--- a/model/prov-constraints.html	Mon Jul 23 09:42:47 2012 +0100
+++ b/model/prov-constraints.html	Mon Jul 23 09:59:38 2012 +0100
@@ -1115,6 +1115,8 @@
    </li>
     <li><span class="name">wasInvalidatedBy(id;e,attrs)</span> <span class="conditional">IF AND ONLY IF</span> <span class="name">wasInvalidatedBy(id;e,-,-,attrs)</span>.
    </li>
+    <li><span class="name">wasDerivedFrom(id;e2,e1,attrs)</span> <span class="conditional">IF AND ONLY IF</span> <span class="name">wasDerivedFrom(id;e2,e1,-,-,-,attrs)</span>.
+   </li>
     <li><span class="name">wasAssociatedWith(id;e,attrs)</span> <span class="conditional">IF AND ONLY IF</span> <span class="name">wasAssociatedWith(id;e,-,-,attrs)</span>.
    </li>
     <li><span class="name">actedOnBehalfOf(id;a2,a1,attrs)</span> <span class="conditional">IF AND ONLY IF</span> <span class="name">actedOnBehalfOf(id;a2,a1,-,attrs)</span>.
@@ -1123,7 +1125,7 @@
  </div>
 
  <div class="remark">
-<p>
+<!--<p>
    Note that there is no expansion rule for <span class="name">wasDerivedFrom</span>.    In a derivation of the form
   <span class="name">wasDerivedFrom(id;e1,e2,attr)</span>, the
   absence of the optional activity, generation and use identifiers
@@ -1132,7 +1134,7 @@
   class="name">wasDerivedFrom(id;e1,e2,a,g,u,attr)</span> where some
   activity, generation and use are given explicitly.
  The short
-   form is not defined in terms of the long form in this case.</p>
+   form is not defined in terms of the long form in this case.</p>-->
 
   <p>
   There
@@ -1980,11 +1982,11 @@
     statements, due to inferences.  Uniqueness constraints are
     enforced through <a>merging</a> pairs of statements subject to
     equalities.  For example, suppose we have two activity statements
-    <span class="name">activity(a,t1,-,[a=1])</span> and <span
-    class="name">activity(a,-,t2,[b=2])</span>.  The <a>merge</a> of
+    <span class="name">activity(a,2011-11-16T16:00:00,t1,[a=1])</span> and <span
+    class="name">activity(a,t2,2011-11-16T18:00:00,[b=2])</span>.  The <a>merge</a> of
     these two statements (describing the same activity <span
     class="name">a</span>) is <span
-    class="name">activity(a,t1,t2,[a=1,b=2])</span>.  </p>
+    class="name">activity(a,2011-11-16T16:00:00,2011-11-16T18:00:00,[a=1,b=2])</span>.  </p>
 
     <p> Merging can be applied
    to a pair of terms, or a pair of attribute lists.