hello, do you want to ask which patents in the United States can be retrieved from the appft sub-library of the U.S. patent and trademark office? The appft sub-database of the US Patent and Trademark Office can retrieve American invention patents, appearance patents, plant patents and so on. Appft sub-library, as the database of patent applications published by the US Patent and Trademark Office, can query many patents including invention patents, appearance patents and plant patents. Just open the AppFT page and use the confirmed CPC classification to search in the authorization database. The word patent comes from Latin Litteraepatentes, which means open letters or public documents. It is a certificate used by medieval monarchs to issue certain privileges, and later refers to the exclusive right certificate signed by the British king himself.