--- a/rdf-concepts/index.html	Thu May 10 17:26:02 2012 +0100
+++ b/rdf-concepts/index.html	Thu May 10 20:12:28 2012 +0100
@@ -5,7 +5,7 @@
     <title>RDF 1.1 Concepts and Abstract Syntax</title>
     <style type="text/css">
 .figure { font-weight: bold; text-align: center; }
-table.xsd-types td, table.xsd-types th { border: 1px solid #ddd; padding: 0.1em 0.5em; }
+table td, table th { border: 1px solid #ddd; padding: 0.2em 0.5em; }
     </style>
     <script src='../ReSpec.js/js/respec.js' class='remove'></script>
     <script class='remove'>
@@ -254,6 +254,10 @@
     that describes the denoted resource by means of
     <a title="RDF statement">RDF statements</a>.</li>
     </ul>
+</section>
+
+<section id="vocabularies">
+    <h3>RDF Vocabularies and Namespace IRIs</h3>
 
     <p>An <dfn>RDF vocabulary</dfn> is a collection of <a title="IRI">IRIs</a>
     with clearly established <a title="referent">referents</a>
@@ -263,9 +267,32 @@
     RDF vocabularies. Some such vocabularies are mentioned in the
     Primer [[RDF-PRIMER]].</p>
 
-    <p class="issue">It has been suggested that this specification should
-    also define terms such as “<dfn>namespace</dfn>”, “<dfn>namespace IRI</dfn>”,
-    and “<dfn>namespace prefix</dfn>”.</p>
+    <p>The <a title="IRI">IRIs</a> in an <a>RDF vocabulary</a> often share
+    a common substring known as a <dfn>namespace IRI</dfn>.
+    Some namespace IRIs are associated by convention with a short name
+    known as a <dfn>namespace prefix</dfn>. Some examples:
+
+    <table rules="all" summary="Some example namespace prefixes and IRIs">
+      <tr><th>Namespace prefix</th><th>Namespace IRI</th><th>RDF vocabulary</th></tr>
+      <tr><td>rdf</td><td><a href="http://www.w3.org/1999/02/22-rdf-syntax-ns#"><code>http://www.w3.org/1999/02/22-rdf-syntax-ns#</code></a></td><td>The RDF built-in vocabulary [[RDF-SCHEMA]]</td></tr>
+      <tr><td>rdfs</td><td><a href="http://www.w3.org/2000/01/rdf-schema#"><code>http://www.w3.org/2000/01/rdf-schema#</code></a></td><td>The RDF Schema vocabulary [[RDF-SCHEMA]]</td></tr>
+      <tr><td>xsd</td><td><a href="http://www.w3.org/2001/XMLSchema#"><code>http://www.w3.org/2001/XMLSchema#</code></a></td><td>The <a>RDF-compatible XSD types</a></td></tr>
+    </table>
+
+    <p>In some contexts it is common to abbreviate <a title="IRI">IRIs</a>
+    that start with <a title="namespace IRI">namespace IRIs</a> by using the
+    associated <a>namespace prefix</a>. For example, the IRI
+    <code>http://www.w3.org/1999/02/22-rdf-syntax-ns#XMLLiteral</code>
+    would be abbreviated as <code>rdf:XMLLiteral</code>.
+    Note however that these abbreviations are <em>not</em> valid IRIs,
+    and MUST NOT be used in contexts where IRIs are expected.
+    Namespace IRIs and namespace prefixes are <em>not</em> a formal part of the
+    RDF data model. They are merely a syntactic convenience for
+    abbreviating IRIs.</p>
+
+    <p>The term “<dfn>namespace</dfn>” on its own does not have a
+    well-defined meaning in the context of RDF, but is sometimes incorrectly
+    used to mean “<a>namespace IRI</a>” or “<a>RDF vocabulary</a>”.</p>
 </section>
 
 
@@ -697,8 +724,7 @@
     <p>The <a title="literal">literals</a> that can be defined using this
     datatype are:</p>
 
-    <table border="1" cellpadding="5" summary=
-    "This table lists the literals of type xsd:boolean.">
+    <table rules="all" summary="This table lists the literals of type xsd:boolean.">
       <tr>
         <th>Literal</th>
         <th>Value</th>
@@ -734,7 +760,7 @@
     listed in the following table are the
     <dfn>RDF-compatible XSD types</dfn>. Their use is RECOMMENDED.</p>
  
-    <table class="xsd-types" rules="all">
+    <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>
@@ -1109,6 +1135,7 @@
   <h2>Changes from RDF 2004</h2>
 
   <ul>
+    <li>2012-05-10: Added an informative subsection on <a href="#vocabularies">RDF vocabularies and namespace IRIs</a>.</li>
     <li>2012-05-09: Removed an example from the conformance section that didn't make sense any more with the modified <code>rdf:XMLLiteral</code>. Added some new issue boxes.</li>
     <li>2012-05-09: <code><a>rdf:XMLLiteral</a></code> no longer requires lexical forms to be canonicalized, and the value space is now defined in terms of [[DOM-LEVEL-3-CORE]] (<a href="https://www.w3.org/2011/rdf-wg/track/issues/13">ISSUE-13</a>)</li>
     <li>2012-05-09: Removed Section 3 <em>RDF Vocabulary IRI and Namespace</em>; its contents will be folded into the RDF Schema document</li>