as ISO's assume control of transmission systems and consolidate their related OASIS functions. OASIS impacts After the doors opened to allow power marketers to move their electricity purchases across multiple transmission systems, many transmission operators saw their transmission systems loaded to much higher levels. Even though transmission services are generally obtained "point-to-point", in actuality power flows divide among numerous paths according to the properties of electricity and thus the actual energy flows follow the path of least resistance—actually the flows are based on the relative (not least) inverse of the resistances in parallel circuits. A result of the long distance electricity transactions being scheduled was the impact of "loop flows" caused by energy flowing on these alternate paths. Transmission system operators were faced with a dilemma: The problems were often being caused by external influences, and the only way available to them to reduce the stress on the transmission system was to curtail their own transmission sales. This resulted in a loss of revenue and still did not always solve the overloading problems. The North American Electric Reliability Corporation (NERC) stepped in to address this new problem that threatened the North American power grid by introducing the NERC Tagging application. NERC Tags captured entire transactions from beginning to end. This let them string together all the transmission legs obtained on various OASIS nodes, and then determine how the total schedule impacted transmission systems, and what priorities of transmission were used in the schedule. This let them determine which schedules should be curtailed to relieve loading on transmission systems. NERC also assumed initial control of the Transmission System Information Networks (TSIN), a database of electric power system data. In 2012 the North American Energy Standards Board (NAESB), an industry council, assumed responsibility for TSIN. It is now the "OATI Web Registry" and requires that users be registered. The registry is a web-based database containing a comprehensive listing of generation points, transmission facilities and delivery points as well as transmission and generation priority definitions with regard to the applications that use it (the various OASIS nodes as well as the NERC Tagging application). See also United States energy ISO RTO Independent system operator (ISO) Regional transmission organization (RTO) Transmission system operator (TSO) References External links North American Energy Standards Board OATI Web Registry Login Interface Electric power transmission systems Electric power distribution United States Department of Energy