1202.03(b) Practices of the Trade 
In determining whether a proposed mark is inherently distinctive, factors to be considered include whether the subject matter is unique or unusual in a particular field, as opposed to a mere refinement of a commonly adopted and well-known form of ornamentation for a particular class of goods that would be viewed by the public as a dress or ornamentation for the goods. See, e.g., In re General Tire & Rubber Co., 404 F.2d 1396, 1398, 160 USPQ 415, 417 (C.C.P.A. 1969) (affirming the ornamentation refusal of a mark comprising three narrow white concentric rings of approximately equal width applied to the outer surface of a dark sidewall tire; mark was a refinement of the practice, which consumers were familiar with, of whitewalls as decoration on tires); In re Chung, Jeanne & Kim Co., 226 USPQ 938, 941-42 (TTAB 1985) (finding that stripe design applied to sides of sport shoes was mere refinement of the common and well-known form of ornamentation in the field of sports shoes).
Even if a proposed mark is not inherently distinctive, it may be registered on the Principal Register if it has become distinctive of the applicant’s goods in commerce. See TMEP §1202.03(d). The practices of the trade may be relevant in assessing the applicant’s burden of proving that the proposed mark has become distinctive. Typically, more evidence is required if the proposed mark is a type of ornamental matter used so frequently in the relevant industry that consumers would be less apt to discern a source-indicating significance from its use. See Anchor Hocking Glass Corp. v. Corning Glass Works, 162 USPQ 288, 292-99 (TTAB 1969) (extensive evidence of record supported that cornflower design was recognized as a trademark for coffee percolators, culinary vessels, and utensils). Cf. In re Villeroy & Boch S.A.R.L., 5 USPQ2d 1451, 1454 (TTAB 1987) (affirming refusal to register design of morning glories and leaves for tableware, the Board noting that the design "has not been shown to be other than another decorative pattern without trademark significance . . . .").
If the applicant cannot show that the proposed mark has acquired distinctiveness, the mark in an application under §1 or §44 of the Trademark Act may be registered on the Supplemental Register if it is capable of distinguishing the applicant’s goods or services. 15 U.S.C. §1091. The practices of the trade may be relevant in determining whether a proposed mark is capable of distinguishing the goods or services. If the practices of the trade suggest that certain matter performs the function of a trademark by signifying to purchasers and prospective purchasers the goods of a particular entity and distinguishing them from the goods of others, the matter is assumed to be capable of distinguishing the applicant’s goods and, therefore, may be registered on the Supplemental Register. See In re Todd Co., 290 F.2d 597, 599-600, 129 USPQ 408, 410 (C.C.P.A. 1961) (holding that repeating pattern of green lines, used to cover the entire back surface of safety paper products (e.g., checks), was registrable on the Supplemental Register for safety paper products, where the record showed that it had long been the practice in the industry to use distinctive overall surface designs to indicate origin of the products).