--- a/model/optional.html	Fri Mar 30 12:15:35 2012 +0100
+++ b/model/optional.html	Fri Mar 30 12:26:50 2012 +0100
@@ -12,7 +12,7 @@
 <li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#end.time">time</a>
 </ol>
 
-<h4>Optional entity/agent/activity/generation/usage</h4>
+<h4>Optional entity/agent/activity</h4>
 <ol>
 <li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#generation.activity">activity</a>
 <li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#start.trigger">trigger</a>
@@ -20,14 +20,19 @@
 <li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#association.agent">agent</a>
 <li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#association.plan">plan</a>
 <li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#responsibility.activity">activity</a>
-<li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#derivation.activity">activity</a>
-<li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#derivation.generation">generation</a>
-<li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#derivation.usage">usage</a>
 <li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#revision.responsibility">responsibility</a>
 <li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#quotation.quoterAgent">quoterAgent</a>
 <li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#quotation.originalAgent">originalAgent</a>
 </ol>
 
+<h4>Optional derivation-related</h4>
+<ol>
+<li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#derivation.activity">activity</a>
+<li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#derivation.generation">generation</a>
+<li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#derivation.usage">usage</a>
+</ol>
+
+
 <h4>Optional attributes</h4>
 <ol>
 <li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#entity.attributes">attributes</a>