Section 20(6) in The Indian Postal Service (Group 'A') Rules, 1987
(6)Senior Deputy Director General/Chief Postmaster General. - appointment to the Senior Deputy Director General/Chief Postmaster General shall be made on the basis of selection on merit from amongst officers of Senor Administrative Grade of the service with three years regular service in the grade.[(6A) Principal Chief Postmaster General. - Appointment to the post of Principal Chief Postmaster General shall be made on the basis of selection on merit from amongst Senior Deputy General/Chief Postmaster General holding posts on regular basis in the grade.][(7) Members of the Postal Service Board. - Appointment to the post of Member, Postal Services Board shall be made by selection by merit from amongst officers holding posts on regular basis in the grades of Principal Chief Postmaster General, Senior Deputy Director General and Chief Post Master General.] [Inserted by Notification No. G.S.R. 761(E), dated 8.11.1999][(8) Where juniors who have completed their qualifying/eligibility service are being considered for promotion, their seniors would also be considered provided they are not short of the requisite qualifying/eligibility service by mores than half of such qualifying/eligibility service or two years, whichever is less and have successfully completed their probation period for promotion to the next higher grade along with their juniors who have already completed such qualifying/eligibility service.] [Substituted by Notification No. G.S.R. 185(E), dated 18.3.1997]
