 Major additions to the RNTCP, over and above the structures established under the NTP, was the establishment of a sub-district supervisory unit, known as a TB Unit, with dedicated RNTCP supervisors posted, and decentralization of both diagnostic and treatment services, with treatment given under the support of DOT (directly observed treatment) providers.Large-scale implementation of the RNTCP began in late 1998.Expansion of the programme was undertaken in a phased manner with rigid appraisals of the districts prior to starting service delivery.