In continuation of the discussion, I would like to add further as follows:
Leave as a welfare benefit
Leave is a welfare benefit extended to employees under establishment-specific labor legislation. The types and the number of such leave vary according to the type of the establishment. For instance, the workers of a factory under the Factories Act, 1948, are entitled to only one type of statutory leave called Annual Leave with Wages. No statutory provisions for other kinds of leave like casual leave, sick leave, etc., exist because of the shift working pattern and the mandatory seventh-day off following six days of work.
Leave under the Shops and Establishments Acts
Under the Shops and Establishments Acts, employees are entitled to three kinds of leave, namely Casual Leave, Sick Leave, and Privilege Leave. However, some factory managements grant Casual Leave to their workers either as per the Standing Orders or under collective bargaining agreements. Therefore, what a statute prescribes is only the minimum, and it is up to the employers to decide, either on their own or through collective bargaining, the granting of any extra leave or leave in excess of the statutory minimum.
Leave policy considerations
Regarding the aspect of leave availing, such as the combining of various types of leave at a stretch, pro-rata sanction to employees of certain statuses like probationers, FTC employees, the facility of encashment above the statutory provisions, etc., these matters should be included in the Leave Policy of the individual organization.