Section 272(6) in The Naval Ceremonial, Conditions Of Service And Miscellaneous Regulations, 1964
(6)(a)Ex-Servicemen re-entering after having been absent from the service for more than 3 years (more than 5 years in the case of Reservists) shall not be permitted to count their previous service and shall be treated as new entrants. Sailors re-entering within 3 years (5 years in the case of Reservists) will count their previous qualifying service for all purposes.(b)On re-entry Ex-Servicemen shall be required to sign a fresh engagement either to complete time for pension or to serve for a period of 10 years or up to the age of superannuation of the rate in which re-entered, whichever is least.