--- a/model/working-copy/wd6-prov-dm-with-core.html	Mon May 21 11:56:11 2012 +0100
+++ b/model/working-copy/wd6-prov-dm-with-core.html	Mon May 21 14:56:11 2012 +0100
@@ -404,7 +404,7 @@
 <div style="text-align: center; ">
   <figure style="max-width: 70%; " >
 <!--  <img src="uml/essentials.svg" alt="PROV Core Structures" style="max-width: 70%; "  /> -->
-   <img src="images/OverviewDiagram.png" alt="Simplified  Overview of PROV-DM" style="max-width: 70%; "  />
+   <img src="../images/OverviewDiagram.png" alt="Simplified  Overview of PROV-DM" style="max-width: 70%; "  />
 <figcaption id="prov-core-structures">Figure 1: PROV Core Structures</figcaption>
   </figure>
 </div>
@@ -524,7 +524,7 @@
 
 
 <section id="section-agents-attribution-association-responsibility"> 
-<h2>Agents, Attribution, Association, and Responsibility</h2>
+<h2>Agents and Responsibility</h2>
 
 <p>The motivation for introducing  agents in the model is to express the agent's responsibility for activities that happened and entities that were generated. </p>
 
@@ -628,18 +628,18 @@
 <section id="section-prov-extended"> 
 <h2>PROV Extended Structures</h2>
 
-<p>While PROV Core focuses on essential provenance structures commonly found in provenance descriptions, extended structures 
-are designed to support more advanced uses of provenance.</p>
-
-
-
-
-
-<section id="section-prov-extended-approach"> 
-<h2>Approach</h2>
+<p>While the core of PROV focuses on essential provenance structures commonly found in provenance descriptions, extended structures 
+are designed to support more advanced uses of provenance. 
+The purpose of this section is twofold. First, mechanisms to specify these extended structures are introduced.  Second,  two further categories of provenance structures are overviewed: they cater for provenance of provenance and collections,  respectively.</p>
+
+
+
+
+<section id="section-prov-extended-mechanisms"> 
+<h2>Mechanisms to Define Extended Structures</h2>
 
 <p>Extended structures are defined by a variety of mechanisms that we
-describe in this section: subtyping, expanded relations, optional
+outline in this section: subtyping, expanded relations, optional
 identification, and new relations.</p>
 
 
@@ -673,7 +673,7 @@
 plan.  Hence, an activity may reflect the execution of a plan that was
 designed in advance to guide the execution.  Hence, an expanded
 association relation allows a plan a plan be linked to an
-activity. Plan and full association are defined as follows. </p>
+activity. Plan is defined by subtyping and full association by an expanded relation, as follows. </p>
 
 <p>
 <span class="glossary-ref" data-ref="glossary-plan"  data-withspan="true">
@@ -707,15 +707,27 @@
 </section>
 
 
-<section id="section-prov-extended-approach-xxx"> 
-<h2>Optional Identification</h2>
-
-
-</section>
-
-
-<section id="section-prov-extended-approach-new-relations"> 
-<h2>New Relations</h2>
+<section id="section-prov-extended-approach-optional-identification-new-relation"> 
+<h2>Optional Identification and New Relations</h2>
+
+<p>We have seen that some concepts exhibit a core use, expressed as
+binary relation, and an extended use, expressed as n-ary relation.  In
+some cases, mapping the concept to a relation, whether binary or
+n-ary, is not sufficient: instead, it may be required to able to
+identify an instance.</p>
+
+<p>In such circumstances, PROV-DM allows an optional identifier to be
+expressed to identify an instance of an association between two or
+more elements.  These identifier can then be referred to as part of
+other concepts.</p>
+
+<div class="conceptexample" id="identifier-example">
+<p>A service may read a same configuration file on two different occasion: each  usage can be identifed by its own identifier, allowing them to be distinguished.
+</div>
+
+<p>Finally, PROV-DM supports further relations that are not subtypes or expanded versions of existing relations.</p>
+
+
 
 
 </section>
@@ -767,12 +779,21 @@
 
 
 
-
+</section>
 </section>
 
 
 <section id="prov-n"> 
-<h2>PROV-N: The Provenance Notation</h2>
+<h2>The Provenance Notation</h2>
+
+<div class="note">
+I am unclear where this section should go.
+<ul>
+<li>Completely delete it, since it's the purpose of the prov-n document.
+<li>Move it to a new section "preliminary" (1.3 or 2.): problem, it exposes a serialization too early in this document.
+<li>Move it to appendix: problem, the notation used in section 4/5 is not explained.
+<li>Leave it here ....
+</div>
 
 
 <p>To illustrate the application of PROV concepts to a concrete example (see <a href="#prov-dm-example">Section 3</a>) and to provide examples of concepts (see <a href="#data-model-components">Section 4</a>),
@@ -819,7 +840,7 @@
 </pre>
 </div>
 
-</section>
+
 
 </section>