XrML and Emerging Models of Content Development and Distribution
http://www.gilbane.com/whitepapers/contentguard/GRWP042302.pdf

Trippe, Bill
Gilbane Report
2005

Abstract:

With the publication of XrML 2.0, ContentGuard provides an open, flexible, and extensible means of expressing digital rights that not only addresses copy protection, but, as importantly, offers a much broader and powerful means for publishers to experiment with and deploy new business models.