Section 10(4)(a) in The Orissa Grama Panchayats Act, 1964
(a)The wards in which the density of population of the Scheduled Castes and the Scheduled Tribes is higher in the Grama shall be reserved by the Collector for the Scheduled Castes and the Scheduled Tribes, respectively and shall rotate in the descending order at every general election [and in case of backward class of citizens such reservation and rotation shall be in the prescribed manner.]