The holding of positions within the purview of section 305(b) of the Act shall be unlawful unless the holding shall have been authorized by order of the Commission. Nothing in this part shall be construed as authorizing the holding of positions within the purview of section 305(b) of the Act prior to order of the Commission on application therefor. Applications must be filed and authorization must be granted prior to holding any interlocking positions within the purview of section 305(b) of the Act; the Commission will consider late-filed applications on a case-by-case basis. The term “holding,” as used in this part, shall mean acting as, serving as, voting as, or otherwise performing or assuming the duties and responsibilities of officer or director within the purview of section 305(b) of the Act.