2 . 3 . 5 Rights Expression Languages

This chapter provides an overview of the field of rights expression languages (RELs). It justifies the need for rights expression languages in today’s DRM systems and adresses the requirements which have to be met by these languages. An REL is basically a means of expressing the rights of a party to certain assets. Therefore, all rights languages have a similar basic language concept, which is also introduced in this chapter. Standardization is a critical success factor for RELs, thus all important standards and other initiatives are briefly described as well. The chapter also deals with current and potential fields of application for RELs, after which two practical examples (XML instances) of rights languages are presented. Finally, the chapter gives an overview of the current market situation and trends in the field of DRM middleware and implementations using RELs.