(a) “Tax commission, ” “State Tax Commission” or “department” means the Department of Revenue of the State of Mississippi.

(b) “Commissioner” or “Chairman of the State Tax Commission” means the Commissioner of Revenue of the Department of Revenue.

(c) “Person” means and includes any individual, firm, copartnership, joint venture, association, corporation, estate, trust or other group or combination acting as a unit, and includes the plural as well as the singular in number.

(d) “Taxpayer” means any person liable for or having paid any tax to the State of Mississippi under the provisions of this article.

(e) “Producer” means any person who produces or severs or who is responsible for the production of salt from the earth or water for sale, profit or commercial use.

(f) “Production” means the total amount or quantity of marketable salt produced by whatever measurement used.

(g) “Value” means and includes the purchase price or royalty, cost, and any other expense as determined by generally accepted accounting principles of underground mining and handling of production to the point where processing begins.

(h) “Processing” means an activity of an industrial or commercial nature wherein labor or skill is applied, by hand or machinery, to raw materials so that a more useful product or substance of trade or commerce is produced for sale.

(i) “Engaging in business” means any act or acts engaged in by producers, or parties at interest which results in the production of salt from the soil or water, for storage, transport or further processing.

(j) “Salt” means a substance which is chemically classified as sodium chloride.