Dewey-free (also Dewey free, Dewey-less, or word-based) refers to library classification schemes developed as alternatives to Dewey Decimal Classification (DDC). Dewey-free systems are often based on the subject headings developed by the Book Industry Study Group, and are typically implemented in libraries with smaller collections. Instead of using numerical notation to indicate a document's shelving location, Dewey-free systems organize documents alphabetically by natural language words. Dewey-free systems have been implemented in both public and school libraries.