As used in these rules, the following definitions apply:

(1) "Billing location" means the zip code or county of the purchaser's destination of the petroleum product; additional information, such as terminal of delivery and customer name, is optional.

(2) "Department" means the department of natural resources and conservation, provided for in Section 2-15-3301 , MCA.

(3) "Firm" means any person, as defined in Section 90-4-302 , MCA, engaged in any activity covered by these rules.

(4) "Gas plant operator" means a person that owns, operates, or controls the operation of one or more natural gas processing plants or fractionators, meeting the definition of "refinery" in Section 90-4-302 (9) , located in Montana.