ISO 999
ISO standard / From Wikipedia, the free encyclopedia
ISO 999 (Information and documentation—Guidelines for the content, organization and presentation of indexes) is an ISO standard which provides the information industry with guidelines for the content, organisation and presentation of indexes to a wide range of documents including books, Periodicals, electronic documents, films, images, maps, and three-dimensional objects.[1] It covers the choice and form of headings and subheadings used in index entries once the subjects to be indexed have been determined.