An application for a patent for design shall be limited to one design. However, two or more similar designs of the same product, or two or more designs for products sold in sets or used in the same category, may be filed as one application. The so-called two or more designs of products sold or used in the same category or set means that all products belong to the same category in the classification table and are customarily sold or used at the same time, and all products have the same design concept. Where multiple similar designs of the same product are filed as one application, the other designs of the product shall be similar to the basic design in the brief description. There are no more than ten similar designs in an application for a patent for design. Where two or more designs are filed as one application, the serial number of each design shall be marked before the name of each picture or photograph of each design product.