Section 2(6) in Tamil Nadu Municipal (Non-Centralized-Regular) Public Health Establishment Regulations, 1976
(6)Duty. - A person is said to be on duty as a member of the establishment: -(a)when he is performing the duties of a post borne on the establishment or is undergoing the probation,(b)when he is on joining time, or(c)when he is absent from duty during authorized holidays or on casual leave taken in accordance with the instructions regulating such leave issued by the State Government, having been on duty immediately before and immediately after such absence.
