http://www.legislation.gov.uk/ukpga/2000/38/section/75/enactedTransport Act 2000Local GovernmentKing's Printer of Acts of Parliament2021-08-03 Part IAir trafficChapter IVCharges for air servicesChargesSpecifications: supplementary 75 1 This section applies for the purposes of specifications under section 73(1). 2 The CAA may specify— a different amounts or methods in respect of different descriptions of services; b different amounts or methods in respect of different classes or descriptions of aircraft; c different amounts or methods in respect of different circumstances in which aircraft are used. 3 In specifying amounts or methods the CAA must have regard to— a tariffs which are approved under any international agreement to which the United Kingdom is a party; b tariffs which in the CAA’s opinion are likely to be approved under any such agreement before or within one month after the date when the specifications are to take effect; c tariffs which in the CAA’s opinion are likely to be approved, before or within one month after the date when the specifications are to take effect, under any international agreement to which the United Kingdom is likely to be a party before or within one month after that date. 4 Methods may be expressed by reference to such factors (including exchange rates between currencies) as the CAA thinks fit. 5 A description of services may be expressed by reference to such factors (including the area in respect of which they are provided) as the CAA thinks fit. 6 A description of operators and owners may be so general as to refer to all operators and owners. 7 Owners and operators may be specified (or of a description specified) if the services concerned are available for the aircraft concerned, and it is immaterial whether or not the services are actually used or could be used with the equipment installed in the aircraft.