§ 249. Educational or training leaves of absence. The local director of probation, chief probation officer, or other head of a probation department, bureau or unit, if he is the appointing authority therefor, or otherwise such appointing authority, with the approval of the board of supervisors of the county or the appropriating body of the city having jurisdiction, may grant any probation officer or officers employed therein leave of absence, with or without pay, for attendance at graduate schools located within the state whose programs are registered by the regents to pursue any course of study or training that is of substantial assistance in probation work, or to receive additional training in another probation department, bureau or unit in New York state. The time during which a probation officer is absent, pursuant to such leave, shall not constitute an interruption of continuous employment and such officer shall not be subjected, directly or indirectly, to any loss or diminution of time service, increment, vacation or holiday privileges, or any other right or privilege, by reason of such absence, or be prejudiced, by reason of such absence, with reference to continuance in office or employment, or promotion.