Two instruments do the work. The Electronically Transmitted Postal Ballot System (ETPBS), built by C-DAC as a two-tier system, serves service voters — military, paramilitary and diplomats. Separately, the Conduct of Election Rules, 1961 were amended to create the "absentee voter" category: those on duty in aviation, shipping, railways and emergency services, journalists covering the poll, senior citizens and persons with disabilities. Eligibility is notified by the Government in consultation with the Election Commission, but the operational decision — which categories may use it in a given poll — rests with the ECI.