--- a/model/prov-constraints.html	Thu Sep 06 08:28:04 2012 +0200
+++ b/model/prov-constraints.html	Thu Sep 06 08:46:52 2012 +0200
@@ -1827,7 +1827,16 @@
   inferences.  This issue is discussed in more detail under <a
    href="#uniqueness-constraints">Uniqueness Constraints</a>.
   </p>
-
+  
+<p>In a [definition|inference], term symbols such as <span class="name">id</span>, 
+	<span class="name">start</span>, <span class="name">end</span>, <span class="name">e</span>, 
+	<span class="name">a</span>, <span class="name">attrs</span>,
+	are assumed to be variables unless otherwise specified.  These variables are scoped at 
+	the [definition|inference|constraint] level, so the rule is equivalent to any one-for-one 
+	renaming of the variable names.  When several rules are collected within a [definition|inference] 
+	as an ordered list, the scope of the variables in each rule is at the level of list elements, and so reuse of 
+	variable names in different rules does not affect the meaning.
+</p>
 <section>
   <h4>Optional Identifiers and Attributes</h4>
 
@@ -2782,7 +2791,16 @@
     <li><em>impossibility constraints</em>, which forbid certain
     patterns of statements in <a>valid</a> PROV instances.
     </ul>
-
+  </p>
+  <p>As in a [definition|inference], term symbols such as <span class="name">id</span>, 
+	<span class="name">start</span>, <span class="name">end</span>, <span class="name">e</span>, 
+	<span class="name">a</span>, <span class="name">attrs</span> in a constraint,
+	are assumed to be variables unless otherwise specified.  These variables are scoped at 
+	the [definition|inference|constraint] level, so the rule is equivalent to any one-for-one 
+	renaming of the variable names.  When several rules are collected within a constraint
+	as an ordered list, the scope of the variables in each rule is at the level of list elements, and so reuse of 
+	variable names in different rules does not affect the meaning.
+</p>
   <section
   id="uniqueness-constraints">