The Commission proposed to direct that the North American Electric Reliability Corporation, the Commission-certified Electric Reliability Organization, submit to the Commission modifications to Reliability Standard TPL-001-5.1 (Transmission System Planning Performance Requirements) within one year of the effective date of a final rule in this proceeding to address reliability concerns pertaining to transmission system planning for extreme heat and cold weather events that impact the reliable operations of the Bulk-Power System. Specifically, we proposed to direct NERC to develop modifications to Reliability Standard TPL-001-5.1 to require: development of benchmark planning cases based on information such as major prior extreme heat and cold weather events or future meteorological projections; planning for extreme heat and cold events using steady state and transient stability analyses expanded to cover a range of extreme weather scenarios including the expected resource mix’s availability during extreme weather conditions, and including the broad area impacts of extreme weather; and corrective action plans that include mitigation for any instances where performance requirements for extreme heat and cold events are not met (Docket No. RM22-10-000).