IFS programmer's manual (release 2).

The Interpretive Frame System (IFS) is a tool for creating application software with sophisticated interactive interfaces. IFS is based on the notion of a frame network. A frame network consists of many interconnected modules called frames, each of which represents a logical activity in the system. Frames are written in a high-level language. Besides the usual computational constructs such as conditionals, loops, or arithmetics and Boolean expressions, the IFS language also includes facilities for building program/program interactions, such as subprocess invocations or coprocess communications, and constructs for building user/program interactions such as menus or forms. IFS is a suitable tool to integrate existing programs by providing a uniform and easy-to-use user interface. It can also be used to build a new system in a top-down manner by first defining the network of frames and their interactions and user interface, then programming problem-specific parts. Therefore, it provides a general framework supporting any combination of top-down and bottom-up software development methodologies. This paper gives an overview of the frame network concept, the user interface of frame network systems, the frame programming language, and the IFS system implementation.