18 C.F.R. § 39.1
As used in this part:
Bulk-Power System means facilities and control systems necessary for operating an interconnected electric energy transmission network (or any portion thereof), and electric energy from generating facilities needed to maintain transmission system reliability. The term does not include facilities used in the local distribution of electric energy.
Cross-Border Regional Entity means a Regional Entity that encompasses a part of the United States and a part of Canada or Mexico.
Cybersecurity Incident means a malicious act or suspicious event that disrupts, or was an attempt to disrupt, the operation of those programmable electronic devices and communications networks including hardware, software and data that are essential to the Reliable Operation of the Bulk-Power System.
Electric Reliability Organization or "ERO" means the organization certified by the Commission under § 39.3 the purpose of which is to establish and enforce Reliability Standards for the Bulk-Power System, subject to Commission review.
Electric Reliability Organization Rule means, for purposes of this part, the bylaws, a rule of procedure or other organizational rule or protocol of the Electric Reliability Organization.
Interconnection means a geographic area in which the operation of Bulk-Power System components is synchronized such that the failure of one or more of such components may adversely affect the ability of the operators of other components within the system to maintain Reliable Operation of the facilities within their control.
Regional Advisory Body means an entity established upon petition to the Commission pursuant to section 215(j) of the Federal Power Act that is organized to advise the Electric Reliability Organization, a Regional Entity, or the Commission regarding certain matters in accordance with § 39.13 .
Regional Entity means an entity having enforcement authority pursuant to § 39.8 .
Regional Entity Rule means, for purposes of this part, the bylaws, a rule of procedure or other organizational rule or protocol of a Regional Entity.
Reliability Standard means a requirement approved by the Commission under section 215 of the Federal Power Act, to provide for Reliable Operation of the Bulk-Power System. The term includes requirements for the operation of existing Bulk-Power System facilities, including cybersecurity protection, and the design of planned additions or modifications to such facilities to the extent necessary to provide for Reliable Operation of the Bulk-Power System, but the term does not include any requirement to enlarge such facilities or to construct new transmission capacity or generation capacity.
Reliable Operation means operating the elements of the Bulk-Power System within equipment and electric system thermal, voltage, and stability limits so that instability, uncontrolled separation, or cascading failures of such system will not occur as a result of a sudden disturbance, including a Cybersecurity Incident, or unanticipated failure of system elements.
Transmission Organization means a regional transmission organization, independent system operator, independent transmission provider, or other transmission organization finally approved by the Commission for the operation of transmission facilities.
18 C.F.R. §39.1