
+ and dates.</p>
+
+ <p>The editors acknowledge valuable contributions from the
+ following: <!--</p>
+
+ <ul>-->
+ <!--<li>-->Frank Manola, <!--</li>-->
+
+ <!--<li>-->Pat Hayes, <!--</li>-->
+
+ <!--<li>-->Dan Brickley, <!--</li>-->
+
+ <!--<li>-->Jos de Roo, <!--</li>-->
+
+ <!--<li>-->Dave Beckett, <!--</li>-->
+
+ <!--<li>-->Patrick Stickler, <!--</li>-->
+
+ <!--<li>-->Peter F. Patel-Schneider, <!--</li>-->
+
+ <!--<li>-->Jerome Euzenat, <!--</li>-->
+
+ <!--<li>-->Massimo Marchiori, <!--</li>-->
+
+ <!--<li>-->Tim Berners-Lee, <!--</li>-->
+
+ <!--<li>-->Dave Reynolds <!--</li>-->
+
+ <!--<li>-->and Dan Connolly. <!--</li>-->
+<!--
+ <li class="todo">[[[Other contributors]]]</li>
+ </ul>
+-->
+</p>
+ <p>Jeremy Carroll thanks <a href="mailto:oreste@w3.org">Oreste
+ Signore</a>, his host at the <a href="http://www.w3c.it/">W3C
+ Office in Italy</a> and <a href="http://www.isti.cnr.it" lang="it"
+ xml:lang="it">Istituto di Scienza e Tecnologie dell'Informazione
+ "Alessandro Faedo"</a>, part of the <a href="http://www.cnr.it"
+ lang="it" xml:lang="it">Consiglio Nazionale delle Ricerche</a>,
+ where Jeremy is a visiting researcher.</p>
+
+ <p>This document is a product of extended deliberations by the
+ RDFcore Working Group, whose members have included:
+
+<!--</p><ul>-->
+ <!--<li>-->Art Barstow (W3C), <!--</li>-->
+
+ <!--<li>-->Dave Beckett (ILRT), <!--</li>-->
+
+ <!--<li>-->Dan Brickley (ILRT), <!--</li>-->
+
+ <!--<li>-->Dan Connolly (W3C), <!--</li>-->
+
+ <!--<li>-->Jeremy Carroll (Hewlett Packard), <!--</li>-->
+
+ <!--<li>-->Ron Daniel (Interwoven Inc), <!--</li>-->
+
+ <!--<li>-->Bill dehOra (InterX), <!--</li>-->
+
+ <!--<li>-->Jos De Roo (AGFA), <!--</li>-->
+
+ <!--<li>-->Jan Grant (ILRT), <!--</li>-->
+
+ <!--<li>-->Graham Klyne (Nine by Nine), <!--</li>-->
+
+ <!--<li>-->Frank Manola (MITRE Corporation), <!--</li>-->
+
+ <!--<li>-->Brian McBride (Hewlett Packard), <!--</li>-->
+
+ <!--<li>-->Eric Miller (W3C), <!--</li>-->
+
+ <!--<li>-->Stephen Petschulat (IBM), <!--</li>-->
+
+ <!--<li>-->Patrick Stickler (Nokia), <!--</li>-->
+
+ <!--<li>-->Aaron Swartz (HWG), <!--</li>-->
+
+ <!--<li>-->Mike Dean (BBN Technologies / Verizon), <!--</li>-->
+
+ <!--<li>-->R. V. Guha (Alpiri Inc), <!--</li>-->
+
+ <!--<li>-->Pat Hayes (IHMC), <!--</li>-->
+
+ <!--<li>-->Sergey Melnik (Stanford University) and <!--</li>-->
+
+ <!--<li>-->Martyn Horner (Profium Ltd). <!--</li>-->
+ </p> <!--</ul>-->
+ <p>This specification also draws upon an earlier RDF Model and
+ Syntax document edited by Ora Lassilla and Ralph Swick, and RDF
+ Schema edited by Dan Brickley and R. V. Guha. RDF and RDF Schema
+ Working Group members who contributed to this earlier work are:
+
+ <!--</p><ul>-->
+ <!--<li>-->Nick Arnett (Verity), <!--</li>-->
+
+ <!--<li>-->Tim Berners-Lee (W3C), <!--</li>-->
+
+ <!--<li>-->Tim Bray (Textuality), <!--</li>-->
+
+ <!--<li>-->Dan Brickley (ILRT / University of Bristol), <!--</li>-->
+
+ <!--<li>-->Walter Chang (Adobe), <!--</li>-->
+
+ <!--<li>-->Sailesh Chutani (Oracle), <!--</li>-->
+
+ <!--<li>-->Dan Connolly (W3C), <!--</li>-->
+
+ <!--<li>-->Ron Daniel (DATAFUSION), <!--</li>-->
+
+ <!--<li>-->Charles Frankston (Microsoft), <!--</li>-->
+
+ <!--<li>-->Patrick Gannon (CommerceNet), <!--</li>-->
+
+ <!--<li>-->R. V. Guha (Epinions, previously of Netscape
+ Communications), <!--</li>-->
+
+ <!--<li>-->Tom Hill (Apple Computer), <!--</li>-->
+
+ <!--<li>-->Arthur van Hoff (Marimba), <!--</li>-->
+
+ <!--<li>-->Renato Iannella (DSTC), <!--</li>-->
+
+ <!--<li>-->Sandeep Jain (Oracle), <!--</li>-->
+
+ <!--<li>-->Kevin Jones, (InterMind), <!--</li>-->
+
+ <!--<li>-->Emiko Kezuka (Digital Vision Laboratories), <!--</li>-->
+
+ <!--<li>-->Joe Lapp (webMethods Inc.), <!--</li>-->
+
+ <!--<li>-->Ora Lassila (Nokia Research Center), <!--</li>-->
+
+ <!--<li>-->Andrew Layman (Microsoft), <!--</li>-->
+
+ <!--<li>-->Ralph LeVan (OCLC), <!--</li>-->
+
+ <!--<li>-->John McCarthy (Lawrence Berkeley National Laboratory), <!--</li>-->
+
+ <!--<li>-->Chris McConnell (Microsoft), <!--</li>-->
+
+ <!--<li>-->Murray Maloney (Grif), <!--</li>-->
+
+ <!--<li>-->Michael Mealling (Network Solutions), <!--</li>-->
+
+ <!--<li>-->Norbert Mikula (DataChannel), <!--</li>-->
+
+ <!--<li>-->Eric Miller (OCLC), <!--</li>-->
+
+ <!--<li>-->Jim Miller (W3C, emeritus), <!--</li>-->
+
+ <!--<li>-->Frank Olken (Lawrence Berkeley National Laboratory), <!--</li>-->
+
+ <!--<li>-->Jean Paoli (Microsoft), <!--</li>-->
+
+ <!--<li>-->Sri Raghavan (Digital/Compaq), <!--</li>-->
+
+ <!--<li>-->Lisa Rein (webMethods Inc.), <!--</li>-->
+
+ <!--<li>-->Paul Resnick (University of Michigan), <!--</li>-->
+
+ <!--<li>-->Bill Roberts (KnowledgeCite), <!--</li>-->
+i
+ <!--<li>-->Tsuyoshi Sakata (Digital Vision Laboratories), <!--</li>-->
+
+ <!--<li>-->Bob Schloss (IBM), <!--</li>-->
+
+ <!--<li>-->Leon Shklar (Pencom Web Works), <!--</li>-->
+
+ <!--<li>-->David Singer (IBM), <!--</li>-->
+
+ <!--<li>-->Wei (William) Song (SISU), <!--</li>-->
+
+ <!--<li>-->Neel Sundaresan (IBM), <!--</li>-->
+
+ <!--<li>-->Ralph Swick (W3C), <!--</li>-->
+
+ <!--<li>-->Naohiko Uramoto (IBM), <!--</li>-->
+
+ <!--<li>-->Charles Wicksteed (Reuters Ltd.), <!--</li>-->
+
+ <!--<li>-->Misha Wolf (Reuters Ltd.) and <!--</li>-->
+
+ <!--<li>-->Lauren Wood (SoftQuad). <!--</li>-->
+ <!--</ul>--></p>
+
+ <h2 class="nonum"><a id="section-References" name=
+ "section-References">9. References</a></h2>
+
+ <h3><a id="section-Normative-References" name=
+ "section-Normative-References"></a>9.1 Normative References</h3>
+
+ <dl>
+
+
+ <dt><a id="ref-rdf-semantics"
+ name="ref-rdf-semantics"></a>[RDF-SEMANTICS]</dt>
+ <dd><cite><a href="http://www.w3.org/TR/2004/REC-rdf-mt-20040210/">RDF Semantics</a></cite>, Patrick Hayes, Editor, W3C Recommendation, 10 February 2004, http://www.w3.org/TR/2004/REC-rdf-mt-20040210/ . <a href="http://www.w3.org/TR/rdf-mt/">Latest version</a> available at http://www.w3.org/TR/rdf-mt/ .</dd>
+
+
+ <dt><a id="ref-rdf-syntax"
+ name="ref-rdf-syntax"></a>[RDF-SYNTAX]</dt>
+
+ <dd><cite><a href="http://www.w3.org/TR/2004/REC-rdf-syntax-grammar-20040210/">RDF/XML Syntax Specification (Revised)</a></cite>, Dave Beckett, Editor, W3C Recommendation, 10 February 2004, http://www.w3.org/TR/2004/REC-rdf-syntax-grammar-20040210/ . <a href="http://www.w3.org/TR/rdf-syntax-grammar/">Latest version</a> available at http://www.w3.org/TR/rdf-syntax-grammar/ .</dd>
+
+
+ <dt><a id="ref-rdf-mime-type" name=
+ "ref-rdf-mime-type"></a>[RDF-MIME-TYPE]</dt>
+ <dd>
+ <cite><a href="http://www.iana.org/assignments/media-types/">MIME Media Types</a></cite>, The Internet Assigned Numbers Authority (IANA). This document is http://www.iana.org/assignments/media-types/ . The <a href="http://www.w3.org/2001/sw/RDFCore/mediatype-registration">registration for <code>application/rdf+xml</code></a> is archived at http://www.w3.org/2001/sw/RDFCore/mediatype-registration .
+ </dd>
+
+
+ <dt><a id="ref-xml" name="ref-xml"></a>[XML]</dt>
+
+ <dd><cite><a href=
+ "http://www.w3.org/TR/2000/REC-xml-20001006">Extensible Markup
+ Language (XML) 1.0, Second Edition</a></cite>, T. Bray, J. Paoli,
+ C.M. Sperberg-McQueen and E. Maler, Editors. World Wide Web
+ Consortium. 6 October 2000. This version is
+ <span>http://www.w3.org/TR/2000/REC-xml-20001006</span>. The
+ latest version of XML is available at <a href=
+ "http://www.w3.org/TR/REC-xml">http://www.w3.org/TR/REC-xml</a>.</dd>
+
+ <dt><a id="ref-namespaces" name=
+ "ref-namespaces"></a>[XML-NS]</dt>
+
+ <dd><cite><a href=
+ "http://www.w3.org/TR/1999/REC-xml-names-19990114/">Namespaces in
+ XML</a></cite>, T. Bray, D. Hollander and A. Layman, Editors.
+ World Wide Web Consortium. 14 January 1999. This version is
+ <span>http://www.w3.org/TR/1999/REC-xml-names-19990114/</span>.
+ The <a href="http://www.w3.org/TR/REC-xml-names/">latest version
+ of Namespaces in XML</a> is available at
+ http://www.w3.org/TR/REC-xml-names/.</dd>
+
+ <dt><a id="ref-rfc-2279" name="ref-rfc-2279"></a>[RFC-2279]</dt>
+
+ <dd><i><a href="http://www.ietf.org/rfc/rfc2279.txt">RFC 2279
+ - UTF-8, a transformation format of ISO 10646</a></i>, F.
+ Yergeau, IETF, January 1998. This document is
+ http://www.ietf.org/rfc/rfc2279.txt.</dd>
+
+
+ <dt><a id="ref-uris" name="ref-uris"></a>[URI]</dt>
+
+ <dd><cite><a href="http://www.ietf.org/rfc/rfc2396.txt">RFC
+ 2396 - Uniform Resource Identifiers (URI): Generic
+ Syntax</a></cite>, T. Berners-Lee, R. Fielding and L. Masinter,
+ IETF, August 1998. This document is
+ http://www.ietf.org/rfc/rfc2396.txt.</dd>
+
+ <dt><a id="ref-rfc-2732" name="ref-rfc-2732"></a>[RFC-2732]</dt>
+
+ <dd><i><a href="http://www.ietf.org/rfc/rfc2732.txt">RFC 2732
+ - Format for Literal IPv6 Addresses in URL's</a></i>, R. Hinden,
+ B. Carpenter and L. Masinter, IETF, December 1999. This document
+ is http://www.ietf.org/rfc/rfc2732.txt.</dd>
+
+
+ <dt><a id="ref-unicode" name="ref-unicode"></a>[UNICODE]</dt>
+
+ <dd><cite>The Unicode Standard, Version 3</cite>, The Unicode
+ Consortium, Addison-Wesley, 2000. ISBN 0-201-61633-5, as updated
+ from time to time by the publication of new versions. (See <a
+ href=
+ "http://www.unicode.org/unicode/standard/versions/">http://www.unicode.org/unicode/standard/versions/</a>
+ for the latest version and additional information on versions of
+ the standard and of the Unicode Character Database).</dd>
+
+ <dt><a id="ref-nfc" name="ref-nfc"></a>[NFC]</dt>
+
+ <dd><a href=
+ "http://www.unicode.org/unicode/reports/tr15/"><cite>Unicode
+ Normalization Forms,</cite></a> Unicode Standard Annex #15, Mark
+ Davis, Martin Dürst. (See <a href=
+ "http://www.unicode.org/unicode/reports/tr15/">http://www.unicode.org/unicode/reports/tr15/</a>
+ for the latest version).</dd>
+
+
+ <dt><a id="ref-rfc-3066" name="ref-rfc-3066"></a>[RFC-3066]</dt>
+
+ <dd><i><a href="http://www.ietf.org/rfc/rfc3066.txt">RFC 3066
+ - Tags for the Identification of Languages</a></i>, H.
+ Alvestrand, IETF, January 2001. This document is
+ http://www.ietf.org/rfc/rfc3066.txt.</dd>
+
+<dt>
+ <a id="ref-xml-xc14n" name="ref-xml-xc14n">[XML-XC14N]</a>
+ </dt>
+ <dd><cite><a href="http://www.w3.org/TR/2002/REC-xml-exc-c14n-20020718/">Exclusive XML Canonicalization Version 1.0</a></cite>, J. Boyer, D.E. Eastlake 3rd, J. Reagle, Authors/Editors. W3C Recommendation. World Wide Web Consortium, 18 July 2002. This version of Exclusive XML
+Canonicalization is <span>http://www.w3.org/TR/2002/REC-xml-exc-c14n-20020718/</span>.
+The <a href="http://www.w3.org/TR/xml-exc-c14n/">latest version of Canonical XML</a> is at http://www.w3.org/TR/xml-exc-c14n.
+ </dd>
+
+ <dt><a id="ref-xml-schema2" name=
+ "ref-xml-schema2"></a>[XML-SCHEMA2]</dt>
+
+ <dd><cite><a href="http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/">XML Schema
+ Part 2: Datatypes</a></cite>, W3C Recommendation, World Wide Web
+ Consortium, 2 May 2001.This version is
+ http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/. The <a href=
+ "http://www.w3.org/TR/xmlschema-2/">latest version</a> is available at
+ http://www.w3.org/TR/xmlschema-2/.</dd>
+
+
+ </dl>
+
+ <h3><a id="section-Informative-References" name=
+ "section-Informative-References"></a>9.2 Informational
+ References</h3>
+ <dl>
+
+ <dt><a id="ref-rdf-tests"
+ name="ref-rdf-tests"></a>[RDF-TESTS]</dt>
+<dd><cite><a href="http://www.w3.org/TR/2004/REC-rdf-testcases-20040210/">RDF Test Cases</a></cite>, Jan Grant and Dave Beckett, Editors, W3C Recommendation, 10 February 2004, http://www.w3.org/TR/2004/REC-rdf-testcases-20040210/ . <a href="http://www.w3.org/TR/rdf-testcases/">Latest version</a> available at http://www.w3.org/TR/rdf-testcases/ .</dd>
+
+
+ <dt><a id="ref-rdf-vocabulary"
+ name="ref-rdf-vocabulary"></a>[RDF-VOCABULARY]</dt>
+<dd><cite><a href="http://www.w3.org/TR/2004/REC-rdf-schema-20040210/">RDF Vocabulary Description Language 1.0: RDF Schema</a></cite>, Dan Brickley and R. V. Guha, Editors, W3C Recommendation, 10 February 2004, http://www.w3.org/TR/2004/REC-rdf-schema-20040210/ . <a href="http://www.w3.org/TR/rdf-schema/">Latest version</a> available at http://www.w3.org/TR/rdf-schema/ .</dd>
+
+
+ <dt><a id="ref-rdf-primer" name="ref-rdf-primer">[RDF-PRIMER]</a>
+ </dt>
+
+<dd><cite><a href="http://www.w3.org/TR/2004/REC-rdf-primer-20040210/">RDF Primer</a></cite>, Frank Manola and Eric Miller, Editors, W3C Recommendation, 10 February 2004, http://www.w3.org/TR/2004/REC-rdf-primer-20040210/ . <a href="http://www.w3.org/TR/rdf-primer/">Latest version</a> available at http://www.w3.org/TR/rdf-primer/ .</dd>
+
+
+ <dt><a id="ref-charmod" name="ref-charmod"></a>[CHARMOD]</dt>
+
+ <dd><cite><a href=
+ "http://www.w3.org/TR/2003/WD-charmod-20030822/">Character Model
+ for the World Wide Web 1.0</a></cite>, M. Dürst, F. Yergeau,
+ R. Ishida, M. Wolf, T. Texin, Editors, World Wide Web
+ Consortium Working Draft, work in progress, 22 August 2003.
+ This version of the Character Model is
+ http://www.w3.org/TR/2003/WD-charmod-20030822/. The <a href=
+ "http://www.w3.org/TR/charmod/">latest version of the Character
+ Model</a> is at http://www.w3.org/TR/charmod/.</dd>
+
+ <dt><a id="ref-xml-1-1" name="ref-xml-1-1"></a>[XML-1.1]</dt>
+
+ <dd><cite><a href="http://www.w3.org/TR/2002/CR-xml11-20021015/">Extensible Markup
+ Language (XML) 1.1</a></cite>, John Cowan, Editor.
+W3C Candidate Recommendation 15 October 2002.
+This version is
+ http://www.w3.org/TR/2002/CR-xml11-20021015/. The <a href=
+ "http://www.w3.org/TR/xml11/">latest version</a> is available at
+ http://www.w3.org/TR/xml11/.</dd>
+
+
+
+ <dt><a id="ref-xml-schema1" name=
+ "ref-xml-schema1"></a>[XML-SCHEMA1]</dt>
+
+ <dd><cite><a href="http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/">XML Schema Part 1: Structures</a></cite>
+ W3C Recommendation, World Wide Web
+ Consortium, 2 May 2001.
+This version is
+ http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/. The <a href=
+ "http://www.w3.org/TR/xmlschema-1/">latest version</a> is available at
+ http://www.w3.org/TR/xmlschema-1/.</dd>
+
+ <dt><a id="ref-xml-names11" name=
+ "ref-xml-names11"></a>[XML-NAMESPACES-1.1]</dt>
+
+ <dd><cite><a href="http://www.w3.org/TR/2003/PR-xml-names11-20031105/">Namespaces
+ in XML 1.1</a></cite>, Tim Bray, Dave Hollander, Andrew Layman,
+ Richard Tobin, Editors. W3C Proposed Recommendation 05 November 2003.
+This version is
+ http://www.w3.org/TR/2003/PR-xml-names11-20031105/. The <a href=
+ "http://www.w3.org/TR/xml-names11/">latest version</a> is available at
+ http://www.w3.org/TR/xml-names11/.</dd>
+
+ <dt><a id="ref-xml-infoset" name=
+ "ref-xml-infoset"></a>[XML-INFOSET]</dt>
+
+ <dd><i><a href="http://www.w3.org/TR/2001/REC-xml-infoset-20011024/">XML
+ Information Set</a></i>, John Cowan and Richard Tobin, W3C
+ Recommendation, 24 October 2001. This document is
+http://www.w3.org/TR/2001/REC-xml-infoset-20011024/.
+The <a href=
+ "http://www.w3.org/TR/xml-infoset/">latest version</a> is available at
+ http://www.w3.org/TR/xml-infoset/.</dd>
+
+ <dt>
+ <a id="ref-xpath" name="ref-xpath">[XPATH]</a>
+ </dt>
+ <dd><cite><a href="http://www.w3.org/TR/1999/REC-xpath-19991116">XML Path Language (XPath) Version 1.0</a></cite>, J. Clark and S. DeRose, Editors. World Wide Web Consortium, 16 November 1999. This version of XPath is <span>http://www.w3.org/TR/1999/REC-xpath-19991116</span>. The <a href="http://www.w3.org/TR/xpath">latest version of XPath</a> is at <span>http://www.w3.org/TR/xpath</span>.
+</dd>
+
+ <dt><a id="ref-owl" name="ref-owl"></a>[OWL]</dt>
+<dd><cite><a href="http://www.w3.org/TR/2004/REC-owl-ref-20040210/">OWL Web Ontology Language Reference</a></cite>, Mike Dean and Guus Schreiber, Editors, W3C Recommendation, 10 February 2004, http://www.w3.org/TR/2004/REC-owl-ref-20040210/ . <a href="http://www.w3.org/TR/owl-ref/">Latest version</a> available at http://www.w3.org/TR/owl-ref/ .</dd>
+
+ <dt><a id="ref-rdf-ms" name="ref-rdf-ms"></a>[RDF-MS]</dt>
+
+ <dd><cite><a href=
+ "http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/">Resource
+ Description Framework (RDF) Model and Syntax
+ Specification</a></cite>, O. Lassila and R. Swick, Editors. World
+ Wide Web Consortium. 22 February 1999. This version is
+ http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/. The <a href=
+ "http://www.w3.org/TR/REC-rdf-syntax/">latest version of RDF
+ M&S</a> is available at
+ http://www.w3.org/TR/REC-rdf-syntax/.</dd>
+ <dt><a id="ref-xhtml" name="ref-xhtml"></a>[XHTML]</dt>
+
+ <dd><cite><a href=
+ "http://www.w3.org/TR/2002/REC-xhtml1-20020801/">XHTML
+1.0 The Extensible HyperText Markup Language (Second Edition)</a></cite>,
+
+ World
+ Wide Web Consortium. 26 January 2000, revised 1 August 2002. This version is
+ http://www.w3.org/TR/2002/REC-xhtml1-20020801/. The <a href=
+ "http://www.w3.org/TR/xhtml1/">latest version of XHTML 1</a> is available at
+ http://www.w3.org/TR/xhtml1/.</dd>
+
+
+ <dt><a id="ref-iri" name="ref-iri"></a>[IRI draft]</dt>
+
+ <dd><i><a href="http://www.w3.org/International/iri-edit/draft-duerst-iri-04"
+>Internationalized Resource Identifiers (IRIs)</a></i>, M. Dürst
+ and M. Suignard, Internet-Draft, June 2003, expires December 2003. This document
+ is <span>http://www.w3.org/International/iri-edit/draft-duerst-iri-04</span>.</dd>
+ <dt><a id="ref-TAG" name="ref-TAG"></a>[TAG]</dt>
+
+ <dd><i><a href="http://www.w3.org/2001/tag/issues"
+>TAG Issues List</a></i>, W3C Technical Architecture Group.
+ This document
+ is <span>http://www.w3.org/2001/tag/issues</span>.</dd>
+</dl>
+ <h1><a id="changes" name="changes"></a>
+<a id="section-Revisions" name="section-Revisions">Appendix
+ A:</a> Revisions Since Last Call Working Draft of
+<a href="http://www.w3.org/TR/2003/WD-rdf-concepts-20031010/">10 October 2003</a> </h1>
+<p>
+There were no substantive changes.
+</p>
+<p>
+The following editorial changes have been made:
+</p>
+<dl>
+<dt>Wording of Graph Equivalence</dt>
+<dd>Following a
+<a href="http://lists.w3.org/Archives/Public/www-rdf-comments/2003OctDec/0118">suggestion</a> from
+ter Horst,
+the wording of
+<a href="#section-graph-equality">Section 6.3</a> has been improved.
+</dd>
+<dt>Avoid 'globally'</dt>
+<dd>In response to a
+<a href="http://lists.w3.org/Archives/Public/www-rdf-comments/2003OctDec/0118">comment</a> from
+ter Horst,
+the wording of
+<a href="#section-URI-Vocabulary">Section 3.2</a> has been changed,
+replacing a single phrase to avoid the word 'globally',
+which was undefined and unclear.
+</dd>
+<dt>%s in RDF URI References</dt>
+<dd>
+Following a
+<a href="http://lists.w3.org/Archives/Public/www-rdf-comments/2003OctDec/0123">comment</a> from
+Patel-Schneider, an additional
+note has been added, concerning %-escapes in
+<a href="#section-Graph-URIref">section 6.4 RDF URI References</a>.
+A new informative reference to the
+<a href="#ref-TAG">[TAG]</a> issue list has been added.
+</dd>
+<dt>References</dt>
+<dd>Dated references RDF and OWL documents have been updated.</dd>
+</dl>
+
+ <hr />
+ <div class="metadata">
+ <p><a href="metadata.rdf"><img
+ src="rdf_meta.gif" alt="RDF/XML Metadata" /></a></p>
+
+</div>
+ </body>
+</html>
+