--- a/model/optional.html	Mon Apr 02 10:11:32 2012 -0400
+++ b/model/optional.html	Mon Apr 02 15:51:13 2012 +0100
@@ -20,7 +20,7 @@
 <li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#start.trigger">trigger</a> (existence of trigger implied, if not specified)
 <li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#end.trigger">trigger</a> (existence of trigger implied, if not specified)
 <li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#association.agent">agent</a> (existence of agent implied, if not specified)
-<li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#association.plan">plan</a> (<b>no plan implied</b>, if unspecified, there may be none)
+<li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#association.plan">plan</a> (<b>no plan implied</b>, if unspecified, there may be none, see <a href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm-constraints.html#optional-attributes4">here</a>)
 <li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#responsibility.activity">activity</a> (existence of activity implied, if not specified)
 <li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#revision.responsibility">responsibility</a> (<b>no agent implied</b>, if unspecified)
 <li><a class='attribute' href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#quotation.quoterAgent">quoterAgent</a> (<b>no agent implied</b>, if unspecified)

--- a/model/prov-dm-constraints.html	Mon Apr 02 10:11:32 2012 -0400
+++ b/model/prov-dm-constraints.html	Mon Apr 02 15:51:13 2012 +0100
@@ -544,7 +544,8 @@
 
 <p>In this section, we revisit the types and relations of PROV-DM that have constraints associated with their definitions.  </p>
 
-<p>PROV-DM allows for some attributes to be optionally expressed. Unless otherwise specified, when an optional attribute is not present in a description, some value SHOULD be assumed to exist for this attribute, though it is not known which.</p>
+<p>
+<div id="optional-attributes1">PROV-DM allows for some attributes to be optionally expressed. Unless otherwise specified, when an optional attribute is not present in a description, some value SHOULD be assumed to exist for this attribute, though it is not known which.  </div>
 
 
 
@@ -682,7 +683,7 @@
 <h3>Start</h3>
 
 
-<p>An <a>activity start event</a> is the <a title="event">instantaneous event</a> that marks the instant an activity starts. It allows for an optional time attribute.  Activities also allow for an optional start time attribute.  If both are specified, they MUST be the same, as expressed by the following constraint.
+<p>An <a>activity start event</a> is the <a title="event">instantaneous event</a> that marks the instant an activity starts. It allows for an optional time attribute.  <span id="optional-attributes2">Activities also allow for an optional start time attribute.  If both are specified, they MUST be the same, as expressed by the following constraint.</span>
 </p>
 
 <div class='constraint' id='unique-startTime'>
@@ -694,7 +695,7 @@
 <h3>End</h3>
 
 
-<p>An <a>activity end event</a> is the <a title="event">instantaneous event</a> that marks the instant an activity ends. It allows for an optional time attribute.  Activities also allow for an optional end time attribute.  If both are specified, they MUST be the same, as expressed by the following constraint.
+<p>An <a>activity end event</a> is the <a title="event">instantaneous event</a> that marks the instant an activity ends. It allows for an optional time attribute.  <span id="optional-attributes3">Activities also allow for an optional end time attribute.  If both are specified, they MUST be the same, as expressed by the following constraint.</span>
 </p>
 
 <div class='constraint' id='unique-endTime'>
@@ -786,7 +787,7 @@
 <h3>Component 2: Agents and Responsibility</h3>
 
 
-<section id="recod-attribution">
+<section id="term-attribution">
 <h3>Attribution</h3> 
 
 
@@ -811,10 +812,12 @@
 <section id="term-Association">
 <h4>Association</h4>
 
+<div id="optional-attributes4">
 <p>In an association of the form <span class="name">wasAssociatedWith(a, ag, -, attr)</span>, the absence of a plan means: either no plan exists, or a plan exists but it is not identified.</p>
 
 
 <p>In an association of the form <span class="name">wasAssociatedWith(a, -, pl, attr)</span>, an agent exists but it is not identified.</p>
+</div>
 
 
 <div class="interpretation-forward">
@@ -1039,6 +1042,11 @@
 <h3>Alternate</h3>
 </section> 
 
+<div class="interpretation-forward">
+For the interpretation of alternate, see <a href="#alternate-ordering">alternate-ordering</a>.
+</div>
+
+
 
 <p>Alternate is <em>reflexive</em>. Indeed, <span class="name">alternate(e,e)</span> holds for any entity <span class="name">e</span> since any entity is always a specialization of another entity.</p>
 
@@ -1430,10 +1438,6 @@
 
 <p>Finally, two entities that are alternate of each other need to have some overlap.</p>
 
-<div class="note">
-Introduce a relation overlap to simplify these constraints
-</div>
-
 <div class='interpretation' id='alternate-ordering'>
 Given two agents <span class="name">e1</span> and <span class="name">e2</span>, <span class='conditional'>if</span> <span
 class="name">alternate(e2,e1)</span>