--- a/rdf-concepts/index.html Mon Jun 17 10:38:13 2013 -0700
+++ b/rdf-concepts/index.html Wed Jun 19 12:25:18 2013 -0400
@@ -140,10 +140,6 @@
<section id="section-Introduction" class="informative">
<h2>Introduction</h2>
- <p class="issue">This is a work-in-progress Working Draft. Various open
- issues are flagged throughout the text with boxes like this.
- <a href="#sotd">Feedback</a> on these issues is particularly welcome.</p>
-
<p>The <em>Resource Description Framework</em> (RDF) is a framework
for representing information in the Web.</p>
@@ -163,8 +159,8 @@
<li>the <a href="http://www.w3.org/TR/rdf-schema/">RDF Vocabulary
Description Language</a> (RDFS) [[RDF-SCHEMA]],</li>
- <li>the <a href="http://www.w3.org/TR/rdf-mt/">formal
- model-theoretic semantics for RDF and RDFS</a> [[RDF-MT]].</li>
+ <li>the <a href="http://www.w3.org/TR/rdf11-mt/">formal
+ model-theoretic semantics for RDF and RDFS</a> [[!RDF-MT]].</li>
</ul>
<section id="data-model">
@@ -203,7 +199,7 @@
<a>language-tagged strings</a>, denote plain-text strings in a
natural language.</p>
- <p>The assertion of an <a>RDF triple</a> says that <em>some relationship,
+ <p>Asserting an <a>RDF triple</a> says that <em>some relationship,
indicated by the <a>predicate</a>, holds between the
<a title="resource">resources</a> <a title="denote">denoted</a> by
the <a>subject</a> and <a>object</a></em>. This statement corresponding
@@ -243,19 +239,22 @@
A very brief, informal and partial account follows:</p>
<ul>
- <li>IRIs have global scope: An IRI is assumed to <a>denote</a>
- the same <a>resource</a> regardless of where the IRI occurs.</li>
-
+ <li>IRIs have global scope: Two different appearances of an IRI
+ <a>denote</a> the same <a>resource</a>.</li>
+
<li>By social convention, the
<a href="http://www.w3.org/TR/webarch/#uri-ownership">IRI owner</a>
- [[WEBARCH]] gets to say what an <a>IRI</a> <a title="denote">denotes</a>.
- They do this when “<dfn>minting</dfn>” a new IRI.</li>
+ [[WEBARCH]] gets to say what what the intended (or usual)
+ referent of an <a>IRI</a> is. Applications and users need not
+ abide by this intended denotation, but there may be a loss of
+ interoperability with other applications and users if they do
+ not do so.</li>
<li>The IRI owner can establish the intended <a>referent</a>
by means of a specification or other document that explains
what is denoted. For example, the
<a href="http://www.w3.org/TR/vocab-org/">Organization Ontology
- document</a> [[VOCAB-ORG]] specifies the referents
+ document</a> [[VOCAB-ORG]] specifies the intended referents
of various IRIs that start with
<code>http://www.w3.org/ns/org#</code>.</li>
@@ -348,7 +347,7 @@
<ul>
<li>An <a>IRI</a>, once <a title="minting">minted</a>, should never
- change its <a>referent</a>. (See
+ change its intended <a>referent</a>. (See
<a href="http://www.w3.org/TR/webarch/#URI-persistence">URI
persistence</a> [[WEBARCH]].)</li>
<li><a title="literal">Literals</a>, by design, are constants and
@@ -379,9 +378,9 @@
<p>An <a>RDF dataset</a> is a collection of
<a title="RDF graph">RDF graphs</a>. All but one of these graphs have
- an associated <a>IRI</a>. They are called
- <a title="named graph">named graphs</a>, and the IRI is called the
- <a>graph name</a>.
+ an associated <a>IRI</a> or blank node. They are called
+ <a title="named graph">named graphs</a>, and the IRI or blank node
+ is called the <a>graph name</a>.
The remaining graph does not have an associated IRI, and is called
the <a>default graph</a> of the RDF dataset.</p>
@@ -394,20 +393,13 @@
<section id="entailment">
<h3>Equivalence, Entailment and Inconsistency</h3>
- <p class="issue">The Working Group intends to publish a Working Group
- Note detailing some of its efforts to define a <strong>formal semantics for
- RDF datasets</strong>. It should be referenced here when available. This is
- <a href="http://www.w3.org/2011/rdf-wg/track/actions/209">ACTION-209</a>.
- </p>
-
<p>An <a>RDF triple</a> encodes a <a title="RDF statement">statement</a>—a
simple <dfn>logical expression</dfn>, or claim about the world.
An <a>RDF graph</a> is the conjunction (logical <em>AND</em>) of
- its triples, and the conjunction of two RDF graphs is their <a>union</a>.
- This treatment of RDF graphs as logical expressions is
- normatively defined in the
- <a href="http://www.w3.org/TR/rdf-mt/">RDF Semantics</a>
- specification [[RDF-MT]], using a model-theoretic semantics.
+ its triples. The union of two RDF graphs that do not share blank
+ nodes is their <a>conjunction</a>. If two <a>RDF graph</a>s share blank
+ nodes, then conjoining them may require merging as defined in the
+ RDF Semantics specification [[RDF-MT]], using a model-theoretic semantics.
It yields various relationships between RDF graphs:</p>
<dl>
@@ -608,8 +600,7 @@
<section id="section-Graph-Literal">
<h2>Literals</h2>
- <p>Literals are used to denote values such as strings, numbers and dates
- by means of a lexical representation.</p>
+ <p>Literals are used for values such as strings, numbers and dates.</p>
<p>A <dfn>literal</dfn> in an <a>RDF graph</a> consists of two or three
elements:</p>
@@ -641,6 +632,8 @@
[a-zA-Z0-9]{1,8})*</code>
before normalizing to lowercase.</p>
+ <p>Multiple literals may have the same lexical form.</p>
+
<p>Concrete syntaxes MAY support <dfn title="simple literal">simple
literals</dfn>, consisting of only a <a>lexical form</a>
without any datatype IRI or language tag. Simple literals only
@@ -779,7 +772,7 @@
<li>Exactly one <dfn>default graph</dfn>, being an <a>RDF graph</a>.
The default graph does not have a name and MAY be empty.</li>
<li>Zero or more <dfn title="named graph">named graphs</dfn>.
- Each named graph is a pair consisting of an <a>IRI</a>
+ Each named graph is a pair consisting of an <a>IRI</a> or a blank node
(the <dfn>graph name</dfn>), and an <a>RDF graph</a>.
Graph names are unique within an RDF dataset.</li>
</ul>
@@ -805,7 +798,9 @@
<h3>RDF Dataset Isomorphism</h3>
<p id="section-graph-equality">Two <a title="RDF Dataset">RDF datasets</a>
- <var>(DG1, NG1)</var> and <var>(DG2, NG2)</var> are dataset-isomorphic if
+ (the RDF dataset <var>D1</var> with default graph <var>DG1</var> and named
+ graph <var>NG1</var> and the RDF dataset <var>D2</var> with default graph
+ <var>DG2</var> and named graph <var>NG2<var>) are dataset-isomorphic if
and only if:</p>
<ol>
<li><var>DG1</var> and <var>DG2</var> are graph-isomorphic;</li>
@@ -930,11 +925,15 @@
Datatypes</a></em> [[!XMLSCHEMA11-2]]. The XML Schema built-in types
listed in the following table are the
<dfn>RDF-compatible XSD types</dfn>. Their use is RECOMMENDED.</p>
+
+ <p>Readers might note that the xsd:hexBinary and xsd:base64Binary
+ datatypes are the only safe datatypes for transferring binary
+ information.</p>
<table rules="all" summary="A list of the RDF-compatible XSD types, with short descriptions">
<tr><th></th><th>Datatype</th><th>Value space (informative)</th></tr>
- <tr><th rowspan="4">Core types</th><td><a href="http://www.w3.org/TR/xmlschema11-2/#string"><code>xsd:string</code></a></td><td>Character strings</td></tr>
+ <tr><th rowspan="4">Core types</th><td><a href="http://www.w3.org/TR/xmlschema11-2/#string"><code>xsd:string</code></a></td><td>Character strings (but not all Unicode character strings)</td></tr>
<tr><td><a href="http://www.w3.org/TR/xmlschema11-2/#boolean"><code>xsd:boolean</code></a></td><td>true, false</td></tr>
<tr><td><a href="http://www.w3.org/TR/xmlschema11-2/#decimal"><code>xsd:decimal</code></a></td><td>Arbitrary-precision decimal numbers</td></tr>
<tr><td><a href="http://www.w3.org/TR/xmlschema11-2/#integer"><code>xsd:integer</code></a></td><td>Arbitrary-size integer numbers</td></tr>
@@ -1310,6 +1309,7 @@
<section class="appendix informative" id="changes">
<h2>Changes between RDF 2004 and RDF 1.1</h2>
+ <!--
<p class="issue">The Working Group intends to publish a separate
Working Group Note entitled
@@ -1318,6 +1318,7 @@
Some or all material in this section may be moved to that document. In the
meantime, the <a href="#change-log">Change Log</a> is a good indication
as to what else has changed and why.</p>
+ -->
<p>This section discusses changes between the
<a href="http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/">2004
@@ -1372,11 +1373,17 @@
<em>RDF 1.1 Concepts and Abstract Syntax</em>.</p>
<ul>
+ <li>2013-06-19: Noted that RDF Dataset graph names may be blank nodes (<a
+ href="https://www.w3.org/2011/rdf-wg/track/actions/274">ACTION-274</a>, <a
+ href="https://www.w3.org/2013/meeting/rdf-wg/2013-06-12#resolution_1">resolution</a>)</li>
+ <li>2013-06-19: Changes in response to <a
+ href="http://lists.w3.org/Archives/Public/public-rdf-wg/2013May/0221.html">a
+ review by Peter Patel-Schneider</a></li>
<li>2013-06-05: Minor change to note to specify the value space and lexical space of language tags (<a href="http://www.w3.org/2011/rdf-wg/track/actions/265">ACTION-265</a>, <a href="https://www.w3.org/2013/meeting/rdf-wg/2013-05-22#resolution_3">resolution</a>)</li>
<li>2013-05-08: Minor change to note that a badly formed language tag is a syntax error (<a href="http://www.w3.org/2011/rdf-wg/track/actions/262">ACTION-262</a>)</li>
<li>2013-05-08: Migrated language related to datatype maps to recognized datatype IRIs (<a href="http://www.w3.org/2011/rdf-wg/track/issues/118">ISSUE-118</a>)</li>
<li>2013-05-08: Editorial changes in response to <a href="http://lists.w3.org/Archives/Public/public-rdf-wg/2013May/0058.html">a discussion of literal equality</a></li>
- <li>2013-05-08: Editorial changes in response to <a href="http://lists.w3.org/Archives/Public/public-rdf-wg/2013May/0075.html">review by Sandro Hawke</a></li>
+ <li>2013-05-08: Editorial changes in response to <a href="http://lists.w3.org/Archives/Public/public-rdf-wg/2013May/0075.html">a review by Sandro Hawke</a></li>
<li>2013-05-07: Revised the definition of blank nodes (<a href="http://www.w3.org/2011/rdf-wg/track/issues/107">ISSUE-107</a>)</li>
<li>2013-05-07: Defined the consequence of a literal being ill-typed (<a href="http://www.w3.org/2011/rdf-wg/track/issues/109">ISSUE-109</a>)</li>
<li>2013-05-07: Clarified the existence of null control characters in xsd:strings (<a href="http://www.w3.org/2011/rdf-wg/track/issues/126">ISSUE-126</a>)</li>