Knowledge Management System (KMS), a descendant of ZOG, was developed at Carnegie Mellon University. It was designed to manage fairly large hypertext networks across local area networks. KMS is based on the basic unit called the frame. A frame can contain text, graphics, or images. Frames are connected to other frames via links. Links are of two types: tree items to represent hierarchical relationships and annotation items to represent referential relationships. In KMS, there is no distinction between browsing and authoring modes. Users can make changes to a frame or create links at any time and these changes are saved automatically [Acksyn et al., 1988].
KMS supports features such as aggregation, keyword searching, tailorability, collaboration, concurrency control, data integrity and security. It has been used for collaborative work, electronic publishing, project management, technical manuals and electronic mail.