+ There are three ODRL Policy subclasses (Agreement, Offer, Set), plus four non-normative ODRL Policy subclasses (Assertion, Privacy, Request, Ticket). Direct instances of the odrl:Policy class must be understood as policy odrl:Set policies. This subsection describes how are these policies to be understood in relation to semantics.
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A odrl:Set policy must be considered by an ODRL Evaluator. The odrl:Set is not necessarily linked to odrl:Offer nor odrl:Agreement.
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An odrl:Offer policy must not be considered by an ODRL Evaluator. It is created by an odrl:Assigner as a mere proposition.
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An odrl:Agreement policy must be considered by an ODRL Evaluator as any other odrl:Set policy. It represents the accord between (at least) one odrl:Assigner and a odrl:Assignee. An instance of odrl:Agreementmay have a way for the odrl:Assigner to trace to its related odrl:Offer.
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+ 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).
+ 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 factuality 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).
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+ Some examples of these state of the world RDF triples are:
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Current Time: a unit of time that represents the current time of the state of the world.
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Time Range: a tuple of time values that represent a start and an end.
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List of Languages: a sequence of languages from a taxonomy (e.g. iso639).
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Executed actions: a collection of executed actions.
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Parties: parties involved in a given state that have a odrl:function within the policies.
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Semantics of Permission, Prohibition, and Obligation
The deontic modalities of Permissions, Prohibitions and Obligations can be represented in ODRL as instances of the classes