An interstate natural gas pipeline that transports under part 284 of this chapter may include in its tariff a charge, not related to facilities, for standing ready to supply gas to sales customers in accordance with the following principles:
(a) The pipeline may not recover take-or-pay or similar charges from suppliers by any other means.
(b) The pipeline must allow its sales customers to nominate levels of service freely within their firm sales entitlements or otherwise employ a mechanism for the renegotiation of levels of service at regular intervals.
(c) The pipeline must announce prior to nominations by the customers a firm price or pricing formula for the service, and hold that price or pricing formula firm during the interval arranged in paragraph (b) of this section.
(d) By nominating a new level of service lower than its current level, a customer has consented to any abandonment sought by the pipeline commensurate with the difference between the current level of service and the nominated level.