Duty exemption certificate requirements revised for defence contractors and defence PSUs; new exempt items added. Amendment prescribes that contractors of Research and Development Laboratories or Establishments under the Ministry of Defence require the duty exemption certificate to be signed by the Chief of Resources, and that Public Sector Undertakings under the Ministry of Defence require the certificate to be signed by the functional Director. The amendment also adds X-ray machines and their components for baggage examination and radio communication test sets to the list of exempted items for defence, police and anti-smuggling uses.