Mass. Gen. Laws ch. 184 § 31
A conservation restriction means a right, either in perpetuity or for a specified number of years, whether or not stated in the form of a restriction, easement, covenant or condition, in any deed, will or other instrument executed by or on behalf of the owner of the land or in any order of taking, appropriate to retaining land or water areas predominantly in their natural, scenic or open condition or in agricultural, farming or forest use, to permit public recreational use, or to forbid or limit any or all (a) construction or placing of buildings, roads, signs, billboards or other advertising, utilities or other structures on or above the ground, (b) dumping or placing of soil or other substance or material as landfill, or dumping or placing of trash, waste or unsightly or offensive materials, (c) removal or destruction of trees, shrubs or other vegetation, (d) excavation, dredging or removal of loam, peat, gravel, soil, rock or other mineral substance in such manner as to affect the surface, (e) surface use except for agricultural, farming, forest or outdoor recreational purposes or purposes permitting the land or water area to remain predominantly in its natural condition, (f) activities detrimental to drainage, flood control, water conservation, erosion control or soil conservation, or (g) other acts or uses detrimental to such retention of land or water areas.
A preservation restriction means a right, whether or not stated in the form of a restriction, easement, covenant or condition, in any deed, will or other instrument executed by or on behalf of the owner of the land or in any order of taking, appropriate to preservation of a structure or site historically significant for its architecture, archeology or associations, to forbid or limit any or all (a) alterations in exterior or interior features of the structure, (b) changes in appearance or condition of the site (c) uses not historically appropriate, (d) field investigation, as defined in section twenty-six A of chapter nine, without a permit as provided by section twenty-seven C of said chapter, or (e) other acts or uses detrimental to appropriate preservation of the structure or site.
An agricultural preservation restriction means a right, whether or not stated in the form of a restriction, easement, covenant or condition, in any deed, will or other instrument executed by or on behalf of the owner of the land appropriate to retaining land or water areas predominately in their agricultural farming or forest use, to forbid or limit any or all (a) construction or placing of buildings except for those used for agricultural purposes or for dwellings used for family living by the land owner, his immediate family or employees; (b) excavation, dredging or removal of loam, peat, gravel, soil, rock or other mineral substance in such a manner as to adversely affect the land's overall future agricultural potential; and (c) other acts or uses detrimental to such retention of the land for agricultural use. Such agricultural preservation restrictions shall be in perpetuity except as released under the provisions of section thirty-two. All other customary rights and privileges of ownership shall be retained by the owner including the right to privacy and to carry out all regular farming practices.
A watershed preservation restriction means a right, whether or not stated in the form of a restriction, easement, covenant or condition, in any deed, will or other instrument executed by or on behalf of the owner of the land appropriate to retaining land predominantly in such condition to protect the water supply or potential water supply of the commonwealth, to forbid or limit any or all (a) construction or placing of buildings; (b) excavation, dredging or removal of loam, peat, gravel, soil, rock or other mineral substance except as needed to maintain the land and (c) other acts or uses detrimental to such watershed. Such watershed preservation restrictions shall be in perpetuity except as released under the provisions of section thirty-two. All other customary rights and privileges of ownership shall be retained by the owner, including the right to privacy.
An affordable housing restriction means a right, either in perpetuity or for a specified number of years, whether or not stated in the form of a restriction, easement, covenant or condition in any deed, mortgage, will, agreement, or other instrument executed by or on behalf of the owner of the land appropriate to (a) limiting the use of all or part of the land to occupancy by persons, or families of low or moderate income in either rental housing or other housing or (b) restricting the resale price of all or part of the property in order to assure its affordability by future low and moderate income purchasers or (c) in any way limiting or restricting the use or enjoyment of all or any portion of the land for the purpose of encouraging or assuring creation or retention of rental and other housing for occupancy by low and moderate income persons and families. Without in any way limiting the scope of the foregoing definition, any restriction, easement, covenant or condition placed in any deed, mortgage, will, agreement or other instrument pursuant to the requirements of the Rental Housing Development Action Loan program or the Housing Innovations Fund program established pursuant to section three of chapter two hundred and twenty-six of the acts of nineteen hundred and eighty-seven or pursuant to the requirements of any program established by the Massachusetts housing partnership fund board established pursuant to chapter four hundred and five of the acts of nineteen hundred and eighty-five, including without limitation the Homeownership Opportunity Program, or pursuant to the requirements of sections twenty-five to twenty-seven, inclusive, of chapter twenty-three B, or pursuant to the requirements of any regulations or guidelines promulgated pursuant to any of the foregoing, shall be deemed to be an affordable housing restriction within the meaning of this paragraph.
Mass. Gen. Laws ch. 184, § 31