Section 415(d), Title IV, of the Domestic Volunteer Service Act of 1973, Pub. L. 93-113, 87 Stat. 412, provides that VISTA Volunteers who have successfully completed their period of service shall be eligible for appointment in the Federal competitive service in the same manner as Peace Corps Volunteers as prescribed in Executive Order No. 11103 (April 10, 1963). This section further provides that the Director of ACTION shall determine who has successfully completed his period of service in accordance with regulations he shall prescribe.