10) interface – an electrical, electronic or optical system, with or without software, which permits interconnection, cooperation and exchange of signals of a given form between equipment connected through this interface according to the relevant technical specification; 11) application programme interface – software which permits connection, cooperation and information exchange between applications provided by broadcasters or service providers and digital television equipment that enables conveyance of digital signals for the provision of television or radio services; 12) radio interface – an interface which permits radio connection, cooperation and information exchange between radio equipment; 13) interoperability of services – the ability of telecommunications networks to effectively cooperate for the purpose of ensuring mutual access for users to services provided within those networks; 14) cost calculation – calculation by a telecommunications undertaking of costs related to the provision of services, separately for each service for which the undertaking is obliged to calculate costs, according to the cost calculation description approved for a given financial year by the President of the Office of Electronic Communications, hereinafter referred to as the President of UKE; 15) collocation – granting physical space or technical equipment in order to place and connect equipment necessary for an operator connecting its network to another operator’s network or using access to the local loop; 16) (deleted); 17) communication – any information exchanged or transmitted between specific users by means of publicly available telecommunications services; this does not include information transmitted as part of radio or television transmissions broadcast by a telecommunications network, excluding information related to an identifiable subscriber or to the user receiving the information; 18) consumer – any natural person who requests or uses publicly available telecommunications services for purposes outside his/her trade, business or profession; 19) local loop – a physical circuit connecting a network termination point directly to an access point of the public fixed telecommunications network, in particular to its main distribution frame or an equivalent device; 20) local sub-loop – a partial local loop connecting a network termination point to an intermediate access point of the public fixed telecommunications network, in particular to its concentrator or another device for indirect access to the public fixed telecommunications network; 20a) multiplex – combined stream of digital data, consisting of two or more streams made of data being part of radio or television content and of additional data, including in particular data related to conditional access systems or additional services; 21) emergency number – a number specified in the Act or in the national numbering plan for public telecommunications networks which is made available to statutory emergency services; 22) geographic number – a number from the national numbering plan where part of its digit structure contains geographic significance used for routing calls to a fixed location of the network termination point; 23) non-geographic number – a number from the national numbering plan which does not contain a digit structure determining geographic significance, in particular public mobile telecommunications network numbers, free phone numbers and premium rate numbers; 23a) digital receiver – a consumer device intended for the reception of digital television transmissions, including at least a tuner (with a high frequency head and demodulator), demultiplexer and decoders for received services as well as a picture display (iDTV) or without a picture display;

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