Section 16(1)(d) in The Punjab School Education Board Leave Regulations
(d)Save in the case of leave preparatory to retirement "leave not due" may be granted to an employee in permanent employ for a period not exceeding 360 days during his entire service out of which not more than 90 days at a time and 180 days in all, may be otherwise than on medical certificate. Such leave will be debited against the half pay leave the employee may earn subsequently.