Media Rights Information

Action: PLING Recommendations to W3C Media Annotations WG on use of  
"rights information" (from XMP)

Please refer to these documents:
    Media Annotations Use Case and Requirements
    <http://dev.w3.org/2008/video/mediaann/mediaont-req/mediaont-req.html 
 >

    XMP Specification (PDF)
   <http://www.adobe.com/devnet/xmp/pdfs/XMPSpecificationPart2.pdf>

The XMP spec (on Page 31) lists 5 properties for rights management:
  - Certificate
  - Marked
  - Owner
  - UsageTerms
  - WebStatement

Is these the best way to express rights policy information?
Are there better options?

Cheers...  Renato Iannella
NICTA