--- a/model/prov-dm-constraints.html	Mon Apr 02 09:38:28 2012 +0100
+++ b/model/prov-dm-constraints.html	Mon Apr 02 09:44:00 2012 +0100
@@ -592,7 +592,7 @@
 
 <p>An activity is delimited by its <a title="activity start event">start</a> and its <a title="activity end event">end</a> events; hence, it occurs over
 an interval delimited by two <a title="event">instantaneous events</a>. However, an activity need not mention time information, nor duration, because they may not be known.
-An  attribute-value pairs for an activity remain unchanged.  They represent's the activity's situation during the activity's interval, i.e. an interval between two instantaneous events in the world, namely its <a title="activity start event">start</a> event and its <a title="activity end event">end</a> event.
+An activity's attribute-value pairs are expected to describe the activity's situation during its interval, i.e. an interval between two instantaneous events, namely its <a title="activity start event">start</a> event and its <a title="activity end event">end</a> event.
 </p>
 
 <div class="interpretation-forward">
@@ -621,14 +621,14 @@
 
 
 <p>A <dfn id="dfn-Generation">generation</dfn> is an instantaneous world <a title="entity generation event">event</a>, the completed creation of a new
-entity by an activity. This entity become available for usage after this <a title="event">instantaneous
+entity by an activity. This entity becomes available for usage after this <a title="event">instantaneous
 event</a>. This entity did not exist before creation. 
  This <a title="event">instantaneous event</a> encompasses a description of the modalities of generation of this entity by this activity, by means of key-value pairs.</p> 
 
 
 
 <p>
-A generation's id is OPTIONAL. It MUST be used when annotating generations (see Section <a href="#term-annotation">Annotation</a>) or when defining precise
+A generation's id is OPTIONAL. It MUST be used when annotating generations or when defining
 derivations (see <a href="#Derivation-Relation">Derivation</a>).
 </p>
 
@@ -662,7 +662,7 @@
 
 
 <p>
-A usage id is OPTIONAL. It MUST be present when annotating usages (see Section <a href="#term-annotation">Annotation</a>) or when defining precise derivations (see
+A usage id is OPTIONAL. It MUST be present when annotating usages or when defining derivations (see
 <a href="#Derivation-Relation">Derivation</a>).</p>
 
 <p>