Person in charge of planning the expansion, investments, operation and maintenance of all or part of a Regional Transmission System or Local Distribution System, including its connections to the National Transmission System. The assets may be self-owned or third-party owned. For all purposes, they are the companies that have Regional Transmission System or Local Distribution System Usage Charges approved by CREG. The Grid Operator must always be a residential public utilities company. The minimum unit of a Local Distribution System or Regional Transmission System to request Usage Charges corresponds to a Municipality. (Source: R.CREG – 097- 2008. Art 1)