--- a/model/ProvenanceModel.html	Tue Sep 06 14:51:33 2011 +0100
+++ b/model/ProvenanceModel.html	Tue Sep 06 17:07:29 2011 +0100
@@ -108,6 +108,46 @@
 <h2>Motivation and Requirements</h2>
     </section> 
 
+    <section> 
+<h2>A Conceptualization of the World</h2>
+
+
+<p>In the world (whether real or not), there are things, which can be
+physical, digital, conceptual, or otherwise, and activities involving
+things.  Words such thing or activity should be understood with
+their informal meaning.</p>
+
+<p>When we talk about things in the world in natural language and even when we assign identifiers, we are often imprecise in ways that make it difficult to clearly and unambiguously report provenance: a resource with a URL may be understood as referring to a report available at that URL, the version of the report available there today, the report independent of where it is hosted over time, etc.</p>
+
+<p>Hence, to disambiguate things and their situation in the world as perceived by us, we introduce the concept <dfn id="concept-characterized-thing">characterized thing</dfn>, which refers to a thing and its situation in the world, as characterized by someone.</p>
+
+<div class="xmpl">
+Different users may take different perspective about a resource with a URL, which are referred to as
+three different characterized things:
+<ul>
+<li>a report available at  URL, </li>
+<li>the version of the report available there today, </li>
+<li>the report independent of where it is hosted over time.</li></ul></div>
+
+
+<p>We do not assume that any characterization is more important than any other, and in fact, it is possible to describe the processing that occurred for the report to be commissioned, for individual versions to be created, for those versions to be published at the given URL, etc., each via a different characterized thing that unambiguously characterizes the report appropriately.</p>
+
+<p>In the world, <dfn id="concept-activity">activities</dfn> involve
+things in multiple ways: they consume them, they process them, they
+transform them, they modify them, they change them, they relocate
+them, they use them, they generate them, they are controlled by them,
+etc.</p>
+
+
+<p>In our conceptualization of the world, punctual events, or <dfn id="concept-event">events</dfn> for short, happen in the world, which mark changes in the world, in its activities, and in its things. In this specification, it is assumed that a partial order exists between events. How practically such order is realized is beyond the scope of this specification. Possible implementations of that ordering include a single global notion of time and Lamport's style clocks.</p>
+    </section> 
+
+    <section> 
+<h2>The Provenance Abstract Syntax Notation</h2>
+
+    </section> 
+
+
     <section class="informative"> 
 <h2>Example</h2>
 
@@ -311,6 +351,7 @@
 
 <div class='resolved'>Data model vs Language. Misc comments raised at <a href="http://www.w3.org/2011/prov/track/issues/62">ISSUE-62</a></div>
 
+
 <p>In the world (whether real or not), there are things, which can be
 physical, digital, conceptual, or otherwise, and activities involving
 things.  Words such thing or activity should be understood with

--- a/model/extra.css	Tue Sep 06 14:51:33 2011 +0100
+++ b/model/extra.css	Tue Sep 06 17:07:29 2011 +0100
@@ -126,3 +126,22 @@
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+.xmpl::before {
+    content:    "Example";
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