A nurse who is assigned to be “in charge” of a unit at SMMC, outpatient clinics, or the Jail for four (4) or more hours of a shift shall be paid an additional thirty dollars ($30.00) for that shift provided that no more than one nurse is assigned “in charge” of each unit for each shift. For RN’s who have regularly been assigned as a “charge nurse” for thirty (30) days or more immediately before a paid holiday, sick leave or the start of a vacation, the applicable additional pay shall be included in the RN’s holiday or vacation pay.