--- a/model/ProvenanceModel.html	Mon Oct 10 12:39:17 2011 +0100
+++ b/model/ProvenanceModel.html	Mon Oct 10 13:45:37 2011 +0100
@@ -832,9 +832,9 @@
 <p>
 The following process execution assertion</p>
 <pre class="example">
-processExecution(pe1,add-crime-in-london,t+1,t+1+epsilon,[host="server.example.org"])
+processExecution(pe1,add-crime-in-london,t+1,t+1+epsilon,[host="server.example.org",type="app:edit"])
 </pre>
-<p>identified by identifier <span class="name">id</span>, states the existence of an activity with recipe link <span class="name">add-crime-in-london</span>, start time <span class="name">t+1</span>, and end time <span class="name">t+1+epsilon</span>, running on host <span class="name">server.example.org</span>.  The attribute <span class="name">host</span> is application specific, but MUST hold for the duration of activity.
+<p>identified by identifier <span class="name">id</span>, states the existence of an activity with recipe link <span class="name">add-crime-in-london</span>, start time <span class="name">t+1</span>, and end time <span class="name">t+1+epsilon</span>, running on host <span class="name">server.example.org</span>, and of type <span class="name">edit</span> (declared in some namespace with prefix <span class="name">app</span>).  The attribute <span class="name">host</span> is application specific, but MUST hold for the duration of activity.  The attribute <span class="name">type</span> is a reserved attribute of PROV-DM, allowing for subtyping to be expressed.
 </p>
 
 <p>The mere existence of a process execution assertion entails some event ordering in the world, since the start event precedes the end event.  This is expressed by constraint <a href="'#start-precedes-end'">start-precedes-end</a>.</p>
@@ -2298,6 +2298,8 @@
 
 <li>Namespaces allow attributes and names to be qualified. </li>
 
+<li>Subtyping is allowed by means of the reserved attribute <span class="name">type</span>.</li>
+
 <li>Domain specific values can be expressed by means of typed literals. </li>
 </ul>