--- a/rdf-primer/index.html	Thu Nov 28 16:50:19 2013 +0100
+++ b/rdf-primer/index.html	Fri Nov 29 13:40:34 2013 +0100
@@ -250,13 +250,24 @@
    <pre>
       &lt;subject&gt;  &lt;predicate&gt; &lt;object&gt;
     </pre>
+    
     <p>The <strong>subject</strong> represents the resource we like to
     make a statement about. The <strong>predicate</strong> represents
     a property of the subject. The
-    <strong>object</strong> represents the value of the property 
+    <strong>object</strong> represents a value of the property 
     for this subject. Because RDF statements consist of three elements they are called
     <strong>triples</strong>.</p>
 
+    <p class="issue">Alternative phrasing of the previous paragraph:
+    An RDF statement represents a relationship between two resources.
+    The subject and the object represent the two resources being
+    related; the predicate represents the nature of their
+    relationship. The relationship is phrased in  a directional way
+    (from subject to object and is called in RDF a
+    <strong>property</strong>.  Because RDF statements consist of
+    three elements they are called <strong>triples</strong>.
+    </p>
+
     <p>Informally speaking, RDF allows us to make
     statements of the form:</p> 
 
@@ -378,13 +389,18 @@
       <h3>Blank nodes</h3>
 
       <p>IRIs and literals together provide the basic material for
-      writing down RDF statements. In addition, it is sometimes handy to
-      be able to talk about resources which have no identifier. For example, we might
-      want to state that the Mona Lisa painting has in its background
-      an unidentified tree which we know to be a cypress tree.
-      Resources such as the unidentified cypress tree are called <a
+      writing down RDF statements. In addition, it is sometimes handy
+      to be able to talk about resources without bothering to use an
+      identifier.  For example, we might want to state that the Mona
+      Lisa painting has in its background an unidentified tree which
+      we know to be a cypress tree. Resources such as the unidentified
+      cypress tree are called <a 
       href="http://www.w3.org/TR/rdf11-concepts/#section-blank-nodes">"blank 
-      nodes"</a> in RDF. </p>
+      nodes"</a> in RDF. A blank node indicates an un-named
+      thing. Blank nodes are like simple
+      variables in algebra; they represent some thing without saying
+      what their value is.
+      </p>
 
       <p>Blank nodes can appear in the <strong>subject and object
       position</strong> of a triple. They can be used 
@@ -490,12 +506,10 @@
 
     <p>RDF Schema uses the notion of "class" to
     specify categories that can be used to classify resources. The
-    term "property" is used to model predicates.  The main modeling
-    constructs in RDF Schema are listed in the table below:
+    relation between an instance and its class is modelled through the
+    "type" property. The main modeling
+    constructs in RDF Schema are listed in the table below:</p>
 
-    <p class="issue">
-    TODO: rephrase/extend the above based on Pat's comments
-    </p>
 
 <table id="table-rdf-schema">
   <tbody>
@@ -543,9 +557,9 @@
 </table>
 
 <p class="note">The syntactic form (second column) is in a prefix
-notation wich will be 
-discussed in more detail in Sec. <a href="#section-graph-syntax">"Writing RDF
-Graphs"</a>. The fact that the constructs have two different prefixes
+notation wich is discussed in more detail in Sec.
+<a href="#section-graph-syntax">"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>
@@ -590,7 +604,7 @@
   Data Cloud</a>.</dd>
 
   <dt><a href="http://www.w3.org/2004/02/skos/">SKOS</a></dt>
-  <dd>SKOS is a meta-vocabulary for publishing classification schemes
+  <dd>SKOS is a 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
@@ -601,8 +615,9 @@
 <p>For a formal specification of the semantics of the RDF Schema
 constructs the reader is referred to
 the RDF Semantics document [[RDF11-MT]]. Users interested in more comprehensive
-semantic modeling of RDF data might consider using the Web Ontology
-Language OWL [[OWL2-OVERVIEW]]. </p>
+semantic modeling of RDF data might consider using the OWL
+[[OWL2-OVERVIEW]]. OWL is a RDF vocabulary, so it can be
+used in combination with RDF Schema.</p>
 
 </section>
 
@@ -629,10 +644,6 @@
     TODO: Add graph diagram to stress abstract graph syntax.
     </p>
 
-   <p class="issue">
-    TODO: Add example with a bnode, here or in Appendix.
-    </p>
-
     <section id="subsection-turtle">
 
       <h3>Turtle</h3>
@@ -732,6 +743,20 @@
 datatype of language-tagged strings is never specified explicitly
 in Turtle.</p>
 
+<p>Below is sample Turtle syntax for blank nodes, using the
+earlier cypress-tree example:</p>  
+
+<pre class="example">
+  @prefix dbpedia: &lt;http://dbpedia.org/resource/&gt; .
+  @prefix lio: &lt;http://purl.org/net/lio#&gt; . 
+
+  dbpedia:Mona_Lisa lio:shows _:x .
+  _:x rdf:type dbpedia:Cypress .
+</pre>
+
+<p>The term <code>_:x</code> is a blank node. It represents some
+unamed tree, which is stated to be a cypress tree. </p>
+
 <p>The above is by no means a full account of the Turtle syntax. For
 more details about the syntax of Turtle the reader is referred to the
 Turtle document [[TURTLE]].</p>