Describes the Relational Data File, a computer-based data retrieval system now partly operational, capable of storing millions of facts and of retrieving data both directly and through logical inference. A large collection of information about cybernetics research was used as the database. Facts are stored in the form of sentences in an artificial information language, each representing a binary relationship between two entities. Data are entered by means of special input forms; a translation program in a special programming language, FOREMAN, derives the relational sentences that are then internally coded and stored in the data file. An intensional file that stores facts about relationships permits many data sentences to be derived when needed, rather than stored explicitly. Counting space for all auxiliaries, one IBM 1301 disk holds 232,000 sentences in the information language. The system operates on an IBM 7044 computer. (See also RM-4793.) 35 pp. Ref.