(1) State the nature of the conduct constituting the alleged violation of this subchapter which is under investigation and the provision of law applicable thereto;

(2) Describe the class or classes of material to be produced thereunder with such definiteness and certainty as to permit such material to be fairly identified;

(3) Prescribe a return date which will provide a reasonable time within which the material so demanded may be assembled and made available for inspection and copying or reproduction; and

(4) Identify the custodian to whom such material shall be made available or the official before whom such oral examination shall take place or with whom such written reports shall be filed.