--- a/model/prov-n.html	Wed Jul 11 16:10:38 2012 +0100
+++ b/model/prov-n.html	Wed Jul 11 17:03:38 2012 +0100
@@ -2099,17 +2099,47 @@
 <section id="exceptions-summary">
 <h3>Summary of additional validity rules for grammar productions</h3>
 
+Some of the grammar productions allow for expressions that are syntactically correct, and yet according to [[PROV-DM]] they are not acceptable, because additional semantic rules are defined for those expressions.
+ The following table provides a summary of such expressions along with examples of syntactically correct but unacceptable expressions, and the additional semantic rules.</p>
+
 <div style="text-align: left;">
 <table border="1" style="margin-left: auto; margin-right: auto;">
-<caption id="validity-rules-table">Summary of additonal rules for grammar productions</caption>
+<caption id="validity-rules-table">Summary of additional semantic rules for grammar productions</caption>
 <tr><td><a><b>Production</b></a></td>
-     <td><b>Syntactically correct forms</b></td>
+     <td><b>Examples of syntactically correct expressions</b></td>
      <td><b>Additional semantic rule</b></td>
 </tr>
 <tr><td><a class="grammarRef" href="#prod-generationExpression">Generation expression</a></td>
-    <td><span class="name">wasGeneratedBy(e2, -, -)</span><p/><span class="name">wasGeneratedBy(-; e2, -, -)</span></td>
+    <td><span class="name">wasGeneratedBy(e2, -, -)</span><br/><span class="name">wasGeneratedBy(-; e2, -, -)</span></td>
     <td>At least one  of <a href="http://www.w3.org/TR/prov-dm/#generation.id"><span class='attribute'>id</span></a>, <a href="http://www.w3.org/TR/prov-dm/#generation.activity"><span class='attribute'>activity</span></a>, <a href="http://www.w3.org/TR/prov-dm/#generation.time"><span class='attribute'>time</span></a>, and  <a href="http://www.w3.org/TR/prov-dm/#generation.attributes"><span class='attribute'>attributes</span></a> MUST be present.</td>  
 </tr>
+<td><a class="grammarRef" href="#prod-usageExpression">Usage expression</a></td>
+<td><span class="name">used(a2, -, -)</span><br/><span class="name">used(-; a2, -, -)</span></td>
+<td>At least one  of <a href="http://www.w3.org/TR/prov-dm/#usage.id"><span class='attribute'>id</span></a>, <a href="http://www.w3.org/TR/prov-dm/#usage.entity"><span class='attribute'>entity</span></a>, <a href="http://www.w3.org/TR/prov-dm/#usage.time"><span class='attribute'>time</span></a>, and  <a href="http://www.w3.org/TR/prov-dm/#usage.attributes"><span class='attribute'>attributes</span></a> MUST be present</td>
+<tr>
+<td><a class="grammarRef" href="#prod-startExpression">Start expression</a></td>
+<td> <span class="name">wasStartedBy(e2, -, -, -)</span><br/><span class="name">wasStartedBy(-; e2, -, -, -)</span></td>
+<td>At least one  of <a href="http://www.w3.org/TR/prov-dm/#start.id"><span class='attribute'>id</span></a>, <a href="http://www.w3.org/TR/prov-dm/#start.trigger"><span class='attribute'>trigger</span></a>, <a href="http://www.w3.org/TR/prov-dm/#start.starter"><span class='attribute'>starter</span></a>, <a href="http://www.w3.org/TR/prov-dm/#start.time"><span class='attribute'>time</span></a>, and  <a href="http://www.w3.org/TR/prov-dm/#start.attributes"><span class='attribute'>attributes</span></a> MUST be present</td>
+<tr>
+
+<tr>
+<td><a class="grammarRef" href="#prod-endExpression">End expression</a></td>
+<td><span class="name">wasEndedBy(e2, -, -, -)</span><br/><span class="name">wasEndedBy(-; e2, -, -, -)</span></td>
+<td>At least one  of <a href="http://www.w3.org/TR/prov-dm/#end.id"><span class='attribute'>id</span></a>, <a href="http://www.w3.org/TR/prov-dm/#end.trigger"><span class='attribute'>trigger</span></a>, <a href="http://www.w3.org/TR/prov-dm/#end.ender"><span class='attribute'>ender</span></a>, <a href="http://www.w3.org/TR/prov-dm/#end.time"><span class='attribute'>time</span></a>, and  <a href="http://www.w3.org/TR/prov-dm/#end.attributes"><span class='attribute'>attributes</span></a> MUST be present</td>
+</tr>
+
+<tr>
+<td><a class="grammarRef" href="#prod-invalidationExpression">Invalidation expression</a></td>
+<td><span class="name">wasInvalidatedBy(e2, -, -)</span>  <br/><span class="name">wasInvalidatedBy(-; e2, -, -)</span></td>
+<td>At least one  of <a href="http://www.w3.org/TR/prov-dm/#invalidation.id"><span class='attribute'>id</span></a>, <a href="http://www.w3.org/TR/prov-dm/#invalidation.activity"><span class='attribute'>activity</span></a>, <a href="http://www.w3.org/TR/prov-dm/#invalidation.time"><span class='attribute'>time</span></a>, and  <a href="http://www.w3.org/TR/prov-dm/#invalidation.attributes"><span class='attribute'>attributes</span></a> MUST be present</td>
+</tr>
+
+<tr>
+<td><a class="grammarRef" href="#prod-associationExpression">Association expression</a></td>
+<td><span class="name">wasAssociatedWith(a, -, -)</span> <br/><span class="name">wasAssociatedWith(-; a, -, -)</span></td>
+<td>At least one of <a href="http://www.w3.org/TR/prov-dm/#association.id"><span class='attribute'>id</span></a>, <a href="http://www.w3.org/TR/prov-dm/#association.agent"><span class='attribute'>agent</span></a>,  <a href="http://www.w3.org/TR/prov-dm/#association.plan"><span class='attribute'>plan</span></a>, and  <a href="http://www.w3.org/TR/prov-dm/#association.attributes"><span class='attribute'>attributes</span></a>  MUST be present</td>
+</tr>
+
 </table>
 </div>