Ill. Admin. Code tit. 62 § 250.10
"Act" - means the Oil and Gas Wells on Public Lands Act [5 ILCS 615 ].
"Department" - means the Illinois Department of Natural Resources.
"Drilling unit" - means a tract of land with sufficient acreage to allow an oil and gas well to be drilled in accordance with the Illinois Oil and Gas Act and implementing rules (62 Ill. Adm. Code 240).
"Office" - means the Office of Mines and Minerals in the Illinois Department of Natural Resources.
"Permittee" - means a person or entity who applies for and is issued a permit by the Office to explore unproven territory.
"Proven territory" - means territory so situated with reference to known producing wells as to establish the general opinion that, because of its relation to them, petroleum is contained in it. [5 ILCS 615/1 ]
"State owned land" - means a tract of land where the State owns 100% of the underlying mineral interests and the tract covers a large enough acreage to allow a properly spaced oil and/or gas well to be drilled in accordance with the Illinois Oil and Gas Act.
"Unknown territory" - means territory determined, in accordance with Section 250.20 of this Part, to lack proven petroleum reserves.
Ill. Admin. Code tit. 62, § 250.10