52 Pa. Code § 69.14
An NGDC should, in addition to performing any other roles such as selling natural gas, function as the system operator in ensuring that its distribution system is designed, constructed, managed and operated to safely and reliably receive and deliver natural gas throughout its facilities to customers connected to them. An NGDC, in performing its responsibilities as a system operator, may retain or acquire gas supply assets as required to perform its system operator functions in a manner which permits it to operate its system in a safe and reliable manner. The identity of the gas supply assets utilized by the NGDC to perform its system operator function should be reviewed by the Commission annually in the NGDC's Section 1307(f) proceeding as part of the NGDC's reliability plan.
52 Pa. Code § 69.14
This section cited in 52 Pa. Code § 69.11 (relating to definitions); and 52 Pa. Code § 69.19 (relating to operational and capacity councils).