Use of rights expression languages for protecting multimedia information

Digital rights management is a key issue in music distribution throughout the Web. The authorization model is an important concept in DRM because it is used by any implementation which makes an authorization decision, for example when trying to decide if a user can exercise an action over a music album or a track. We present in this paper an implementation for the authorization model defined by the MPEG-21 REL standard. It is currently the only one that has been presented as reference software. The definitions of the data types for the different elements that form the authorization model are presented too.