--- a/rdf-primer/index.html	Tue Nov 12 12:52:18 2013 +0100
+++ b/rdf-primer/index.html	Tue Nov 12 14:34:55 2013 +0100
@@ -462,46 +462,111 @@
     term "property" is used to model predicates.  The main modelling
     constructs in RDF Schema are listed in the Table below:
 
-<table border="1" id="table-rdf-schema">
+<table id="table-rdf-schema">
   <tbody>
     <tr>
-      <th>RDF Schema construct</th>
+      <th>Construct</th>
       <th>Description</th>
-    </tr>
-    <tr>
-      <td>rdfs:Class</td>
-      <td>The class of RDF classes.</td>
-    </tr>
-    <tr>
-      <td>rdf:Property</td>
-      <td>The class of RDF properties.</td>
-    </tr>
-    <tr>
-      <td>rdf:type</td>
-      <td>Subject (any resource) is an instance of object (a class)</td>
+      <th>Syntactic form</th>
     </tr>
     <tr>
-      <td>rdfs:subClassOf</td>
-      <td>Subject (a class) is a subclass of object (a class)</td>
-    </tr>
-    <tr>
-      <td>rdfs:subPropertyOf</td>
-      <td>Subject (a property) is a subproperty of object (a property)</td>
+      <td>Class (a class)</td>
+      <td>class of RDF classes.</td>
+      <td>rdfs:Class</td>
     </tr>
     <tr>
-      <td>rdfs:domain</td>
-      <td>Domain of subject (a property) is object (a class)</td>
+      <td>Property (a class)</td>
+      <td>class of RDF properties.</td>
+      <td>rdf:Property</td>
     </tr>
     <tr>
+      <td>type (a property)</td>
+      <td>subject (any resource) is an instance of object (a class)</td>
+      <td>rdf:type</td>
+    </tr>
+    <tr>
+      <td>subClassOf (a property)</td>
+      <td>subject (a class) is a subclass of object (a class)</td>
+      <td>rdfs:subClassOf</td>
+    </tr>
+    <tr>
+      <td>subPropertyOf (a property)</td>
+      <td>subject (a property) is a subproperty of object (a property)</td>
+     <td>rdfs:subPropertyOf</td>
+   </tr>
+    <tr>
+      <td>domain (a property)</td>
+      <td>domain of subject (a property) is object (a class)</td>
+      <td>rdfs:domain</td>
+    </tr>
+    <tr>
+      <td>range (a property)</td>
+      <td>Range of subject (a property) is object (a class)</td>
       <td>rdfs:range</td>
-      <td>Range of subject (a property) is object (a class)</td>
     </tr>
   </tbody>
-  <caption>Main RDF Schema constructs</caption>
 </table>
-    
 
-    <p>@@ Discuss FOAF, Dublin Core, schema.org, SKOS and WordNet as typical examples</p>
+<p class="note">The syntactic is a prefix notation wich will be
+discussed in more detail in Sec. <a href="">"Writing RDF
+Graphs"</a>. The fact that the constructs have two different prefixes
+(<code>rdf:</code> and <code>rdfs:</code>) is a somewhat annoying
+historical artefact, which is preserved for backward
+compatibility.</p>
+
+<p>With the help of RDF Schema one can build a semantic model of RDF data. A simple
+example:</p>
+
+  <pre class="example" id="rdfs-example">
+  &lt;Person&gt; &lt;type&gt; &lt;Class&gt;
+  &lt;is a friend of&gt; &lt;type&gt; &lt;Property&gt;
+  &lt;is a friend of&gt; &lt;domain&gt; &lt;Person&gt;
+  &lt;is a friend of&gt; &lt;range&gt; &lt;Person&gt;
+  &lt;is a good friend of&gt; &lt;subPropertyOf&gt; &lt;is a friend of&gt;
+  </pre>
+
+<p>One of first RDF Schemas used worldwide is the
+<a href="http://www.foaf-project.org/">"Friend of a Friend"</a> (FOAF)
+schema for describing social networks. Other examples of RDF
+vocabularies are:</p>
+
+<dl>
+  <dt><a href="http://dublincore.org/documents/dcmi-terms/">Dublic Core</a></dt>
+  <dd>The Dublic Core Metadata Initative maintains a metadata element
+  set for describing a wide range of resources. The scheme provides
+  properties such as "creator", "publisher" and "title".</dd>
+
+  <dt><a href="http://schema.org/">schema.org</a>
+  <dd>Schema.org is a vocabulary developed by a group of major search
+  providers. The idea is that webmasters can use these terms to markup
+  webpages, so that search engines understand what the pages are
+  about.</dd>
+
+  <div class="issue">Check with DanBri about how to forumulate
+  relationship between schema.org and RDF schema.</div>
+  
+  <dt><a href="http://wordnet.princeton.edu/">WordNet</a></dt>
+  <dd>WordNet is a lexical database of English terms, grouped in sets
+  of synonyms, with a range of semantic interrelations. W3C make an
+  <a href="http://www.w3.org/2006/03/wn/wn20/">RDF version</a>
+  available of WordNet 2.0, which was one 
+  of the first elements of the <a href="http://linkeddata.org/"Linked
+  Data Cloud</a>.</dd>
+
+  <dt><a href="http://www.w3.org/2004/02/skos/">SKOS</a></dt>
+  <dd>SKOS is an RDF vocabulary for publishing classification schemes
+  such as terminologies and thesauri on the Web. SKOS is since 2009 a W3C
+  recommendation and is widely used in the library world. Library of
+  Congress published its Subject Headings as a <a
+  href="http://id.loc.gov/authorities/subjects.html">SKOS
+  vocabulary</a>.</dd> 
+</dl>
+
+<p>RDF Schema provides basic facilities for modelling semantics of RDF
+data. For a specification of these semantics the reader is referred to
+the RDF Semantics document [[RDF11-MT]]. For more comprehensive
+semantic modelling of RDF data W3C recommends the use the Web Ontology
+Language OWL [[OWL2-OVERVIEW]]. </p>
 
 </section>