Section 17(5) in The Indian Postal Service (Group 'A') Rules, 1987
(5)Notwithstanding anything contained in sub-rules (3) and (1) no vacancies reserved for the Scheduled Castes or the Scheduled Tribes shall be carried forward to any year of the examination.(a)to such an extent that the total number of vacancies so carried forward together with the vacancies reserved for candidates who are members of the scheduled castes and Scheduled Tribes for that year exceeds 560% of the total vacancies in that year, or(b)if such vacancies, which are to be carried forward, continuously remained unfilled for a period of three recruitment years,Provided that in the third recruitment year vacancies reserved for the Scheduled Castes and the Scheduled Tribes shall be filled by the Scheduled Tribes and the Scheduled Castes respectively, if candidates of respective communities are not available.
