Wis. Stat. § 341.52

Registration plates for dealers, distributors, manufacturers, and transporters are subject to the provisions of s. 341.12 (2) and (3) except s. 341.12 (3) (c). In addition, each plate may have displayed upon it a decal or sticker displaying letters that is approved by the department and that is capable of distinguishing the plate from any other plate which may be issued to the same dealer, distributor, manufacturer, or transporter. If such a decal or sticker is displayed on a plate, the decal or sticker shall be affixed on the right side of the plate directly to the right of, and in line with, the numbers or letters or both composing the registration number required under s. 341.12 (3) (a).