Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 32, § 57

A veteran, including an army nurse, who has been in the service of the commonwealth, or of any county, city, town or district or any housing authority or any redevelopment authority thereof, for a total period of ten years in the aggregate, may, upon petition to the retiring authority, be retired, in the discretion of said authority, from active service, at one half of the highest annual rate of compensation, including any bonuses paid in lieu of additional salary or as a temporary wage increase in addition to his regular compensation, and including any allowance for maintenance, payable to him while he was holding the grade held by him at his retirement, and payable from the same source, with a further allowance of one per cent for each additional year of service over ten, but not to exceed sixty-five per cent in any case, if he is found by said authority to have become incapacitated for active service; provided, that he has a total income from all sources, exclusive of such retirement allowance and of any sum received from the government of the United States as a pension for war service, not exceeding one thousand dollars.