Future operating document retrieval systems may be based on fully-automatic information analysis methods instead of manual indexing, and on real-time search procedures which allow the user to interact with the system during the search process. Performance characteristics are first given for fully-automatic information retrieval systems, and comparisons are made with presently operating partly-manual systems. Thereafter, various user-controlled search strategies are described, and the potential of these strategies in improving systems performance is discussed. The evaluation results for the real-time retrieval procedures are used to derive design criteria for future automatic information systems.