--- a/model/prov-dm-constraints.html	Mon Apr 02 20:13:57 2012 +0100
+++ b/model/prov-dm-constraints.html	Mon Apr 02 20:23:08 2012 +0100
@@ -1088,6 +1088,11 @@
 </pre>
 </div>
 
+<p>The above example shows that  <span class="name">customerInChairAt6pm</span> and <span class="name">customerInChairAt7pm</span> are two alternate entities that have no overlap, while <span class="name">womanInRedDress</span> and <span class="name">customerInChairAt6pm</span> do overlap.
+The following example   illustrates another case of non-overlapping alternate entities.
+</p>
+
+<div class="anexample">Two copies of the same book, where copy A was destroyed before copy B was made.</div>
 
 
 </section>