MPEG-21 Rights Data Dictionary

MPEG doc#: N7433
Date: July 2005
Author: Chris Barlas

1         Overview

In 2001 ISO/IEC JTC 1/SC 29/WG 11 (MPEG) determined that a standard for rights semantics was essential for the exchange of rights expressions between different digital proprietary rights management applications. However, at the time MPEG decided to define a standard, there were many content metadata schemes already available and it was considered essential to ensure they could be incorporated into the proposed MPEG rights data dictionary. This requirement is satisfied by the MPEG Rights Data Dictionary, use of which is intended to facilitate the accurate exchange and processing of information between interested parties involved in the administration of rights in, and use of, Digital Items.

2         Description

The MPEG-21 Rights Data Dictionary (RDD) comprises a set of clear, consistent, structured, integrated and uniquely identified terms to support the MPEG-21 Rights Expression Language (REL) as specified in ISO/IEC 21000-5. A methodology and structure for the Dictionary is also standardised, along with the method by which  further Terms can be added to the Dictionary through a Registration Authority.

The RDD is a prescriptive Dictionary, in the sense that it defines a single meaning for a Term, but it is also inclusive in that it can recognise and incorporate terms and definitions governed by organisations other that MPEG. These terms can be incorporated through an ontological process called mapping. The standard specifies an audit process so that additions, amendments and deletions to terms and their attributes can be tracked.

Finally, the MPEG-21 RDD recognises legal definitions only as terms from other organisations that can be mapped into the RDD Dictionary through the Registration Authority. Terms that are directly authorised by the RDD Registration Authority neither define nor prescribe intellectual property rights or other legal entities.

3         Relationship of ISO/IEC 21000-6 with existing Metadata Schemes

As noted above, as well as providing terms for the REL, the RDD and the Registration Authority is designed to support the mapping of terms from different namespaces. The purpose of such mapping is to enable the transformation of metadata from the terminology of one namespace into that of another namespace. This will facilitate the communication of meaning between communities having different metadata schemes. The mapping process, specified to ensure minimum ambiguity or loss of semantic integrity, will be the responsibility of the Registration Authority, which is required by the standard to provide automated term look-up.

4          Methodology of ISO/IEC 21000-6

The RDD has the characteristics of a structured ontology, in which meaning, once it has been defined, can be passed on from one term to another by logical rules of association such as inheritance and opposition. In recognition of the great diversity and complexity associated with multimedia content, it is designed to represent as many different specialisations of meaning as its users require, and to show their relationships in a structured way in order to support the mapping and transformation of terms between different schemas and systems.

5         Terms in ISO/IEC 21000-6

The MPEG-21 RDD contains about 2000 standardised terms. The majority of these are necessary for the structure of the RDD and for enabling extensibility of the Dictionary.  Other terms are directly related to the use creation of REL permissions and the expression of rights ownership.

Included in these terms are the fourteen rights set out here.