A transmission system operator (TSO) is a stand-alone natural gas or electric transmission company that owns transmission facilities and provides system operation functions. In some cases, they may also facilitate markets though this function is more commonly handled by separate exchanges. The designation is commonly used in Europe and is a defined term under European Union regulations. Gas TSOs provide gas scheduling and operations functions across their transmission pipelines and may also manage gas storage. Electric TSOs provide functions including transmission scheduling, reserves and other ancillary services acquisition, real-time balancing, and system operations across their transmission networks.