--- a/rdf-primer/index.html	Mon Nov 11 22:38:47 2013 +0100
+++ b/rdf-primer/index.html	Mon Nov 11 23:20:27 2013 +0100
@@ -367,9 +367,9 @@
 
     </section>
 
-    <section id="subsection-graphs">
+    <section id="subsection-multiple-graphs">
 
-      <h3>Graphs</h3>
+      <h3>Multiple graphs</h3>
 
       <p>RDF provides a mechanism to group RDF statements in multiple
       graphs and associate each graph with an IRI.<p> 
@@ -407,10 +407,27 @@
       <p>These two graphs constitute an RDF <i>dataset</i>. RDF datasets are collections of 
       RDF graphs.</p>
 
+    <p class="note">Multiple graphs are a recent extension of the RDF
+    data model. The original data model assumed that all triples are
+    part of the same (large) graph. In practice, RDF tool builders and
+    data managers needed a mechanism to talk about subsets of
+    triples. Multiple graphs were first introduced in the RDF query
+    language SPAQL. The RDF data model was therefore extended with a notion of
+    multiple graphs that is closely aligned with SPARQL. </p> 
+
     </section>
 
 </section>
 
+<section id="section-vocabulary">
+
+    <h2>RDF Vocabularies</h2>
+
+    <p></p>
+
+</section>
+
+
 <section id="section-graph-syntax">
 
     <h2>Writing RDF graphs</h2>
@@ -430,6 +447,8 @@
       writing, ease of parsing and readability. Our single-graph example can be
       represented in Turtle as follows.</p>
 
+      <p>@@ explain example step-by-step</p>
+
       <pre class="example" id="turtle-example">
 @base &lt;http://example.org/&gt; .
 @prefix foaf: &lt;http://xmlns.com/foaf/0.1/&gt; .
@@ -545,19 +564,20 @@
    </section>
 
 
+<section id="section-semantics">
 
-<section id="section-vocabulary">
-
-    <h2>RDF Data and Vocabularies</h2>
+    <h2>RDF Graphs and what you can do with them</h2>
 
     <p></p>
 
 </section>
 
-<section id="section-semantics">
+   <section id="section-data">
 
-    <h2>RDF Graphs and what you can do with them</h2>
+    <h2>RDF Data</h2>
 
+   @@ RDF sources, linked data, alignment with SPARQL
+   
     <p></p>
 
 </section>