All officers and employees of the state of Idaho who shall be members of the national guard or who shall be reservists in the armed forces of the United States, shall be entitled each calendar year to one hundred twenty (120) hours of military leave of absence from their respective duties without loss of pay, time, or efficiency rating during which they shall be engaged in military duty ordered or authorized under the provisions of law. State employees assigned to "uncommon tours of duty" shall have the above-referenced one hundred twenty (120) hours of leave prorated proportionally to the number of hours in their regularly scheduled biweekly pay period. Administration of paid leave for "uncommon tours of duty" shall be consistent with the federal office of personnel management (OPM) definitions and pay administration guidance for similarly situated federal employees.