Grade means any one of the officially established grades of potatoes, and size means any one of the officially established sizes of potatoes, as defined and set forth in:
(a)
The United States Standards for Potatoes issued by the United States Department of Agriculture ( §§ 51.1540 to 51.1556 of this title), or amendments thereto, or modifications thereof, or variations based thereon;
(b)
The United States Consumer Standards for Potatoes as issued by the United States Department of Agriculture ( §§ 51.1575 to 51.1587 of this title), or amendments thereto, or modifications thereof, or variations based thereon; or
(c)
Standards for potatoes issued by the State from which the potatoes are shipped, or amendments thereto, or modifications thereof, or variations based thereon.