--- a/model/prov-dm-constraints.html Mon Apr 02 09:21:17 2012 +0100
+++ b/model/prov-dm-constraints.html Mon Apr 02 09:38:15 2012 +0100
@@ -542,7 +542,9 @@
<h2>PROV-DM Definitional Constraints and Inferences</h2>
-<p>In this section, we revisit the types and relations of PROV-DM, and examine the constraints associated with their definitions. </p>
+<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>
@@ -557,9 +559,9 @@
<p>
An <dfn>entity</dfn> is a thing one wants to provide provenance for and whose situation in the world is described by some attribute-value pairs. An entity's attribute-value pairs are specified when the entity description is created and remain unchanged. An entity's attribute-value pairs are expected to describe the entity's situation and (partial) state during an entity's characterization interval,
- i.e. a continuous interval between two <a title="event">instantaneous events</a> in the world, namely its <a title="entity generation event">generation event</a> and its <a title="entity invalidation event">invalidation event</a>.</p>
-
-<p>If an entity's situation changes in the world, this may result in its description being invalid, because one or more attribute-value pairs no longer hold. In that case, from the PROV viewpoint, there exists a new entity, which needs to be given a distinct identifier, and associated with the attribute-value pairs that reflect its new situation in the world.</p>
+ i.e. a continuous interval between two <a title="event">instantaneous events</a>, namely its <a title="entity generation event">generation event</a> and its <a title="entity invalidation event">invalidation event</a>.</p>
+
+<p>If an entity's situation or state changes, this may result in its description being invalid, because one or more attribute-value pairs no longer hold. In that case, from the PROV viewpoint, there exists a new entity, which needs to be given a distinct identifier, and associated with the attribute-value pairs that reflect its new situation or state.</p>
@@ -575,19 +577,12 @@
<div class="interpretation-forward">
-For the interpretation of an activity, see <a href="#generation-precedes-invalidation">generation-precedes-invalidation</a>.
+For the interpretation of an entity, see <a href="#generation-precedes-invalidation">generation-precedes-invalidation</a>.
</div>
-<div class='issue'>The characterization interval of an entity record is currently implicit. Making it explicit would allow us to define alternateOf and specializationOf more precisely.
-Beginning and end of characterization interval could be expressed by attributes (similarly to activities).
-How do we define the end of an entity? This is <a href="http://www.w3.org/2011/prov/track/issues/204">ISSUE-204</a>.
-</div>
-
-
-
-
- </section>
+
+</section>
<section id="term-Activity">