As used in this chapter, unless the context otherwise requires: “Conservation easement” means a nonpossessory interest of a holder in real property, whether easement appurtenant or in gross, acquired through gift, purchase, devise, or bequest imposing limitations or affirmative obligations, the purposes of which include retaining or protecting natural or open-space values of real property, assuring its availability for agricultural, forestal, recreational, or open-space use, protecting natural resources, maintaining or enhancing air or water quality, or preserving the historical, architectural or archaeological aspects of real property. “Holder” means a charitable corporation, charitable association, or charitable trust which has been declared exempt from taxation pursuant to 26 U.S.C. § 501(c)(3) and the primary purposes or powers of which include: (i) retaining or protecting the natural or open-space values of real property; (ii) assuring the availability of real property for agricultural, forestal, recreational, or open-space use; (iii) protecting natural resources; (iv) maintaining or enhancing air or water quality; or (v) preserving the historic, architectural or archaeological aspects of real property. “Public body” means any entity defined in § 10.1-1700. “Third party right of enforcement” means a right provided in a conservation easement to enforce any of its terms granted to a governmental body, charitable corporation, charitable association or charitable trust which, although eligible to be a holder, is not a holder.