--- a/model/prov-constraints.html	Thu Jul 19 10:40:15 2012 +0100
+++ b/model/prov-constraints.html	Thu Jul 19 10:48:11 2012 +0100
@@ -1654,6 +1654,17 @@
 </p>   </div>
 
 
+   <hr />
+   <p id='entity-activity-disjoint_text'> Furthermore,  identifiers
+   of relationships in PROV uniquely identify a relation (except for wasInfluencedBy), through
+  the following key constraints:
+  </p>
+  <div class='constraint' id='entity-activity-disjoint'>
+    <p>It is not the case that <span  class="name">entity(id,attrs1)</span>
+<span  class="name">activity(id,_t1,_t2,attrs2)</span>.
+</p>   </div>
+
+
 <hr>