Section 108A. A city by ordinance and a town by by-law may establish, and from time to time amend, a plan classifying any or all positions, other than those filled by popular election and those under the direction and control of the school committee, into groups and classes doing substantially similar work or having substantially equal responsibilities. Such city or town may in like manner or in a city by vote of the city council, subject to the provisions of its charter, and in a town by vote of the town at a town meeting, establish, and from time to time amend, a plan establishing minimum and maximum salaries to be paid to employees in positions so classified, and such salary plan may provide for the attainment of such maximum salaries by periodical step-rate increases based on length of service. Nothing in this section shall be construed to conflict with the provisions of chapter thirty-one. Any by-law adopted under the provisions of this section shall not be subject to section thirty-two of chapter forty.

In any city or town for which a classification plan has been established in accordance with the provisions of paragraph (b) of section five of said chapter thirty-one, the city or town affected thereby shall, within one year after receiving notice from the administrator of the effective date of such classification plan or of said amendment or change, establish, amend or change, as the case may be, a compensation plan with a minimum and maximum salary for each group of positions. No rule or regulation or change in rules or regulations shall be promulgated as a part of any such compensation plan except after a public hearing held not less than two weeks nor more than two months after notice thereof shall have been posted in a conspicuous place in the city or town hall and in at least five other convenient and conspicuous places and shall also have been published on one or more days in one or more newspapers having a circulation in the city or town. Every notice posted shall contain, or have subjoined or annexed thereto, a copy of the proposed rule or regulation. If such rule or regulation or change therein is to be adopted by vote of the town or by by-law, the publication of the proposed rule, regulation or change in the warrant for the town meeting shall be deemed to satisfy the requirements of this paragraph.