Nothing in this Subdivision shall preclude an employer from applying different standards of compensation, or different terms, conditions, and privileges of employment, which are pursuant to a merit system or seniority system, or pursuant to the provisions of Section 6(d) of the Fair Labor Standards Act (29 U.S.C. 206(d)), or a system of employment which measures earnings by quality or quantity of production, or which provides the aforesaid different standards of compensation, terms, conditions, and privileges of employment, based upon at different locations, provided that the aforesaid different standards of compensation, terms, conditions, and privileges of employment are not established for the purpose of discrimination.