*** SPECIAL STUDIES & BACKSTOPPING - ENGINEERING SERVICES *** In addition to the field staff, a group of specialists at ITU headquarters is responsible for giving high-level advice and rendering short-term assistance to Member States upon request. These specialists work in areas such as demand forecasting, network planning, traffic engineering, transmission systems, radio and satellite communications, broadcasting, frequency management, cable networks, maritime mobile communications, as well as in the areas of restructuring and telecommunications policy. This form of support may be provided either by short missions (not exceeding four weeks) to the requesting Member States or by correspondence, depending on the type of assistance required. The related activities may be undertaken either by BDT specialists based at ITU headquarters, or by outside experts if the required speciality cannot be covered by headquarters staff.. Examples of engineering services include advice on the planning of telecommunication networks, preparation of specifications, evaluation of bids, operational aspects, and studies and analyses of existing systems and facilities, including the financial and economic aspects. If required, the engineers may also participate in meetings, conferences or seminars on specific technical subjects. These services are normally provided free of charge to the requesting Member administrations and have no effect on UNDP country allocations. Requests may be submitted to the BDT by letter, telex or telefax, with details of the type of assistance required. The BDT specialists are also available for consultation by the staff of administrations visiting ITU headquarters for conferences, meetings, etc.