Ill. Admin. Code tit. 17 § 4010.110
As used in this Part, the following terms have the meanings indicated, except where context requires otherwise:
"Commission" means the Illinois Nature Preserves Commission.
"Department" means the Illinois Department of Natural Resources.
"Illinois Natural Areas Inventory" is a comprehensive list of natural areas of statewide significance as defined in the Illinois Natural Areas Inventory - Technical Report (White, 1978). The Illinois Natural Areas Inventory is maintained by the Department.
"Natural heritage resource" is a community of wild plants and animals, a population of a species of plant or animal, or a physical feature which was present as part of the Illinois landscape prior to settlement by immigrants from Europe and is now rare, declining, or less abundant than formerly.
"Register of Land and Water Reserves (or register)" is a list of areas registered in accordance with the Illinois Natural Areas Preservation Act (Ill. Rev. Stat. 1991, ch. 105, par. 701 et seq.) [525 ILCS 30 ], together with records concerning them.
"Registration agreement" is a legal instrument that conveys conservation rights consistent with the provisions of the Real Property Conservation Rights Act (Ill. Rev. Stat. 1991, ch. 30, par. 400 et seq.) [765 ILCS 120 ].
Ill. Admin. Code tit. 17, § 4010.110