--- a/model/ProvenanceModel.html Tue Sep 06 22:11:32 2011 +0100
+++ b/model/ProvenanceModel.html Tue Sep 06 22:25:44 2011 +0100
@@ -629,7 +629,7 @@
<p>The activity that a process execution is a representation of has a duration, delimited by its start and its end events; hence, it occurs over an interval delimited by two events. However, a process execution need not mention time information, nor duration, because they may not be known.</p>
-<p> A process execution assertion, noted <span class="name">processExecution(id,rl,st,et)</span>:
+<p> An instance of a process execution expression, noted <span class="name">processExecution(id,rl,st,et)</span> in the Provenance Abstract Syntax Notation:
<ul>
<li> contains an identifier <span class="name">id</span>;
<li> MAY contain a <a href="#expression-RecipeLink">recipe link</a> <span class="name">rl</span>;
@@ -669,11 +669,27 @@
-<p><dfn id="dfn-Generation">Generation</dfn> represents the creation of a new characterized thing by an activity. This characterized thing did not exist before creation.</p>
+<p>In PIDM, a <dfn id="dfn-Generation">generation expression</dfn> is a representation of a world event, the creation of a new characterized thing by an activity. This characterized thing did not exist before creation. </p>
+
+<p>In the Provenance Abstract Syntax Notation, a generation expression's text matches the <span class='nonterminal'>generation</span> production of the grammar defined in this specification document.</p>
+
+<div class='grammar'>
+<span class="nonterminal">generation</span> :=
+<span class="name">wasGeneratedBy</span>
+<span class="name">(</span>
+<span class="nonterminal">identifier</span>
+<span class="name">,</span>
+<span class="nonterminal">identifier</span>
+<span class="name">,</span>
+<span class="nonterminal">role</span>
+[<span class="name">,</span>
+<span class="nonterminal">time</span>]
+<span class="name">)</span><br/>
+</div>
-<p>A Generation assertion, noted <span class="name">wasGeneratedBy(e,pe,r,t)</span>:
+<p>An instance of a generation expression, noted <span class="name">wasGeneratedBy(e,pe,r,t)</span> in the Provenance Abstract Syntax Notation:
<ul>
<li> refers to an entity <span class="name">e</span>, which represents the characterized thing that is created;
<li> refers to a process execution <span class="name">pe</span>;
@@ -683,9 +699,11 @@
</p>
<p>
+The following generation assertion
<pre class="example">
wasGeneratedBy(e2,pe1,out)
</pre>
+states the existence of an event in the world, at which a new characterized thing, represented by entity denoted by <span class="name">e2</span> is created by an activity, represented by a process execution, denoted <span class="name">pe1</span>.
</p>
<p>A given entity can be generated at most by one process execution in the scope of a given <a href="#expression-Account">account</a>.