Ceremonial Days - Substitution. All indigenous Australian employees shall, in substitution for a public holiday specified within this clause, be entitled to the National Aboriginal Day of Celebration as a Public Holiday without loss of pay on the day it is celebrated in the State in which the employee is employed. Provided that by mutual agreement in lieu of this day being taken as a substituted public holiday it may be taken as an annual leave day or may be taken out of accumulated time in lieu accrual.