The state law defining Group 2

from MGL Chapter 32, § 3

Group 2. - Public works building police; permanent watershed guards and permanent park police; University of Massachusetts police; employees of the Massachusetts Port Authority, comprising guards, guard sergeants, head guard and chief of waterfront police; officials and employees of the department of public safety having police powers; employees of a municipal department who are employed as fire or police signal operators or signal maintenance repairmen; ambulance attendants of a municipal department who are required to respond to fires and perform duties assigned to them; employees of a city or town who are employed as licensed electricians and elevator maintenance men employed by a county; employees of Cushing hospital; employees of the trial court of the commonwealth who hold the position of chief probation officer, assistant chief probation officer, probation officer in charge or probation officer, chief court officer, assistant chief court officer or court officer; officers and employees of the general court having police powers; employees of the commonwealth or of any county, regardless of any official classification, except the sheriff, superintendent, deputy superintendent, assistant deputy superintendent and correction officers of county correctional facilities, whose regular and major duties require them to have the care, custody, instruction or other supervision of prisoners; and employees of the commonwealth or of any county whose regular and major duties require them to have the care, custody, instruction or other supervision of parolees or persons who are mentally ill or mentally defective or defective delinquents or wayward children and employees of Cushing hospital.