Semantics of policies further explained, derived from Joshua Cornejo …

…contributions
w3c · May 22, 2024 · c064ffc · c064ffc
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 		<title>ODRL Formal Semantics</title>
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@@ -102,8 +99,28 @@ <h2>Introduction</h2>
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 		</section>			
 
+		<section id="sectionPolicies">	
+			<h2>Semantics of Policies</h2>	
+			There are three ODRL Policy subclasses (Agreement, Offer, Set), plus four non-normative ODRL Policy subclasses (Assertion, Privacy, Request, Ticket). Direct instances of the <code>odrl:Policy</code> class must be understood as policy <code>odrl:Set</code> policies. This subsection describes how are these policies to be understood in relation to semantics.
+			<br/>
+			<li>A <code>odrl:Set</code> policy must be considered by an ODRL Evaluator. The <code>odrl:Set</code> is not necessarily linked to <code>odrl:Offer</code> nor <code>odrl:Agreement</code>.<br></li>
+			<li>An <code>odrl:Offer</code> policy must not be considered by an ODRL Evaluator. It is created by an <code>odrl:Assigner</code> as a mere proposition.</li>
+			<li>An <code>odrl:Agreement</code> policy must be considered by an ODRL Evaluator as any other <code>odrl:Set</code> policy. It represents the accord between (<i>at least</i>) one <code>odrl:Assigner</code> and a <code>odrl:Assignee</code>. An instance of <code>odrl:Agreement</code>may have a way for the <code>odrl:Assigner</code> to trace to its related <code>odrl:Offer</code>.</li>
+			<br/>
+			The ODRL Evaluator requires a formal representation of the state of the world to perform computations on both the access control and the policy monitoring scenarios. This state of the world may include current date, current location of the assignee or the history of performed actions. This document does not formally specify how to represent the necessary entities (e.g. country codes). </br>
+			The formal representation of the world can be a set of RDF triples. The existence of these triples does not entail their represented world is a reality: the <i>factuality</i> of the class instances is not entailed, and hypothetical computations are possible. The implementor of the ODRL Evaluator may want to describe the factuality of relevant class instances. RDF triples to represent the state of the world may be generated as observations from the world generated by third parties (extrinsic), by the ODRL Evaluator user or by any other source (intrinsic).
+			<br/>
+			Some examples of these state of the world RDF triples are:
+				<ul>
+				<li><b>Current Time</b>: a unit of time that represents the current time of the state of the world.</li>
+				<li><b>Time Range</b>: a tuple of time values that represent a start and an end.</li>
+				<li><b>List of Languages</b>: a sequence of languages from a taxonomy (e.g. <a href="https://www.iso.org/iso-639-language-code#">iso639</a>).</li>
+				<li><b>Executed actions</b>: a collection of executed actions.</li>
+				<li><b>Parties</b>: parties involved in a given state that have a <code>odrl:function</code> within the policies.</li>
+				</ul>
+		</section>
 
-<section id="section2">	
+<section id="sectionPermissionsProhibitionsObligations">	
 <h2> Semantics of Permission, Prohibition, and Obligation</h2>	
 
 	The deontic modalities of <b>Permissions</b>, <b>Prohibitions</b> and <b>Obligations</b> can be represented in ODRL as instances of the classes