A model system (called DATAPLAN) is proposed for generation, access, and control of a shared database by casual users in their own terminology. The DATAPLAN system achieves this goal by planning a dialog which hierarchically defines the possible universe of discourse where casual users can communicate with the database. The plan is executed on the domains of hierarchical semantics, and controlled by pattern matching with a goal and generative backtracking mechanism. To ensure flexible and smooth communication of casual users with the shared database, the system generates individualized user class "fuzzy" interfaces. They are composed of multiplex associations of the attributes and values of the shared database with those of casual user classes in varying degrees. © 1976 American Elsevier Publishing Company, Inc.