between control centres the IEC developed the IEC 60870 set of standards. Inter-Control Center Communications Protocol The Inter-Control Center Communications Protocol (ICCP or IEC 60870-6/TASE.2) is being specified by utility organizations throughout the world to provide data exchange over wide area networks (WANs) between utility control centers, utilities, power pools, regional control centers, and Non-Utility Generators. ICCP is also an international standard: International Electrotechnical Commission (IEC) Telecontrol Application Service Element 2 (TASE.2). Background Inter-utility real time data exchange has become critical to the operation of interconnected systems in most parts of the world. For example, the development of electricity markets has seen the management of electricity networks by a functional hierarchy that is split across boundaries of commercial entities. At the top level there is typically a system operator with coordination responsibilities for dispatch and overall system security. Below this are regional transmission companies that tie together distribution companies and generating companies. In continental power systems there is now considerable interconnection across international borders. ICCP allows the exchange of real time and historical power system information including status and control data, measured values, scheduling data, energy accounting data and operator messages. Historically there has been reliance on custom or proprietary links and protocols to exchange real time data between systems. ICCP began as an effort to develop an international standard for real-time data exchange within the electric power utility industry. A working group was formed in 1991 to develop a protocol standard, develop a prototype to test the specification, submit the specification to the IEC for standardisation and carry out interoperability testing between developing vendors. The initial driver was to meet European Common Market requirements in 1992. The official designation of the first protocol was TASE.1 (Telecontrol Application Service Element-1). The second protocol TASE.2 making use of the Manufacturing Message Specification (MMS) appears to be the version that has become the most popular. In the US, ICCP networks are widely used to tie together groups of utility companies, typically a regional system operator with transmission utilities, distribution utilities and generators. Regional operators may also be connected together to co-ordinate import and export of power between regions across major inter-ties. ICCP Functionality Basic ICCP functionality is specified as “Conformance Blocks” listed below. The objects that are used to convey the data are defined in various parts of IEC 60870-6. Block Description Data Examples: Periodic System Data: Status points, analogue points, quality