tion to ing to a service with primary status, regardless of the dates of manage the assignment of spectrum in the various bands are re- viewed in Section 26.4 below. registration of the assignments, and station S has no remedy if station P interferes with its signals. Amendments to the international table of frequency allocations If safety considerations do not arise, if there is no internationally and the Radio Regulations are discussed and agreed at World Ad- agreed plan, and if the radio services to which the stations involved ministrative Radio Conferences of the ITU. belong are the same, or have equal allocation status in the frequency band, the operating organisations involved, assisted if necessary by their administrations, determine together what could be done to 26.3.2 Allocations for industrial, scientific and eliminate the interference. This may involve modifying one or other mqedical applications. of the stations or modifying the emissions. As a last resort, it is customary for the opportunity to use the frequency without inter- Not all generators of radio frequency energy are radio systems. ference to be conceded to the station with the earlier date of Some industries use high frequency power, for example, for the heat registration in the MIFR but administrations are not committed to treatment of metals and for drying and welding non-metallic ma- doing this. terials. Some scientific machines, most notably sub-atomic particle accelerators, use radio frequency energy on a massive scale. Some apparatus used in medical diagnosis and treatment also uses radio International frequency allocation frequency energy. Domestic and commercial microwave ovens are everywhere. All of these devices radiate some energy inadvertently. 26.3.1 Allocations for radio systems Similarly there is substantial radio frequency radiation from electri- cal power transmission plant, electrical traction systems and above In the early years of radio, only the lowest few megahertz of the all from petrol driven motor vehicles. radio sp