All leaves, except military leave, shall be from a date certain to a date certain; however, any leave may be extended to a later specified date upon written request from the teacher. The procedure for extending a leave and the conditions under which a leave may be extended are the same as those used when originally requesting and granting the leave. Military leave and leave to hold legislative office shall be granted for whatever period may be required. Leave to visit a spouse, child or parent deployed for military duty out of the country who has been granted rest and recuperation leave shall be granted for no longer than ten (10) days.
T.C.A. § 49-5-704