Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 149, § 51

Before operating on Sunday, every employer subject to section forty-eight or fifty A shall post in a conspicuous place on the premises a schedule containing a list of his employees who are required or allowed to work on Sunday, and designating the day of rest for each. No employee shall be required or allowed to work on the day of rest designated for him.