(a) Except for size and color, the square background required by §172.510(a) for certain placards on rail cars, and §172.507 for placards on motor vehicles containing a package of highway route controlled quantity radioactive materials, must be as follows:

(b) In addition to meeting the requirements of §172.519 for minimum durability and strength, the square background must consist of a white square measuring 141⁄4 inches (362.0 mm.) on each side surrounded by a black border extending to 151⁄4 inches (387.0 mm.) on each side.

[Amdt. 172-29, 41 FR 15996, Apr. 15, 1976, as amended by Amdt. 172-64, 46 FR 5316, Jan. 19, 1981; Amdt. 172-78, 48 FR 10226, Mar. 10, 1983]