Аннотация:Presents a new human-computer interaction style named Flexible Scenario Interface (FSI), reflecting psychological and cognitive ergonomics requirements of software system interfaces to endusers. Authors consider FSI along with such primary interaction styles as Q&A, menu selection, and form fillin. Advantages and shortcomings of conventional interaction styles for user support in purposeful activity of problem solving are discussed, and general requirements of interfaces for sophisticated and highly specific software systems are stated. The main conclusion is that Q&A and hierarchical menus fail in case of such programs, so authors attempt to develop a new universal interaction style -- FSI. FSI is based on Schank and Abelson scenario approach to formalized description of standard sequences of interrelated acts, and uses network representation of scenarios. There are three types of network nodes (atomic scenes, which provide bonds with application part of a program; complex scenes, or subscenarios, which can be decomposed into atomic ones; and modifiers, which influence the developing of specific scenario) and three types of links (permitted, prohibited, and recommended by the system guide) in FSI. System guide is the intelligent part of interface, which uses knowledge about standard scenarios to guide user in realization of optimum performance during its problem solving activity. The main ideas of FSI are the following: displaying of scenario graph directly onscreen; realization of user support with system guide; and visualization of scenario transformations as immediate feedback of user actions and data processing results. The use of FSI is demonstrated by Persoplan, a prototype decision support system.