The cost of the purchase of capacity for the purpose of this Rule and Miss. Code Ann. § 77-3-93 and § 77-3-95 shall be that charge or expense associated with the purchase of capacity, as that term is defined in Miss. Code Ann. § 77-3-91(f)& (g). When the cost of capacity is not separately stated, then the cost of capacity shall be that portion of the charge which represents the availability of the generating unit or units or which represents a firm commitment to supply energy for a period in excess of thirty (30) days.
39 Miss. Code. R. 1-25-101