(a) Where fur products, or fur mats and plates, are composed in whole or in substantial part of paws, tails, bellies, gills, ears, throats, heads, scrap pieces, or waste fur, such fact shall be disclosed as a part of the required information in labeling, invoicing, and advertising. Where a fur product is made of the backs of skins, such fact may be set out in labels, invoices, and advertising.

(b) Where fur products, or fur mats and plates, are composed wholly or substantially of two or more of the parts set out in paragraph (a) of this section or one or more of such parts and other fur, disclosure in respect thereto shall be made by naming such parts or other fur in order of predominance by surface area.

(c) The terms substantial part and substantially mean ten per centum (10 percent) or more in surface area.

(d) The term assembled shall not be used in lieu of the terms set forth in paragraph (a) of this section to describe fur products or fur mats and plates composed of such parts.