With respect to each employee of a retail or service establishment exempt from the overtime pay requirements of the Act pursuant to the provisions of section 7(i), employers shall maintain and preserve payroll and other records containing all the information and data required by § 516.2(a) except paragraphs (a) (6), (8), (9), and (11), and in addition: (a) A symbol, letter or other notation placed on the payroll records identifying each employee who is paid pursuant to section 7(i). (b) A copy of
(a) Where the employer's business operations are conducted in more than one establishment, as in the various units of a chain-store system or where branch establishments are operated in conjunction with a main store, the employer is entitled to exemption under section 13(a)(2) or (4) for those of his employees in such business operations, and those only, who are "employed by" an establishment which qualifies for exemption under the statutory tests. For example, the central office or central warehouse