Section 202(4) in The Naval Ceremonial, Conditions Of Service And Miscellaneous Regulations, 1964
(4)Lieutenant-Commander.-(a) The grant of acting rank of Lieutenant-Commander shall be in the nature of a quasi-permanent promotion to this rank. Promotion shall be by selection from among all eligible officers.(b)Promotions shall normally be made half-yearly on the 30th June and the 31st December and shall be effective from those dates.
