The Generic Product Identifier (GPI) is a 14-character hierarchical classification system created by Wolters Kluwer's Medi-Span that identifies drugs from their primary therapeutic use down to the unique interchangeable product regardless of manufacturer or package size. The code consists of seven subsets, each providing increasingly more specific information about a drug available with a prescription in the United States. The GPI is created and maintained by UpToDate, Inc a Wolters Kluwer Company.