Sec. 6. (a) For the director to accept an applicant's self-bond, the total amount of the outstanding and proposed self-bonds of the applicant for surface coal mining and reclamation operations in the United States may not exceed twenty-five percent (25%) of the applicant's tangible net worth in the United States.
(b) For the director to accept a corporate guarantee, the total amount of the corporate guarantor's present and proposed self-bonds and guaranteed self-bonds for surface coal mining and reclamation operations in the United States may not exceed twenty-five percent (25%) of the guarantor's tangible net worth in the United States.