A design patent is definite under 35 U.S.C. § 112 if one skilled in the art, viewing the design as would an ordinary observer, would understand the scope of the design with reasonable certainty 

The United States Patent and Trademark Office (USPTO) rejected a design patent application under 35 U.S.C. § 112 as being indefinite and not enabled. The Patent Trial and Appeal Board (PTAB) affirmed that rejection. The patent applicant appealed the ruling to the Federal Circuit, which reversed the PTAB for misapplying § 112 to design patent claims. 

The design patent application presented a two-dimensional plan-view drawing to claim a design for a shoe bottom. The USPTO and the PTAB rejected the claim as leaving the design open to multiple interpretations regarding the depth and contour of the shoe bottom. The Federal Circuit held that indefiniteness for a design patent turns on whether one skilled in the art, viewing the design as an ordinary observer, would understand the scope of the design with reasonable certainty. So long as the scope is clear with reasonable certainty, a design patent can disclose multiple embodiments within its single claim and use multiple drawings to do so. Here, the ornamental design of the shoe bottom was capable of being disclosed and judged from a two-dimensional view, irrespective of the fact that multiple depths and contours may fall within the scope of the claim.

A copy of the opinion can be found here