Section 125(3)(b) in The Naval Ceremonial, Conditions Of Service And Miscellaneous Regulations, 1964
(b)Acting Sub-Lieutenants. - On completion of [6 months] [Substitued by S.R.O. 237, dated 24th May, 1975] service as Midshipmen and provided they are reported as "Satisfactory" by the Commanding Officer, Indian Naval Ship SHIVAJI, officers shall be promoted to the rank of Acting Sub-Lieutenant with the seniority of the date of promotion.