18 CFR § 281.205 - General rules.
(a) Priority of service categories - 1) Priority 1. Each interstate pipeline shall establish a new high-priority use category of service designated priority one (1) which shall include all the high-priority entitlements calculated in accordance with § 281.206 and those storage injection volumes calculated in accordance with paragraph (c)(2) of this section.
(2) Priority 2. Each interstate pipeline shall establish a new priority of service category designated priority two (2) which shall include all the essential agricultural use requirements calculated in accordance with § 281.207 and those storage injection volumes calculated in accordance with paragraph (c)(2) of this section.
(3) Other priority of service categories. Each interstate pipeline may retain the priority of service categories in its currently effective tariff, but such categories shall be placed at priorities below the new priorities 1 and 2. Each interstate pipeline shall reduce the entitlements in all other existing categories of service to the extent such entitlements have been placed into the new priority of service categories 1 or 2.
(b) Method of curtailment. All deliveries to all customers of the interstate pipeline for all volumes of natural gas not included in priorities 1 and 2 shall be fully curtailed by the interstate pipeline before priorities 1 and 2 entitlements are curtailed. Deliveries for priority 2 entitlements shall be fully curtailed by the interstate pipelines (in accordance with the currently effective curtailment plan) before priority 1 entitlements are curtailed by the interstate pipelines. Nothing in this paragraph is intended to alter the operation of any “small customer” or “small distributor” exemption or waiver (as defined in an interstate pipeline's currently effective curtailment plan).
(c) Storage - 1) General rule. Interstate pipelines shall classify customer storage injection volumes in the same manner as that used in the currently effective curtailment plan.
(2) Storage sprinkling. Interstate pipelines which classify customer storage injection volumes on the basis of the actual end-use of the natural gas shall recalculate storage injection volumes placed in each priority of service category based upon the index of entitlements to be filed on September 15.
(3) Other treatment of storage. Except as provided in paragraph (c)(2) of this section, no interstate pipeline shall recalculate or reclassify any customer storage injection volumes, and no customer storage injection volumes shall be included as priority 1 or 2 entitlements.