Section 17. In addition to the trustees and members of the board of investment, the officers of a mutual bank shall be a president, 1 or more vice presidents, a treasurer, a clerk and, subject to applicable provisions of the by-laws, such other officers as from time to time may be determined by the trustees to be necessary for the management of the affairs of such corporation; provided, that the duties of any such other officer shall not be in conflict with those of the president or treasurer. As used in this section and in section 20 and sections 2 and 5 of chapter 167J, the term ''operating officers'' shall mean and include the president, vice presidents, any assistant vice presidents, the treasurer, any vice treasurer, assistant treasurers, any branch managers, any person performing the duties of auditor and such other officers as may be designated as operating officers by vote of the board of trustees.

The president shall be a trustee. A vice president may perform the duties of the president to the extent authorized in the by-laws. The treasurer may at the same time be a vice president. A vice treasurer or an assistant treasurer may perform all the duties of the treasurer. The clerk shall be the clerk of the corporation and clerk of the trustees.

An operating officer of the corporation shall not hold the office or perform the duties of president, vice president, cashier or treasurer of a national banking association or a trust company, and the operating officer shall be governed by section 8 of chapter 167J with respect to holding office in another savings bank or in a co-operative bank or federal savings and loan association.