The trend toward greater flexibility in educational methods has led to a need for better and more rapid access to a variety of aural and audiovisual resource materials. This in turn has demanded the development of a flexible, reliable system of hardware designed to aid existing distribution methods in providing such access. The system must be adaptable to various requirements and applications. The technical parameters of such a system and some practical applications of it are presented here. The system described is an encoding/decoding control system for use in association with electronic distribution systems such as radio and television. It provides remote control of aural and audiovisual tape recording devices. The application requires a highly reliable, narrow band system compatible with all applicable communication methods. Design philosophy is based on digital techniques and the use of integrated circuits throughout. Verification interrogation includes time and frequency checks for each code segment. Data concerning the occurrence of recognizable code segments within random program audio has been documented. Adaptation of the encoder to automatic control has been considered, as has the man-machine interface aspect of valid code generation. (Author/JK)