ancillary service — a service necessary for the operation of a transmission or distribution system 17.

control — rights, contracts or any other means which, either separately or in combination and having regard to the considerations of fact or law involved, confer the possibility of exercising decisive influence on an undertaking, in particular by: ownership or the right to use all or part of the assets of an undertaking; rights or contracts which confer decisive influence on the composition, voting or decisions of the organs of an undertaking 34.

customer — a wholesale or final customer of electricity 7.

direct line — either an electricity line linking an isolated generation site with an isolated customer or an electricity line linking an electricity producer and an electricity supply undertaking to supply directly their own premises, subsidiaries and eligible customers 15.

distributed generation — generation plants connected to the distribution system 31.

distribution — the transport of electricity on high-voltage, medium-voltage and low-voltage distribution systems with a view to its delivery to customers, but does not include supply 5.

distribution system operator — a natural or legal person responsible for operating, ensuring the maintenance of and, if necessary, developing the distribution system in a given area and, where applicable, its interconnections with other systems and for ensuring the long-term ability of the system to meet reasonable demands for the distribution of electricity 6.

economic precedence — the ranking of sources of electricity supply in accordance with economic criteria 16.

electricity derivative — a financial instrument specified in points 5, 6 or 7 of Section C of Annex I to Directive 2004/39/EC of the European Parliament and of the Council of 21 April 2004 on markets in financial instruments OJ L 145, 30.4.2004, p. 1. , where that instrument relates to electricity 33.

electricity supply contract — a contract for the supply of electricity, but does not include an electricity derivative 32.

electricity undertaking — any natural or legal person carrying out at least one of the following functions: generation, transmission, distribution, supply, or purchase of electricity, which is responsible for the commercial, technical or maintenance tasks related to those functions, but does not include final customers 35.

eligible customer — a customer who is free to purchase electricity from the supplier of his choice within the meaning of Article 33 12.

energy efficiency/demand-side management — a global or integrated approach aimed at influencing the amount and timing of electricity consumption in order to reduce primary energy consumption and peak loads by giving precedence to investments in energy efficiency measures, or other measures, such as interruptible supply contracts, over investments to increase generation capacity, if the former are the most effective and economical option, taking into account the positive environmental impact of reduced energy consumption and the security of supply and distribution cost aspects related to it 29.

final customer — a customer purchasing electricity for his own use 9.

generation — the production of electricity 1.

horizontally integrated undertaking — an undertaking performing at least one of the functions of generation for sale, or transmission, or distribution, or supply of electricity, and another non-electricity activity 23.

household customer — a customer purchasing electricity for his own household consumption, excluding commercial or professional activities 10.

integrated electricity undertaking — a vertically or horizontally integrated undertaking 20.

interconnected system — a number of transmission and distribution systems linked together by means of one or more interconnectors 14.

interconnector — equipment used to link electricity systems 13.

long-term planning — the planning of the need for investment in generation and transmission and distribution capacity on a long-term basis, with a view to meeting the demand of the system for electricity and securing supplies to customers 25.

micro isolated system — any system with consumption less than 500 GWh in the year 1996, where there is no connection with other systems 27.

non-household customer — a natural or legal persons purchasing electricity which is not for their own household use and includes producers and wholesale customers 11.

producer — a natural or legal person generating electricity 2.

related undertaking — affiliated undertakings, within the meaning of Article 41 of the Seventh Council Directive 83/349/EEC of 13 June 1983 based on Article 44(2)(g) The title of Directive 83/349/EEC has been adjusted to take account of the renumbering of the Articles of the Treaty establishing the European Community in accordance with Article 12 of the Treaty of Amsterdam; the original reference was to Article 54(3)(g). of the Treaty on consolidated accounts OJ L 193, 18.7.1983, p. 1. , and/or associated undertakings, within the meaning of Article 33(1) of that Directive, and/or undertakings which belong to the same shareholders 22.

renewable energy sources — renewable non-fossil energy sources (wind, solar, geothermal, wave, tidal, hydropower, biomass, landfill gas, sewage treatment plant gas and biogases) 30.

security — both security of supply and provision of electricity, and technical safety 28.

small isolated system — any system with consumption of less than 3000 GWh in the year 1996, where less than 5 % of annual consumption is obtained through interconnection with other systems 26.

supply — the sale, including resale, of electricity to customers 19.

system user — a natural or legal person supplying to, or being supplied by, a transmission or distribution system 18.

tendering procedure — the procedure through which planned additional requirements and replacement capacity are covered by supplies from new or existing generating capacity 24.

transmission — the transport of electricity on the extra high-voltage and high-voltage interconnected system with a view to its delivery to final customers or to distributors, but does not include supply 3.

transmission system operator — a natural or legal person responsible for operating, ensuring the maintenance of and, if necessary, developing the transmission system in a given area and, where applicable, its interconnections with other systems, and for ensuring the long-term ability of the system to meet reasonable demands for the transmission of electricity 4.

vertically integrated undertaking — an electricity undertaking or a group of electricity undertakings where the same person or the same persons are entitled, directly or indirectly, to exercise control, and where the undertaking or group of undertakings perform at least one of the functions of transmission or distribution, and at least one of the functions of generation or supply of electricity 21.

wholesale customer — a natural or legal person purchasing electricity for the purpose of resale inside or outside the system where he is established 8.