Section 122(11) in The Naval Ceremonial, Conditions Of Service And Miscellaneous Regulations, 1964
(11)Confirmation. - On completion of their probationary period, provided their progress and conduct have been satisfactory, officer entered as Lieutenant, shall be confirmed as such with their original seniority. Acting Sub-Lieutenants, on completion of their probationary period, provided they have passed the examination referred to in sub-regulation (10) and their progress and conduct have been satisfactory, shall be confirmed in the rank of Sub-Lieutenant, with their original seniority.