A database of interests is maintained in a distributed computing system to register the individual interests of users in centrally stored non-textual media files, such as digital voice, music, scanned-in image, and video files. Uniquely named piece table style persistent data structures are employed...http://www.google.co.uk/patents/US4914586?utm_source=gb-gplus-sharePatent US4914586 - Garbage collector for hypermedia systems
