Mass. Gen. Laws ch. 66, § 12

All such records shall be kept in the rooms where they are ordinarily used, and so arranged that they may be conveniently examined and referred to. When not in use, they shall be kept in the fireproof rooms, vaults or safes or buildings, vaults or file rooms that comply with standards of the National Fire Protection Association, or by electronic means with off-site secure storage, or in accordance with standards promulgated by the records conservation board.