In this paper, the authors present a high level, functional approach to the description of a generalized information retrieval system. The description is based on the top-down decomposition of the system into modules and processes and on an appropriate data abstraction. The purpose of this paper is to describe the behavior of the system in terms of the component processes and the interactions of these processes in terms of inputs, outputs, and the associated transformations. It allows one to view the system as a collection of abstract processes, each of which is concisely defined via a notation that describes what is accomplished but not how such a process is to be implemented. Semantically irrelevant details are removed, thereby producing a nonprocedural description which not only elucidates system behavior but serves as a basis for subsequent formal specification.