Formal review _ also known as "preliminary review" and "substantive review" symmetry. Examining the formal conditions of patent applications. China's patent examination system also includes formal examination. When accepting a patent application, the Patent Office first examines whether the patent application documents meet the requirements. Formal examination _ does not involve the substantive conditions of the invention, but it is necessary to examine whether the invention-creation for which a patent is applied involves national security, whether it needs to be kept confidential, whether it violates laws, social ethics and public interests, and whether the patent right is not granted. After the preliminary examination, there will be the following three results: (1) determine the application date and give the application number; (2) inadmissible; (3) correction.

Image trace is a trace left on the bearing object, which can reflect the external structure of the contact part of the modeling object. For example, a fingerprint reflecting the pattern of the mastoid line of the palm; Footprints reflecting the mastoid pattern of the sole or the image characteristics of the sole pattern; Tool marks reflecting the image characteristics of tools and instruments. According to whether the receiver itself has changed convexly or concavely, it can be divided into three-dimensional mark and plane mark. According to whether the contact surface between the molded body and the receiver slides relatively, it can be divided into static traces and dynamic traces, and according to whether the change of the receiver surface is inside or outside the contact surface, it can be divided into internal traces and external traces. It can be used to judge the types of plastic corpses, make the same identification, and provide clues and basis for analyzing and judging the nature of the case, the time and place of committing crimes, the means and process of committing crimes, and the personal characteristics of criminals.