System for controlling the distribution and use of composite digital works
 A system for controlling use and distribution of composite digital works. A digital work is comprised of a description part and a content part. The description part contains control information for the composite digital work. The content part stores the actual digital data comprising the composite digital work. The description part is logically organized in an acyclic structure, e.g. a tree structure. For a composite digital work each node of the acyclic structure represents an individual digital work or some distribution interest in the composite digital work. A node in the acyclic structure is comprised of an identifier of the individual work, usage rights for the individual digital work and a pointer to the digital work. Composite digital works are stored in repositories. A repository has two primary operating modes, a server mode and a requester mode. When operating in a server mode, the repository is responding to requests to access digital works. When operating in requester mode, the repository is requesting access to a digital work. A repository will process each request to access a composite digital work by examining the usage rights for each individual digital work found in the description part of the composite digital work. 
Xerox Corporation
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Mark J. Daniel G. Peter L. T.
Stefik Bobrow Pirolli