Generic Knowledge-Base Editor

From web site: "The GKB-Editor (Generic Knowledge Base Editor) is a tool for graphically browsing and editing knowledge bases across multiple Frame Representation Systems (FRSs) in a uniform manner. It offers an intuitive user interface, in which objects and data items are represented as nodes in a graph, with the relationships between them forming the edges. Users edit a KB through direct pictorial manipulation, using a mouse or pen. A sophisticated incremental browsing facility allows the user to selectively display only that region of a KB that is currently of interest, even as that region changes."